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February 11, 2008 - 12:26pm
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Tubes and a newby question
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You should be hearing the parts of the amplifier "break in". Capacitors will sound somewhat different after a few hours but tubes are pretty much tubes. They warm up and unless they have problems you're good to go. I have no idea what are hearing that is "off" but it probably has more to do with how the amp operates in triode mode than the tubes themself.
In triodes, I get a harsh edge that is not present in push pull and is not how I thought triodes should sound. Perhaps it is some other bit of the machine. Thanks
Interesting.
Triodes generally sound very warm and friendly - exceedingly easy on the ears.
I don't know what you are hearing.
That is what I thought. I have a deeper field in push pull as well. The triode operation is not unpleasant, just has a bit of hash in the mix that is not there with push pull. I have less than 10 hours on the amp so I am hoping it will go away when the unit has more time on it. My old EL34 amp took a good month to settle into its final sound.
You could be hearing the quality of the tube and not a break in effect. Additionally, triode operation will lower the power output while raising the distortion product and the output impedance of the amplifier. If the speakers are not well matched to triode operation, you could be hearing the interaction of output impedance against the load of the speaker. You've not mentioned what amplifier, tubes or speakers you are using and which amplifier you are accustomed to.
Primaluna dialog II and a small set of Maggies, which work very well with my old EL34 push pull amp and sounds fine with the new one on push pull. I am in a near field situation so the volume is never above about 1/4 of the dial. Would it matter if I shifted the speakers from the 4 ohm taps to the 8 ohm?
Sure it will matter since you'll be changing the output impedance which will affect the transfer function of the amplifier. But I doubt it will help as much as it will simply be different. I would say you're just asking too much of the triode operation mode when asking it to drive the low impedance/high inductance load of the Magnepans. There are good reasons pentodes and beam power tubes along with push-pull UltraLinear operation were designed, they solve problems where earlier designs fail. Tube rolling the PrimaLuna's is popular and from all reports has benefits in terms of sound quality. I've never heard the PL products with a Magnepan but I wouldn't expect better tubes to overcome the inherent limitations of disconnecting half the pentode tube's gain stage. It would probably result in better sound overall but I think if you want to experiment with triode operation in a pentode based amplifier you would do better with a speaker more friendly to triode operation.
A very hepfull response. Again, thanks. I'll uptube when I have some more cash and operate in push pul till then as it sounds great in that mode.
Again, thanks...you've helped.
Have fun! Maggies sound great with tubes. Nummy.