Trans-Fi Audio

Home of the Terminator Tonearm

Journey to No-Baffle Speaker System (and back)

My obsession with speakers took over my hifi life, and I am here to report on my journey where I think I may be at the end......after 15 years  




It all started when a client of mine sent me a picture of his set up . I noticed some unfinished speakers in the background, and jokingly asked him when was he going to box them in? He told me they were Bastanis and explained the concept of open baffle which was new to me. I ended up buying his old Prometheus baffles.


Like most of you, I went through many speakers in my lifetime......Wharfdale, Leaks, Kefs, Missions, Pioneer, Yamaha etc.........never found something to settle with long term. But I guess that could be applied to most components in my audio chain.

Not sure if I am getting less fussy or smarter, but the last 15 years have really solidified my system. Keeping away from mainstream, concentrating on products from the little guys with a passion for audio. My amplification is from Temple Audio, my turntable front end is my own, and digital is coming from Limetree Streamer + Chord Qutest. This sets the background for my current set up, but I really want to describe my speaker journey.




It wasn’t until I discovered the Bastanis that something psycho-acoustically switched in my brain. I suddenly started to listen to music rather than the hifi.

I contacted Robert Bastani & populated the baffles with appropriate drivers and made them my own:

I remember running them side by side with my Yamaha NS1000M’s and thought they did something special the Yamaha’s didnt do. I guess it was the live musical presentation that attracted me.

Of course, it wasn’t long before I wanted more. I noticed the 12" woofer (active, sealed box, plate amp) would bottom out playing Police......couldn’t live with that, so I upgraded to the Atlas units, 15” sealed woofers, twin widebands and Gemini tweeters!


This was a creative endeavour, so I had to sit down, calculate measurements and draw the baffles. I had to find a CNC guy to make them. Although I have a workshop and could do the work myself, I usually end up chopping bits off myself..........

A couple of years or so later, Bastanis released his Mandala, which retained the Altlas wideband/tweeter baffle, but added dipole bass in the form of an 18” S-frame. Back to the drawing board and the CNC shop and these were born!


You will notice the Bastanis used active bass, and I went from using built in plate amps to separate units, in this case XTZ (black boxes on floor)



Bass from the Dipole was more open & detailed, but there was a few things I didnt like. It was very fussy regarding room placement. I decided to ditch the S-frame and mount the 18” woofer on the baffle. I was also after a new 18” driver, eventually settling on the AE Dipole 18. My ‘Monster’ series of speakers was born.

These retained the Atlas baffle. Construction was also beefed up using 38mm MDF and painted white.

Before you ask, I have a loving understanding wife..........





I quite enjoyed these speakers, but looking at them I wondered if I could compact them & achieve the same..I fiddled with the format  (I was getting good with Microsoft Draw) and came up with the Mini Monster......back to the Prometheus single wideband arrangement.......

These actually worked very well and I didnt miss the extra wideband of the Atlas.





During this period of time, I expanded the permutation of this design with Selenium NEO 15" drivers. These suited the Open Baffle format and gave deep, clean detailed bass (Note: unfortunately no longer made). They were also lighter than dramatically heavy AE 18's!







My main issue now concentrated on the Gemini tweeter. I was noticing a lot of sibilance on some recordings, and originally I put it down to the recording. It was about this time I was helping my buddy build a set of Duet baffles for his Hawthornes. When they were completed I was stunned by how smooth they sounded!


.....so back to Draw. I wanted something bigger & better!

...and the Trios were born.




These were huge. The 15” at the top is a dual concentric unit with the tweeter positioned behind the magnet firing through the dustcap. Twin Augie woofers below....these things rocked & were smooth. Also, no need for sub-amp as the Hawthornes came with a Crossover.

I spent 6 months with these but I found myself playing my hifi less and less. Whereas my buddy loved his Duets, I was getting bored with my Trios. They were too smooth and laid back.



It was at this stage I sat down and pondered what direction to head in. I didnt like the Bastani tweeter, but really didnt have the electronic knowledge on how to fix it. I wanted to design my own speaker.....but something simple I could cope with.

Enter Full Range, but not in a box.....in an open baffle. After a lot of research, I settled on the Mark Audio Alpair 12P.  I had no idea how this would turn out....but what the hell......…

My experience from listening to FR speakers in the past was not good. Lack of treble was most noticeable, and the units with whizzer cones sounded brittle to me.



So, the Alpairs have a 500 hour run-in time, and they changed noticeably in the coming weeks. I became more and more impressed as they opened up. I thought to myself ......who needs a tweeter?

Also, before I designed this baffle I took note of what the experts were saying. I could increase my bass efficiency by adding a U baffle at the back.....which I did, and the bass increased. More on that later!









I spent a long time living with this format and exhausted all the permutations:


I did notice the narrower the baffle, the better the imaging, but something still not right.


I happen to listen to a lot of different music, and sometimes the music needs volume......lots of it. These just didnt deliver. Adding volume would cause the FR’s to flap like crazy with their compliant surrounds meant for a box. Actually, I didnt need this compliance as I wasn’t relying on them for bass....I had my woofers. I asked John at Temple Audio if there was a way to restrict the bass frequencies reaching the FR’s. He suggested an 80nF capacitor after the volume control but before the amps would work.

I duly installed this in my amp and the FR’s responded. No more flapping cones and the sound became cleaner with more detail. This was a revelation.



In case any of you are wondering, I am not into crossover design and had always driven the woofers actively  Behringer Ultracurve. Coincidentally around this time, they came out with the iNuke series, a powerful amp that had the Ultracurve built in. Not only that, but it was so simple to program even I could do it. They provided software that ran on my laptop and the amp connected via USB. I could dial in the crossover in real time and achieve perfect integration. After a while, I became quite adept.



I then started thinking about an alternative to the Mark Audio drivers. I wanted a Full Range driver, but without the bass and compliant surround. Scouring the web and different forums I came across a PRV thread which recommended the 5MR450-NDY.

https://www.diyaudio.com/forums/full-range/259293-prv-5mr450-ndy-fast-waw-applications.html

This had the frequency range I wanted, no rubber surround, very high powered & efficient (unlike the Alpairs), Neodybnium magnets and cheap to boot. Great reviews on the forum.....what’s not to like? I ordered a pair, designed a baffle, which I made myself as the CNC shop was draining my resources  , and partnered  with my favourite 15 inchers, the Selenium NEOs.
Now this was more like it. The PRV’s sounded great out of the box. The Seleniums delivered bass and slam. The combination was fast & dynamic.
The PRV's had an uncanny ability to go LOUD very fast!



Still, I was not happy with the baffle design. The U-frame at the back promoted by all the OB gurus to increase bass also increased the room nodes by pressuring the waves. The bass I got from totally open baffles was more consistent and room friendly, although not as extended. I also felt the baffle was colouring the sound and introducing artifacts.







At about this time, I came across these:

Now, you can see where I’m heading........




Inspired by this design I came up with a way of taking the drive units out of the U-frame and mounting them on an open ladder frame, something like this.
A trip to my local Wickes procured the materials. I knocked the frames up pretty quick. The design was cheap, simple and fast....but would it work?






With some trepidation I fired them up...........

OMG. I was stunned. This combination never sounded so detailed and clean. Once I dialled in the crossover I was getting plenty of bass. I immediately thought I would never need to see the CNC guy again!

The next few days I was busy testing. I noticed the woofers dumped a huge amount of energy into the frames. This was being transferred into my wooden floor causing the house to shake . Also, I had mounted the PRV on a sub-baffle, and this was prone to vibrate with a nasty buzz at certain frequencies.












For my next design I thought of eliminating the PRV sub-baffle and also trying to compact the design. I came up with this, doubling up the woofers to save space:
This design was smaller, but still a lot of energy transferred to floor and frame. Vibes were so bad with Kraftwerk I thought the PRV would get torn from its mountings and shoot across the room. I added some braces, but still the design was flawed, altho it sounded great. Eliminating the sub baffle really opened up the imaging, so I was heading in the right direction.











In the next iteration I placed the woofers facing each other, simply because they were easier to mount as previously the rear speaker required longe standoffs to clear the frame. In this configuration, BTW, I had to reverse the polarity on one of the woofers to keep them acoustically in phase:

Also, you may have noticed the Neos have been replaced. Since production of them ceased allegedly because the company was unable to get the ore required to make the magnets thanks to China buying it all up.
Looking for an alternative I decided again to depart from the Open Baffle Guru advice of light, efficient fabric surround woofers and went for heavy, high Xmax inefficient designs, in this case, Dayton 390’s. What the hell....watts are cheap nowadays using the Behringer iNukes. Tell you what.....this was a game changing decision and I have never looked back. I had REAL bass now, with deep slam and a weight behind coming from a combined cone mass of 1.2kg.....I never experienced it in a home environment. But If I thought this was bass.....wait till the end and all will be revealed!










So I was vexed by the amount of vibes being transferred to the floor with this arrangement and the rocking back and forth of the frames with subsonic frequencies I was working on a new design. One of my cycling mates was also a carpenter, and I asked for his help with my next project. I wanted to place the woofers low to the ground, but keep the PRV at ear height. We came up with this simple, T-frame arrangement:



The PRV’s were doubled up (why not) and mounted to a pair of 1” aluminium tubes using cable cleats. Substantial 3 x 3 wood was used for the frame make it strong and rigid. With this arrangement the frame did not move. The twin PRV’s projected better and had more depth. This was the best sounding iteration yet.


Still.....I wanted to simplify the design. Looking the the way the woofers were mounted I reasoned if I could join the woofers together, I could use a simpler frame. This was my next design.....a cradle frame:


Here, the woofers could be bolted together using aluminium stand-offs. This could then be treated as a single unit and be supported by the magnets on a wooden cradle with the PRV’s mounted on longer poles to the base:

I am envisaging this as a DIY project. So far, it still involves wood-working skills. Imagine if you could buy the frame off the shelf at minimal cost. The other issue with this design is the cradle still transmits vibrations to the floor and up the poles to the PRV’s. Could I kill 2 birds with one stone?




In my head I had a design to use metal poles and scaffold fittings. Building scaffolding was too big and bulky, but what if they made something smaller?


A bit of googling and I found exactly what I wanted at



Not only that, they would deliver free & cut to size. I designed a metal cradle using 34mm tubes & fittings. Here was the result, £99 delivered!









Another advantage with this ‘modular’ design was it came apart easy for transportation!


I should point out at this stage that our armchair engineers would say this will not work as there would be too much cancellation to get any meaningful bass. I would welcome any skeptics to come and have a listen, and if they don't hear any meaningful bass, I will pay for their petrol home.

It is true, this is not the most efficient way to get bass. It requires possibly double the number of woofers and power vs putting them in a box. However, there is no way I could go back to a boxed speaker arrangement after hearing dipole bass. No box could match the quality I was getting. The texture, purity and detail of this bass is difficult to describe until you experience it. Not only that, it extends deep with the woofers I have chosen which have a Fs of 19.5Hz. They are also very room friendly with bass distributed evenly throughout the room.....no nulls or nodes.









And fully assembled scaffold speaker:


The woofer assembly was now supported hammock style by a 2mm steel cable and is free to oscillate back and forth. I was concerned it might do this while listening to music, but it doesn’t. I tested with a frequency generator and oscillation does not occur until 5hz.








The effect of this is total isolation from the floor, in fact no vibes can be felt from the frame itself, nor in the poles supporting the PRV’s. This was the best sounding design bass with no reaction with the room or floor, and nothing to interfere with the PRV’s.


Cosmetically, of course, not to everyone's taste. They have an industrial look, but surprisingly my other half approves of the minimalist design. The eyes tend to be drawn to the woofers rather than the frame. Probably even less intrusive in black, but I love them as they are!


Another hifi buddy suggested a further modification to isolate the PRV’s by eliminating the cleats holding to the poles. After several protoypes, I worked out a method to hang the PRV’s using a cable similar to the woofers:


Eliminated one of the poles, joined the PRV’s together with a brass joining plate, and suspended by the top magnet on a cable. Very simple and this resulted in even better imaging and detail.





So I have been living with this system with over a year and got the itch again.............................


I alway wondered what would happen with 4 x 18” woofers rather than 15”? TBH, the way I play the system the woofers are on their limit in my room when producing deep bass, being rated @ 500Watts. The 18’s would take 1000Watts and have similar efficiency. I recently bit the bullet and went for the Dayton UM18’s. They were not cheap at a EU rip-off price of 1500EU vs US price of $1000  

A small frame adaptation allowed me to fit these:

Not sure exactly what I was expecting, but compared to the 15’s the system sounds like its been turbocharged. A huge increase in scale and dynamics with a doubling of everything! The bass can really be pushed now, but surprisingly, it stays in its place without overpowering the mid & highs. There is no muddying, just huge clean controlled bass that really slams with rock, but is also textured and detailed with jazz and acoustic music. I can achieve 110db concert  levels that leave my ears ringing with no signs of strains or distortion in the system.

What have I learned on this journey?

•   No baffle at all sounds best with fewer resonances  and better imaging. Bass is not as extended, but this doesn’t matter for upper frequencies using a bass assisted system.

•   You can get huge bass with no baffle, but you need heavy coned inefficent woofers with a large Xmax, low Fs and high wattage.

It took me 15 years to reach this point and I now feel I can relax and listen to a system that will deliver whatever I am in the mood to listen to. I think I now need to look elsewhere to direct my creativity.

BTW, if anyone is interested in any of the projects I made along the way, please contact me.............
Latest changes include replacement of the older Berhinger iNuke amps with the recently introduced NX series. I plumped for a pair of 6000's with the extra power to compfortably drive the UM's.



I  have been experimenting with finding an alternative to PRVs which are hard to beat with its efficiency and high SPL and are a waste in multiples of 4 in a domestic environment.


Thinking in terms of full range mini-arrays to make up SPL's, there are dozens of low watt drivers out there, which I figured used multiple configurations would make up for inefficiency and SPL.

They are also very cheap. These are what I put together to compare & test.

Faital 3FE's (20W each) cost £85 Blue Aran
8 Faital 4FE's (30W each) cost £145
8 PRVs .......over £800!
I chose Faitals mainly because of their efficiency/smoothness/cost & availability in UK.

My testing has revealed the Faitals to be superb drivers. As a general rule with full rangers, I would say smaller diameter drivers have a smoother and higher top end, compromising the low end. In this case, I am not concerned with low mid end as I am using in combination with the woofers. I have, however, rolled off the low end frequency (200hz) these drivers see to take the stress off them.

In brief they are very smooth with more extended treble than PRV's.
The 20Watt 3 inchers started to smell with high concert level SPL's, but weren't distorting.
The 30Watt 4 inchers handled the SPL no issues, and sounded fuller in the vocal range, but not as extended on top.

I experimented by combining  the 3+4" drivers together & eventually settled on a 334433 arrangement.. This array was superb  handling  concert levels with smoothness & air.....and retained the PRV's speed & dynamics. More testing to follow, but I think I have found a combo that will outperform the PRV's at a cut price!

If anyone is concerned about comb filtering, don't be. There is none!

Latest update (June 2020) is the trial of the Tang Band W8-2145. Experience of whizzer cones in the past put me off, but I decided to re-visit.

Glad I did, as the treble on these is very extended and liquid.


I need to also point out I was persuaded by a friend to buy a DEQX when it appeared second hand on ebay in February. I was dead against having something digital in the chain-line, but my friend said if I didn't like it, he would buy it off me. Well.....wow. It was totally transparent, and even running completely flat it was cleaner & more dynamic than my passive pre......so its staying. Have to admit I have not been brave enough to set it up yet, but I have dabbled with the HPF and eq pages. I am finding now that any speaker can be made to sound great with this powerful tool....and all the characteristics that are uncomfortable to listen to can be tamed.


In short, the PRVs. Faitals & Tang Bang can all be made to sound great with eq, but I am noticing something special with the TB's. Watch this space & will report back once fully run in.




LATEST UPDATE OCTOBER 2020

First let me say, I am well pleased with the UM18 /Behringer combination. This gives me everything I want in the bass department and I have not even thought about a replacement.
The Full Ranger, on the other hand, is something I believe can be improved. So I spent most of the summer living with and testing different units.
I went through these 8" whizzer drivers:

The Tang Band W8-1772 was a more refined version of the 2145 with Neodymium magnets and greater efficiency. This was an impressive unit with a full, sparkly lush treble. However, it needed eq with a rising treble rate and a few peaks that needed controlling.


Around this time, one of my buddies with similar system to mine was waxing lyrical about the EMS Field Coils he had running in his system. I had been curious about this technique so ordered a pair of EMS LB8EX MkII. I also needed to order power supplies to drive the coils.


For sure, once run in, these were the best drivers I ever had in my system. My friend hearing them called them 'immersive'. A good description because they totally immerse you in the music without drawing attention to themselves.






They are large heavy units with same efficiency as the 1772's.

Initially treble was quite hard, but this softened with run-in and became similar to the 1772.


The main thing I noticed with run-in, though, was the lower mid. Running these drivers in a baffless configuration really doesn't do anything for lower mid, and this has to be compensated for by the woofers, but with time I noticed this frequency range getting thicker & thicker, so much so I had to reduce my crossover. This is the first time I have had to do this.....but the EMS were outputting so much lower mid, the sound was getting muddy!


Now, the caveat is I still had to apply some eq to tame the 1-4k frequency range, although much less than the Tang Bangs. I am thinking as these run in they may need less & less eq. My buddy is running them without, although he has a baffle.


This seems to be a characteristic of all these full range whizzer drivers I have tried....maybe because I am not using a baffle, or maybe the synergy with the rest of my system. Either way, I cant really recommend any of these drivers if you cant use eq.


Possibly, the best sounding drivers without eq I have tested so far would be the Faital array.

Which brings me to my next update!


So, this is a total departure for me. I have left the design & acoustics to another designer.....in this case Anthony Gallo. I managed to source a refurbished pair of Strada 2's and incorporate them into my system. 

I fired these up with some trepidation.


Initially I thought I had made a mistake. They sounded really dull & subdued :(  Then I remembered I was running them with eq. I removed the eq & ran them flat....they came to life!


Before I pulled the trigger on these, I read all the reviews I could. All very positive, especially with the imaging they produced. This was the first thing that hit me too....and actually, because the are 'baffle-less' the soundstage is very deep taking place behind the speakers....similar to open baffle.


I can detect no boxiness, and if you knock the metal chassis, it sounds totally solid. There is no crossover inside, only an impedance matching transformer and capacitor. They are efficient @ 90db, have huge dynamics and maintain their integrity at volume.


With 50 hours on them, they are still changing. I notice treble becoming more extended, but also lower mid which is huge, I guess effectively due to the sealed box loading. My crossover now has gone from 275hz to 150hz, and I may have to reduce further.


At some point, I will swap with the EMS's to see how they compare, but at the moment, I am really enjoying the Stadas!


New Update Feb 2021

This latest update and direction my journey is taking me in has been a surprise. After doing the whole Open Baffle no cross-over thing, and having formulated certain beliefs along the way,  am now back into sealed boxes & cross-overs  

Trying to follow the purest path of using a single full range driver with a direct connection of voice coil to amp did not work in this type of box-less, no-baffle configuration. All the FR’s I tried all tended to break up around 1-4k which subconsciously was forcing me away from my rock roots, and into softer more acoustic type of music.

My experience with the Gallos has demonstrated a box can be totally inert.....maybe it needs to be made of metal and a funny shape. At least the Gallos conformed to the no electronic cross-over in the way sapping power & detail from the amp belief as they only used a capacitor to protect the tweeter. The Gallo being a no-baffle design retains and openness that is in keeping with Open Baffle character....so I have not moved away from that.

But now, I have gone for sealed box & full blown crossover. The pain & sacrilege!

Let me explain. Going for a single FR driver I was after a point source. Didn’t work out too well, but using a mid & tweeter in dual concentric arrangement would achieve the same thing. I had lived with the Hawthorne Iris in the past....but it was too laid back for me. Having cut my hi-fi teeth on Kef in the 70’s (didn’t we all?) I kept abreast of their developments and was always curious about their Uni-Q driver. I dismissed them because they used a crossover and came in a box.....but now using the Gallos, I was half way there.

I wanted to try something cheap....just to get a taste. Aware of the Home Theatre pods Kef were famous for, I studied the range.
I homed in on the HTS-3001.....3rd Generation pods from 2006.



The Uni-Q driver was using a Neo magnet, a sophisticated crossover & was 88db efficient. The box was cast aluminium and a funny shape. So, we are in Gallo territory, and down 2db on efficiency. I could pick up a pair of these from eBay for £100.....in hifi terms.....a steal, so I pulled the trigger.





I made a simple right angle bracket and mounted the units to the pole above my UM’s. These things were light....2kg compared to my 6kg Gallos!
I fired them up and adjusted the bass to compensate for the lower efficiency and sat down for a listen. Initial impressions were good. Treble was smooth and extended, detail and dynamics were there.......but....ugh....they were boxy and they had a lower mid characteristic I could only describe as ‘tubby’.
I realised I wasn’t going anywhere with these, so replaced the Gallos. This helped me to re-assess and confirm how good they were!

However.....I am a tinkerer by nature, and don’t give up easy. The 3001 pods were reflex loaded with a long plastic port. What if I turned them into sealed units? I don’t need the bass extension anyway.

So next day, I performed some surgery and split the eggs open. I was pleased with the build quality, Kef went through a lot of trouble to make sure nothing rattled internally and everything was properly sealed. They were a bit stingy with the damping foam though with only a 6” square of that white felty stuff.

Anyway, proceeded with the plan of removing the port and sealing the hole. I am lucky to have a small lath so could easily turn an aluminium plug and used some hot melt glue to seal in place. I then proceeded to line the shell with 2mm car sound proofing panels, stuffed the cavity with some denser foam and sealed the unit back together.
Replaced the modified pods and fired up.

Well.....what can I say. My jaw dropped. The box was gone and so was the tubbiness. The presentation was as clean & clear as the Gallos. Now I could hear the Uni-Q driver unhindered by the colouration of the port. This was certainly something I could live with. The point source imaging was on a par with the Gallos, if not better.

Been living with them for 2 days now. I been throwing everything at them to trip them up. They do scale, volume, hard, soft, rock, jazz......I am totally stunned. I have not had a single inkling to put the Gallos back....and I think I know why:

The Kefs are more musical & immersive than the Gallos which are clinical & analytical in comparison.

I have more listening to do and maybe I will come across a flaw. Need to point out that I restrict the bass frequencies going to all my non-bass drivers. This allows them to play cleaner & louder when they are relieved of bass duties.
Will report back in due time!
Well....the single pod update didnt last long! Even though the single pod gave me SPL level of 105db, I couldnt resist doubling them up!

This has resulted in a 6db gain in efficiency (+3db adding extra driver, +3db halving ohms in parallel). Have had to boost subs to keep up!

Cant get over how good this combination sounds in my setup. Kefs are very musical and integrate flawlessly with subs. Crossing still at 120hz, same as Gallos. 


The twin Kefs  now are much fuller in lower mids than Gallo's were, so some recordings of female vocal can sound a bit 'chesty'. I had to compromise and increase roll-off of the Kefs from 100hz to 200hz. That has nailed it now. Hopefully done with updates for a while & I can sit back to enjoy!





KEF Center channel pod update March 2021

Being so impressed with the HTS3001 Satellites, I decided to invest in a pair of 3001 Center channel pods. Unusually, these were dedicated units.....not just a satellite pod turned on its side.....as is the usual practice!


These pods are larger & heavier that the satellite pods as they need to accommodate a pair of tiny woofers. From what I can gather, these liberate the Uni-Q Driver from bass duties, allegedly producing a sonic midrange advantage. The pod is also a sealed unit....no reflex port.


Internally, the pod is divided into 3 sealed compartments by clever use of the crossover circuit boards. I did beef these up with the usual car dampening material, as well as applying to the inside of the pods. I also inserted more foam.

Auditioning these pods was a revelation. They are voiced slightly differently from the satellite pods. Immediately obvious was more emphasis in upper treble seemingly giving more detail. There was also none of the 'tubby-ness' associated with the satellites.....presumably because this is a sealed unit.


The other thing I notice is more lower mid/upper bass detail. Very delicate, and something I am not used to. Hmm....I think I will like these....more listening. Also, a couple of db more efficient than satellite pods.

Just mounting is a bit awkward as they are long & deep. Off center solution mounting to side of pole seems to have worked.

Hear them in action: 3001 / UM18 hybrids

*******************************************************************************



Been living with these CCP's (Center Channel Pods) for a week now and something interesting has come to light that has caused me to re-assess my beliefs on OB.

OB is fine for treble & upper mid. From my experience, I have unfortunately not found a full ranger that will reproduce this frequency range to my satisfaction with all types of music, but splitting the range between different drivers (mid/treble) will work fine, especially if you have expertise in designing crossovers. However, in this short wavelength frequency range I am questioning the benefit of Open Baffle. Certainly, with the design of the  metal pods I have been using in the Gallos & Kefs, the colouration and boxiness associated with many wooden enclosures is non-existent. Also, these designs being 'baffless' allow a wide spread of the sound waves emanating from the front to reach the back and create an openess associated with open baffle. I am certainly not missing the OB presentation.

Regarding the bass frequencies, I think this is where OB is of great value, especially in the configuration and drivers I am using. The face to face -push/pull arrangement gives great control and directionality of the longer wavelengths and  creates fewer room modes.....a problem that has always plagued me with boxed speakers.

The issue with OB bass is getting to the low frequencies with sufficient SPL. So, you can increase the baffle size and achieve lower frequencies & higher SPL's.....but there is a cost. Increasing the baffle size
or incorporating fancy U-frames, W-frames, H-frames etc., also increases the room modes. Damn. I have had situations where my U-framed Dipole 18's totally cancelled the bass in my listening position. What is the point of that?

So, with my face to face naked arrangement how do I get any bass? The secret is choosing the right driver. This needs to have a large heavy cone with big Xmax, and be capable of taking a lot of watts! The UM18's suit this application perfectly. I have been using this arrangement the last 3 years, and have never thought about using anything else. They totally satisfy me reaching seismic depths and power when required, but without inciting any room modes. These will reach 20hz, and the highest I have crossed at was 275hz.

.......but where the bass meets the mid creates an issue that these latest pods have brought to light. I have discovered a frequency range that has  been missing detail in my system, one that these CCP's excel at....the 80-300hz region. Previously, my woofers would be delegated to  produce these frequencies, but the detail the KEFs produce are  a revelation.  I never realised how important this frequency range is, and usually just assumed the woofer would fill it in. In fact, this range includes leading bass edges and lower vocal registers. I was missing, for instance, the fine detail and impact of a plucked bass string and the detail & clarity of deep vocals. I guess this is something the multi-driver guys knew all along, but something I was ignorant of.

My Bastanis used a 12" driver in OB configuration to get down to 80hz. The CCP's use a pair of 3" drivers in a box. Which do you think sounds better? Not sure how you can get an OB driver to produce this frequency that is as detailed & fast as the KEFs. A small, nimble driver used in OB will start to roll off at 500hz. Maybe using a bigger baffle it could be lowered to 300hz. Then you start compromising imaging and baffle effects. 

I had been using my UM's to fill the gap up to 275Hz. Its quite common for woofers to be used in this way.....and you can tailor the crossover via DSP to make a seamless transition. But you can hardly expect a driver that produces 20hz to be very detailed & nimble @ 300hz. Well.....I thought I was faithfully reproducing this frequency.....but the CCP's have showed me clearly not! Perhaps using a lighter coned more efficient fabric surround  woofer would be more nimble? Well. perhaps.....but it would miss out the bottom octave I have become used to, and would not match the attack and detail of the 3" boxed woofers. Dont forget, I have tried!

Its one of those things I never knew was a problem until I heard it. I have been living with OB for years, doing what I thought was a great job crossing between the bass & mid. You don't really know what you're missing until you hear it. It was a similar experience going from a belt drive to direct rim drive.

By the way, the Satellite pods (or the Gallos) I was using previously don't produce detail at this frequency either. This was left to the UniQ driver to produce. With the CCP's, the 3" drivers cross with the UniQ @ 500hz. Something funny going on with the Satellites below 500hz. I reported they were 'tubby' in their stock state, and blocking the reflex port helped. Even so, they still bloated on some material, and I found it was best to roll them off around 150hz.

Here you can see a bigger bass hump in the CCP, yet there is no bloat while listening.... and these will produce useful output to 70hz where I set the HPF to protect the drivers from deep bass excursions. I have dialled in the crossover from the UM18's to the point where they just start to encroach the 3" drivers.

In contrast, the Satellites need to be rolled off higher, between 150-200hz. If I let them extend lower, they sound tubby & muffled.

In summary, this speaker journey has taken me from conventional boxed speakers to a no-baffle, no-crossover woofer assisted full range design to a hybrid no-baffle woofer assisted multiple driver boxed design with crossovers! Nutz...............

..........more listening............






Update end of May 2021: 


My curiosity got the better of me. As I am now back in bookshelf territory I decided to try one of the many formats on offer. Q Acoustics,  Elac, Wharfdale etc., all get acclaim. In the end I got attracted to the Klipsch with its Tractrix horn & seemingly high efficiency which made it stand out from the rest.


Quite enjoying the RP-500M's at the moment. Music seems to flow from them in an unrestricted way. They are slightly more efficient than the Kefs, but image in a similar way....I guess the Tractrix horn acting as a point source. Most noticeable difference is the upper bass slam.


Been living with this setup for a month now....still loving what it does and no desire to change anything.

I have had a few enthusiasts email me to point out I have it the wrong way around....the woofers should be boxed, and the mid/tweeters should be open. Indeed, if you search the I'net, there are many examples of this type of arrangement. But I think I have this right.....I will explain.

Using a boxed speaker for the top, and restricting the bass being fed to it, the quality of the box becomes less relevant. Its the bass frequencies that suffer with resonant boxes, so the more expensive the speaker, the more the manufacturer puts into the box in terms of materials, shape, bracing & isolation in an attempt to render it inert. Restrict the bass the speaker needs to reproduce and this becomes much less of a problem, so you will get away with a cheaper box.

Conversely, I shudder to think of the box that would be necessary to neutralise the resonances emanating from the UM18's, which would be seismic. I don't event want to go there, but have seen the lengths people will go to attempting to create an inert box! Letting them operate in free air surely drastically reduces the loudness of the bass they can produce, but the quality remains unmatched by any boxed speaker I have ever heard.

My experience with open baffle is the problem creating upper bass/lower mid frequencies...say from 100-300hz.
Typically, the drivers I tried roll-off would begin @500hz ( a bit less with a baffle). To fill this gap, the woofer crossover would need to be raised, or a larger (12") driver needs to be used (Bastani).

My experience has shown the woofers or 12" driver will not produce this upper bass frequency with the detail, slam & fidelity of a boxed speaker. Like I often say, you don't know its missing until you hear it. Indeed, I spent years with such a setup without realising!

I think the combination of open woofers and boxed mid/highs is a winner so will be sticking to this.....unless proved otherwise.

Also...it would be easy for me to change the 'flavour' I am getting from the Klipsch by simply substituting another boxed speaker. I have been digesting many reviews, but so far I am not tempted.

....up until Xmas 2021 that is.....

Taking advantage of the January Sales, I took a punt on the above speakers to sample the different flavours.
My sampling was based on the current offers on price these speakers could be purchased for. I then read/watched reviews on to see if they might be of interest.

My previous Klipsch were chosen on efficiency, and there are not many speakers to match them on that. So now were are venturing into unknown territory to me in terms
of what effect inefficiency will have on performance in my system. I will get this out of the way to start with. Once I adjusted relative volumes I didn't notice anything untoward vs the Klipsch......which was a bit of a surprise to me.





The first speakers to arrive were the Mission QX1 Mk1 which were selling for £145.



Excuse the pic quality. They didn't stay in my system for long. They were awful out of the box and I wasn't going to wait for them to open up. They sounded constrained and congested with very subdued treble, which is a pity. They were very well built with aluminium plates sandwiching the carcass. When the rubber surround started hitting the plastic serrated edge plate on some extended bass tracks, I packed them up.






Next to arrive were the Definitive Technology D7's



I never heard of these before, but Amazon was doing a deal for £169, and reviews showed this to be a well made technically advanced design.

Out of the box they were superb.....more on this later.






The Acoustic Q 3020i arrived the next day.


These need no introduction, and again, were superb out of the box. More on this later.





Last to arrive were the Dali Oberon purchased for £295 with 15% off eBay discount.


As you can tell, crappy picture.....didn't stay long in my system. After all the positive reviews this came as a shock to me. Whatever goodness these speakers had was
overshadowed by the sheer treble attack they enveloped me in which totally drowned everything else out. Kind of the opposite to the Missions! They were packed up right away.

I was disappointed as the built quality on these was nothing special. Vinyl wrapped box, mediocre speaker terminals, and yet, were the most expensive here.


For people suspecting a flaw in my system, I am driving them with a pair of UK made Temple Audio MonoBlocks, latest generation, with twin Supercaps power supplies.
These amps are smooth & neutral with the Supercaps eliminating any harshness associated with class D and also imparting dynamics and authority compared to a regular Linear power supply.

So now, I am left with the Def Tech D7's and Acoustic Q 3020i's.

I need to clarify the speakers I chose were at the smaller end of the manufacturers series. Advantage of bigger box/driver is to augment bass and power. I am not interested as running subs and speakers go loud enough. I often find the smaller boxes are more inert, and smaller drivers do better mids. I really feel bass frequencies are better handled by a totally separate driver and kept away from the midrange driver.







Getting back to the speakers in question. The D7's amazed me and continue to do so. The box feels like its filled with concrete. It is solid and heavy. The front baffle is a 6mm aluminium affair bonded to a 19mm MDF box with a 1mm constrained damping bitumen layer. There is also an internal brace within the cabinet.

The tweeter is offset (supplied in mirror image pairs) in a shallow wave guide to reduce edge diffraction. It also incorporates a diffusor.

The mid/bass driver is unusual having a rubber roll surround on its outer and INNER edge and also a diffusor.
Not sure if these diffusors are doing anything, but its the first time I have heard Lauren Mayberry, lead singer in the band Chvrches, to sound vaguely palatable!

First thing that hit me with these boxes was the bass. They went deep, detailed and clean with no bloat despite having a port. In fact, I didn't realise the subs were off!
The balance in my system was perfect. They sounded rich and lush with a sparkly shimmering treble. They were super clean, huge wide soundstage with focussed instruments with plenty of space around them. I felt I was hearing a high end speaker with a budget bargain price!

Comparing to my Klipsch & Q-Acoustics was a level of refinement the other two cannot match, These speakers are gems and keepers.....and thats straight out of the box! As I continue to use them, I can hear the level of refinement increasing as well as the bass and detail as they settle in.






The Acoustic Q's, at £140 are a steal. These are hefty, well made solid boxes.


Drivers look conventional, but the boxes are unusual with very rounded edges and extending very deep.

The sound very balanced and dynamic in my system, and have to say, I prefer them to the Klipsch where I am now noticing  slight lack of coherence between the mid and tweeter. Funny how the mind plays tricks, cos I thought they would be hard to beat  

Compared to the D7's though, both these speakers lack  polish and refinement, sounding slightly rougher.

I will keep the Q's if I fancy a swap once in a while. They may open up more and become more refined with time, but the clear winners are the D7's which I will now sit back and enjoy!






Guess time to add another chapter to this saga, but first need to consolidate where I have come from and the direction I am heading in.


I have abandoned the open baffle and full range drivers for midrange and high frequencies, believing now that boxes & multiple drivers + crossover bring something to the table OB FR’s cant compete with, mainly:

•   Slam & detail in upper bass/lower mids
•   Smooth transitions between mid / treble avoiding the harshness common in all the FR’s I tried.
•   Extension of bass frequency easily down to a useable 60-70hz so I can cross lower with UM18 subs

In the last chapter I stopped at the Def Tech D7. Now, while all this was going on I was also looking at amplifiers, in particular the SMSL SA400 which was a perfect match to my MA400 DAC which I have been super impressed with.

My reasoning was to simplify the current arrangement of DEQX + Temple Mono/superchargers. 

I was doubtful  the SA400 could sound better, but it offered more in terms of clarity, detail & power than I was used to, occupied less space and also had a built-in DSP which allowed a certain amount of control to tailor the sound to my preference. The negatives were I lost the fine control in eq & filters the DEQX offered, including the High Pass Filter I had been using to limit bass reaching the D7’s. The D7’s started bottoming out with the SA400 and no HPF. I could prevent this by reducing the bass db slope, but this was not sharp enough as it affected the mid-range.



So my quest began to find a commercial speaker that would work in this context without bottoming out. As I was so impressed with the D7’s, a pair of second hand D9’s turned up on ebay, I pulled the trigger on those.


These differ from the D7’s by offering more bass with a bigger driver and passive bass radiator instead of a port.
Well, the D7’s had good bass, but the D9’s were scary.

In my stands they shook the floor as the bass radiator was fitted to the top of the box, and faced the ceiling. The vibrations travelled directly down to the floor. Took me a while to figure this out, so I needed to decouple the speakers from the stands. After trying all sorts of materials from squash balls, carpets and various foams, I settled on a 15mm yoga mat which worked great.

While working with this speaker, it reminded me why I retained the OB subs. These things were exciting  modes in my room, in particular @ 50hz where I know I have a resonance. Weird hearing this again as I have been resonance free for years.

Long story short, I could not control the bass output of this speaker unless I used HPF on DEQX which I was trying to get away from, so they had to go!








The Monitor Audio Silvers had been on my shortlist for a while...the 50’s, not the 100’s as they were too extended in the bass department. The 50's were bass light , and had the sort of punchy sound I was after.



Loved them out of the boxes! Bass was well controlled and they didn’t bottom out. Mids were more up-front than the D7’s. Treble maybe not as sweet, but early days. As they began to open up I stated to prefer the sound of the MA’s above everything else. I could happily stop at these!



One thing that bugged me about these 2 way speakers was I had no control over the excursions of the bass/mid driver. I was not comfortable with a single driver handling bass & mids at the same time without DEQX HPF engaged. Surely there must be some deterioration in midrange frequencies coming from a cone doing 10mm excursions?






I started looking at the ELAC  Uni-fi series which had a dual concentric mid/treble driver a la KEF and a completely separate bass driver.

I ordered their first generation UNI-FI UB5 which had a rear port.

Have to say, was not too impressed with this speaker out of the box. It gave a dull, veiled presentation. I had read it can take up to 500 hours to open up. I also read its crossover presents a difficult load to the amplifier. When my SA400 went into protection mode at volume, I packed them away and returned them.







I liked the 3-way separate woofer idea and researched the newer UNI-Fi iterations. The reference UBR62 was getting glowing reports, but was criticised for its lack of bass extension....perfect for my application. It also had a port & was bi-wireable (future updates?). I managed to acquire and open-box pair & encorporate them into my system.

Hmm....initially I was dubious as these had quite a bit of bass bloat. I blocked the ports & they were a lot better. Like the reviews, they imaged like crazy and presented a huge soundstage. The mids were clean and very detailed.. These characteristics improved with run-in and so did the bloat, which disappeared, allowing the ports to run totally open now. Comparisons with the MA’s which had a good few hours on them at this stage was still a toss-up.

Liking these Uni-fi’s quite alot now after 50 hours. They integrate well with the SA400 & UM18 subs.....not missing the DEQX/Temple combo. I am also reassured that even though the woofer may be doing violent excursions (without bottoming out, BTW), the mids are not being affected. They have surpassed the MA’s now which sound rather 2D in comparison & I will be selling.

....so....this chapter is over for now. .......but I do have something else on order  .........................







ACOUSTIC ELEGANCE AE1 ACTIVE

Had these on order before the Elacs. Took 6 weeks to arrive!

What I am trying to do here is get away from the DEQX and simplify the system. Using the DEQX, I can get most speakers to sound good.
Main problem I found is integrating the various bookshelves with the subs without using any filtering.

So the D9's had to go......way too much bass.

The Monitor Audio Silver 50's were great in this application, but bettered by the Elacs which were the best imaging  and detailed speakers yet. Balance was slightly on the warm side, but upper bass was snappy and detailed.

The AE1's sounded 'thin' in comparison....but I am suspecting the Elacs were too 'full'. Some tracks the upper bass was overblown (Eagles Hotel California),and of course, I have no control. Balance is perfect on AE1's, and you know how it is. After u acclimatise u dont notice thinness. It might just be the extreme clarity the AE1's have.

Main thing that hit me initially with AE1's is the punch & control. Kick drum is more of a click than a thump vs Elacs. The subs fill in the thump. the Elacs were contributing to the thump, but i ran a sweep test  and there is absolutely no output from the AE1's below 40hz. The cones dont move. On the Elacs, the cones move at 5hz. This suggests the AE1 has a HPF which is really good because the bass/mid driver wont be affected by sub bass. Having one cone do both bass & mid worried me as I do like deep bass tracks.

The Elacs were 3 ways, the mids not affected.

Having lived with the AE1 for a day now, I am understanding what they are all about. Synergy. You know buying a new amp is always a  risk seeing how it will drive the speakers. Well, Acoustic Energy took care of all that! Dynamics on this speaker are scary and I have never heard such control across the whole frequency range.

They are super efficient and had I to raise the gain on the Subs by 12db to match volume, but part of this is due to the RCA outs from the DAC I am feeding them with. These things are EXCITING to listen to! Even the wife stayed in the room listening for hours.....usually she leaves after 10 mins! She loved them! The Klipsch were exciting too, but nowhere near as refined.

They will handle anything you throw at them...acoustic, rock, jazz, electro. Huge soundstage, precision imaging, clarity, texture...they do it all.

I wanted to keep the Elacs, but what for? They will sound dull & boring in comparison, so I sent them back. I'm thinking end-game here!

This guy sums up:





April 2022.

Loving the AE1 Actives, but cant get the Elac Unifi's out of my head!

There was certainly something special about the mids. There were difficulties with integrating with subs because of their bass output being too much for subs, and the lack of dynamics because of their elaborate crossovers. So I pulled the plug on the Elac Navis Actives.....

The difference with the AE1's is these are a 3-way, so the midrange driver is freed of bass duties. This gives more clarity & detail, a trait I loved with the Unifi References. But now, these actives give me the dynamics and bass control I was missing.


There are DIP switches on the rear which can cut or boost hi, mids & lows, but of particular interest to me was the High Pass Filter. This sharply  cuts the amount of bass the Navis receives allowing better integration with the UM18 subs. No more compromises now, and I have finely tuned this integration  giving me the best upper bass slam, timbre & detail yet.


The other thing is these go really LOUD as I accidentally found out. After the initial shock, I discovered there was no compression, grain or distortion.

Everything remained in its place as if I was listening at low volumes. Wow!


......will I stop here?

 

May 2022:

Have to report an update.....but not to the speakers. Navis continue to please & amaze me!
Here, the update is to my DAC where I have followed the recommendations of THIS dude!

For sure all the things Srboljub says about the SMSL M500 mk2 are true, and the slam/dynamics have noticeably improved over the M400. If I were to be picky about the Navis, they could be to be more on the laid back side rather than forward. Now I would say they present a perfect balance.


****************************************************************************************************************************************************************************

JOURNEY SUMMARY


Few things I learnt from this experience:


1. OB Full rangers might be fine for jazz & quartets using a tube amp, but they wont do rock. To much breakup in the upper frequencies.

Really need to hand over to a tweeter with a proper crossover so the driver is cut off before breakup. May as well use  a good mid + tweeter arrangement.


2. Not good using OB to get upper bass slam between 100-300hz. To produce these frequencies you would need at least a 10-12" driver, a la Bastani.

Doing it without the box will produce the frequencies, but with hardly any slam. To achieve this you need to create a pressurised environment with a box. The advantage of this is you can use a much smaller driver which will be lighter & faster giving more detail & texture. The box will also allow the driver to play lower and easliy achieve 70hz before handing over to the sub woofer.


3. Using 3-way configuration for the box as opposed to 2-way frees up the midrange of performing bass duties. This ensures the midrange remains coherent and detailed with complex loud music, especially with deep bass.


4. Using UM18's in the clamshell configuration produces the best deep bass which integrates with the room without causing excessive room modes.

It may not be the most efficient way to produce bass, but it certainly is the best, most natural sounding! 


Integrating the sub bass with the bookshelves is another chapter, which I have explained below.......




How I integrated bookshelf speakers with OB subs (without DSP) to create a mind-blowing system!

Didnt quite realise the problems that would manifest, especially coming from Open Baffle tops and having DSP at my disposal.

Initially, testing bookshelves that went low (40-50hz) incited room modes....something I was not accustomed as these are practically non-existent with OB. Previously I could control this with my DEQX, and set up a cut-off point....or High Pass Filter (HPF)......usually between 60-70Hz. Since the brief was to get rid of the DEQX and simplify the system, I had to approach this from another direction.....so I selected smaller bookshelves that were light on bass.

Hmm....this was not easy as so many manufacturers try to squeeze as much bass out of the box as possible often resulting in low quality boomy bass. Speakers that weren’t too bad were the Klipsch RP-500 (although had to block port) Definitive Technology D7 & Monitor Audio Gen7 Silver 50. Nevertheless, they all had a slight amount of boom.

The other issue is I like to listen to Electronic music, which goes real low. Not being able to restrict the low frequencies reaching the woofer/mid caused the D7’s to bottom out. The Klipsch & MA’s were better, but I noticed the midrange thicken up & sound stressed while flapping about trying to reproduce the bass frequencies. I figured maybe if I went for 3 way bookshelves, the mid range would be spared as the crossovers would be acting as a HPF.

Thats when I got into the ELACs, which made numerous 3 way compact bookshelves at reasonable prices using their Uni-Fi co-axial drive unit.

The first one I tried were the Uni-Fi BS U5 Slim. Ugh.....didnt like these at all. Very laid back and veiled. Also, apparently a difficult load to drive and sent my amp into protection mode when playing at realistic volumes.

I updated to the Uni-Fi Reference. These were much better, and I spent a lot of time with them. They had a lot of ‘body’ to start with which was not unpleasant. Bass boom was well controlled and the mids remained coherent at volume. After a couple of months, though, I started getting bored. They were not dynamic enough for my tastes. I blamed this on the crossover which was a huge circuit occupying 2 boards. For sure this needed to be complex coping with 3 drive units. It sapped a lot of power.

At this point I wandered into Active Speakers. I was piqued by a review on the Acoustic Energy AE1. Although this was only a 2 way, it had built in amps, so I wondered if there would be more control on the mid/woofer.

......well, indeed there was! It was as though they had a built in HPF. Bass was controlled, not excessively boomy and had a sharp cut-off so the mids did remain co-herent at volume. Sub integration with my UM18’s was easy and seamless. After about a month or so though, I started missing the Unify Reference. There was something about their mids that was special. I decided to look at the Elac Navis.....an 3 way active version of the Uni-fi BS U5’s.

Well, this was a surprise. Turned out to pair perfectly and left the AE1’s for dust! I had more sound control  with an array of DIP switches at the back, one of which actually controlled a built-in  HPF. Also I had a choice of High & Low gain. As I was not using a dedicated pre-amp, but driving direct from the DAC (SMSL M500 Mk2). I found the High gain to be more dynamic. These actives bore no resemblance to the passive version. These things punched, were very clean with spacious instrument separation, imaged like crazy, and went very loud with no signs of compression or stress. Integration with the UM18s was easy & seamless thanks to the HPF option, crossing @ 65Hz. There was not even a hint of bass boom on the Navis, and these are easily the best speakers I have ever had in my system.


To conclude, I feel this combination of boxed bookshelves and the UM18 clamshell arrangement for deep bass is the way to go. Bass integrates with the room without inciting modes caused by pressurised waves emanating from a box. Deep bass is natural, clean, textured & effortless with no bloat or resonances to colour the sound. It extends down below 20hz. Upper bass is punchy, detailed & textured, something OB has trouble doing. The Active Navis are almost like having DSP....the analogue HPF option being the next best thing.

Very happy where I am at the moment!