It's certainly an interesting mix of technologies!
I suspect both transformers will cost $$$$$.
As far as I can tell, it should work fine although I have reservations about it's cost effectiveness when an all solid-state design could produce equal or better results at a fraction of the cost.
Brian.
An all out solid-state is indeed more superior both in term of linearity and power efficiency. This is a fact which I won't deny. In audio system however, sometime a little distortion is preferred, especially in guitar amplifier, where the soft and gradual clipping of the tube is desired when the amp is driven into saturation, unlike transistors, they tend to saturate very abruptly. Aside from the electrical aspect, I personally perfected tubes for their glow and glassy look
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Power efficiency however is poor for traditional valve amp. This is why I decided to implement a mix technology, and removed all the power wasted in the pre-amp and rectifying stage found in traditional tube amp(2/3 of the wasted power), while still retain the traditional tube sound.
It's certainly an interesting mix of technologies!
I suspect both transformers will cost $$$$$.
A suggestion - why not try a constant current generator instead of the cathode resistor. In theory the current is constant anyway because one 6CA7 will counter-balance the other but it would be interesting to see if actually forcing it to be constant would help, particularly as they start to age.
Brian.
A constant current generator is a top idea! I tried it in LTspice, and it worked. I will give it a ago when the time come. I suspected that by having a constant current sink there will greatly help improve the PSRR and CMRR of the stage. It properly will also help force the bias current to be stable as the tube age.
Shouldn't the thread be posted in the Tubes and Retro section? :smile:
Besides other points that have been mentioned, I'm not sure if the LT3080 will survive under all possible switch-on transients. I would provide zener clamping diodes for the set terminals to be on the safe side.
FvM, I thought it would be more appropriate to post it here, since there are not much of a valve concept here. The majority of the design is solid-state.
Zener clamping diode across the LT3080 sound pretty good for me. To be honest, I think getting this power supply to survive during turn on transient will be the most difficult part of this project. I hope that the relay current limiting concept on the power supply will take care of this problem.
How often will you replace the worn out or burnt out vacuum tubes??
I have never own any tube amps, this will be my first if I can successfully build it, but a quick search on Google pointed to some where between 2 to 5 years with moderate usage.