Ultra Linear & Triode Mode

Dear all,

My tube amp is switchable from UL to Triode mode, will in UL mode shorten the power tube's life faster as it's giving more output watt from it?

Thank you.

Tube life depends on how high its biased not entirely on how its connected up. If power tubes can be biased lower for better longivity at the expense of some sonic sacrifice, lowering the bias is likely a prudent option. How high tubes are biased are varied and determined by the manufacturer for reasons best known to them.
Only switch between UL or Triode mode when amplifier is OFF. Please google about tube bias for further learning and better understanding of tube amplification.

Actually I am not very sure what is my amp biasing for the power tubes since it is a auto biasing amp. Will need to check by a qualified technician later when changing the caps.

So switching between UL & Triode mode does not affect the tube's life except the bias rating?

Thank you.

Auto bias only maintains the preset bias current within a certain tolerance and maintain balance throughout between the 2 push pull tubes. It does NOT maintain the bias if any tube goes defective.
Yep, a qualified tech can check the existing bias but need to be experienced if need to back down. Can't back down too much as the sonics will suffer.
Yes, the amount of bias have everything to do with the longivity of the tube. Especially power tube.

Thank you CMboy for your reply. Will seek Mr. Oh advice when he is doing the caps change for me.

AFAIK, Mr Oh is most skilled with digital and solid state equipment not tube circuit modding. Due respect to him with no intent to run him down.

On another note, it took me years to finetune my own tube amps to get the bess possible sound from it AND to match to my OWN loudspeaker frequency response. I've customize my own amp to best match my own speakers and thats it to satisfy myself only and always aware of its limitations UNLESS I make radical circuit changes which is going to cost me more silly money. It may NOT sound good when paired with another make of loudspeakers in the same room or another place. Its quite tricky and entails closely listening to a wide range of test music, NOT something soldered in and voila!
Not too long ago, I read somewhere someone in a LEAK amplifier forum changed nearly everything save the tranny and chassis, for significant improvement. Yes to improvement, but its technically a Leak amp NO more.

Other than Mr. Oh, I have no more alternative to look for. Octave is price KILLER. Any other good technician can you recommend? My friend has just collected his Conrad Johnson pre & Audio Note Conqueror power amp from Mr. Oh & he is happy with his service & the performance now after repairing.

Sorry brader..I don't dare recommend. Perhaps here got some experienced dude reading this...hopefully not trigger happy modder.

I know what you mean & feel for not recommending, Good never mind, if not good blaiming also susah, right?

You could still ask Mr Oh if you're comfortable and confident. Its your call. But if it results in not getting the sound you expect or want after mods, then what?

cmboy is being modest. They are quite a lot of modders also being modest I guess.

Perhaps you may want to list down what are 'sound' u wish to hear and let us share and see.

to start with, what I think as routine beside changing the correct tubes are

1. power supply upgrade, capacitors bigger and better capacity. To do this, I use PSU designer II. http://www.duncanamps.com/software.html . Check the biasing, from the input, driver to power stage.
normally I use Nichicon for ps and would use blackgate for bypass
2. resistors at signal path change to Riken. too many Riken is no no.
3. CCS for improved bass response and channel balance
4. signal cap such as Mundorf SIO or VCAP. I go for Mundorf Supreme.

anyone else with recommendation

Acquire a decent oscilloscope and audio signal generator set if you're serious about tuning and modding. They're great tool aids that see things your ear can't hear.

the osci would be good for setting the global feedback resistor that give the best resonse before going into oscillations. it is also good for checking the signal before clipping and for proper adjustment of biasing.