gofar99 wrote:Hi, It kind of depends on the amp. Sometimes a new tube will have a slightly different sonic signature than one from the same brand of earlier manufacture. Also even though you can bias them they may have different gain and may introduce distortion. I always replace in pairs. With the cost of matching now very reasonable with most of my suppliers doing it for about $1-2 it is cheap insurance that the tubes will play well together.
Ottermel wrote:I replace only the bad tube and re-bias them all again!
hossfly10 wrote:Ottermel wrote:I replace only the bad tube and re-bias them all again!
IMHO that is a bad idea. You should always replace them in pairs at the least on each channel.
Reason being...yes, if you have manual bias, you can bias them into matching output, however, if the tubes are wildly mismatched, it will stress them and can cause early failures.
It is just good practice to be proactive with power tube replacement, because if one goes south quickly it can become an expensive amp repair, and is much less likely to happen with matched tubes instead of "force matching" them with bias, for lack of a better term.
Plus it gives you a spare in case one does lay down unexpectedly.
As I said, just MHO, but when you are talking about a maintenance item costing $100-200 for a really nice pair of tubes in a $1000+ amp, it really just makes long term sense.
cminor7b5 wrote:The main reason I asked is I preferred the sound of the original tubes.
Slate Audio 2015 wrote:Hello. The cost of EL34 tubes is very reasonable. Why wait till another tube fails, then another. Change them all at the same time, that way you will be running on full performance that can be relied on. As for the type of EL34, most are made at the same factory, either in the Eastern Bloc or the States under licence, then branded. Electro Harmonics for example will serve just as well as some over hyped re-branded types, and will not make you feel that you have been harvested.