First retube...

A

andydeedpoll

i do love smilies...
Hi there - I'm about to buy some new tubes for my Peavey Classic 30. I was going to replace all the tubes at once, after a few funny crackly noises from the amp were diagnosed at the shop I bought it as tubes getting a bit old (they're about a year old, and it's been played quite a lot.) Any reccomendations/hints for someone retubing an amp for the first time? I've already been shown how to take the tubes out and put them back in again... Do I need to make sure that they power amp tubes are matched in some way? Like the outside and inside ones need to be the same, or something? :confused:

I found this company, who'll sell me a package deal to fit the amp for £56 (sort of what I was hoping to spend on a set of new tubes for the amp.) - I like the idea that I don't need to worry I'm buying the right thing! Haha.

And just as an afterthought - Am I completley off the mark when I ask if removing two of the power tubes decreases the power of the amp, letting me push the pre amp tubes a bit more? I'm recalling half-read information from a year ago there though :o

Thanks for any help,

Andrew.
 
andydeedpoll said:
And just as an afterthought - Am I completley off the mark when I ask if removing two of the power tubes decreases the power of the amp, letting me push the pre amp tubes a bit more? I'm recalling half-read information from a year ago there though :o

Thanks for any help,

Andrew.
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it's true you can pull the outputs but ya have to be careful to do it in pairs (as in one from each side)... most amps work in a push-pull configuration which means this one is pushing while that one pulls... and ya want them to work in tandem... BTW... the overall level may not change as much as you 're thinking... you will be at @1/2 the power and that's only a 3db decrease...

and dont forget to rebias...
 
I hear this "rebias" thing mentioned, but I don't know how to do it - Can I do it myself, or do I need a shop to do it for me?

Thanks for the help,

Andrew.
 
andydeedpoll said:
I hear this "rebias" thing mentioned, but I don't know how to do it - Can I do it myself, or do I need a shop to do it for me?

Thanks for the help,

Andrew.
Click to expand...

If you have to ask what rebiasing is, you should take it to a shop to have it done. There are different ways of doing it, but they all take some specialized equipment and an understanding of what biasing is and what it does.
 
ggunn said:
If you have to ask what rebiasing is, you should take it to a shop to have it done. There are different ways of doing it, but they all take some specialized equipment and an understanding of what biasing is and what it does.
Click to expand...

Right, ok - and I have to do it when I change the tubes, or is that just recommended?

Andrew.
 
andydeedpoll said:
Right, ok - and I have to do it when I change the tubes, or is that just recommended?

Andrew.
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Only if you change the power tubes (preamp tubes don't use the bias voltage), and only if your amp is one with an adjustable bias (some aren't). There's no way to tell just by looking at an amp whether or not it has an adjustable bias and the owner's manual probably won't say, but your local tech will know.
 
Retubing

I work on tube amps everyday , bro , the output tubes are sold in matched pairs , don't buy them unless they are matched , I recommend Ruby tubes for a blues tone and JJ Telsa for the heavy tones(metal, grunge) preamp tubes are preamp tubes if want a durable tube with good gain buy JJ Tesla ther are tones of others as well some peeps like EH(Elektro Harmonex). Now Rebiasing , if you buy the tubes that go in the amp no rebaising is needed, if you want to try a different type of tubes(different brand same model(6L6 or EL34)) then probably , and I would have it done by a tech.


Rock On
 
Another plus 1 for Bob and eurotubes. After adding the bias mod to my 5150 and adding a set of jj's from bob...well...wow!

Another note...There is no bias adjustment on the Classic 30. Just add a set of matched power tubes (Bob will set you up) and you are good to go.
 
yes , after looking at my schematic of the Classic 30 , it is a Quad of EL84's , and no Bias pot , so it would a mod to rebias this amp. I would just buy a quad of Peavey replacement tubes(if I was happy with the tone of the stock amp), same with all the others. I haven't done biz with Eurotubes so I can't say anything about bob, I buy from Antique Electronics , I would provide a link but I am not allowed yet. google it comes up pretty fast, if I don't buy from thenm I buy from Guitar Centers of Brook and May's (Brook N May's ar e Cheaper on replacemnet Peavy tubes).

Rock On
 
just because it doesn't have a bias pot doesn't make it non-adjustable... seriously folks... it's just a different method... there are fixed resistors in there that get swapped out until you find the right combination...

there are two conditions where an adjustment would not be necessary....

1. it's been properly adjusted and your useing the same rating of tube...
notice i said rating not just brand...

2. both class A and cathode biased (also called self biasing) dont have/require a bias circuit...

to not rebias as some suggest here on occasion is foolhardy... ya may luck out but it may catch up to ya too.... lets see... who was it just fried an amp recently around here????
 
for simply replacing the tubes in this or any tube amp , replacing with the same tubes does not require rebaising , I do the tubes on a least 10 amps a week. I haven't fried 1 yet.
 
Jack1962 said:
for simply replacing the tubes in this or any tube amp , replacing with the same tubes does not require rebaising , I do the tubes on a least 10 amps a week. I haven't fried 1 yet.
Click to expand...

if the same for you means brand and rateing then that's fine... but if you're changing brands then it really is best to rebias.... you'll get the best the tube is capable of and they last longer...
 
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