I live approximately six miles from SY and after several months, we finally had time for personal introductions and I spent a rewarding evening listening to SY's 'Noise'. We got down to business right away. We switched liberally between CD and vinyl. Fortunately, no brain probes were involved. Lucky me!
If anyone has inquiries regarding buzzing, hissing, humming, or downright rude noises coming from his concoction, let me lay all doubts to rest. It was quiet. VERY quiet. Now I did not go to the speakers and lay my ear next to either one, but I never listen that way!
So I ended up having to fight the urge to drool because the music was very enjoyable and SY can attest that my full attention was on the music. In conclusion, I will do everything in my power to convince SY to finish his MM version. My guess is that it would make some great noise in my personal system!
Thanks, SY for the invitation!
If anyone has inquiries regarding buzzing, hissing, humming, or downright rude noises coming from his concoction, let me lay all doubts to rest. It was quiet. VERY quiet. Now I did not go to the speakers and lay my ear next to either one, but I never listen that way!
So I ended up having to fight the urge to drool because the music was very enjoyable and SY can attest that my full attention was on the music. In conclusion, I will do everything in my power to convince SY to finish his MM version. My guess is that it would make some great noise in my personal system!
Thanks, SY for the invitation!
I'm thinking something like this -- the board splits in half (use your band saw or some aircraft snippers):
An externally hosted image should be here but it was not working when we last tested it.
On a PCB
Here's HMVS on a PCB -- the Sowter trafos not yet mounted:
Here's HMVS on a PCB -- the Sowter trafos not yet mounted:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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That's another valid design path which I didn't explore. I like esthetically to use tubes exclusively as the signal amplifiers in this design, there's an extra tube section available, and I've had great luck with ECC88 cathode followers. But one might get an equally excellent result using (effectively) a source follower. The downside is that it reduces the effective plate load, though I suspect not enough to materially affect the circuit performance (haven't measured or simmed the effect of the load shunting the source to ground).
Thanks SY. Not my design, but I have played around with it a bit and like it. f you have a chance, move all those jumpers you can find (4) over to the other position, which will setup the amp for a WE connection.
Also, Doug is working on a new bias scheme:
There's more info here:
Prototypers wanted
Also, Doug is working on a new bias scheme:
An externally hosted image should be here but it was not working when we last tested it.
There's more info here:
Prototypers wanted
Here's some measurements -- these are rough and dirty -- with 500uV 1kHz in the 2nd harmonic is down 62dB and the 3rd harmonic is down 95db. There are no other harmonics. Gain on one channel is 53dB, the other is 55dB.
the blister on my thumb disappeared -- I really hotted up the 1.8K resistors for a few moments.
the blister on my thumb disappeared -- I really hotted up the 1.8K resistors for a few moments.
Here are two charts. Indeed the ECC88 plays the dominant role -- the ElectroHarmonix 2nd Harmonic is down 89 dB -- Also got the gain in both channels within a fraction of a dB -- had to resolder the trim resistors on the depletion MOSFETs. Further -- it is much quieter from an electrical noise standpoint at 7:00 in the morning.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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