Positive Feedback ISSUE 67
may/june 2013


Where Have I Been? To DIY Heaven!
by Larry Cox


I've not been reviewing much lately because I've been experimenting with DIY gear. It's a little funny that my interest in audio arose from subjectivist origins, which is to say that I shopped for a sound, the technology behind it be damned. But, with this foray, I'm finding myself much more interested in the hardware and the technology. I still trust my ears, but I'm getting more structured about my approach.

My foray into DIY started about three years ago in part because manufacturers generously spoiled my ears with great sounding gear. Unfortunately, much of what I liked/loved was more expensive than I was willing to afford. While I can pay the toll to get past "GO," my listening time is dwindling as I spend more and more time as a dad (everything I was afraid it would be, and I love it!). Couple the rising costs of digital gear in 2010 with the rapid turnover in technology; it seemed like a bad idea to plunk big bucks in the morning on a DAC that will be eclipsed in the afternoon of my purchase. Perhaps change is still rapid, but it seems we're temporarily at a new price/performance plateau.


While my DIY/Solder/Design skills might be of the toddler level, I am getting better with a soldering iron and the other accouterments of making something myself. At the start, I was ill equipped to figure much out of what needed to be done. Luckily I found a fellow ATC speaker owner (James Arnott) who built a DIY DAC from Twisted Pear Audio. Let me say something about ATC owners—it seems to me that ATC owners tend to be willing to accept the "problem" of accurate replay of poor recordings. A component can still be considered "good" even if replay shines a light on the warts of a recording.

TPA was among the first to design and build a DAC using the then relatively unknown, but now ubiquitous and well known, ESS Technology Sabre DAC. TPA started with Wolfson and Burr-Brown DACs eventually making their way to ESS's Sabre DAC—the 9008. I held out until TPA offered the "9018 Reference" DAC chip, with design hints to Twisted Pear Audio provided by "Dustin" at ESS.

When I undertook building the Buffalo 32 DAC in 2009 or 2010, there was no integration guide to tell you what power supplies were needed, trivial to someone who understands electronics, not trivial to me. Nor were there connection guides for the digital side of things—again, non-trivial to me. Thankfully, James, a helpful British DIY fellow, encouraged my efforts and provided guidance that TPA didn't. Thanks so much James! Without the help of someone like James, I'd have been sunk. Now TPA provides guides, voluntarily developed by Leon van Bommel, that allow someone of my skill level—if an absence of skill can actually be called a skill level—build a mighty fine DAC with some ease.

My DAC has mono power supplies for each channel, with a separate power supply for the digital section. Right now, I have a pretty decent DAC, built in home for about $800 in parts. As designed, my Buffalo will take DSD, though I have no idea whether it is capable of double or quadruple DSD; I expect not.

By way of comparison, I borrowed an Ayre QB-9 USB DAC and connected it to my computer using Lotus Design's horrifically expensive USB cable, and compared it to my Buffalo DAC using the hiFace USB cable. The differences in sound were difficult to tell and amounted to a comparison of Row K seating to Row M seating. Yes, there were differences but they were very slight, if present at all. In fairness to the Ayre piece, my Linux box was not optimized for first tier sound, so the Ayre might have wiped the floor with my system were it optimized, but as configured it did not.

Blue Goo

Since finishing my DAC, and after the Ayre comparison, I have further experimented with DIY goodies. I stumbled across Antivibration Magic. This is a paint that is infused with, or has suspended in it, a material that is said to be amongst the densest on the planet. It's $95 for what appears to be a trivial amount of product.

A word of warning, however. Its shelf life is not indefinite. Be prepared to experiment to the bottom of the bottle in a month or two, or the bottom of your bottle will be caked dry. I was able to use it for about two months before I discovered the hardened insides. I was able to apply sufficient quantities to the video and audio circuit boards and capacitors on my aging and ergonomically awful DVD player; experimented with painting seven tubes in my preamp, and painted the capacitors and three of the circuit boards in my DAC. I also painted the tops of some of the capacitors in the amp packs in my ATC speakers. Oh, and Francisco Duran painted the video board in his Blu Ray player. That's a sufficient number of places to diddle and come up with a sense of the goo's worth. I'd say, it's good value.

My experimentation started with painting the fuses on my horrible Philips 1080i DVD player. I hate this player. I truly want it to fail. After ten years of use, it has withheld the secret of the magic amount of force needed to engage the buttons on the front panel, as well as the precise angle at which to hold the remote to have a lottery's chance at it working. Since it works and I'd be happy if it stopped, I tried the AVM on this thing. So I painted the fuses in the DVD player. Can't cause any problems, right? Probably won't do anything, either, right?

Whammo! Video improved, deeper color saturation, quieter more film-like images. My wife repeatedly commented, "Wow, what's new!" Initially I was thrilled thinking that she really enjoyed the increase in performance, but it turns out she was sniffing to see if I'd bought a new DVD player. Ha! I want to. Maybe this is priming the pump for another purchase.

And then the other shoe dropped. The AVM was arguing to wait on purchasing a Blu Ray Player; crap, this stuff is playing for the other side! After stewing for a week about this Benedict Arnold and not wanting to win that particular argument, I applied more of the seemingly magic stuff. This time I painted thin coats to the tops of capacitors on the video board. Damn! The Philips didn't fail and the sonic and video gains were complimented further. Not willing to take a bullet for the team, I now must either drop 16 tons on it, or simply buy a new Blu Ray player without justification.

Next I soldiered on with the AVM and my paint brush and applied some goo to the bottom of the circuit boards of my DAC, and as my son says, "Holy cannelloni!" A quieter more "still" background, richer timbre, and another stage of improvement! This $95 tweak was adding hundreds of dollars of improvement to my system.

Next I tried some AVM on some unbranded 12AX7s and 12AU7s in my E.A.R. 864 preamp. I picked a pair of "identical looking" 12AX7s. My friend John and I inserted one after the other, both untreated, with the volume at the same level. One tube was clearly quieter and exhibiting less ringing than the other. So, we painted a thin strip around the ringing tube. Quiet! In fact, with comparison, the painted tube was now quieter than the non-ringing tube. Next, I painted the tube that rang less; WOW, again, quieter, richer, and a denser more harmonically saturated sound.

I then inserted my NOS Mullards in place of the unbranded but painted 12AX7s. Darned near the same sound. Hmm. Would the blue goo make another difference with the NOS Mullards? Whereas the paint on the unbranded 12AX7s closed the gap, paint on the NOS Mullards reopened up the gap.

So, what is this Antivibration Magic stuff? I'm not sure. I've been told it is a paint infused with a very dense material, irridium? This experiment led me to reflect on damping components. It occurred to me, in a rather hard to follow path of logic, that the damping or quieting of both tube and solid state gear might reveal the reason high-end or high-performance manufacturers resort to massive face plates - not just for appearance's sake. Though many "practical" audio enthusiasts (not audiophiles) pooh-pooh thick face plates, I can imagine a role here.

Those Are Some Big 'Uns!

Still standing in the waters of DIY I have designed and built two subwoofers. What a gas! Frankly, with this project I began to enjoy the designing and building as much as listening, though I am enjoying the heck out of listening. These subs perform very well, thank you very much, and it's not my ears alone that voice that opinion. Our Francisco Duran has given my subs a thumbs up, figuring that two, TWO! 15" drivers would be too much. But no, in Frank's estimation they disappeared sonically. Frank's comment was that he only noticed their presence when I removed them from the system. An audiophile friend, who was also sure my subs would be too much, was surprised, and thought the performance excellent and seamless.

The drivers are identical, but the cabinets are not. One sub is in a 2.1 cubic foot cabinet, the other in a 4.4 cubic foot cabinet, both are sealed designs. The first with a QTC of about .7 has a punchier sound that doesn't dig as deep as the latter. The larger sub has a QTC of closer to .5, is more relaxed, full sounding, and with a more varied timbre.

I've had four commercial subwoofers in this listening room. One, ATC's C4 subwoofer ($5,200), was fantastic; it was part of an all ATC surround system. Two other subs were courtesy of Hsu Research (TN 1220HO ~ $800 and ULS15 ~$1050) and I'd say they were well worth their commercial price. The final sub was part of a Totem Dream Catcher system that was simply in the wrong sized room. With all of these subwoofers, however, I found integration easy, contrary to the hand wringing and kvetching widely relayed on the internet.

My subs are sealed for two reasons. Sealed subs are easier to build and design than ported subs. Among other challenges, designing a cabinet to integrate a port that doesn't have too much wind speed to create "port chuffing" is difficult. Secondly, sealed designs roll off their frequency response more gradually than most ported subs, which is how sound rolls off in nature, gradually.

A QSC RMX 2450, a pro audio amp, drives each four Ohm subwoofer with 750 watts. I had to replace the noisy fan in the amp, as I could hear it working during quieter passages. The drivers are Acoustic Elegance AV15H, rated to take 1000 watts continuously. So, I could try a bit more power, but... that'll be another project. I bought some, or all, of that on the used market for well below $800!

The subwoofers do dual duty though my Onkyo SC PRC885(b) preamp processor, which provides its own room correction. With the flip of a switch the subs are providing bass for my E.A.R. 864 preamp, using a Minidsp which uses a shelf filter boosting 15Hz to 35Hz about four dB, this added about $145 to the cost.

It probably should be said that the 15" drivers are awesome for movies, and perhaps unnecessary for most music. My collection of music, excluding electronic or synthesizer music, has very little with bass below 30Hz. The subs have provided a foundation to the music I didn't know I was missing. The effect is to disconnect the sound of music from my main speakers—music just appears between them now.

With movies, however, my room throbbed at the appropriate moments during Terrance Malick's fantastic but emotionally disturbing The Tree of Life, with knick-knacks bouncing throughout the room. The scene in Polar Express with the train's raised wheels slamming into the ice was shocking the first time I heard it. I've found myself watching more action films, in part because I like to hear my Franken-subs knead the room with bass! And let me tell you, you've never heard a Super Mario Brother's "butt smash" without subwoofers plying the deeper waters of sound.

This rambling note is simply to mark that I started on one side of the divide of audio and am now rather happily on the other. I listen to way more music these days than gear. I have a system that makes me happy both for what I've been able to create for myself as an audio hobbyist, and for what I get to hear as an audio sound hobbyist. For some this is the best my system has sounded. I especially love that I've helped create parts of my system rather than simply swiped a credit card to have what I have.

When I can provide a clear note on designing a subwoofer, or at least my subwoofers, I'll share that, and perhaps other areas of DIY I experiment with. I have reviews of an upgraded Minidsp device to deliver soon, as well as a review of PS Audio's P3 Power Plant. So, I'll see you in writing soon.