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Triode versus Ultralinear/Pentode

Does triode always sound better than ultralinear/pentode in circuits and parts of similar quality? I'm not really interested in SETs, but triode wiring of EL34/6550 etc. I have a CAT JL2 wired which has 6550s connected in triode and is the best amp I have ever heard in my system. I also have a Music Reference RM9 MKII with EL34s connected in ultralinear and am considering having them rewired for triode operation as I assume that is one of the reasons the CAT sound so good (those transformers may also have something to do with it). Thanks.
pubul57
onemug
784 posts
 
NO. But that's only because you used the "always" word. :-)

Wiring triode may reduce some distortion, you can probably use less feedback, a good thing IMO. But you end up with a lot less power and that won't set too well with some speakers. At least you could go back if it didn't work.
tobias
1,534 posts
 
I have an Audio Space AS-3i with a triode/ultralinear switch on the front panel. This is my story...

I've used both EL34s and KT66s in this amp. With the EL34s there was more power available, of course. I ran the amp all the time in triode mode because I found the sound sweeter and more detailed. With KT66 tubes the difference between triode and ultralinear was less obvious. I used ultralinear for the extra power. FInally, though, it began to appear that triode was the nicer one even with KT66s.

Having a switch on the front panel is really useful. There are some discs--rockers, full orchestras--which get a needed boost in impact with the extra power of ultralinear mode. But in the end it's a bedroom system and I do most listening in triode.
newbee
4,767 posts
 
I've never listened to a pure triode designed amp so this is definitely a FWIW.

I have three amps were you can select triode/ultralinear on the fly. One, (a Cary) in triode sound much the same as two other's in ultralinear. In ultralinear it becomes slightly hard. All have low negative feed back.

With the speakers (3 different pairs)I have used with these three amps, best described as relatively neutral 3 way cone designs with a gentle impedence curve, unltralinear produces what I consider natural and 'linear'. When put into triode the mid-range power seems to deminish and the center sound stage recesses. A very relaxed sound but on a lot of music it sounds a bit thin.

I suspect triode might be a mode that would sound best used with more aggressive speakers (no shortage of those in the high end).

I do like to use triode for background music however. Apart from it being 'relaxed' at about half power the tubes and amp run cooler and I suspect last a lot longer.
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