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Retubing Question

I just got my amp back from ARC corp with new 6922 signal tubes installed. I have seen on audiogon,the same tubes for less then half the price. I know ARC has some markup in the tubes it sells. Now my question. Could I have done this myself, buying the tubes off of audiogon and saved some money,Or do the tubes need to be adjusted in someway. I understand about matched sets, and I do not have any equiment to test the tubes. As you can tell,I am just learning about tube replacement. Thanks for your feedback.
Brouch
brouch
justlisten's avatar
justlisten
489 posts
 
most of the time, esp with driver tubes, i like to compare tube replacement with replacing a light bulb ....pretty much the same.
marakanetz's avatar
marakanetz
5,473 posts
 
6922 tube is already matched to itself since it's dual triode. It could be connected as an input tube(inverting connection) or the gain tube(non-inverting connection). dealers and manufacturers do have a large markup on them so buying them from internet or parts dealers such as partsexpress, partsconnexion, angela is the best way. Watch for the very best deals at angela instruments(www.angela.com) when re-tubing your equipment. I recently got power tubes EI34's for near $14 per piece per matched quad.
chestarr
3 posts
 
How about checking a bias on new tubes?
Can anyone tell me how to check a bias ?
marakanetz's avatar
marakanetz
5,473 posts
 
Chestarr,
If your equipment needs biassing than this information will probably be given you by manufacturer.
You should measure bias current and set-up potentiometers to vary vias current to the specified value by manufacturer. Definitely you'll need multimeter. A pretty descent one is available from RadioShack.
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