It doesn't matter if the tubes are matched in the Prima Luna. The adaptive bias circuit sets the idle bias current of the output tubes by sensing a voltage drop across a resistor. That voltage modulates a transistor to either increase or decrease the current to set it and then keep it at spec value. If the tubes are unmatched, or they change with age, the individual transistor for each tube adjusts accordingly. Doesn't matter how off spec the tubes are mismatched as long as they can be adjusted to maintain the design idle current.
Primaluna evo 400 - unmatched tubes
Hi
quick history....i recently borrowed a primaluna evo 100 from the local store and loved it so bought the evo 300 and immediately bought 4 matched KT150's for it, but then 2 weeks later wish i bought the evo 400 ! so my local store let me return the 300 (small restocking fee) and now i have the 400. Sounds like a lot of $$ but I'm thinking this is a lifetime purchase so have justified it that way ;-)
Because I had 4 KT150s that i bought for the evo 300 i decided to buy another 4 so i could fill the 8 tube requirement of the evo 400. I'm driving magnepan .7's so more power the better. By the way the primaluna sounds great with these speakers....I've found a low end i'd never heard even when driving with 150wpc solid state and the sound is very natural, pleasant, and unfatiguing to my ears. The KT150's in my system sound much better than the EL-34's. They sound fuller and more spacious. I sat there last night and kept wanting to play just one more song....they drew me in. The choice of tubes is related to the speaker being driven so the EL-34's may sound better on a different speaker.
Anyhow to the issue......when i installed the 8 tubes in the amp i totally forgot they were actually 2 matched quad sets so in effect i have mixed them up. Will it matter? should i have put in a matched set per channel? Will the autobias feature negate any issues?
The 2 sets were bought from different suppliers but i don't think there would be any different markings as they were both tung-sol branded.
quick history....i recently borrowed a primaluna evo 100 from the local store and loved it so bought the evo 300 and immediately bought 4 matched KT150's for it, but then 2 weeks later wish i bought the evo 400 ! so my local store let me return the 300 (small restocking fee) and now i have the 400. Sounds like a lot of $$ but I'm thinking this is a lifetime purchase so have justified it that way ;-)
Because I had 4 KT150s that i bought for the evo 300 i decided to buy another 4 so i could fill the 8 tube requirement of the evo 400. I'm driving magnepan .7's so more power the better. By the way the primaluna sounds great with these speakers....I've found a low end i'd never heard even when driving with 150wpc solid state and the sound is very natural, pleasant, and unfatiguing to my ears. The KT150's in my system sound much better than the EL-34's. They sound fuller and more spacious. I sat there last night and kept wanting to play just one more song....they drew me in. The choice of tubes is related to the speaker being driven so the EL-34's may sound better on a different speaker.
Anyhow to the issue......when i installed the 8 tubes in the amp i totally forgot they were actually 2 matched quad sets so in effect i have mixed them up. Will it matter? should i have put in a matched set per channel? Will the autobias feature negate any issues?
The 2 sets were bought from different suppliers but i don't think there would be any different markings as they were both tung-sol branded.
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- 18 posts total
- 18 posts total