Tube Swap & Bias Tutorial Suggestions

[Nostalgic Distortion]

Hello, I have several valve amplifiers & I'm getting the feeling that two of my little Class A 15W heads are going to need some new power tubes soon? The Fender should be fairly easy because apparently you can just have someplace like The Tube Store match the numbers on the existing 6V6 and theoretically as long as everything is the same as what came out I shouldn't have to worry about bias much, or that's what my manual says anyway?

I guess if I can figure out how to set that ones bias as well it would be a good thing but my main concern is my TS15H, this is my main amp & out of the 9 I own it's the one that gets the most use. It's got two 6V6 power tube & two peramp tubes, just like the Fender but from what I've heard they are a bit more challenging when it comes to servicing them? I was hoping maybe someone can point me in the right direction to find something that may help me when I swap them out? Any helpful YouTube videos or literature would be greatly appreciated!

In a perfect world I'd take them to a tech but that's just not an option for me so one way or another I've got to figure this out on my own....

 

[Edgecrusher]

Re: Tube Swap & Bias Tutorial Suggestions

Dont

The TSA15 requires the transformer shunt method to measure the bias.

This is one of those areas that I'm real real reluctant to help anyone with as there are voltages inside that can kill you. You need a bit of a background in tube electronics to do this. Not a ton but some and doing it from a cold start is a bit daunting.

If you really want to know how to do this stuff go pickup a couple of the old RCA receiving manuals and like the tube amp book from aspen pittmann to get you started. When you got a handle on what you can touch and can kill you, THEN open your amp.

At this point take the Ibby to a tech, might also be worth it to call the tube store as those are fixed bias amps if they have tubes that will run at that bias they should be able to get them for you so its just a plug and play deal.

But otherwise until you are 110% sure of what you are doing dont mess with it.

 

[Hank-]

Re: Tube Swap & Bias Tutorial Suggestions

http://www.thegearpage.net/board/in...rmer-shunt-bias-help-on-ibanez-tsa15h.1399944
^link regarding the ibanez amp.

Some amps are fixed bias, fixed adjustable bias & self biasing. You will need to know what type your different amps are. Contacting the manufacturer can help but not always if the person replying back is from the sales division lol.

That's all i point you towards, if you ever get into this process buy a few preliminary items like electrical gloves to avoid getting shocked & eye/face(maybe hear protection too) protection incase you accidentally short a 400V+ fully charged capacitor and it blows up.

Edit:+1 to what Edge said.

 

[Edgecrusher]

Re: Tube Swap & Bias Tutorial Suggestions

electrical gloves to avoid getting shocked

Fine dextrous work is impossible while wearing those. Ive seen lineman wear them, not amp techs.

In my opinion they would give a noob a false sense of security and they might touch things they shouldnt, which at best would result in expensive amp repairs. Being they are unwieldy you are more likely to accidentally bump something. They sure arent a replacement for knowing exactly what you are doing.

 

[zzmoore]

Re: Tube Swap & Bias Tutorial Suggestions

Do you know what biasing is all about, and have you ever worked on a Live Amp before.?
Do you own a decent meter.?
Do you have a schem for that amp.?

 

[Edgecrusher]

Re: Tube Swap & Bias Tutorial Suggestions

Do you know what biasing is all about, and have you ever worked on a Live Amp before.?
Do you won a decent meter.?
Do you have a schem for that amp.?

If he had any of those he wouldnt be here asking for youtube vids...

 

[zzmoore]

Re: Tube Swap & Bias Tutorial Suggestions

Why don't we let HIM answer for himself, and then we can try to help him out.?

 

[Edgecrusher]

Re: Tube Swap & Bias Tutorial Suggestions

Why don't we let HIM answer for himself, and then we can try to help him out.?

Sure... we can let him answer, but it seemed to me like most of your questions (besides owning a multi meter) were answered in his original post.

If YOU want to teach him transformer shunt with forums posts thats up to you. I'm gonna pass and just recommended he take it to a tech.

 

[zzmoore]

Re: Tube Swap & Bias Tutorial Suggestions

.....I was trying to find out what kind of experience he has had, so I asked a few simple questions.
Shunting the OT is The Easiest way to bias an amp, bot not all meters work well in That Situation (does he have a decent meter.?)
It helps, but is not necessary, to have an understanding of what purpose biasing serves in a guitar amp (does he know what biasing is all about.?) It certainly sheds some light on Why he needs to bias the amp.
So before anybody worries about what method to use, it would be helpful to know his level of experience he has, and what kind of tools he might own.
Maybe his amp is Cat Biased, so this might all be for naught. Maybe the amp has 1 Ohm series Cat Resistors, and that would make his life easier (does he have a schem for this amp.?)
good luck

 

[Edgecrusher]

Re: Tube Swap & Bias Tutorial Suggestions

.....I was trying to find out what kind of experience he has had, so I asked a few simple questions.
Shunting the OT is The Easiest way to bias an amp, bot not all meters work well in That Situation (does he have a decent meter.?)
It helps, but is not necessary, to have an understanding of what purpose biasing serves in a guitar amp (does he know what biasing is all about.?) It certainly sheds some light on Why he needs to bias the amp.
So before anybody worries about what method to use, it would be helpful to know his level of experience he has, and what kind of tools he might own.
Maybe his amp is Cat Biased, so this might all be for naught. Maybe the amp has 1 Ohm series Cat Resistors, and that would make his life easier (does he have a schem for this amp.?)
good luck

Doubt he has a schem for it. I contacted Ibanez and was given an emphatic no that only authorized service centers were provided with them. The amp is not cathode biased it is fixed bias.

There is a reason why I said it needed to be biased by transformer shunt... Maybe just maybe I have encountered this amp before and had to bias it and discovered these things about it already.

 

[zzmoore]

Re: Tube Swap & Bias Tutorial Suggestions

I have never encountered an am That Needed to be shunted, but you say this one does..... I am giving this over to your capable hands.
No need to play the quoting game any longer.
good luck

 

[Hank-]

Re: Tube Swap & Bias Tutorial Suggestions

Fine dextrous work is impossible while wearing those. Ive seen lineman wear them, not amp techs.

In my opinion they would give a noob a false sense of security and they might touch things they shouldnt, which at best would result in expensive amp repairs. Being they are unwieldy you are more likely to accidentally bump something. They sure arent a replacement for knowing exactly what you are doing.

INSULATED! Lol i could not think of that word when i wrote electrical, i was gonna write rubber but there are many thin tearing type in that form on the market. Well atleast with right gloves on, the chances of electrocution are less, better the amp dead than a novice learning amp tech me thinks Besides atleast on a workbench at a repair shop the random distraction are reduced but at home so many things can be distracting like phone, house bell, pets, family members, neighbours, anything to make your hand & eyes shift for a moment & disaster can happen.