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.
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.
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..........
Before you ask, I have a loving understanding wife..........
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!
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.
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.
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 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.
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.
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.
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.
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!
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:
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.
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!
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.
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.
BTW, if anyone is interested in any of the projects I made along the way, please contact me.............
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.
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.