What's your power stage ? SS or valve ?
If you are looking for valve type distortion without the expense of valves the circuit attached does the job well.
If you are looking for valve type distortion without the expense of valves the circuit attached does the job well.
An externally hosted image should be here but it was not working when we last tested it.
I read somewhere the mu is 110 and so more than a 12ax7.
The gain is likely to be less than 110.
That volume control is unconventional. It will turn-down, but not to zero. We normally ground one end of the pot and add a small blocking cap to the cathode follower.
Given your power amp, I do not see why you need a cathode follower.
The power amp looks dubious to me. Rock-N-Roll was born on shrill pentodes, not mellow triodes. Those 6080-class pass-tubes will be so mellow that I doubt you can drive them to clipping with driver on the same supply. (And if it aint clipped it aint RnR, not even Texas Swing.)
Bass *may* be different.
That preamp gain-tube is an odd 12AX7 and gain will be nearer 50.
Do we even know how much gain is needed??
At this point, I would be plagiarizing. Surely somebody somewhere has built a well-accepted tube bass amp (B-15)? You can put Russian tube in and paint it red. But stealing the core of a design is likely a better (or easier) path than clean-sheet engineering or taking a poll on the interweb.
For *guitar*, we assume that full-up 20mV in should bring the output to clipping, and dialed-back >200mV should not clip early. Speaker voltages tend to be 10V-20V zone. This means you want a gain near 1,000 from guitar to speaker. (More if you have tone control loss.)
Conventional (6V6) power amps tend to be unity-gain grid to speaker. This varies a lot, but is a pencil-mark. So we need gain of 1,000 in preamp and driver.
This 6N13S appears to need 45Vrms grid drive to make 13V in 8r, gain of 0.28. So we need more gain.
6N2P preamp will be gain near 50. 6N9S driver will be gain like 40. 50*40*0.28= gain of 577. 22mV at pickup makes 13V at speaker. So I guess it isn't far out.
Given your power amp, I do not see why you need a cathode follower.
The power amp looks dubious to me. Rock-N-Roll was born on shrill pentodes, not mellow triodes. Those 6080-class pass-tubes will be so mellow that I doubt you can drive them to clipping with driver on the same supply. (And if it aint clipped it aint RnR, not even Texas Swing.)
Bass *may* be different.
That preamp gain-tube is an odd 12AX7 and gain will be nearer 50.
Do we even know how much gain is needed??
At this point, I would be plagiarizing. Surely somebody somewhere has built a well-accepted tube bass amp (B-15)? You can put Russian tube in and paint it red. But stealing the core of a design is likely a better (or easier) path than clean-sheet engineering or taking a poll on the interweb.
For *guitar*, we assume that full-up 20mV in should bring the output to clipping, and dialed-back >200mV should not clip early. Speaker voltages tend to be 10V-20V zone. This means you want a gain near 1,000 from guitar to speaker. (More if you have tone control loss.)
Conventional (6V6) power amps tend to be unity-gain grid to speaker. This varies a lot, but is a pencil-mark. So we need gain of 1,000 in preamp and driver.
This 6N13S appears to need 45Vrms grid drive to make 13V in 8r, gain of 0.28. So we need more gain.
6N2P preamp will be gain near 50. 6N9S driver will be gain like 40. 50*40*0.28= gain of 577. 22mV at pickup makes 13V at speaker. So I guess it isn't far out.
I'm running the 6N13 at 120V/105ma, so the grid sits around -35V, and the driver is powered from a boost converter that I've increased to about 360V. In hi-fi the amp will put out about 10W clean. The first pot would be volume, the second would be gain. I'm going for mostly clean channel anyway. To swing 13V into 8R (21W) the 6N13s need to swing 130V into the OPT which isn't likely using 25VA OPTs and a 150V B+. I guess if I need more gain I can make the cathode follower into a grounded cathode stage. I could also use 6F12P for the bass amp.
As far as the sound of the amp when I overdrive it with music it sounds graceful compared to my KT88 build.
In reality I'd like to make the power amp AB2 but I haven't figured out the driver yet.
As far as the sound of the amp when I overdrive it with music it sounds graceful compared to my KT88 build.
In reality I'd like to make the power amp AB2 but I haven't figured out the driver yet.
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