Trans-Fi Audio

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Journey to No-Baffle Speaker System

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!