choke or resistor??

[swt]

I've read discussions about replacing the choke with a resistor...what are the final suggestions about this and filtering. What about having the choke, and a smaller series resistor, to add a little sag, but also don't loose the sponginess ( is that a word??) or prevent stiffness in the amp? maybe i'l try it and let you know...

[pedro]

Hi
I just went with a 500ohm 10watt cement in my 50W ODS build and it sounds just fine.

I think if you really want sag then there are plenty of ways to do it - do a search for relevant posts here. Or you could adjust your circuit and use a tube rectifier for plenty of PS sag under heavy load.

cheers
Pete

[glasman]

Hi
I just went with a 500ohm 10watt cement in my 50W ODS build and it sounds just fine.

I think if you really want sag then there are plenty of ways to do it - do a search for relevant posts here. Or you could adjust your circuit and use a tube rectifier for plenty of PS sag under heavy load.

cheers
Pete

The tube rectifier is not a bad idea. For more sag use a 5U4GB. Just make sure that the rectifier filament supply has enough current capability. The 5AR4 is also a good choice, but does not drop as much voltage as a 5U4. For 100 W amps plan on a separate filament transformer and a couple of tubes in parallel.

Also remember that you will need to reduce the power supply caps so that the first filter section is 60uf or less total.

Given all that.... a resistor is a great way to go.

For a little more sag try placing the resistor before the first filter bank, then it will also sag the plates of the output tubes (leave the choke in its normal position). You will probably have to reduce the resistor to around 100 to 150 ohms to make it sound decent.

Alternately you could put the resistor in the center tap of the transformer to ground and then a simple SPST switch could be used to cut out the sag circuit. Of course this assumes that a bridge rectifier is not being used for the HV.

Gary