Miles's Taste Tests for the Sovtek/Electro-Harmonix 6V6

These results were first posted in the alt.guitar.amps newsgroup.

Intro

When I first heard about these tubes, I assumed the EH meant Electro-Harmonix (it does), and I was fairly excited. I was a big fan of the original company and its founder, Mike Matthews, and was really happy to see the company return. Based on my experiences with EH products, I looked forward to trying these tubes.

The tubes arrived in standard Sovtek boxes, and the pair was matched to within 0.1mA. The tubes look as if they are made well.

Unlike the Sovtek 12AX7LPS, there's no doubt when these tubes are lit. When powered up, they glow brightly at the base, and a bit at the top.

According to both the Sovtek and EH sites, these tubes were developed to ``perform reliably in circuits that operate in excess of the published ratings.'' They didn't send Lord Valve any data sheets, but here's what he had to say about testing them:

``I burned the 12 samples in at 510 volts, 15 watts dissipation. Not a single one croaked during the 27-hour burn period. I am unaware of *any* other types, including Brimar, Tung-Sol, RCA, Philips, etc. which could equal this. All 100 tubes in the initial order survived a 24-hour burn at 425 volts, and all passed the hammer test. 7 pieces were rejected for various reasons including noise, excessive current at standard test voltages, microphonics, etc. This 7% failure rate has been matched (in my experience) only by the Visseaux 6V6s.''

The EH and Sovtek engineers say they used the RCA blackplate 6V6GT as a benchmark while designing the 6V6EH.

The Rig

I used these in a Silvertone 1263 head through a cabinet loaded with two Peavey Scorpion 12" speakers. Others should be posting reviews in more common amps, but this is reasonably representative of quite a few 6V6 rigs. The amp puts 375 volts into the output transformer, and 310 volts on the screen grids. It's currently biased for about 25mA, so I didn't rebias for these tubes (22mA as delivered by Lord Valve).

My standard tubes in this amp are a pair of RCA blackface (labeled Emerson) 6V6s. These aren't the loudest tubes around, but they sound awesome, and are a hard act to follow. I've used other tubes as well, but didn't have any handy for this test.

I played quite a bit on my Hagstrom (two single coil, early DiMarzio SDS-1s wired for all possible combinations) and my son's BC Rich ST Platinum (Strat clone with an S S H pattern of more modern pickups).

I swapped the tubes several times, playing a minimum of 1/2 hour each time, and for several hours when I could. I always let the amp completely cool between tube swaps, to assure similar warmup conditions.

I was often playing with nobody else around, so I couldn't easily do a blind test. However I approached this as professionally as possible; I'm used to having to evaluate and compare things on their own merits.

Results

I like these tubes! Not as much as the RCAs, but a lot. They have a few quirks, which I'll delineate, but otherwise they are very good.

These were louder than the RCAs, about what I would hope for from a good quality 6V6. They have a bit more top end; they're perfectly capable of ice pick treble (not that I want any, thank you very much), but roll off the highs a bit and they're fine. They reproduce picking dynamics well, but present some anomalies in subtle areas. For instance, when playing at higher volumes, they compress the sound just a bit; they don't handle loud but subtle as well as some tubes.

On the other hand, the best tremolo sound I ever got from this amp was with the EH tubes - well beyond anything else. (The tremolo circuit modulates the 1st preamp grid, so go figure.) But with the Strat set to the neck/middle pickups, they wouldn't really carry the SRV phasey sheen like the RCAs. A bit odd.

They do great with humbuckers and single coils. The DiMarzios were just a bit muddy at full overdrive, but that's a problem SDS-1 pickups exhibit with lots of tubes (and most amps, tube or SS).

The tubes kept up with the volume knob, all the way to max overdrive. Whether clean, mildly distorted blues, or hard rock, they sound very good. Plenty of wonderful harmonics in overdrive mode, even more so than my beloved RCAs, especially at max volume.

They didn't sound quite as good when I got them. They improved after a few hours break-in, and still need 10 or 15 minutes of warmup to sound their best (they certainly aren't alone in this regard). There's still something just a tad sterile about them; I can't decide what. But it's pretty subtle, and would not stop me from using them. (In fact, I plan to leave them in for a while longer to see how they fare over time.)

The Bottom Line

They have a few quirks, but overall they're very good, modern tubes. They're powerful, handle both clean and dirty sounds quite well, and seem perfectly happy at the moderately high voltages in this amp. (I know some designs push 6V6s past 400V, but the original 6V6GT stated max. plate voltage was 350V.)

I rate the RCAs a 9 out of 10 (they could be louder and yield a bit more headroom), and the 6V6EH a solid 8. The 6V6EH lost ground because of how it handled the Strat in between pickup positions and the slight compression at higher volumes. (Before now I would have rated the RCAs close to 9.5, but the EH had even more distortion harmonics, and the EH helped the trem, knocking the RCAs down. Otherwise the RCAs lacked only a bit of power.)

Bottom line? I think these tubes are winners. The Russians (with EH help) have finally produced a good 6V6! Could they be better? Somewhat. But they could also be much, much worse.

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Last updated: 24 July 2000
Taste Test copyrighted 1999 by Miles O'Neal, Austin, TX. Incidentals copyright 1999 Miles O'Neal, Austin, TX. All rights reserved.

Miles O'Neal <meo@XYZZY.rru.com> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514