18Watt.com

I wonder if you could wire in a 10 or 25 ohm pot between one of the EL84 cathodes and the bias resistor and then dial in a little "unmatching". Then tweak it by ear to taste.

The hum is the only real problem - a badly matched pair will hummmm ...

There are some designs that have balance pots to minimise the hum.

Your ears - that's all. The other stuff can be both misleading, and give you an amp that sounds sterile by comparison. Just pick pairs of tubes that sound great in your amp. Anything else is baloney.

AMEN to that!

OK, Let’s take a step back here and think a bit;

Even if you had a pair of super duper matched tubes within .0001 of a mA, when you’ll play your amp, tubes will not wear out at the same rate so what’s going to happen after a couple of gigs? Your tubes will be…unmatched!
Is your amp going to have a melt down? Nope! Is you amp going to start doing nuclear fission and cause a nuclear holocaust? Probably not. Are the tubes Gods going to come down and haunt you? Well.., if you buy into the tube matching voodoo, then they probably will!

Hey, I remember as a teenage bringing a Dual Showman to a party to find out that one of the tubes had fell at the bottom of the cabinet and broke. What did we do? We went to the local music store, bought a 6L6, popped it in and partied on, all that without biasing! Heck, I’d never even heard of biasing back then!!

Like Zaphod_Phil said, use your ears and forget about that Groove Tubes (and others) tube matching hype.


Ok, rant’s over.. thanks for listening!

I've been slowly building up a small NOS stash, and just purchased a pair of 6P14P-K tubes, match is 10 ma apart.....I appreciate the contributors to this thread, the match was a concern, though not red plating.......it does sound good......and will probably sound better when I change the cathode resister in the amp...... running a little cold......

How far apart is too far on the match?
I gather when there's a hum problem it's too far......but at what point in a mismatch does that tend to be?........
Much respect, and thanks in advance...........

New here!! 1st Post - Guitarist / indie audio engineer - just checking if I install two Telefunken EL84's Power Tubes from Germany NOS - non matched pair - testing "strong" - that my new VOX AC10 C1 amp will be OK. I like the Telefunken sound - bright Beatles'/rock. Concerned about voiding warranty.

Hard to see "red-plating" as amp has a closed back. I like the idea of working with even-ordered harmonics to get a great rock / blues sound. "Hum" will be the test if anything is wrong.

Right now, new amp is very quite: Sweetwater installed JJ's in both Preamp (2) / Power Tubes (2). If / when I hear noise, it goes away depending on 1) how close I am to the amp and 2) the direction my guitar faces the amp. Four feet away from amp = no noise. Some noise when gain is turned up past 1pm.

Apartment studio. VOX AC10 C1 = Gain 9:00 and MV anywhere from 11:00 to Max. EQ = Bass rolled off to 9:00 (gets rid of boomy sound with E Chord), Treble @ Noon, with Reverb Off. With these settings, I get a clean sound that works well with fuzz pedals. Putting amp on a Gator stand further reduces a boomy low end sound.

Today, will be installing Telefunken ECC83 NOS tubes (2) into the Vox AC10 C1 preamp section: recently discovered a batch of tubes and a Precision Tube Tester hidden in a corner behind a Ludwig bass drum. Cleaning the studio has rewards! Want to see if sound gets better from what JJ' Tubes can do.

New to Strat guitars / Vox amps. For years, played a Tele / EMG 85s with a Fender 1966 Blackface Champ (Telefunken ECC83) modded by Gerald Weber (Studio Rec/Stage gigging - mic'd) - Texas Tone (on/off) Raw vs EQ sound, Feedback (on/off), and a larger "Texas sized" OT.

Mismatched tubes also increase the standing flux in the core of the output transformer. Depending on the severity of the imbalance, this can cause early saturation, which limits output power. Tubes that are burned in, then matched, will usually maintain good balance for most or all of their life. Whether companies like Groove Tubes do this, I don't know. I suggest checking with Jim Mcshane if you think this service would be helpful. He has an excellent reputation for providing good quality tubes.

http://www.mcshanedesign.net/tubes.htm

Jack

I am not sure if the OP's query has been answered above or not. But here is my response anyway.

From reports on here almost any pair of valves will be less likely to cause issues than the JJ EL84s fitted. There are many cases of failures. Just the EL84s for some reason. Personally I would not hesitate to choose the Telefunkens anyway. How long they work at optimum level will depend on how you use the amp. At domestic power output levels I suspect they will last as long as you want them to. I have used many pairs of random power valves with no issues for the amps in question. For a while I drove myself nuts trying different combinations and listening for benefits.

Dd

Daviedawg wrote: ↑

Fri 08/13/21 2:22 am

I am not sure if the OP's query has been answered above or not. But here is my response anyway.

From reports on here almost any pair of valves will be less likely to cause issues than the JJ EL84s fitted. There are many cases of failures. Just the EL84s for some reason. Personally I would not hesitate to choose the Telefunkens anyway. How long they work at optimum level will depend on how you use the amp. At domestic power output levels I suspect they will last as long as you want them to. I have used many pairs of random power valves with no issues for the amps in question. For a while I drove myself nuts trying different combinations and listening for benefits.

Dd

Though I really like the sound of JJ ecc83s I can never trust them anymore. Too much failure . I'm pretty happy with sovtek 12ax7a. They're very reliable. Ok, there are better sounding tubes out there, but less reliable IME. The EL84M is the only tube that survives for years in my Vibro King's reverb

Bieworm wrote: ↑

Fri 08/13/21 6:23 am

Though I really like the sound of JJ ecc83s I can never trust them anymore. Too much failure . I'm pretty happy with sovtek 12ax7a. They're very reliable. Ok, there are better sounding tubes out there, but less reliable IME. The EL84M is the only tube that survives for years in my Vibro King's reverb

I've had zero issues with new production Mullard, or Tung Sol. No issues with Sovteks either, and depending on which type, some of them sound very good. The Sovtek 12AX7WA and WB varieties sounded good to me.

JMPGuitars wrote: ↑

Fri 08/13/21 8:37 am

Bieworm wrote: ↑

Fri 08/13/21 6:23 am

Though I really like the sound of JJ ecc83s I can never trust them anymore. Too much failure . I'm pretty happy with sovtek 12ax7a. They're very reliable. Ok, there are better sounding tubes out there, but less reliable IME. The EL84M is the only tube that survives for years in my Vibro King's reverb

I've had zero issues with new production Mullard, or Tung Sol. No issues with Sovteks either, and depending on which type, some of them sound very good. The Sovtek 12AX7WA and WB varieties sounded good to me.

My choice is the WA sovtek.
I use tung sol often too. Mullards are always more expensive, but to me they don't sound much different from an EHX or Sovtek to justify the price. The JJ are always cheaper, and I find the ECC83 very good in V1 position. They seem to sound a little darker and beefier.. but the quality!!! OMG!!!

Bieworm wrote: ↑

Fri 08/13/21 9:13 am

My choice is the WA sovtek.
I use tung sol often too. Mullards are always more expensive, but to me they don't sound much different from an EHX or Sovtek to justify the price. The JJ are always cheaper, and I find the ECC83 very good in V1 position. They seem to sound a little darker and beefier.. but the quality!!! OMG!!!

You need to pay attention to the mids. They all sound good, but they all sound a little different. I don't think one is better than the other among those.

Liquidfusion wrote: ↑

Thu 08/05/21 2:46 pm

New here!! 1st Post - Guitarist / indie audio engineer - just checking if I install two Telefunken EL84's Power Tubes from Germany NOS - non matched pair - testing "strong" - that my new VOX AC10 C1 amp will be OK. I like the Telefunken sound - bright Beatles'/rock. Concerned about voiding warranty.

Hard to see "red-plating" as amp has a closed back. I like the idea of working with even-ordered harmonics to get a great rock / blues sound. "Hum" will be the test if anything is wrong.

Right now, new amp is very quite: Sweetwater installed JJ's in both Preamp (2) / Power Tubes (2). If / when I hear noise, it goes away depending on 1) how close I am to the amp and 2) the direction my guitar faces the amp. Four feet away from amp = no noise. Some noise when gain is turned up past 1pm.

Apartment studio. VOX AC10 C1 = Gain 9:00 and MV anywhere from 11:00 to Max. EQ = Bass rolled off to 9:00 (gets rid of boomy sound with E Chord), Treble @ Noon, with Reverb Off. With these settings, I get a clean sound that works well with fuzz pedals. Putting amp on a Gator stand further reduces a boomy low end sound.

Today, will be installing Telefunken ECC83 NOS tubes (2) into the Vox AC10 C1 preamp section: recently discovered a batch of tubes and a Precision Tube Tester hidden in a corner behind a Ludwig bass drum. Cleaning the studio has rewards! Want to see if sound gets better from what JJ' Tubes can do.

New to Strat guitars / Vox amps. For years, played a Tele / EMG 85s with a Fender 1966 Blackface Champ (Telefunken ECC83) modded by Gerald Weber (Studio Rec/Stage gigging - mic'd) - Texas Tone (on/off) Raw vs EQ sound, Feedback (on/off), and a larger "Texas sized" OT.

NOS GERMANY TELEFUNKEN EL84 ?
Installed into a Vox AC style guitar amplifier?
Oh my! The sacrilege!!!
Certainly they must sound tasty and delicious.
However, in my experience, many EL 84 guitar amplifiers and especially the semi pseudo class A styles of guitar amps such as the Vox AC models , seem to really eat up EL84 valves. The best tones result in about a year of decent service life of an EL 84. This is just my own humble and dumb luck experience. Others may have other opinions. But yes those are a fine valve that I would keep in a glass display case and would break them out only for testing and comparison as well as on very special occasions to audition!
Seriously, I would save those for special occasions or special recording sessions or some very special amplifier besides the Vox.
As for the ECC 83 NOS Telefunken and most any other 12ax7 preamp applications, there is no perceived or required matching. However, in the case of phase inverter application it is often desirable to have the tubes internal twin triode halves matching.
Getting back to those Telefunken ECC 83 preamp tubes. If they are indeed orig, vintage German specimens,,,
Well, I wouldn't use them because they will spoil your ears of anything lessor! LoL!!!
They will sound great inside your Vox and I won't admonish you for the application inside the Vox because they will serve many many years of faithfully service. Basically, I wouldn't want to prematurely wear out the NOS Telefunken EL84 s in a supposed "class A" guitar amp application! Use a NOS Mullard, a Bugle Boy, or best yet a NOS Sylvania but God save the Telefunken!
You will enjoy the Ecc83s!
As for final output tube matching?
Does it not make sense to have at least some sort of control or baseline to get you into the ballpark scientifically?
Maybe they didn't match in the good ol days, but we know much more today about the science of the various nuances that effect guitar amplifier tone. Everything that is considered good amplifier engineering design practice flys in contradiction to best guitar tone?
Remember the old vintage gear was designed by budget not best tech. We now are begining to have a much greater understanding about the contribution of budget design idiosyncrasies effect the tone of musical instrument amplification in a most pleasant way. After all it isn't electric guitar without the electric guitar amplification. Best linear amplification practices produce a sterile tone. The amplifier flavors the tone every bit as much as certain tone woods enhance a 200 yr old Strativarious Violin.
We have the technology and a better understanding of how the design shortcomings of our most reverent vintage designed gear contributed to that mojo. Some mojo may be overstated or misunderstood , but we are getting better at quantifying the Mojo. Ultimately it is the players ears and preferences . That is a given, but does it not make good sense to have a known baseline such as the documentation of test curve data and matching tubes. All being the same we can design the other factors such as output transformation imbalances and bias point and other parameters.
And yes there is indeed big enough variability in all vacuum tube devices to warrant a basic rudimentary match.
That's my own two cents worth of opinion. For whatever that's worth with inflation! Whatever works for you is what matters.

southboundsuarez wrote: ↑

Sat 08/28/21 6:41 pm

And yes there is indeed big enough variability in all vacuum tube devices to warrant a basic rudimentary match.
That's my own two cents worth of opinion. For whatever that's worth with inflation! Whatever works for you is what matters.

Is there? The question of tube matching is a fairly polarized topic. Many well respected guitar techs, including Zaphod_Phil on this site (search for his opinion on the topic) would argue that guitar tone is better with unbalanced tubes.

I obviously love tube tracing, but I don't have an opinion on tube matching or not. I would need to A/B record the same amp with matched and unmatched tubes... BUT FIRST would have to determine what margin of error is considered matched or unmatched, along with what variables are matched within that margin. Then trace the tubes and see if any of the tubes actually match even if advertised as such. Then prepare a recorded guitar loop so the playing doesn't vary between the recordings. Then have somebody else record the actual production, and have a 3rd person play the samples back to have a proper double blind taste test. Or I could skip all that work and continue not having an opinion on the subject.