Retubing My Crate

[thrashncrust]

alright, i just bought a crate BV120H for 335, and i wanna retube it so it has more gain. i believe it has 4 12ax7's and 4 6L6/5881's , also, would i need to have it rebiased?

[Slabbefusk]

If your after more gain try the Sovtek 12AX7LPS tubes, theyre good gain, get the microphonic tested ones if you can.

[Paul Marossy]

Getting it rebiased wouldn't hurt. All the amp gurus suggest rebiasing the amp anytime you change out the power tubes. You can actually probably pop a new matched set in there and not worry about it unless there is an obvious problem with the plates glowing cherry red or something.

[Drak]

I have -never- heard of simple retubing for 'more gain'.

UNLESS you are substituting a tube of more gain structure for one of lesser gain, like subbing in a 12AX7 for a 12AU, AY, or AT 7. Or a 6SL7 for a 6SN7, something like that.

You might be tossing a lot of $$$'s into the dumpster there if you think you're going to hear some sort of fire breathing difference. I'll bet you don't hear any appreciable difference at all except it might sound -better-, (not more gainful) IF the tubes in it are worn out. But you'll just be hearing it the way it was supposed to sound with fresh tubes, and that's all.

I've swapped tubes tons of times, but I'm talking about swapping GOOD OLD tubes, like Mullards, RCA's, Mazdas, Visseauxs, that kind of thing. And yes, they make a difference, but it's really like maybe 2%, it's just a shift in tone from one to another, not a massively noticable increase in gain. Maybe a 'touch' more gain from one tube to another, but probably nothing anyone would ever notice much from the 10th row.

You'd be better off spending $50.00 on a pedal if more gain is what you want.

And yes, you will -have- to have it rebiased if you expect to hear your amp working properly within it's listed bias range. It could quite possibly sound WORSE if you don't have it rebiased.

Getting it rebiased wouldn't hurt. All the amp gurus suggest rebiasing the amp anytime you change out the power tubes. You can actually probably pop a new matched set in there and not worry about it unless there is an obvious problem with the plates glowing cherry red or something. cool.gif

If Perry were here Paul, you would get slapped with that big THIS IS BAD AND OR WRONG INFORMATION picture that got plastered on deadmike the other day, because what you said is plain wrong, and you could help him do damage to his amp by giving out bad/false/wrong information like that.

Please don't contribute information unless you know what you're talking about.

There are lots of areas I know little to nothing about, and you'll never see me posting on those subjects, because I don't know what I'm talking about, and I don't want to lead someone on like I do when in fact, I dont.

Can you probably pop in a new pair of power tubes without checking the bias without frying your amp?

Probably yes.

Is this the PROPER way to retube an amp?

HELL NO.

[Paul Marossy]

If Perry were here Paul, you would get slapped with that big THIS IS BAD AND OR WRONG INFORMATION picture that got plastered on deadmike the other day, because what you said is plain wrong, and you could help him do damage to his amp by giving out bad/false/wrong information like that.

Please don't contribute information unless you know what you're talking about.

There are lots of areas I know little to nothing about, and you'll never see me posting on those subjects, because I don't know what I'm talking about, and I don't want to lead someone on like I do when in fact, I dont.

Can you probably pop in a new pair of power tubes without checking the bias without frying your amp?

Probably yes.

Is this the PROPER way to retube an amp?

HELL NO.

I disagree about power tube bias. It has been my experience that it isn't as big a deal as people make it out to be. Before power tubes became really expensive, people didn't care about biasing the tubes. They just popped them in there like they were changing light bulbs.

Yes, it is true that your amp can get damaged if you are not careful, but it's not as likely as people would want you to believe. You can tell a lot about what is going on in the tube by observing the color/quality of the glow inside the tube without touching the bias. Tube biasing is mainly touted because it lengthens the life of your power tubes, and makes amp techs more money. The "proper" way to do it is subjective in itself, IMO. The thing that gets affected the most is the tone. The bias can make it sound its best to you, but even then, that might be "out of spec".

I have built my own amps, and work on my own tube amps, so I'm not speaking in complete ignorance.

Incidentally, I have restored my '74 Twin Reverb:

http://www.diyguitarist.com/GuitarAmps/TwinReverb.htm

Reverse engineered the Seymour Duncan Convertible and most of its modules:

http://www.diyguitarist.com/GuitarAmps/Convert.htm

And built three tube amps so far:

http://www.diyguitarist.com/GuitarAmps/FireFly.htm

http://www.diyguitarist.com/GuitarAmps/OctalFatness.htm

http://www.diyguitarist.com/GuitarAmps/Spitfire.htm

And I have hung out at the Ampage Guitar Amp forum quite a bit and also recently at AX84 to some extent.

Edited December 10, 2004 by Paul Marossy

[Maiden69]

Paul, i know jack about biasing an amp, but iknow about sound, and I changed the tubes on a friend carvin MTS series combo, because the dude at the electronics store said that it was going to be just like new, and when we fire the thing up it didn't even sounded like the old tubes did. So a trip to my buddy with the MTS head, which he re-biased after getting it sent from Carvin, and the amp sounded a lot better, more gain, more headroom than with the tubes it came from factory,

So if it is not a big deal for you, you might have had good luck while doing your amp or something because my experience is that it will definately be beneficial to the sound of the amp.

[Drak]

I agree with pretty much everything you said.

1) As long as you're working on your own amps

2) As long as you understand what you're doing

3) As long as you know what to be on the lookout for

4) As long as your amp has been properly serviced, or serviced at all.

5) As long as you're competant and versed in tube amp nomenclature (ooooohhh!)

But giving out information like that to someone who POSSIBLY knows NOTHING AT ALL about tube amps and how they operate and how to keep them healthy, happy, warm and fuzzy is bad information.

So on the specifics, I agree with you.

But on the information you gave out, I hold my ground.

I think you see my point. There are a LOT of people who read these forums who never post at all, and they could damage their amp following advice like that.

For example:

16 year old kid, finds a great deal on an old tube amp, in working condition.

He reads a post somewhere about how swapping tubes can really bring that bad puppy to life.

He doesn't know from Bo Diddley anything about a tube amp.

He spends $200.00 on a retube, and since he read your post, figures he can just pop 'em in and go.

Amp hadn't been serviced in 25 years, new tubes throw bias off.

Takes out something on the board, the board is full of 30 year old components.

Blows fuse.

Kid then wraps old fuse w/ aluminum foil (cuz he read that on -another- cool thread by someone else giving out good information.

Blamo.

He's out the bread for the amp

He's out $200.00 for tubes

He's out $200.00 for tech fees to straighten everything out

He's pissed off.

$400.00+ buys a lot of things.

It could happen.

If you understand tube amps, you should then understand who ELSE out there could be reading YOUR posts and post with the proper cautions if you're going to throw out info like that.

[Paul Marossy]

OK, Drak, you have a point. I forget that about the kind of stuff that you mention at these forums sometimes. I'll remember that in the future.

[Drak]

Not to worry, I wasn't that serious about it anyway except to note that you never know who's reading the things you post, so you have to consider that sometimes.

[Paul Marossy]

Point well taken.

[thrashncrust]

I have -never- heard of simple retubing for 'more gain'.

well i remember the high gain retube kits for the 5150's , i was talking about something like that

[Drak]

I just didn't want you to waste your money, that's all.

[JohnnyG]

the kits probablly will have been a set of different preamp tubes that have higher gain characteristics and would work in the amp. tbh if you already have 12ax7s in the preamp then to the best of my knowledge they are the highest gain generally used dual triodes.there may be others about butyoud have to look

[Kevan]

There's one other thing you guys left out: DEATH!

Messing around inside a tube amp *can* kill you.

BE VERY VERY CAREFUL and don't go where you shouldn't go. Leave that to the pros.

There are caps inside a tube amp that can hold their voltage for a decade or longer, so even if the amp's been unplugged for a year, it can still send enough voltage thru your system to stop your heart.

You should be fine with simply changing tubes out, but unless it's a switch on the back of the amp, biasing should be left to a professional amp tech.

Is biasing necessary? Depends on how long you want to keep your power tubes around, and what you want your overall sound to come out as. Unbiased power tubes will burn up/wear out quicker than biased ones. They can also sound 'fuzzy' or even cut out at times. Sometimes it can lead to cooking other components inside the amp (transformers, boards, fuses, etc). Sometimes, nothing happens at all.

My suggestion: Pay the $20 and get it biased by a pro. Ask the pro questions while you're there. Learn a little.

I agree with Drak & Paul- you're not going to turn a '74 Twin into a Diezel, or vice versa, simply by swapping out the power and preamp tubes. You can, however, adjust the gain (up or down) a little bit by choosing the the appropriate tubes in both the power *and* preamp section. I have 14 power tubes and 22 preamp tubes between my main 3 amps (15, 14, 7). I did a bunch of research online, talked to some friends, and then a little field testing of my own to find the tubes that I felt worked best with the respective amps. It took me a while, but now I'm quite content on the volume, tone, and gain, of each amp setup.

Remember: Your ears hear things differently than mine do. Sure, reviews help, but they're not the final say. Testing by yourself is the only way to get the results you want.

I buy all my tubes from TubeStore.com. There are some good reviews and fairly thorough information about each tube they have on their site. Do some reading and make a wish list. :-)

Now go enjoy that sweet tube tone!

(as I fire up the Line6 Spider next to me...heh heh)

[Paul Marossy]

I also get a lot of my tubes from thetubestore.com or ebay, which can have some good deals if you know what you're looking at.

[Drak]

excessive gratuitous gear post, edited per unnecessary.

[Kevan]

Paul- I enjoyed your amp building links. Great work, man!

[Paul Marossy]

Drak - Man, you have an expensive habit!

Kevan - Thanks, I'm glad that you enjoyed those webpages. Maybe sometime I'll tackle something more complicated and more along the lines of "my own" design.