Tube Testing

[Nelskie]

OK Fret Net Tube Gurus - Here's something that came whistling in from left field today.

My 2001 Cyber Twin uses (2) 12AX7 tubes in the pre-amp stage. Seeing that the tubes that are in there now (I'm assuming that they're original) are getting close to (5) years old, I thought it might be time to change them out for something else. Having read on some online forums that the Electro-Harmonix tubes work very well with this amp, I decided to go over to the Tube Depot to see what the cost would be for a pair. It was at this point that I found a drop-down menu next to the tube, and in that menu a number of options for "testing" the tube(s).

http://www.tubedepot.com/eh-12ax7.html

Well, I'm no expert when it comes to "tube-testing", and am wondering if there are benefits to doing it. These were the options that were given:

1.) Standard test
2.) High gain test + $2
3.) Matching + $2
4.) Balanced triodes + $2
5.) Matched / balanced triodes + $4
6.) Low noise & microphincs + $4

Now these costs are per / tube, so if you wanted to have some testing done, you could stretch that $7.95 original price tag to nearly $20 / ea. That would bring the cost of the pair to around $40. Not huge dollars by any means, but again, it would be helpful to know what testing options would really have the biggest effect, or which ones were the most necessary.

Two other things I found out about the Cyber Twin today: 1.) There isn't a lot of information available on the internet on these amps - mods, patch settings, or general maintenance - even on the Fender Forum; and 2.) Nearly every amp website I checked out had nothing but searing contempt and riducule for this Fender amp model. And that's putting it very lightly. Oh well, as an avid PODxt user, I guess I should be used to it by now.

Insights and opinions are welcomed.

[SuperSwede]

I found this page for you Nelskie, there seems to be some sysex (you need midi for this) patches here (and text versions as well)...

http://www.patchwizard.com/pw_FCTPP01.htm

And here:

http://www.sysexdb.com/synth_detail.asp?dv=196

Here you got a editor that you can hook up to the cyber twin via midi:

http://www.patchwizard.com/pw_download.htm

[Spudman***]

Personally I wouldn't worry a lot about testing your preamp tubes. It's not worth the $. Just get a pair that everyone else likes and put em in. The EH are good from the ones that I have. Even some of the Chinese and Sovteks are good. Since you are modeling I wouldn't worry about high end preamp tubes because you are changing sounds anyway.

[6STRINGS 9LIVES]

Nelskie...5 years is nothing on a 12ax7,, .. unlikely there would be any degradadation in spec or tone , may be just a little warmer .I have amps with old tubes that work just great 30-40 years old and sound better than current replacements . do a little research on "nos tubes " they are the hot ticket tone wise , more expensive but you are buying a brand new old tube which are without a doubt sonically superior .. check out mullard tubes in particular they are the holy grail when it comes to 12ax7, 12ax7a 12au, rca blackplates are awesome as well , personally i prefer rca blackplates in my fender amps .. for moderate operation times 2-3 hours per day they will last a long , long time ...one word of caution however , nos tubes are extremly addictive , there is no goin back , there is a difference . 6S9L

[Nelskie]

Swede - Thanks for the links. Patch wizard has some good stuff there.

69SL / Spud - Thanks for the input. I do have another question, though. I shot an e-mail off to J & J / Eurotubes, and they recommended a completely different tube. Here is their response:

For the Cyber Twin, we would go with a pair of the ECC83S preamp tubes that are matched and have a gain factor between 105 and 110 which will not hurt the clean tones. These will fatten up the drive sounds and add warmth to your tone. The JJ's have a very deep tight low end, a natural harmonically rich mid and a smooth sweet high end with a nice sparkle that's not brittle.

Can you use an ECC83S tube in place of a 12AX7? I mean, I'm just walking around in the dark here.

[ZoSo65]

Can you use an ECC83S tube in place of a 12AX7?

Yes sir, not a problem.
ECC83 is the European number for the 12AX7, some tubes even have both codes stamped on them.

[Nelskie]

ECC83 is the European number for the 12AX7, some tubes even have both codes stamped on them.

Thanks ZoSo - I was wondering what was up with that.

[duhvoodooman***]

By the way, Electro Harmonix are basically Sovtek tubes--made in the same factory, from what I've read.

And, yes, confirm what ZoSo said--two different names for the same tube.

Tough to go wrong with Eurotubes, but also keep in mind that JJ Tesla is all they sell. Not that that's a problem--excellent tubes from all I've read, and I'm certainly pleased with the set I put in my Delta Blues!

That "adder menu" from Tube Depot seems pretty gimmicky to me. As a contrast, check out the various 12AX7's available from South Valley Vintage Amps. This guy individually tests every tube he sells and records the results (inlcuding gain, balance, noise, shorts & grid emission) on a label affixed to the box--all for no extra charge! Read his "Tube Q&A" page--very interesting stuff. He rejects a significant quantity of the tubes he receives and won't sell them to his customers. I have one of his Groove Tubes "Mullard Reissue" 12AX7's in my VOX AD30VT.

Another comment--tube matching is only important for buying pairs or quad of power tubes. So don't pay extra for it for preamp tubes!

And even if the EH's in your Cyber Twin are still fine, it doesn't hurt to have a couple of spares on hand and do a little tube swap experimenting!

[Spudman***]

Can you use an ECC83S tube in place of a 12AX7? I mean, I'm just walking around in the dark here.

ECC83 What a splendid idea. I'd go for it.

[Nelskie]

DVM - Thanks for the good info, and link to S. Valley. I have a tendency to agree with you on the tube-testing thing - it does indeed seem very "gimmicky", esp. for players who may not be "in the know".

Another question I'd like to ask is this: what do the #'s behind the 12AX designation mean. For instance, the Fender website listed the Cyber Twin's pre-amp tubes as 12AX7WA. Looking at the S. Valley website, I see that have a Groove Tubes Mullard re-issue that is listed as a 12AX7-M. Do these letter designations have any bearing on whether or not the tube will fit in the amp?

My interest in changing out the tubes in my Cyber Twin stems primarily from the significant tonal improvements I've attained from re-tubing my C30 and Valve Jr. True, it may not be a necessity, but since I've never done it with a modeling amp, I'm just wondering if there are benefits to be had. The amp sounds great right now. But what if it could sound better?

[duhvoodooman***]

Another question I'd like to ask is this: what do the #'s behind the 12AX designation mean. For instance, the Fender website listed the Cyber Twin's pre-amp tubes as 12AX7WA. Looking at the S. Valley website, I see that have a Groove Tubes Mullard re-issue that is listed as a 12AX7-M. Do these letter designations have any bearing on whether or not the tube will fit in the amp?

These suffixes seem to designate minor differences in internal construction or just a way to differentiate the tube. For example, the "M" on the GT Mullard tube designates nothing more than that it's designed to emulate the original Mullard construction. Any 12AX7 should work for you, AFAIK.

As to whether or not it will actually sound better in your Cyber Twin....guess you'll have to try one and let us know!

[tot_Ou_tard]

I too have some tubes from South Valley Vintage Amps. The noise grades are all good, but the balance grades vary from C to B. I asked the owner about the importance of balance & he said that unless it was used as a phase inverter it wouldn't matter (& maybe not even then). Balance measures the how closely matched the two triodes on the tube are. He said that he was not familiar with the Valvetonix line (which is where my tubes were destined to live).

Today I found a site that mentioned that VOX choose the EH's because the balance was consitent. This makes sense as the Valvetronix uses one triode for class A type amps and both triodes (one as push and one as pull) for class A/B amps. I have no idea if it really matters, but it wouldn't hurt to ask that you get a tube with good balance ratings if you are replacing the tube in a Valvetronix product. If someone wanted to do some testing they could dial up a Class A/B model with two tubes that were identical except for their balance ratings.

That is *waaaAAAaay* too obsessive for me, but I'd be happy to hear the reviews.

[tot_Ou_tard]

These suffixes seem to designate minor differences in internal construction or just a way to differentiate the tube. For example, the "M" on the GT Mullard tube designates nothing more than that it's designed to emulate the original Mullard construction. Any 12AX7 should work for you, AFAIK.

As to whether or not it will actually sound better in your Cyber Twin....guess you'll have to try one and let us know!

As Voodoo sez: they'll all work fine, they just designate different tonal & gain characteristics.

[ZoSo65]

Here's a little something I found on matched pairs:

First of all, “matched” refers to set of power amp tubes. Preamp tubes are not sold as matched sets, nor are matched sets required.
In the early days of tubes amps nobody really worried about matched sets of power amp tubes, and many manufacturers to this day still do not. I have even heard it theorized that part of the old Fender "sound" was due to the fact that they did not care about matched tubes. They just plugged in the tubes, dialed in a recommended bias voltage, and that was it.

Tubes will test differently from day to day because of fluctuations in the power supply and "drift" in the tube over time as it ages. The first 100 hours of playing, and especially the first 24 to 48 hours, may change matching significantly enough to render it a useless consideration.
Even "burned in" tubes can and will drift over time. Any supplier who tells you that "burned in tubes will not drift" is either lying to you, or does not know what they are talking about.
For that matter, pick up one tube of your new “matched” set. Shake it real hard for a few seconds. Guess what? You no longer have a matched set. Vibration and heat have a major affect on tubes.

Saying that matched tubes are absolutely necessary is a bit of Mojo in itself. This issue is not as big a deal as a lot of people make it out to be. For this to be a big deal, you have to assume symmetrical power supply, and zero component tolerance. Still, it is a good idea to have the tubes matched as closely as possible. It sounds better, tubes may last a little longer, and hum and noise will sometimes be reduced.
Most power amp tubes are sold in matched sets anyway. It bugs the crap out of me though, to see sellers charging extra for "premium matching" or some other such nonsense. It's really just a big ripoff in most cases. For most amps, a plate current match within 20% is acceptable, and 10% is excellent. Matching any closer than that is not necessary in my opinion.

[Bloozcat]

The only current production tube that has the 'WA' designation after the 12AX7 is the Sovtek 12AX7WA, which is the reigning champ OEM pre-amp tube for most manufacturers. This tube is one of the more unremarkable tubes on the market and as such is probably the most swapped out pre-amp tube in the world. A lot of tube sellers don't even bother to carry them, or do so only for those customers who insist on using the exact same tube as that which came with their amp. Of the currently produced pre-amp tubes, the "new" Mullard 12AX7-M and the "new" Tung-Sol 12AX7A are the two that consistantly garner the highest accolades in the tube world. The JJ's are ok, but they tend to be dark sounding. The Chinese Shuguang 9th generation 12AX7 gets pretty high marks too as a high gain 12AX7 type. Another decent one is the Sovtek 12AX7LPS, which is the only Sovtek tube I've ever liked. One word of caution on the new Mullard 12AX7-M; buy it only from a tube dealer who tests his tubes and will replace defective ones. The rejection rate due to failures on the 12AX7-M's is quite high, so you only want those that have been pre-screened.

Then there's NOS (New Old Stock)....
These are my favorite tubes, not only for their tone - which IMHO is superior - but for their longevity as well. These tubes were made at a time when tubes were the cutting edge of technology. They were made to be robust, and many were made with the extra requirement of having to be "Mil-Spec". These tubes are expensive though, and continue to go up in cost as the supply dwindles. You would be hard pressed to find an NOS 12AX7 for under $30.00 ea. right now, unless you luck upon a supply somewhere. Tube vendors all know what they're worth and charge accordingly. The trick in the NOS market today is in finding NOS tubes that are not the brands that everyone knows, but that still deliver the performance that you need. A case in point: There's a tube known as a BEL 12AX7. It was made in India by Mullard on Mullard equipment for NATO contracts. It is essentially just like one of the coveted Mullard Blackburn 12AX7 tubes that sell for $100.00 or more ea. The BEL can be had for $30.00 ea. I have several in my amps.

All six of my amps are tube amps, so I am constantly searching for deals on pre, power, and rectifier tubes. Since I prefer the more expensive NOS variety, I have to spend a lot of time looking.

If you'd like Nelskie I can give you the names of the tube dealers I use regularly. First decide which way you want to go - new or NOS - and that will dictate which vendors and the cost.

[Spudman***]

Blooz
If you don't mind posting it...go ahead and let us know where we can get these tubes. I have 5 tube amps myself with the possible addition of the Epi Jr. making 6. It would be a good resource for us Fretters to know where to get NOS tubes and to have the recommendation from you.

[Nelskie]

If you'd like Nelskie I can give you the names of the tube dealers I use regularly. First decide which way you want to go - new or NOS - and that will dictate which vendors and the cost.

Blooz - If you wouldn't mind doing that, I and the rest of the tube-hounds here at FN would be very appreciative. Or, just PM me if you'd rather not disclose your sources in open forum.

Guys, thanks for your insightful responses. My initial gut-feeling is to check out some new tubes, rather than the spendier NOS units. With the Cyber Twin being a modeling amp and all (er, I mean cybernetic amp), I'm wondering as to whether or not putting some really good tubes in it will have a benefit equivalent to their cost. If it were an all-tube rig, yeah, I'd probably consider going that route. Right now, those Mullard re-issues sound like an interesting option. Not only will they add some tonal excitement, they'll fit the bill price-wise, too. I'm also considering the Electro-Harmonix 12AX7-EH's. I've read some good things about their performance in this particular amp.

Spud -

I have 5 tube amps myself with the possible addition of the Epi Jr. making 6

Possible addition? Now that's funny! It sounds more like a "matter of time" thing to me.

[Spudman***]

Spud -

Possible addition? Now that's funny! It sounds more like a "matter of time" thing to me.

OK, I'm busted. Sure I'm going to get one cause I'm a tube junkie. What did you think? That I had any kind of restraint whatsoever? Nope, not me. I'm addicted to that rush.

And if anyone can tell me the band that wrote that last sentence I will mail to them the new Flowerkings CD Paradox Hotel.

[Robert****]

I KNOW that line, Spud! It's some band I grew up listening to. Hmm....

Mr. Big?