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Old 09-14-2013, 11:52 AM   #1
Woffelz
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How do I tell which tube has gone bad?

I warmed up and then turned on my Peavey Valveking 100 today and found that the volume wasn't consistant. Could someone please tell me which tube has gone bad? The power tubes at the back were all glowing orange as usual, but I can't see the pre-amp tubes because they have shields on.

Also, it has four 6L6GC power tubes [says on the tubes] and I'm guessing three 12AX7 pre-amp tubes [can't see, but this is on the specs - not going to confirm it because it's had two previous owners]
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Last edited by Woffelz : 09-14-2013 at 11:54 AM.
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Old 09-14-2013, 11:56 AM   #2
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You substitute in your spares one at a time testing it in between each swap.
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Old 09-14-2013, 11:58 AM   #3
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If it was used, just get a whole set power and pre and swap them out
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Old 09-14-2013, 01:55 PM   #4
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Quote:
Originally Posted by Cathbard
You substitute in your spares one at a time testing it in between each swap.


I meant that I don't know if it's the pre-amp tubes or the power tubes [sorry for not making that clear]. I have to order spares first. The reason I don't have any [or want to replace the whole set, as RobbGnarly suggested] is that it costs a lot and I don't the use the amp a whole lot anyway.
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Old 09-14-2013, 02:48 PM   #5
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Quote:
Originally Posted by Woffelz
I warmed up and then turned on my Peavey Valveking 100 today and found that the volume wasn't consistant. Could someone please tell me which tube has gone bad? The power tubes at the back were all glowing orange as usual, but I can't see the pre-amp tubes because they have shields on.

Also, it has four 6L6GC power tubes [says on the tubes] and I'm guessing three 12AX7 pre-amp tubes [can't see, but this is on the specs - not going to confirm it because it's had two previous owners]


You are correct, 3 preamp tube and 4 power.

Power tubes should really be replaced as a set. Valveking has the heaters wired in series instead of parallel..... One heater dies and your amp goes down.

If you have 1 spare preamp tube you can switch that in and out of the spot but at this point you don't know if it is power or preamp tubes.
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Old 09-14-2013, 02:54 PM   #6
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Quote:
Originally Posted by Woffelz
I meant that I don't know if it's the pre-amp tubes or the power tubes [sorry for not making that clear]. I have to order spares first. The reason I don't have any [or want to replace the whole set, as RobbGnarly suggested] is that it costs a lot and I don't the use the amp a whole lot anyway.

You can get some decent tubes for relatively cheap.

Where are you located?

Ruby 6l6GC are the same as GT 6l6GC and way cheaper. The last quad I bought was $40 and you can get pre amp tubes for $10-$13 each for JJecc83

Do what I started doing a while ago, buy spares when you have the extra cash handy. I have a few sets of 6l6 and EL34 on hand and a few 12ax7's laying around as spares.
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Old 09-15-2013, 05:55 AM   #7
Woffelz
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Quote:
Originally Posted by Robbgnarly
You can get some decent tubes for relatively cheap.

Where are you located?

Ruby 6l6GC are the same as GT 6l6GC and way cheaper. The last quad I bought was $40 and you can get pre amp tubes for $10-$13 each for JJecc83

Do what I started doing a while ago, buy spares when you have the extra cash handy. I have a few sets of 6l6 and EL34 on hand and a few 12ax7's laying around as spares.


Those sounds like nice prices! Anywhere I can find that sort of deal in the UK?
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Old 09-15-2013, 06:45 AM   #8
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You'll need one of the UK guys to help you out on that.
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Old 09-15-2013, 07:18 AM   #9
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Preamp valves - http://www.watfordvalves.com/product_detail.asp?id=694
Power valves - http://www.watfordvalves.com/product_detail.asp?id=1977

A full set will still set you back 70 + postage but that's a damn good price for a quad and the preamp valves.
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Old 09-15-2013, 07:41 AM   #10
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^+1
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Old 09-15-2013, 03:35 PM   #11
Woffelz
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Thanks for the help everyone!
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