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  #1  
Old 03-06-2013, 01:05 AM
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Join Date: Jul 2009
Ampeg SVT CL power section/tube questions

A few quick questions, tried to search but i guess its hard to find specific information on this...figured i would just ask.

My SVT blew a tube, i have no idea how but a tube did indeed crack. The tubes are sovteks and i have a few EHX tubes laying around...i did purchase a matched triplet of sovteks from thetubestore.com so i should just need to replace one section.

1. I noticed that in the ampeg svt cl manual, the bias knobs are described as handling the bias of the three left and the three right tubes. im assuming this is how the sections are divided, but i guess im asking for some clarification: the sections arent divided horizontally, but rather from left to right? Im a little confused as im wondering which tubes i would actually replace, and where the line of division occurs. (a visual aid would be incredibly helpful!)

2. i have a show in a few days, so in case my tubes arent here on time, the 5 remaining EXH tubes i have are matched and the 5 remaining sovtek tubes are matched (supposedly..see below) as well- though not to the EXH tubes...is it a bad idea to mix to brands if the sections are independent?

3. the sovteks i currently have are supposed to be matched, yet they still burn blue (i havent had them for that long) which gives me the impression the tubes still need to "burn in". HOWEVER, how can the tubes be matched if they havent burned in? im certainly no amp tech, so i apologize for any forehead slapping.

anyhow, thats that. i thank you for your patience.
  #2  
Old 03-06-2013, 01:10 AM
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AMPEG SVT CLASSIC -Tube Layout ????


aaaaaaaaaand i just found this thread, so i guess question 1 is solved.
  #3  
Old 03-06-2013, 01:36 AM
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OK, so we'll skip #1...

2. It's fine. As long as they're matched and biased, it matters not if they're two different brands. Sovtek and EHX are the same company anyway.

3. Tubes don't need to be burned in to work right. Some companies and tube sellers will do a burn-in for you, but that's just to make sure they're solid and likely to keep working. Don't worry about the glow being blue. Different tubes glow differently, even similar makes.
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Old 03-06-2013, 01:38 AM
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Hey man, same amp, same problem, same situation, just last month.

Everything is cool if you have matched tubes within the left or right bias group. You can run minus a tube if you have to. Just readjust the bias on that side to make up for it. Pull the bad tube and adjust the bias so that it has the least amount of hum. It'll get you through the show.

As for the tubes blue glow, that is perfectly normal. They will also change colour with the intensity of which you play.

Hope this helps.
John E.
  #5  
Old 03-06-2013, 01:45 AM
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Join Date: Jul 2009
ahhhh, this certainly does help to quell my fears.

i had heard that EHX and sovtek are the same...makes sense, russian tubes and all.

so the tubes glowing blue wont affect the bias, if im understanding that correctly
  #6  
Old 03-06-2013, 01:50 AM
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correct.
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  #7  
Old 03-06-2013, 01:52 AM
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http://www.uraltone.com/blog/wp-cont.../ampegsvt3.jpg

in this picture, how would the sections be divided?

im sorry, im directionally challenged
  #8  
Old 03-06-2013, 01:53 AM
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top two, bottem 1 for the left side?
  #9  
Old 03-06-2013, 01:59 AM
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Yep. Triangles, not rows.
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