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Topic: Power tubes out of order? |
Abe Levy
From:
California, USA
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Posted 11 Jul 2014 5:37 pm |
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I had the power tubes out of my silver face dual showman reverb and accidentally mixed them up. Does it matter what order I put them back in? Or do I need to have it biased again if they're put in in a different order? Thank you!
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Mostly Pre-1970 guitars. |
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Bill L. Wilson
From:
Oklahoma, USA
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Posted 11 Jul 2014 9:41 pm The Old Order.
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| The order shouldn't matter at all, for the power tubes, it's the pre-amp tubes, that have a specific order. |
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Tim Marcus
From:
San Francisco, CA
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Posted 12 Jul 2014 12:06 am
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Unless they are using 2 mismatched sets to balance out the sides of a quad in case yes, it will matter
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Milkmansound.com |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 12 Jul 2014 6:13 am
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| Tim Marcus wrote: |
| Unless they are using 2 mismatched sets to balance out the sides of a quad in case yes, it will matter |
I just checked Schematic Heaven... *all* variants of the DSR used balance instead of bias... so one side of the finals were *never* adjusted, the control only worked on the other side.
So one side has a pot, and the other has fixed resistors, setting the bias. If your tubes are matched, then you have no worries. If they're seriously unmatched, and balanced out with the control, then you might have problems.
Most folks have the control converted to full bias (does both sides at the same time) and buy matched quads... this lets you set the bias, instead of just matching the finals. Any tube-amp tech can do this cheaply (basically move one wire). If your circuit is still original, then your amp was never 'biased' in the first place... only set for balance.
You can have another pot added and have the best of both worlds... bias *and* balance. Again, not an expensive mod (I do it without drilling holes) and it gives the most flexibility when setting up new outputs.
If you have one of those infra-red thermometers (with the laser pointer in them) you can take the temperature of your tubes... if they're all the same you can forget about it. If one side's much hotter than the other then I'd have it looked at. It has to be in Play (not Standby) and warmed up for this to work.
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Too much junk to list... always getting more. |
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Bill L. Wilson
From:
Oklahoma, USA
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Posted 12 Jul 2014 8:51 am The Mismatch.
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| What can happen if you do have, say one cheap Chinese tube, and a couple of Groove Tubes, and a Sovtec, all jumbled up in a Twin? We had to do this awhile back, at a gig and my friend just left'em in there for several months, and it seemed to work OK. He's one of those guys who's not into changing things if it's workin' at all. In my Twin, I have a set of Sovtec 5881's, and I don't think they're matched, but they were Biased, and that Twin, w/JBL's, will part The Red Sea. I buy all of my guitar gear at an independent shop, so I'm not sure if anything is matched, all I know is, he's cheaper than Guitar Center, on anything he sells, by a long shot. |
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Tim Marcus
From:
San Francisco, CA
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Posted 12 Jul 2014 9:14 am
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as long as the current draw matches within 3-5mA on either side of the output transformer it should be fine.
If you have 2 mismatched pairs, and distribute them on either side of the quad, it will still function as a quad. However, a big difference in current draw on either side can give you more intermodulation and distortion.
A perfectly balanced set is really what you want for ultimate clean - however, you may not like ultimate clean. Tube amps are perfect for experimentation because the tubes are external and easy to place. Just make sure you don't burn your finger tips!
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Milkmansound.com |
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Abe Levy
From:
California, USA
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Posted 12 Jul 2014 6:49 pm
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Thanks for the replies. So just to be sure, seems like the worst that can happen is more distortion and shorter tube life... But it won't hurt the amp? I ask because I have had a couple of gigs this week that i needed the amp for so could fake it in. I am recording a record next week so hope to take it in this week, but I'm hoping I didn't mess anything up by playing it loud for a few hours...
Thanks again for the help!
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Mostly Pre-1970 guitars. |
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Tim Marcus
From:
San Francisco, CA
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Posted 12 Jul 2014 10:55 pm
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Nope! It's actually kind of hard to damage a tube amp permanently. I've been trying for years! They just keep going and going!
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Milkmansound.com |
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Kevin Raymer
From:
Chalybeate, Kentucky, USA
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Posted 13 Jul 2014 2:35 pm
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Worst case...
If it sound bad..
Swap them..
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Kevin Raymer
Zum / Knaggs / Breedlove
Fractal Audio |
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