Tube Amp Archive

Thanks Martin. I will look at the triode operation and cap behavior closer, then chew on that explanation a bit. What would be the difference in result if the Rk of the preceding stage was not bypassed?

Sorry to dredge this up, but I need to ask why the 91k resistor in the circuit being discussed is not considered to be in parallel since it is connected to ground just as the 1M is? Any info you could add towards further understanding would be appreciated. Thanks

I'm now using this method and plan to either elevate or run DC on the preamp heaters.

I was using this method which needed some improvement to be more effective. It also interfered with the way I wanted the signal wiring layout.

What do you think of the Epi SoCal transformers and sound? Do you know the primary impedance of the OT?

Yes, unloaded. The load will pull that voltage down.

LOL, it is from the SoCal 50. I still have a SoCal, but it is in pieces because I was going to build something else in the Chassis. That amp is heavy duty with lots peripheral features and a thick PCB. The signal path / circuit could be a bit better.

Thanks for the pictures.

I think that elevating the heaters deals with the heater 'signal' leaking through to the cathode. Whereas heater lead dress (eg twisting) deals with reducing the radiated field from the (balanced) heater wiring. And signal lead dress (eg cross at right angles, maintain clearance) deals with reducin...

Not in this amp. If there is room left, I may do that. Do you have a schematic of a reliably quiet and compact DC heater setup? Here is one I have.

jelle wrote:

CoffeeTones wrote:Or anyone who knows for certain...

Besides the power cord itself, is any of the wire heavier than 20 AWG in the AC and DC power supplies?

On the ones I have seen, none of the wire (besides the power cord) was heavier than 20 AWG.

Jelle

www.welagen.com

Perfect! Thank you very much.

Gerald

Either should be fine, but you've got to start using the search function, theres are a ton of pics of real dumble amps, BOMs for all D amps etc. :-) Please don't take this the wrong way. As I said above, I did search and have looked at pictures as well as BOMs. I wanted a direct answer from someone...

The Soldano uses DC referenced, elevated heaters. About 50V above ground. Do you do that along with the untwisted, equidistant heater wiring?

Yes, the EF86 could be worked out fairly easy. IMO, looping any resistors or links across and above the heater wire is not much different from looping the heater wires around the tube, it seems to recreate the hum loop that we were trying to be eliminate in the beginning. Below is a parallel wired 1...

I've tried the Merlin approved heater wiring and it would be fine in some cases, however in other cases it is not so good. For example, if you have a parallel wired preamp tube, an EF86, or even a cathode follower with it's socket mounted plate resistor. With those, it is too bothersome and too clos...

Thanks for the replies and sharing of knowledge and advice.