Can i replace choke with a resistor?

[daz]

I read that to big a choke can cause an amp to sound stiff. My new EL34 build does seem less cushy and sorta stiff. i'm using a 20H choke as in the matchless chieftain. In order to determine if it IS contributing to a stiffness in the tone, can i replace it with a reEL34 plates are at 390v and the dual cap can is 32/32.

[cbarrow7625]

Yes. There is no inherent problem doing that. It won't filter the DC as well though. You are just changing the power supply topology. A choke is not "required" for a capacitive pi filter, just a resistance in that place in the circuit. BTW, since the power tubes get their voltage off of the first power supply node (before the choke), this really won't make much difference in the squishyness of the power section of the amp.

That being said, you can try some other things that will let you keep the superior filtering of the choke & add some spongieness to the feel of the amp.

1.) Just add a resistor in series with the choke (100 - 1000 Ohms maybe?). You get to keep the choke for good filtering but still add some "sag". However, this will still not affect the power tubes (as noted above).

2.) Add some low value, high wattage resistors in series with the rectifier (either on the AC side or directly following the dioides, I don't think it matters much). This is a poor man's tube rectifier simulator. The voltage drop across the resistors will change with current draw & affect the voltage rails of the entire amp, including the power section, similar to a tube rectifier. Start with something small (like 22-47 Ohms) and work your way up from there until you get the feel you like. Keep the choke in the circuit.

[daz]

Well, if you're sure a R won't change anything i'll leave it as is, tho i may give the sag R in series with the choke a shot. Before or after the choke, or does it matter? (assuming 5 watt?) By the way, it's a tube rectifier.

[kg]

Yes. There is no inherent problem doing that. It won't filter the DC as well though. You are just changing the power supply topology. A choke is not "required" for a capacitive pi filter, just a resistance in that place in the circuit. BTW, since the power tubes get their voltage off of the first power supply node (before the choke), this really won't make much difference in the squishyness of the power section of the amp.

if the g2 supply is post-choke, as is typical, then the amp certainly WILL get softer with the additional DCR in the supply rail.

basically any time you talk about multigrid power tubes, forget the plate. the screen is where it is at... it is basically the "plate" of a triode. put a stiff, well filtered screen supply in and you have a low noise, stout amp. put a lot of series R, or multiple big screen stoppers in and the amp gets squishy.

[daz]

So then i guess mooreamps was right when he said his 5.6k screen R's make his amps squishier than those with 1k screens like mine. I tried 2k but no big difference I may have to try his 5.6k's.