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Re: Mark IIC+ Schematic online. (soon)

9/25/1998 1:28 AM
Re: Mark IIC+ Schematic online. (soon)
Steve , look at the schematic of Messa's  
Studio .22 .  
All sections ( preamp , power amp and  
power suply ) are exactly the same as in  
R. Smith's ( Dynawat )patent .
9/25/1998 2:08 AM
Steve A.

    Thanks! I took a look and it sure looks like the patent drawing! If your print is any better than mine maybe you can tell me the value of R101 (the resistor to ground from the grid of the V5B). On the patent drawing it is reference #9. It *looks* like it says 1500 (ohms) but I wanted a second opinion on it.  
Steve Ahola  
P.S. Do you have a Studio .22, or have you had a chance to play one very much? I was just wondering if it really has better dynamics than a typical 2-EL84 amp. The 220k grid resistors are much higher than the typical design (470 to 2k2) among other differences. The power supply resistor between the plate and screen B+'s is 5K6, much higher than the dc resistance of a choke (~100 ohms).
9/25/1998 3:37 AM

You are right .  
R101 = 1500 ohms .  
I have traded for Studio .22 schematics,  
but I had a chance to play on .22 .  
I didn't have a chance to play it  
very loud , so I haven't noticed  
anything spectacular .  
R. Smith claims that higher value of  
power suply resistor contributes to  
" spongy " tone or something , but  
only at full power I guess .  
This 5k6 resistor idea looks like  
famous " sag " using a SS rectification .
9/25/1998 3:41 AM

One thing more !  
Grid resistors ( 220 k ) are much  
higher than usual ones ,but I have noticed that grid resistors in Marshall JCM2000 were even higher ( 560k I think )  
and power amp was without feedback  
( as VOX AC30 )!

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