Personally, I would sell the amp and look for a lower powered amp if you determine that you really don't need that much power. Two hundred watts is usually way more than one really needs for almost any speaker. I generally don't like the sound of higher powered tube amps that are running a multitude of high-powered tubes, like KT88, KT120, and KT150. These types of amps tend to be "hard" or "harsh" sounding compared to lower powered amps running the likes of 6L6 or KT66 tubes. I would take a 40 watt KT66 or an even smaller 6L6 amp any day over a high-powered tube brute.
Lowering Tube power amp output
Hello everyone,
Wanted to ask the tube power amp users here if there is a way to reduce power output/ heat generation from the amp. I have a Rogue Audio Zeus amp which is rated at 200w/ channel. Can removing some power tubes reduce output power and lower heat dissipation? How can I lower its power draw effectively without causing any damage to unit
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- 17 posts total
@tubelvr1 The more powerful you make a tube amp (unless its an OTL) the more limited its bandwidth becomes, due to the output transformer. What this means is that for the most part smaller tube amps sound better (except for OTLs where bigger ones sound better). So rather than remove tubes to reduce power getting a smaller amp is good advice. FWIW the output transformer is designed to provide a certain load for the power tubes provided its output is loaded correctly (for example an 8Ohm speaker is connected to the 8Ohm taps). When you remove tubes that load that the transformer provides will change and so the remaining tubes won't be loaded correctly and most likely will be too low of a load for the remaining tubes. This will lead to excess distortion, the tubes running hotter and their reliability compromised. So don't do it!! |
I’ve heard you can start removing push-pull pairs on each side (normally 3 push-pull pairs per side), but as noted this will be suboptimal. You’ll have to re-bias if you do this. You can also just drop the tube biases down from the standard 40mA to say 35mA, for a slight reduction in heat. Rogue is great to chat with if you want their guidance on this. If you’re concerned about heat dissipation, an amp with a dozen KT88 and 6 small tubes is not a great match. As others have suggested, it’s probably a good idea to trade the amp in. Many audiophiles without heat concerns would love to have that amp! |
- 17 posts total