May 2018

Roll Your Own
Roger Skoff wonders about one kind of Do-It-Yourselfism.
Article By Roger Skoff

  It was probably back in the late 1980s that I got my first pair of Acoustat model 1+1 speakers. Was married at the time, and my wife and I had heard the original Apogee ribbon speakers ($15,000) at a friend's house and loved them, to the point that we were thinking seriously about buying a pair. Because they were so very expensive, though, (remember when this was and what things cost back then) we agreed that if we were going to spend all that much money on a pair of speakers, we ought to make certain that what we were getting would be the very best our money could buy.

The best way to know that, of course, is to go and listen to everything on the market, but about the only place we knew where that might be even remotely possible was at the Consumer Electronics Show (CES). That's "for the trade, only", but fortunately I had friends in the industry and was able to get passes for the two of us to the upcoming Winter CES in Las Vegas, which was only a month or two off. (In those days, there was also a Summer CES in Chicago.)

We went to the Show for the specific purpose of finding speakers to buy, and the budget limit we set ourselves was the price of the Apogees. The surprise was that, although we saw and listened to a great number of speakers (including the Apogees, and many of them, particularly the Thiel CS3) were very fine, indeed, the ones we finally selected as best for us were Acoustat electrostatics – and not even Acoustat's top-of-the-line model 4+4s, but their newly-released model 1+1, which, although they had less powerful bass, had the same overall sonic "signature" as the larger Acoustat models and imaged better, were far less "beamy" in the highs, and had a much broader listening "sweet spot". Another surprise was that the 1+1s were only $1500 – just one tenth as much as we had been prepared to pay.

Still one more surprise was that, even though they had impressed us mightily at the Show – far more than others many times their price – when we bought them, got them home, and set them up, they sounded… awful! I remember thinking at the time that the best way I could describe them would be to say that they sounded like a less-than-wonderful shirt-pocket transistor radio.

That couldn't be, I thought; there must be something wrong with the way I had hooked them up or with something else in my system. After all, my wife and I had both heard them at CES and they had sounded nothing at all like what we were hearing at home. After trying everything else I could think of and checking everything else in the system, all to no avail, I finally found the number and called Acoustat, where I had the good fortune of being able to speak with Jim Strickland, the speakers' designer, tell him what was happening; and ask him what to do about it.

It turned out that electrostatic speakers – or least the ones from Acoustat – require a "burn-in" period before they can sound right. Electrostatics work by placing a charged diaphragm between two charged "stators" (one on either side of the diaphragm), with the (changing with the music) audio signal applied to either the diaphragm or to the stators, so that either the diaphragm charge changes and the stators' charge stays fixed, or the other way around. In either case, the result will be that the diaphragm will be attracted to one of the stators and simultaneously repelled by the other one, with the result that, as the musical signal changes, the pattern of attraction and repulsion changes and the diaphragm is forced to move and produce sound.

What Jim Strickland said, as I recall, was that, when they're first "fired-up", the electrostatic charges on the diaphragm and on the stators may take some time to become evenly distributed and will, until then, result in below normal performance. It may also be, he said, that during the manufacturing process, the diaphragm is not evenly tensioned and will require some time to, by stretching in the overly tight spots, even itself out and finally meet its performance "specs".

Whichever of those it was – or perhaps both – it took a good week of constant play before the speakers sounded as good as they had at CES, and that left me wondering how it was that Strickland or any other designer of a product that required a long burn-in time could ever know when he had done his work properly. Wouldn't he, when it doesn't sound right after just a day or two, go back to the drawing board and try a different design?

That same kind of question occurred to me when later, as a reviewer for Sounds Like... Magazine, I was sent a very expensive tube preamp to audition and write about.

When that unit arrived, I put it into the system, let it warm up, and listened. And what I heard was awful – dark, bloated; not at all either to my taste or what I would have expected to hear from a long-time famous brand.  Again, I got on the phone and called the designer, telling him what I had heard; saying that it was a possibly defective unit, and offering to either cancel the review or let him send me a different unit to write about. What he said in response caught me completely off guard: "Oh yeah", he told me; "I put Chinese tubes in that one. I thought you'd like them better, but never mind, keep the preamp you've got; I'll just send you Russian tubes for it."

And he did. And when I put them in, the difference was night and day. If we had been doing blind testing, there would have been no possibility that I would ever have guessed the new sound to come from the same preamp.

And that was my first introduction to what we now call "tube rolling" – trying different brands of the same tube or even different tube models (6L6 to 5881 to EL34) to change and, hopefully improve, the sound of vacuum-tube electronics. And it got me to ask again "How does a designer of this kind of gear know when he's finished?" and "How does he ever know what his circuit actually sounds like when just changing tubes can make it sound like a totally different product?"

Furthermore, because most tube products seem to use more than just a single type of tube (different tubes for different functions within the circuit), it got me to wonder if not just the brand and model of tube but, in a multi-tube product, each possible mix of brands and models of tubes would produce different performance levels and different sound quality: With just five manufacturers of just three interchangeable models of tubes, that would make for 15 potential options for each type of tube in the circuit, and even with only three different types of tubes used in the product, the available number of combinations would be an astonishing 3375! (15 x 15 x 15 = 3375)

If that's the case, then a number of things become possible: first, that no one – not even its designer – has ever heard the optimum sound from any multi-tube product; second, that audiophile "tube rollers" have, as long as the supply of tubes and their budget hold out, virtually unlimited opportunity to diddle with their system and maybe even to find the "magic" combination that will truly give them sonic perfection; and third, that, even if not perfection, successful tube rolling might very well be able to bring less expensive or older tube gear up to performance levels far higher than might otherwise be expected.

That certainly sounds like fun, but I'm an old solid-state guy (mostly Jeff Rowland Design Group and Krell) so, instead of dreaming about what might happen if I were to start swapping-out chips and devices, I'm going to just put on a disc, sit back, close my eyes, and...

Enjoy the music!