Revolutionary or just another try?

[Robert M. Martinelli]

So... they're GOING for a tube that is microphonic. I am skeptical, and ad copy like the above does nothing to reassure me.

....So am I ( to say the least ), to the point that I am starting to think they've found their tubes to BE microphonic, tried to gain some time by postponing the release and distribution dates, didn't manage to fix this issue, so they're now trying to present/sell it as a "feature".

Some will say that getting old I'm getting veeeery bad too, maybe I am biased by having heard and seen too many marketing blurbs later belied by facts, maybe I'm just a sad old disillusioned guy.....In any case I don't think tube microphonics can be considered a good thing....God only knows what can happen by using microphonic tubes if cascading them in some "high gain" guitar amp.....

JM2CW

Best regards

Bob

[Chuck H]

"With the TechTube™ valve the minimal structural restraint design allows tiny amounts of movement in the various components which at times allows a small amount of microphony when driven hard at high frequencies. This, in our opinion, is required to give the TechTube™ valve its fantastic performance in both guitar and HiFi applications, its “life and vitality”, its “fantastic speed”, its “clean chord separation”, its “warmth and smoothness”..."

I'm all for a new tube MFG, but what the hell are they talking about?!?

Since when is "minimal structural restraint" a good thing for a tube"

Microphony creates non linear distortions and instability. How that leads to "fantastic speed" and "clean chord separation" is beyond me. In less than ethereal terms "clean chord separation" contradicts "warmth and smoothness" anyhow.

I suppose "life and vitality" are subjective enough that I'll have to let it go... Or not. Maybe that's the rattling and whistling that developes in two weeks because the tube is made with "minimal structural restraint". 'My amp seems to have a life of it's own since changing to TechTubes'.

It's starting to sound like the same old psuedo tech garbage.

Maybe with their intended microphony these tubes would be good candidates for a Metasonix amp.

Chuck

[theunrulychef]

Send me your tubes, and for $49.95 each + $6.95 Shipping & Handling, I will put them through my special Microphonic Induction Process or MIP®. Your amp has never sounded so ALIVE! I recommend the use of Diablo's specially formulated Tone-Paint on all of your capacitors to fully realize the potential of your new MIP® tubes.

[Steve Conner]

Well, I've ordered one of these tubes and will let you know how it works out. I have some original Mullard ECC83s to compare it with.

[Steve Conner]

I received my E813CC today and have some first impressions to post

First of all, it was expensive! At £30 UK, you wouldn't want to retube a whole amp with them. It arrived by UPS Saver, and the tube itself was packaged in a pretty substantial cardboard box. Also in the package was a silicone tube damper, and a letter saying that the tube damper was included because some people on forums had been complaining about microphonics.

Now, a word or two about how I tested it. I have two homebuilt tube amps, the Ninja Toaster and the Ninja Deluxe. The Toaster is a 60 watt master volume amp capable of pretty high gain, blasting through an EVM12L reissue in a rough copy of the Mesa Thiele cabinet.

The Deluxe is a 40 watt channel switching amp that started out as a Selmer Treble'N'Bass 50. One channel is similar to the old T'n'B layout, while the other has an EF86 bolted onto the front to turn it into a dirty channel. This isn't a master volume amp, but the dirty channel can overdrive its second stage quite heavily. It's fitted in a Mojotone 5E3 cabinet and equipped with a Celestion Gold.

So we have two amps (both described on this forum before) and with both of them, when played at low volume most of the character and "feel" comes from the second stage preamp tube, because it's distorting heavily while the rest of the amp is hardly handling any signal at all. So, I swapped this tube for the E813CC to see what effect it would have.

My first experiment was with the Toaster where it replaced a Mullard ECC83. I was surprised to find that I could actually hear a considerable difference. Blackburn use the words rich, smooth, creamy, (sometimes even smooooooth with extra o's ) and they aren't kidding. I've had this amp for almost 10 years, and I must have tried about 50 different tubes in the V2 position, and I'd have to say that this one has the richest, fattest distortion I've ever heard.

I then tried it in the V2 position of the Deluxe, which previously held an old Philips-Miniwatt ECC81. I'd put in an ECC81 to reduce the gain and smooth out the distortion a bit, because it was a bit too harsh and gainy with an ECC83. Again though, the Techtube seemed smoother still.

I swapped the tubes back and forth a few times, and it really does seem that Blackburn have created the most tubey tube ever. But is this all good? The downside, for me, was that sometimes it seemed a bit dull. With the gain cranked full up in the Toaster, it couldn't help but be aggressive, but at lower gain settings the original Mullard seemed to deliver more upper midrange harmonics, bite and splatter on pick attacks, and I felt the same when comparing it to the Philips tube in the Deluxe.

However, when it came to playing more adventurous chord voicings with a bit of dirt (which personally I love doing) the smoother Techtube did seem to live up to the promise of "note separation". In both amps it was able to create a lovely warmth and gruffness without any hint of the nasty grating noises I could provoke from the other tubes by playing dissonant intervals. (if you don't know what I mean, try it with a Tube Screamer, but not after a heavy meal...)

Finally, I swapped it into the Toaster's V1 position with the gain up full, to evaluate microphonics. Tapping the tube envelope with a fingernail produced a very obvious Ping! from the speaker. The original V1 (a Mullard box plate ECC83) produced a somewhat quieter Plonk! So definitely some microphonics, but didn't seem to be a huge difference.

Conclusion: I think this is a very interesting tube. Judging from what I've heard, and what I know about the CRT electron guns it's made out of, I wouldn't be surprised if it turned out to have almost a remote-cutoff characteristic, that looked nothing like the characteristic curves of an original ECC83. Considering that Blackburn probably designed it this way to minimize dissonant harmonics, whereas the original ECC83 was presumably just as linear as possible, we could in fact be looking at Tube 2.0.

I'll post a follow-up once I've traced the tube characteristic curves. We shall see if there's any substance to my subjective rantings!

Note for American readers: Please read 12AX7 for ECC83, and 12AT7 for ECC81, they're the same thing.

[Daver]

Great review! I'm interested in the characteristic curves. A guy who owns an amp I built for him recently retubed it with the Tech Tubes. He loves them even more that his NOS Mullard and Telefunkens. He is also running one in his XITS amp. I ordered two just to see for myself if they're "all that". I'm cautiously optimistic. Thanks.
Dave

[tubeswell]

Hi Steve

I'd be interested to know what plate and bias voltages were you running on the techtube? (and if you have any soundbytes of the toaster with the techtube inside?)

[Steve Conner]

Hi all,

I've just noticed that the characteristic curves are right there on the E813CC datasheet.
http://techtubevalves.com/valves/e813cc_data_sheet.pdf

Compare the "Plate characteristic" to the one on page 6 of the original Mullard datasheet:
http://www.r-type.org/pdfs/ecc83.pdf

To me, that looks as if there's definitely some remote-cutoff action going on. (Draw a loadline and look at the intersection points with the curves.)

I'll still go ahead and do some tests, though it will probably consist of putting a triangle wave through a triode stage to see the non-linearity, or putting a sine wave through and doing a FFT analysis to see the harmonic distortion.

I'm at a jam session tonight with the Toaster and will try to get some sound clips. In part 2 of this review I'll measure plate voltages and so on, and publish them along with the linearity results. For now, I'll say that the Toaster uses the standard 100k/1.5k plate and cathode resistors in this stage, while the Deluxe uses 220k/2.2k, and in both cases the supply is around 200-250V.

[Steve Conner]

I managed to record two sound clips, one with the Techtube and one with the white label Mullard ECC83 I showed earlier. In the spirit of scientific enquiry, I'm not telling which is which.

OK, it's not really that scientific (or that good either!) you can hear me fiddling with tone controls and pickup switches on the guitar, and the other guys in the band joining in now and again.

And the fundamental problem is that I knew what tube was in use, which could bias my playing style. To do a really fair test I'd need to digitize the guitar signal before it went into the amp, and then replay it through the amp, to make sure the input signal is exactly the same for each tube. I could probably do this if anyone was really that interested.

Guitar: PRS McCarty with strings in need of changing.
Amp: Ninja Toaster set up as above, overdrive mostly from first stage of V2.
Recording equipment: IRiver IHP-120 with home-made stereo condenser mic, uncompressed 44.1kHz/16 bit. Clips were compressed to 192k MP3 with Audacity.

If anyone has any requests (more gain? less gain? different riffs? better chops?) post away... Test results on linearity etc. will follow next week.

[Steve Conner]

Whoops

[Daver]

I'll take a guess that clip #2 is the Tech Tube. It sounds a bit smoother. I just got two of these and have tried them in one amp so far. They do have a smoothing effect on the tone. In this amp they are slightly dull sounding compared to some other tubes and I do mean slightly. More experimenting for me. Thanks to Steve for the clips.
Dave

[Tom Phillips]

Comment on the physical size.
Comparing the data sheet to the old Mullard, it appears that they adhered to the old tube envelope size specifications. I'm glad to see that. Some of the modern tubes are too "Fat" to fit in some applications.
From the photos that Steve posted it also looks like the pin size is good. I,ve seen some chineese tubes with pins that were lighter guage than NOS and they dis not hold tight in the tube sockets.

Thanks for all the information you have posted.

Tom

[tedmich]

silicone oil would make for good heat transfer and dampen most any microphonics; you could use a PID fuzzy logic controller and a diverter valve/radiator, and resistive heater to control the temp very precisely. Maybe hemp oil?

[tubeswell]

Hi Steve
Do you have any clean clips?

[Steve Conner]

OK, time for part 2 and a half.

At tubeswell's suggestion, I recorded two clean clips using the same two tubes (or do I mean valves, they are both British after all...) you heard in the previous recordings. Again I won't tell which is which. I used the Deluxe this time, because it has more of a standard topology (though still nothing like a real tweed Deluxe!) and placed the tubes under test in V1 of the clean channel. So, the first stage is connected to the input jack, then comes the tonestack and volume knob, then the second stage.

Reverb on the clips is the amp's own spring reverb. Bum notes are model's own. ;-)

Which do you think is which? Which do you prefer? Can you hear any difference? I'd expect the difference to be subtle, since neither section of the tube is being driven very hard at all.

I also pulled the back off the amp and measured the voltages. For the Mullard they were as follows:

Supply node 259V
V1A: Plate 132.0V, cathode 1.261V, grid 0V (assumed)
V1B: Plate 129.0V, cathode 1.299V, grid 0V

and for the Techtube:

Supply node 261V
V1A: Plate 132.5V, cathode 1.275V, grid 0V
V1B: Plate 138.6V, cathode 1.221V, grid 0V

(Note: 220k plate resistors and 2.2k cathode resistors on both sections.)

I still haven't thought up a method of comparing the harmonic distortion from the two tubes so as to give a result that's easy to understand.