A n00b question about tube amps

[atticus3897]

i have a question as to what makes different tube amp heads sound different, for instance, say a peavey valveking 100w head (which I own) and a mesa boogie single rectifier are coming out of the same cab, i've only briefly read about these, but here are the specs...

Peavey Valveking:
Four 6L6GC tubes
Three 12AX7 tubes

Mesa Single Rectifier:
Two 6L6 tubes
Five 12AX7 tubes

similarly

Orange Rockoverb:
Four ECC83 tubes
Four EL34 tubes

Marshall JCM2000:
Four ECC83 tubes
Four EL34 tubes

now, shouldnt these sound similar? what else contributes to the sound that these amps give, besides just turning the knobs and changing the settings, i mean in terms of the actual insides of the head itself?

i know barely anything about tube amps, or amps in general for that matter, but im looking to be enlightened

[Milnoque]

You would benefit from reading a book on the subject. "The Tube Amp Book" by Aspen Pittman or "A Desktop Reference of Hip Vintage Guitar Amps" by Gerald Weber would be good choices but there are many others. The question you have asked requires a lot more information than you can get from a venue like this one.

[antichef]

Those books are good. There are a lot of factors, such as the circuit that supports the tubes, the transformers, the speakers, etc., and they all interact with one another.

[eyema_believer]

Originally Posted by atticus3897

i have a question as to what makes different tube amp heads sound different, for instance, say a peavey valveking 100w head (which I own) and a mesa boogie single rectifier are coming out of the same cab, i've only briefly read about these, but here are the specs...

Peavey Valveking:
Four 6L6GC tubes
Three 12AX7 tubes

Mesa Single Rectifier:
Two 6L6 tubes
Five 12AX7 tubes

similarly

Orange Rockoverb:
Four ECC83 tubes
Four EL34 tubes

Marshall JCM2000:
Four ECC83 tubes
Four EL34 tubes

now, shouldnt these sound similar? what else contributes to the sound that these amps give, besides just turning the knobs and changing the settings, i mean in terms of the actual insides of the head itself?

i know barely anything about tube amps, or amps in general for that matter, but im looking to be enlightened

Let me preface this post by saying that I am no where near being a tube amp expert.

While it's true that there are way too many factors to look at specs alone and know how an amp will sound, there are some things that you can figure out.
For instance... any amp with an EL34 or 6L6 power section will have lots and lots of clean head-room. On top of that, those tubes will put out more power per tube than an EL84 or a 6V6. In other words, you will have to turn the amp up to ear-bleeding levels before you get any of the coveted power tube saturation/distortion. I would say most folks on regular stages on the weekends at bars are not pushing thier amps into power tube saturation, because it would be too loud, and thus are not really getting all the "tubey-ness" out of their tube amps.

And so you know, an ECC83 is the same as a 12AX7... those are just different names for the exact same tube. The number of preamp tubes in an amp can tell you about how many gain stages the amp has, but not always. It depends on how they are being used, and if they use different ones for different channels of the amp... how they are cascading the gain stages ect... Some of the tubes may not be for outright gain, but maybe for a phase inverter, or a tube rectifier, but those applications would usually use a different tube than a 12AX7...

At the same time, I'm finding that some of the things people assume are not as true at we would like to think. For instance, people always associate an amp that is powered by EL84s with a Vox AC30 amp. The most popular version of that amp has what they refer to as a "Top Boost" circuit. Well, that puts a lot of "chimey-ness" in the sound, so people automatically assume any amp with EL84s will be "chimey." From my experience, this is not always the case, and if it is, it may not be the EL84s that make it so. To my not-so-expert ears, EL84's impart a sort of "darkish" low-mid growl when you really push them into saturation.

To me, the biggest thing I can tell about an amp by its tubes is roughly how loud it will be. EL34 and 6L6 amps will be loud, and EL84 and 6V6 amps will be not as loud. The "class" of the amp will give an indication as to loudness as well... class AB will produce more watts (and loudness) out of the same tubes than a class A amp.

Peace!

~Shawn

[surfmaster]

the tone stacks will make a drastic difference on the way a particular amp sound.

[famous beagle]

There's also the circuitry involved---the value of resistors and capacitors that are used.

How the amp is biased will also affect the tone.


Outside of tubes though, I'd say speakers and/or open- or closed-back cabinet design probably have the largest impact on tone.

[atticus3897]

thanks guys, i really should check out those books just so i can really go in depth with it, i figured that the tubes were kind of the equivalent to pickups in a guitar, where different things like the wood in the body, the bridge and different stuff can effect the tone, the pickups are pretty much the biggest difference maker (in my opinion in most cases) so i didnt know if it was similar with tubes in an amp. for instance if i put mesa tubes or marshall tubes or orange tubes into my peavey, if they would sound somewhat like those respective amps, or at least have some of those qualities

[dementedchord]

Originally Posted by atticus3897

for instance if i put mesa tubes or marshall tubes or orange tubes into my peavey, if they would sound somewhat like those respective amps, or at least have some of those qualities

that in particular is way off base... the tubes are for the most part the same... there's only like three manufacturers... the boogies and fender are actually sovtek tubes.... (unless they have changed vendors since i got out of that biz)

[DrewPeterson7]

Originally Posted by atticus3897

for instance if i put mesa tubes or marshall tubes or orange tubes into my peavey, if they would sound somewhat like those respective amps, or at least have some of those qualities

Not at all. Switching tubes will have some effect on your tone, true, but the "Mesa" sound or the "Marshall" sound or the "Orange" sound has way more to do with the way the amps are wired, the tone stacks and where they fall in relation to the gain stages, the value of resistors used, etc than the tubes used in the amps.

Even something pretty drastic, like using EL34's in a Rectifier (I do this on occasion) doesn't really change the fundamental sound THAT much. It changes the way the poweramp breaks up a bit, and adds a little more high end crunch and tightens up the lows a little, but the effect is more like twisting the front panel knobs a bit here and there than it is replacing a Rectifier with a JCM800.

[atticus3897]

thanks, helpful info, im not looking to change my tubes, i was just curious what would happen if i did