Using solid state rectifiers on Cary SLI80 Amplifier


One might wonder why experimenting with such a high performing amplifier as this SLI80 Signature is but I would like to try this to see if doing so will tighten bass and/or percussive sounds from things like drums and piano. I’ve tried raising the bias above the Cary recommended 75mA and the sonic difference was significant but, because the higher resulting voltages to the tubes would be continuous while operating, Cary recommended against it primarily because of predicted shortened tube life. I’ve taken their advice and adjusted the amperage down to 80 from the 90mA that I was trying. Now, based partly on Cary’s having switched to solid state rectification in their newer amps, I thought it made sense to try it on this older amp and need advice concerning exchanging the tube diodes with solid state replacements. What I’ve learned from several sources is that the resulting instantaneous power to the tubes and power transformer could cause damage or, at least, blown fuses. Without adding circuit protection that delays the impact, does anyone have experience with this modification or insight otherwise. I do have a variac to lessen the initial impact of this experiment if I decide to do so.  Thank you. 
128x128broadstone
Sounds like you are the R & D engineer for these mods. That means it's all on your shoulders. Good or bad, you'll be the crash test dummy. I'm not sure I would ever do anything to a good amp that wasn't a factory approved modification. But if you got the skills and the wallet to make significant mods, go ahead and have fun. You'll be an expert when you are done and that is worth something. 
I would personally keep the tube rectification....   the amp was voiced that way.   Could be risky, IE costly.....   

One thing I have always  tried to do is stick with OEM parts and values whether it’s a tube amp or a car .    Bias, torque, whatever the spec may be I adhere to it.  It’s worked well 
Performing the surgery you contemplate, unless you are the Cary repair department, will significantly reduce the resale value of the amp.

I bought a new (tube rectified) SLI-80 a couple of years ago. I ordered all the factory mods available. These mods all help to give the unit a more *modern* tube sound. 

Try some new rectifier tubes. I don't necessarily mean vintage/NOS types. Many of those have the stereotypical (no pun intended) tubey, soft bass. 

After much rolling, I settled on Sophia Electric 274b tubes. Everything improved, including bass punch and clarity. 

Of course, you should do as you like. If it were me, and I wanted SS rectification, I'd ship it back to Cary for retrofitting. And maybe hexfreds, and Kimber silver wire, and Mundorf caps...

Good luck!

Can you use 5ar4 rectifier tubes in the cary amp, they have less voltage drop than the 5U4G