Yes, B+power is configured LCLCLC and last LC in preamp unit for channel decoupling. I want to play with different grid leak resistor on input. By now i have tested Vishay RN65D, Kiwame and Caddock MK132 100k. In my setup was best Caddock MK132, but will try another type.(Takman carbon film...) Any suggestion is wellcome 🙂
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Grid choke. Lundahl LL1670 works well instead of a grid resistor on my 833 amps. Looks like a short to ground for DC but a very high impedance to AC, so best of both worlds.
It doesn't look like you have an aversion to chokes...
It doesn't look like you have an aversion to chokes...
Correct, i like choke,but there is no advantage using a grid choke in my system because my DAC has LL1660 on output.
Umm... you can very well use a grid choke with a transformer plate load...
On the other hand, I think I see in your pictures an inductive volume control on the input?
Oh, I misunderstood you, sorry. The *previous* stage is transformer loaded. Indeed, no need for a grid choke.
How is that volume control wired?
How is that volume control wired?
Yes, my source have LL1660 on output. AVC volume control is connected on output of preamp.
I have a similar setup but without the LL1660 before the AVC. I use the AVC as my output "transformer" in parafeed. One less component in the chain that way...sounds very transparent.
I have a pair of the silver wire autoformer modules on order and hopefully that will take the sound to an even higher level.
It's a lossy parafeed (aka damped resonance parafeed or DrP) setup, with a 1uF Duelund CAST as the main parafeed cap, in parallel with a 3.3uF Mundorf Supreme which is in series with an 8080R resistor. The RC formed by the Supreme and the resistor means it is essential out of the circuit except at low frequencies, where the combined caps and resistor act like a 4.3uF parafeed cap. It works very well - a 4.3uF Duelund would be both incredibly expensive and HUGE.
There is a DrP calculator spreadsheet available on the web that's very useful to calculate the proper values for the caps and resistor; alternatively one could use Spice to do the same thing. It's important to take into account the inductance of the AVC and the resistance feeding the parafeed circuit in calculating the proper values.
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Thanks a lot.
I have a #26 pre thinking to covert to a 4P1L.
I may go parafeed instead of buying another LL1660 tranformer.
I have a #26 pre thinking to covert to a 4P1L.
I may go parafeed instead of buying another LL1660 tranformer.