On the 'tube

Will Changing Vacuum Tubes Change Your Amp’s Sound?

2

I've never had different tubes change the amp's tone; but I have had them change the amount of preamp gain and high-end. You're probably thinking, "Hey, that's tone, isn't it?" Well, what I mean is that I noticed JJ preamp tubes lowered the preamp gain and high end of my Vox amps, and Tung Sol tubes did the opposite, but it still sounded like the same amp - the tone was not altered..... I don't know if I'm making sense. I'm going back to sleep.

3

I know that an old Mullard ECC83 that I pulled from a broken tape machine made my Pro Jr sound so much better in the V1 position.

4

Coming at this from a non-amp tech perspective and is probably total BS, but . . .

Depends on what one means by "tone"? Same idea as, does pickup height/poll-piece height change a pickup's tone?

If tone is based on simply circuits and fixed components (transformers and such): e.g., a Vox circuit vs a Fender circuit (I know there are many variations within a brand), resulting in "Vox tone" or a "Fender tone" then it's a fixed thing and the answer is, No. But if tone isnt simply reduced to make, but rather voicing , then tubes and speaker changes do effect voice and do effect tone.

5

I feel that a change of preamp tubes would be more noticeable than power amp tubes. There are those that swear by NOS US or British made power tubes, but aside from reliability, it'd be hard to prove. "Tone" is really subjective from one person to another.

6

different brands of NOS 12AX7s sound different. end of story. i could elaborate in some detail, but if someone doesn't believe there's a difference there's no point trying to convince them. i haven't tried flipping power tubes because they're fairly expensive, but will retube the AC15 at some point. to me, old 6V6s sound different to new ones, but i really don't have a database.

7

Tubes make a difference. I convinced myself through extensive swapping on my CVR over the first few years of owning it. Pre-amp tube swaps change the mood or bite. Some of it is gain change, and then any noise advantage.

My most recent noticeable change was switching back to real NOS Winged C's. The bass response is more to my liking. I had no problems at all with the Tung Sol 6L6WXT+.

It had been a decade or so since having those tubes in. It could well have been the guitars I was favoring at the time, or the space I had. The Winged C's have a tighter punch.

It is a Fixed Bias circuit, but both sets of Tubes were tested twice and matched. Both sets of Tubes still used regularly.

Go figure...

8

I didn’t watch the video yet (and perhaps never will because I hate videos like this) but I have spent time with my amp tech several times playing my guitar while he was changing tubes so I could decide which sound I like best in my old tweed and BF Fender amps.
Some where warmer, some brighter or less full sounding etc. And there were volume differences. So yes, it does make a difference. Perhaps not night and day but I definitely could hear a difference.

9

Coming at this from a non-amp tech perspective and is probably total BS, but . . .

Depends on what one means by "tone"? Same idea as, does pickup height/poll-piece height change a pickup's tone?

If tone is based on simply circuits and fixed components (transformers and such): e.g., a Vox circuit vs a Fender circuit (I know there are many variations within a brand), resulting in "Vox tone" or a "Fender tone" then it's a fixed thing and the answer is, No. But if tone isnt simply reduced to make, but rather voicing , then tubes and speaker changes do effect voice and do effect tone.

– AndyJ

This is sort of what I was trying to get at with my previous post. Those tonal changes are probably things that could be dialed in using the amp's knobs anyway (my Tung Sol preamp tubes increased gain and high-end, which I could have done by adjusting the amp), but did not change the personality of the amp.... or perhaps it does, depending on what "personality" means....

The video above is probably the best way to assess this. By inverting one waveform, if the two cancel each other out, there is no tonal change.

10

I have played guitar professionally for many years and have been a recording engineer. Many say I have good ears. I have also, for a few years, sold vintage vacuum tubes and had many of the best preamp tubes come through my hands. I tried them all in the V1 tube of my Fender Super Reverb. Telefunken, Mullard, Philips/Amperex/Mullard, RCA Blackplates, RCA grey plates, Raytheon shiny plates, Seimens , GE, and many not as exciting brands, and new brands etc etc. and I have to say as long as they were the proper value, tested good and were non microphonic they all sounded great with vary little discernible variance.

Some would sell for way more than others and sometimes people would ask me what they would sound like in this or that spot in their amp and I would have to honestly say that it was purely subjective but I could say that a good, tested and non microphonic tube will sound good in their amp. I had many happy customers and positive ebay feedback.

When these tubes were being used on an everyday basis, very rarely was 'tone' or sound of tubes discussed, especially in tube advertising. It was almost always reliability and longevity. This is a telling point.

However I have found this to be like religion and on occasion when I have shared these views to interested buyers or tube enthusiasts generally people were unhappy as it contrasted with their beliefs.

Tubes as they get used and age have differing amounts of functionality, some get weaker. This will make your amp sound different. Like putting a different value component in an amps circuit can alter the circuit, thus to some degree the sound. Likely there are small variances in values between different manufacturers like all components but they are all inter-changeable. Remember that most amp components and circuits are built with a plus or minus 20% variance expected. I had this read to me like a riot act from a very old electrical guy (in an old electronics store) from one of his manufacturers catalogues. That is what I personally believe people are hearing.

Having been building my own amps for the past bunch of years(and using them live) I have found the biggest single factor in changing your amps tone will be a speaker swap.

I would say that swapping out and old worn tube for a new strong tube will make some difference, Sometimes swapping out a new, or strong tube for an older weaker one will make a difference that may or may not suit a personal preference.

11

I have played guitar professionally for many years and have been a recording engineer. Many say I have good ears. I have also, for a few years, sold vintage vacuum tubes and had many of the best preamp tubes come through my hands. I tried them all in the V1 tube of my Fender Super Reverb. Telefunken, Mullard, Philips/Amperex/Mullard, RCA Blackplates, RCA grey plates, Raytheon shiny plates, Seimens , GE, and many not as exciting brands, and new brands etc etc. and I have to say as long as they were the proper value, tested good and were non microphonic they all sounded great with vary little discernible variance.

Some would sell for way more than others and sometimes people would ask me what they would sound like in this or that spot in their amp and I would have to honestly say that it was purely subjective but I could say that a good, tested and non microphonic tube will sound good in their amp. I had many happy customers and positive ebay feedback.

When these tubes were being used on an everyday basis, very rarely was 'tone' or sound of tubes discussed, especially in tube advertising. It was almost always reliability and longevity. This is a telling point.

However I have found this to be like religion and on occasion when I have shared these views to interested buyers or tube enthusiasts generally people were unhappy as it contrasted with their beliefs.

Tubes as they get used and age have differing amounts of functionality, some get weaker. This will make your amp sound different. Like putting a different value component in an amps circuit can alter the circuit, thus to some degree the sound. Likely there are small variances in values between different manufacturers like all components but they are all inter-changeable. Remember that most amp components and circuits are built with a plus or minus 20% variance expected. I had this read to me like a riot act from a very old electrical guy (in an old electronics store) from one of his manufacturers catalogues. That is what I personally believe people are hearing.

Having been building my own amps for the past bunch of years(and using them live) I have found the biggest single factor in changing your amps tone will be a speaker swap.

I would say that swapping out and old worn tube for a new strong tube will make some difference, Sometimes swapping out a new, or strong tube for an older weaker one will make a difference that may or may not suit a personal preference.

– Toxophilite

This is great to know. I really appreciate this knowledge because I have an amp from the 1990s still with the original tubes. I've been wondering what I'll do once one of them goes. After reading this I'll be more confident about replacing them. Thank you!

12

As others have said using NOS glass usually extends the life of the tube, so just for that, that's what I like to use. I've heard differences in tone, but that just may have been the actual condition of the tube talking. But I consistently have had good luck with Sylvania Green label 12AX7 and 12AT7 tubes, and I had a few sets of Amperex Bugle Boys EL84 tubes that sounded great with everything I've put them in, as if the tone followed the tubes.

Speaking of tubes, the only time I've ever had a real eye opening experience was when I bought a TOPHAT Cub Deluxe Amp from guy. When he sold me the amp he told me he would install a set of brand new JJ 6V6 tubes in it for me, which he did, they were 6V6S variants. I didn't mind that they were new production tubes, as Brian Gerhard who builds these amps ships them with new tubes. Well I never did bond with that amp, it just didn't have the type of overdrive that I normally go for in a 6V6 amp so I was just going to sell it. So when getting ready to sell it, I pulled the tubes as I was going to ship them in their own box, and I accidently dropped one of the 6V6s tubes, and it broke. Fortunately I just received a NOS pair of Sylvania 6V6GT tubes in the mail for another amp. So I figured I'd put them with this amp. I installed them in the TopHat to test them out and make sure they were good and DAMN the amp now sounded GREAT. Needless to say I still have the amp and LOVE it. SInce then I've heard the JJ 6V6S is built more like a 6L6 tube so that's maybe why it didn't sound right to me.

13

Combinations of preamp tubes with varying gain will definitely affect the behavior of the amp: how soon it breaks up, the perceived tonal balance of that breakup.

And power tubes that are going bad (ie, deteriorating or malfunctioning to the point that they fall way out of spec) DEFinitely affect the tone of the amp. (Generally it gets kinda dirty, then real dirty, then real loud, then not loud, then catches fire.)

I've been educated in the behavior of power tubes as they age in the School of Peavey, via the (relatively) fast degradation of EL-84s in the shaker-box of Classic 30 amps. If you're playing it regularly, you can burn through a set of power tubes in a year to 18 months. They lose headroom, get microphonic, set up bizarre resonances somewhere in the spectrum, and finally get so farty and miserable you just can't go on.

You put in a new set and it's like a miracle. You'd certainly say it "changed the tone." But it didn't really; it just returned the amp to its design spec.

I'm with Tox on this: aside from preamp gain behavior with interchangeable tubes of different design spec, what we're hearing as differences as we change tubes is the sum of variances from spec in the tube complement currently installed. With 6-10 tubes in an amp, and a bit of variance one way or the other among them, it makes for an enormously complex and interactive puzzle for committed tube churners.

But - aside from substituting differently-spec'ed (but compatible) tubes, or the bad behavior of failing tubes - swapping equally healthy tubes of the correct spec for each position in your amp will make very subtle, if any, difference. I've never heard the whole character of an amp transformed thus. Changes elsewhere in the signal chain (or, frinstance, with the knobs on your guitar) will make more obvious and profound differences.

As Tox says, the speaker is the biggie. If your tubes are functioning, not overheating, not microphonic, and you're looking to experiment with the amp's character, spending money on a speaker (or pedal!) will buy considerably more bang for the buck.

14

If you use JJ's, you never know what you'll get. With quality tubes, they should all sound the same until you push them into distortion. Then they'll have different distortion characteristics. PreAmp tubes should all sound the same unless you have a hi-gain amp that uses one of them for distortion, in which case there's a difference. If you overdrive the output of your amp a lot, you can experiment with different output tubes. Generally, choose preamp tubes for reliability & low noise. They're just linear amplification. FWIW, the cheaper Sovteks are usually better than the fancier more expensive tubes...12AX7wa, 5881, EL-84's, etc. I haven't run across any good EL-34's or 6V6's in a while, but I'm not doing amp repair full time anymore, so I don't go through nearly as many.

15

Been a die hard tube sniffer for many years now. I gotta say that tube variations in the primary pre-amp slot(s) can do wonders for the overall sound of the amp vis-a-vis tonal weight, sustain and distortion color. Nor does the same tube necessarily work exactly the same way in two different amps - i.e, a different circuit. I've done a lot of experimenting in both my '57 Tweed Deluxe and '57 Tweed Bandmaster to find the perfect signal generator for each. The results, to me at least, have been well worth the effort. Another thing I've discovered is that the right power amp tube also makes a substantial difference, especially in band situations when you really have to start working them.

As for the brand(s) I'm currently using, well, I could tell you but then I'd have to kill you. Just kidding. NO sense trying to sell you on my setup, you have to find the combo that works for you. I will say however that each of my amps is currently enjoying an exceptional NOS (last of my 70s stash) in no 1 position. And even though I've compared these beauties with most of the current offerings and found some pretty road worthy glass among the current crop, Lord help me when the NOS treasures finally wear out...

16

My experience has been exactly as the General has described it. #1 and power tube makes a difference.

17

The best evidence I've seen that the circuit, not the tubes, define the tone of the amp is an Egnater Rebel 20 that I used to own. It allows you to select between (or blend) two types of output tubes: EL84 and 6V6. I've switched between them over and over again, and there was no difference in tone, other than a slight increase in high-end with the EL84s, which I could have achieved by turning the treble knob slightly clockwise.

I remember back in the 90's a friend of mine had an ADA MP-1 rack rube preamp. He put Mesa/Boogie tubes in it so that it would have a "Mesa/Boogie tone". Even in my 20's, ignorant as I was, I knew this guy (a great guitarist, by the way) had no idea what he was talking about.

18

The best evidence I've seen that the circuit, not the tubes, define the tone of the amp is an Egnater Rebel 20 that I used to own. It allows you to select between (or blend) two types of output tubes: EL84 and 6V6. I've switched between them over and over again, and there was no difference in tone, other than a slight increase in high-end with the EL84s, which I could have achieved by turning the treble knob slightly clockwise.

How loud did you play the amp? The differences become more apparent when the master is up and you drive the power tube section. If you use the amp straight clean or as a pedal platform you won't notice this, that's right.

19

The best evidence I've seen that the circuit, not the tubes, define the tone of the amp is an Egnater Rebel 20 that I used to own. It allows you to select between (or blend) two types of output tubes: EL84 and 6V6. I've switched between them over and over again, and there was no difference in tone, other than a slight increase in high-end with the EL84s, which I could have achieved by turning the treble knob slightly clockwise.

How loud did you play the amp? The differences become more apparent when the master is up and you drive the power tube section. If you use the amp straight clean or as a pedal platform you won't notice this, that's right.

– sascha

I plugged straight into it. At lower volumes I heard no difference; when I drove it hard that's when I noticed the EL84s seemed to have more of an "edge", but realistically that "edge" was just a touch more high-end.

20

I plugged straight into it. At lower volumes I heard no difference; when I drove it hard that's when I noticed the EL84s seemed to have more of an "edge", but realistically that "edge" was just a touch more high-end.

– stratman

Thanks, Stratman. Seems different amps act differently. (What a surprise!) Maybe the newer designs are even more "forgiving" than the old classics? The Victory V40 Duchess is another candidate. Available in 6L6 and EL34 version these actually don't seem to differ in terms of sound.

Tube swaps had a noticable impact in some amps I have.

23

I agree with what Mr Zoom and 'Tox said - as long as you're in the linear (non-distorted) region of the amp's output curve - a tube is a tube, as long as it isn't shot. It's only when you're using the amp in the non-linear/distorted/clipped region of its output curve, that different tubes start to sound different, mainly because their compression, clipping (how hard is the sine wave clipping), and harmonic content act differently, due to the different physical make-up of different tubes brands (are they using graphite elements, thoriated tungsten, is the tube envelope glass, metal or ceramic, differences in inter-electrode capacitance, etc.).

24

An interesting point about tubes vs circuit in differences could be made with the Fender early 60s 6G9 tremelux. It has El84s in the power amp but from what I've read still sounds like most fender amps which largely use 6V6s or 6L6s.

Inspired by 6G9, I built a stereo deluxe reverb from scratch which uses Russian equivalent 7189s in the power amps giving the amp a little more clean headroom and making the PA more robust for high voltages. It sounds like a Fender deluxe. The two sides sound a little different but largely because one side is a deluxe reverb through a JBL D123 and the other side is a straight deluxe through an Eminence lil' Texas (largely for weight considerations). Thus one side has one less gain stage and a pretty different speaker. Here it is in a goofy party tune. https://soundcloud.com/user...

25

Just to further my take on the subject, this is how I'd rate the main variables in terms of their effect on adjusting/fine-tuning the color of your favorite tube amp:

  1. Speaker - a complex and significant factor (info all over the net). BTW, I favor AlNiCos types.

  2. Tube variations - as discussed above.

  3. Circuit components - especially the tone filter caps.

  4. Your particular brand of coffee...


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