Swapping tubes for tone and drive...

Bow

Bow

3 Days Drunk
Alrighty all you guru's...

I have a Peavey Classic 30...all tube with a single 12" speaker...

The tubes are stock, what ever Peavey uses and are set up like this...
Power Amp- 4- 6BQ5/EL84’s with 12AX7 driver
Preamp- 2- 12AX7’s


My question is...what can I do to get more drive/crunch out of it? I like the amp, but sometimes I can get the good heavy distortion..

any suggestions? I would like to do it without a pedal...

Thanks
 
You can find tubes that give your amp more distortion. Groove Tubes gives annotation to their tubes from clean to dirty. The system is 1-10 with 1 being the dirtiest and 10 being the cleanest. So you can get your tube type with the level you want.
BUT- When replacing power tubes, it is usually a good idea to have it re-biased. This will have to be dome by an amp shop unless YOU work in an amp shop and know what you're doing. You can replace the pre-amp tubes without having any additional work done.
-H2H
 
Thanks Hard2Hear!

Got any suggestions for tube replacement? I know it will never be a Marshall dirty, vigin killer tone, it is 1 30 watt Peavey, but I would like it pretty dirty on the dirty channel...with the "pre" cranked...
 
I put GT power tubes that were 2's on the dirt scale in my Fender Blues DeVille and it got pretty nasty. I was just about to sell it off but that opened up the sound and I kept it. You're not going to get too heavy with that amp, but it will be more.
 
you know what I do.. is I put an aT7 or even an aU7 in the pre stages.. they sound a little different, and break up a lot easier... What you need to do is experiment with different shit, find out what you like.

and learn to bias your power tubes... its easy, and you can have a LOT of control over the sound. run it hot.. get crazy gain, burn your tubes out quicker. Ive run my amp so hot that I couldn't get a clean tone if i tried.

xoxo
 
Will you guys ever figure out that groove tubes ARE NOT the tube of all tubes? Groove tubes DO NOT make their own tubes, they buy from factories and re-label them then charge you extra $$$$ because they stamped their name on the glass. What makes a tube give your amp more volume/gain/distortion has to do with it's effiecency ratio. You can get the same preformance or better from other brands of tubes. And don't be fooled into thinking that groove tubes are better because they are american made--That is a myth! Many of the factories they buy from are in Russia, Poland, China, Mexico. CHECK OUT http://www.tubestore.com for tons of info on tube makers, amp preformance, how tubes work, and tube selection.
 
but groove tubes ARE cool because of the extensive rating systems they use. You can get a tube with a consistent bias... which is hard to do with other tubes, unless you test them yourself. very user freindly. I use Rubys in the post and Sovtecks in the pres.

xoxo
 
I will not lie...I'm new to tube amps....

Hard2Hear- how was you fender setup originally for tubes in the pre and power section and which model tube did you put in?

camn- since I am a new guy to modding tube amps, can you explain the tubes you selected a little more? I am looking for a starting point....
Also, where can I learn how to bias my tubes? I do electronics for a living...of course...solid state and Suface Mount...which is a tad bit different than tubes!

Daddy-O- I see your point also, I didn't think anyone in the states still made tubes...So if GT just resales, who supplies them? I am a budget limited guitar player...and not to mention, a cheap bastard....

By the way...I looked last night and my Classic 30 has Sovtek in the power section and the preamp tubes are not marked...

thanks for the input you guys!
 
Daddy-O, I agree with camn in that I dont have time or money to go out and buy loads of tubes or try out to see which I like. I know Groove tubes aren't "better", they're just easier to select what I'm looknig for.
camn- I thought biasing was hard??? I heard that if you don't know what you're doing you can get cooked by the stored-up electricity. And I have a bad track record with getting shocked.

My Fender still had the stock "Fender" tubes, it was made before they started putting in the Groove Tubes as stock. I just replaced the pre's with 12ax7a (i think) and those GT's for the power section, I'm thinking 5881's. I'm at work and haven't looked for a while. BUT I was remembering also, I put Mesa tubes in my Pro Jr. and it breaks up alot easier now. It just has 2 12ax7's and 2 EL-84's in it.
 
OK....

OK...so now we are getting somewhere as for where to start...I agree, I don't want to dump a bunch of cash into tubes to find out that I like...I was hoping for a good starting point...

[Edited by Bow on 12-15-2000 at 08:57]
 
Bow, the unmarked tubes in the Classic 30 are probably Chinese, at least they were in both my 30's, and they are not very nice tubes. IMHO you should replace those straightaway...Sovteks will do just fine. Don't spend too much money on them as these amps run hot and mine tended to eat tubes at a pregnant pace. There's a few things you can do to juice these amps a bit, first, the extension jack, if I remember correctly is a switching type that will change your output impedance for an extension cab, just plug a cable into it and it thinks it needs to adjust for 2 spkrs. Also, if you have any pedal that will give you a clean gain boost, throw it in the effects loop and pound the tubes a little harder. It all really depends, though, on what sound you are going after, as this amp just won't do anything metally or modern. It uses EL-84's, great tubes for that chimey Voxy Ac-30ish sound, but if you look at the output transformer in this puppy, it becomes clear that it was designed with economy and value in mind, not for wet- yourself tone. Anyway I do remember seeing somewhere a site devoted to classic 30 mods, if you like to breathe solder like me. One other thing, bigger strings, higher action,spank the plank harder...tendonitis, what tendonitis?
 
ok.. the pres: AX7s are standard issue for preamp stages, because they push a lot of sound. In old Fenders, you would have ONE for each: treble, mids, and bass... and they'd all have a pot to control the power. Not so in your peavy. ANYWAY, AX7s are like your 100-watt twin, in a way. They are loud and good. But to get good sound out of them, you really need to turn them up to 8, and then you start getting some power tube saturation, and thats cool if thats what you are looking for.
With AT7s and AU7s, which are direct replacements for AX7s, you get less output, thus less load to your power stage when you crank it, and they dirty up with less gain from your rig. Good pre-stage overdrive, if thats what you like.

I like an AX in the Bass, AN AT in the mids and an AU in the treble.



Next,the powers:
Biasing IS easy, and you CAN fry yourself. REPEAT: you can easily hurt yourself and your amp by biasing your own tubes.
Just like you can cut yourself fixing your car.
ANYWAY, biasing is comlicated, but itdoesn't have to be, and myself and a number of players I know bias by ear. I don't have the sobriety to explain it right now, but I will in a few days...

till then, gents, keep your ears to the grindstone....

xoxoxo
 
The unmarked tubes in the Peavey Classic 30 are probably Chinese as guessed above (they are in my Peavey Bravo 112).

OK, at least 4 guys asked how the hell to bias tubes. Make that 5. I needs to know too. I gots to know!

And by the way, how can one fry himself in a guitar amp? I can see that happening in a TV set where the picture tube requires kilovolts to get that electron beam a-flowin', but isn't the voltage stepped way down for these cute little amplifier tubes? (100% of which are produced in third world countries.)
 
Bow, Have you tried using an overdrive pedal? Before spending money changing tubes and re-biasing your amp, check your local shops for a second hand TS-9 or some other quality overdrive pedal. You would spend $100 on a great pedal instead of $200 on tubes and bench time at the repair/mod shop. A pedal you can always use and if you don't like the pedal, it's easier to sell and get some of your cash back than used tubes.....

I realize your first post stated that you would like to get tone and more overdrive with out a pedal. So let's look at this from another way.......Your Peavy most likely has a Celestion or Black Widow type speaker. The speaker may be too high of quality for the tone you whant to hear. Sometimes it is better to have primative speaker. Newer speakers are designed to reproduce the sound signal with as little distortion to the sound as possible---in other words newer type pseakers are slower to "break up". A primative speaker with thiner cone matterial and ALNICO magnet will "break up" sooner- translating into more distortion at lower volumes. Any Jessen P-12 re-issues will work well and so will Mojo Tone 12" speakers. Mojo Tone speakers sell for less than $100. I have a Mojo in my '54 Fender Deluxe.

So more than just the tubes play a part in the tone of your amp. You've got to look at the input(guitar +/- pedals) the amp guts(electronics/tubes) and the output(speakers). All three areas play a part in how the amp sounds and works. Do you r play a guitar with double or singal coil pickups? Double coils have higher gain than singles.

Anyway.......my piont to all of this is say----Sometimes you can get the results you want without swapping tubes.

And again, I encourage everyone to check out http://www.tubestore.com for info on tubes. Everyone seems to be concerned about not having time find tubes, so they buy GT's. This site reviews tubes by type and maker and tells you exactly what sound quality a tube will have- along with ratins and prices. Lots of info and tutorials. Very cool site.
 
A couple of things. Camn, I really don't know which old fender amps you are speaking of that had seperate tubes for bass, mid and treble. Usually all the tone pots were in ONE gain stage. Bassmans (5F6 for ex.) had the bass, mid and treble controls between the second and third tube stages. I think the fender super had a mid control on the first stage of the vibrato channel. Many fenders didn't have any mid controls at all. I don't want to bust on you, but when you are giving advice to someone who is new to the field, make sure you have got your facts straight first. A good book to check out with loads of great tube amp info is "A Desktop Reference of Hip Vintage Tube Amps", by Gerald Weber, who is behind the pretty happening Kendrick amps. Sometimes he gets a little too vintage-lusty for my tastes, but this book is pretty cool overall. The peavey Classic 30 has a Sheffield spkr. That's peaveys version of a celestion I guess...I'm not sure who makes it for them. But it sounds like a neato British name, don't it? I fried one of the stock speaks and replaced it with a carvin "british series" and it sounds pretty much the same, though I believe the Peaver had a lower power handling rating. Also there is plenty of current to fry your heart (ventricular fibrillation anyone?) in ANY tube amp.

Peace to all.
 
A few points to remember:
1. 12AX7 HAS A GAIN OF 100
12AT7 HAS A GAIN OF 60
12AU7 HAS A GAIN OF 40
2 Classic 30 has no bias adjust, will have to be biased by selecting resisters.
3. Classic 30 preamp tubes were chinese at one time,power tubes were sovtek.I would suggest sovtek 12ax7lps preamp tubes and sovtek el84m power tubes. This will give more a little more punch and output but will not add more distortion as you were after. 12ax7 has the most gain so you can see that without adding another tube stage you are pretty much maxed out.
4.Any tube amp can KILL YOU, plugged up or not, capacitors can hold a lot of voltage.
 
Sooo.....

Stan- are you saying the lower the gain of the tube, the quicker it starts to break up?

Daddy-O- If I put a pedal in the mix, I am right back to a digitally altered tone...I have a DOD American Metal [FX-56?] that will give me more drive than I know what to do with...but the reason I wanted a tube amp was for tube tone...

effedupstrat- do you have any suggestion for whick Sovteks to put in?

I was also suggested to look into Tesla/JJ 12AX7A's...any thoughts?

Thanks for your help gents! As far as teh voltage and death issues, I work on Heads Up Displays with 12KV anode voltages, so I know where and where not to stick my dripping wet fingers!
 
Bow,
As far as the Sovtek tubes go, I've used the plain ol' 12AX7WA and occasionally the WB's. The B's are a couple of dollars more, but didn't seem to be too different sounding in this amp. I've also used various new old stock RCA's and Sylvania's and a few Amperexes and Telefunkens (insert evil laughter here). My Dad is an ex-technician and radio station engineer who never threw anything away and he also rents out public address systems (75% tube amps) so there's plenty of cool stuff kicking around his ranch. As far as the el-84's, the 84M's seemed to sound a little better than the reg. 84's. If you haven't already you should check out :http://blueguitar.org/c30_mods.htm. There's quite a bit of stuff there concerning mods for this amp. I haven't tried any of them as of YET. So far my energies(and my cool tubes) have been directed at my reissue fender bassman. (I tried some short bottle phenolic base military 6L6WGA's in this amp and it sounded like it would tear my face off!)
Peace.
 
Bow

The higher the gain, the more it can overdrive the following stage. 12at7 and 12au7 has lower gain but can handle more current, thats why you see those tubes in the driver stage of alot amps, they would have less distortion. The 12ax7 has the best chance for high gain distortion, unless you are adding more stages. Lower voltage is one way to make a tube distort more if you are limited to a certain amount of gain stages. If you want a smoother sound with less distortion, use the low gain tubes, otherwise just stick with the 12ax7 's.
 
See, Ive found I can get way better distortion in the actual pre-tubes when using ats and aus. Its kinda like that the difference between big assed power tubes and little ones, only with similar pre stages... the load from my guitar and pedals pushes the little pre tubes harder than it could an aX, giving my a really slick distortion BEFORE ever getting to the power stage. The Overall signal is then amped without any pwertube saturation, giving me a bunch of headroom with consistent tone.

effed up... dont worry about coming down on me, I dont really know anything about electronics and stuff, I do it all by ear. I've turned enough knobs and put in weird parts to kill many an amp, but I dont really know the names of things. My faviroit old fender for tone alone, w/o verb is a tremolux, blonde. And I can totally hear isolated changes in the bass, mids, or treble depending on which pre tube I change... but I just connect the dots in there and hope that things sound good.

Bow- not all pedals are digital. In fact, most aren't. Most are analog, which dont give you a digitally altered tone.

Too bad about no Bias adjust on that 30.

xoxo
 
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