I've been experimenting with DIY double braces made of carbon fiber sheets and thought I'd report back findings. Ever since Rega have introduced their double brace technology in the RP3 and RP6 , I couldn't help but wonder how these may or may not affect a turntable's sound. Frankly, I was skeptical. I also had to wonder about the choice of material - the dreaded plastic aka phenolic resin yet again - used on the RP3, and so I got to thinking about lighter, more rigid materials for an experiment.
I thought of carbon fiber. Why CF? It is not only rigid and light, but absorbs energy very well. And compared to aluminum of the same thickness, costs are about the same, which is not too expensive for the small amount of material I would need. Maybe I could make my own double brace with CF sheets? It can't be any worse than plastic braces or the thin layer of plastic on the plinth, or so I believed.
As a mountain and urban bicyclist, I have learned to maintain, fix, and yes, even upgrade the parts on my bikes, including building bikes from the frame up. I've also built computers and fixed my old cars, before cars became almost impossible to work on due to complexity. I guess this character trait is behind my curiosity with the workings of a turntable, and seeing whether or not I can improve performance incrementally by changing things here or there.
A few years back a friend of mine who was a professional bike racer at the time had been using a CF frame bike, and she had mentioned how she really loved the feel of the bike, even though she couldn't afford it without her sponsorship. Well, I had to try it, and was very surprised at how the bike was not only feather-light, but when riding on pavement, it really did an excellent job of absorbing all the bumps and cracks of the road, much better than steel, let alone aluminum, but the bike was quicker and more responsive at the same time. The only drawback was: if you dropped it on its side on something hard, don't expect it to come away without damage. Yikes.
So, carbon fiber. Used as a tube, it has some limitations. But its strength-to-weight ratio is hard to beat if it's thick enough and you use it as a plank, as I intended to do. So I set out to make a template out of cardboard, measuring and marking out the arm pillar hole, main bearing hole, and screw holes on the plinth. I ordered the CF bars at 1/16" thick and 3"x12" for a total of $40 from McMaster-Carr. And then I waited and debated. CF is not the easiest material to work with. It is hard to cut, you have to be careful of the microscopic fibers lodging under your skin, and it can release noxious fumes if it burns. If I abandon the experiment now, it won't cost me anything other than shipping.
So I talked to my pals here at VE RoDa and bacobits, drawing opinions from them. Then I contacted Pete Riggle, engineer extraordinaire and all around nice guy for turntable advice. All of their feedback helped me to hone my approach, and made me decide to give it a go. At most, I'll have something that I might be able to share with others. At the least, I will have learned something, and scratched my itch to learn more about turntables and how different materials affect sound.
What am I trying to achieve, you may ask? A bigger sound, fuller in the bass, with no loss of boogie or refinement, moving towards the sound of the Shindo/Garrard 301 that is my dream machine. Wouldn't it be nice if the brace could get me there...?
The Process:
Measure twice, cut once. The template fit like a glove, so onward and upward to fabricating the actual braces. CF is indeed hard to work with, at least with hand tools. Doesn't bend, doesn't cut easily, and you need sharp cutting edges. Hint: slow and easy wins the race. Let the tool do the work for you. Take a look at the shots of where the cutting blade slipped. Oops, that will have to be the bottom brace, obviously. The second one came out much nicer. Along the way, I needed to buy more Dremel cutting wheels, a countersink bit, and carbide-tipped hole saws. Bringing the grand total to $100, and two days of fabrication, fitting, and fine tuning.
Anyways, here are some pics of the process:
The System:
Rega P5 as described in my signature below, i.e. modded to the hilt. One thing someone might think is that the VTAF system may have a different result with the braces than the standard Rega mounts may have. This may be true, so take the results below with this caveat in mind. But then again, if it didn't work with stock mounts, Rega wouldn't use it, right?
SAE 1000lt and Shelter 501mkII carts tested. Heed Quasar phono stage to a Juicy Music Peach II linestage, which has two options for output impedance: low and high (90 ohms and 3.5K ohms respectively). The Peach connects to a Pass X150.5 via its single-ended inputs, which have a 20K ohm input impedance. Speakers are DeVore Nines and REL Strata III sub connected to the Pass. Music: Schubert, Ron Carter, Franck, Pretenders, Bach, Curtis Mayfield.
If you do the math, you'll see that the pre/amp combo is on the borderline of acceptable using the high output Z option of the Peach, at least according to common knowledge. In practice, the low Z output has much fuller, dynamic bass than the high Z, this is to be expected with the borderline impedance matching and maybe other design factors. The high Z, aka "Blueberry Mode", is a simpler SET circuit, and has a distinctly "live" sound to it that the low Z doesn't have. I used the Blueberry Mode exclusively in my listening tests, as it more clearly illustrates any changes in bass.
The Results:
I first started with the SAE. I had become familiar with the SAE over about a month before embarking on this experiment. I would say that prior to the braces, the sound was very smooth, very listenable, big soundstage, nice top end, and good bass, but lacking bass extension, and overall, lacking inner resolution when compared to my other carts in my system.
When I put both CF braces on, I immediately didn't like it: lost bass, harsh character, not enjoyable at all. I couldn't take the braces off quick enough. I thought, oh well, I tried. 100 bucks down the drain.
But then I thought, why not just try a CF "armboard", i.e. a single top brace? When I tried this, the SAE gained inner resolution, but lost its trademark smoothness as its overarching trait. Bass was improved, both in midbass fullness and extension, and actually sounded quite a bit like my Shelters sound. Not bad at all. On the Juilliard String Quartet's Death and the Maiden, the quick, intricate bowing work was much, much easier to follow with the brace. On Ron Carter's New York Slick, there was much better tonal balance, and instrumental textures were more clear. Overall, it sharpened the SAE's sound from somewhat smoothed over in the details to being able to run with the big boys, and gave it a much more balanced sound, and while losing its smooth character, at the same time, it wasn't harsh.
Which made me wonder what would happen when I threw my Shelter 501 on. The Shelters are detail monsters. At times, though the 501's midrange is very liquid and warm, on certain recordings the top end would gain a bit of hash. And while the bass on the Shelter is good, probably honestly playing what is there, it cannot compare to the bass volume and extension of the Dynavector 20xl. So I was a bit skeptical how the Shelter would sound with the brace: if it made the SAE come closer to the detail of the Shelter, would it make me run from the room once I put the Shelter on, and how would it affect the bass?
I mounted the Shelter, and put on Death and the Maiden. I have to say that my immediate reaction was: this sounds REALLY GOOD. Much better than I remember the 501 sounding: excellent top-to-bottom cohesion, good top end, liquid midrange, bass was full and punchy, and the sound image was big, tactile and dense, very grounded and solid. The sound was very engaging, musical, and easy to listen to. Not hyper detailed at all, if anything, it brought out the sweetness in the midrange with more clarity. Ron Carter's bass had much more texture than the SAE, better extension, and locatability in the soundstage. I easily relaxed into this sound, this was definitely an improvement. It was like I turned up the "clarity" knob on the preamp, but didn't lose any musicality.
OK, so what about real bass extension, never the 501's strong suit? I put on Franck Organ Chorales 1-3, and sat back. This recording is very good, excellent dynamics, and some serious subterranean bass. Chorale No. 3 has some very nice textures: brassy, light, flute-like sounds contrasting with reedy, gutsy, and earth-moving, as well as very soft and very loud dynamic contrasts. Chorale No. 1 really works out your woofers (and sub, in my case). Well, the Shelter definitely conveyed a major portion of the lowest octaves, but fell short of really moving the earth. Good bass heft, I didn't sense that it was lacking bass overall, but it just couldn't hit the bottom. Then again, it could be a limitation with my sub, I'll have to throw the Dynavector or 901 on to really see. All in all, I don't think I ever really appreciated this cart as much as I do now; I actually don't want to take it out of the system, even though I know the 901 is better, especially in the bass department and overall refinement.
Other Observations:
As some of you know, I have a light rail system very close to my flat. This has wreaked havoc at times with my P5, causing acoustic feedback if I had the volume up too high, and if multiple heavy trains come by simultaneously. Because I can't install a wall mount, I've had to experiment with ways to try to isolate my deck from the daily minor earthquakes that occur due to trains. Up til now, I've been partially successful in that I've minimized the vibrations to the extent that I no longer need a rumble filter, nor do I feel that the train is a hindrance to my enjoyment of my analog setup. Guess what? The brace seems to be help in this regard as well: I haven't seen the intensity of woofer pumping that I used to see. I have been taking my time with testing this out, but it seems that getting the Delrin platter, placing the deck on an acrylic platform on cones, moving the subwoofer, and now adding the brace have helped me get to the point that the musicality is really unaffected by the vibrations - the arm may shake and the music may waver a bit, but I still very much enjoy what I'm hearing, and I know that the problem is temporary and will be resolved quickly.
Conclusion:
Bottom line, I think this is a keeper. I would say it is not a huge difference from before, but it is a definite incremental improvement, and I like what the brace does for my deck. Although it still doesn't sound like a Shindo/Garrard, I very much like what I'm hearing, and I like the direction the brace takes the sound. It's still a P5, only much more refined. The brace actually does seems to provide the more rigid mechanical connection between the arm and the bearing as Rega promises of their version, and the CF brings a bit more control of extraneous vibrations to allow more of the music to come through in a cohesive and musical way.
And although the low Z output still has more bass than the Blueberry Mode, I have been marveling at the better quality and quantity of bass I am getting in Blueberry Mode, despite potential impedance mismatching.
I don't really think I can point to any drawbacks of the CF brace, other than if you don't have the right tools and/or you don't want to take apart your deck and void any warranty and such. And if you biff it like I did, it may not look so great.
So anyone believing that their rigs are lacking in bass may want to investigate making their own armboard out of CF or some other light, rigid material. In fact, I'd be willing to send around my extra brace if anyone is interested. It will work with three-point mount arms, pillar-mount arms, and VTAF mounted arms. And I'm happy to send out a scan of my template as well. And of course, provide more of my experience to anyone interested.
Happy listening!
Wilson
