Improving the Aikido line stage...

[Peter Clements]

I use AC on my Aikido. It works well. I do not like the sound of regs in the heater circuit.

 

[jsn]

I used simple unregulated DC filaments on my aikido microphone preamp. Just a couple 1000uF caps with a 1 ohm resistor between them. I also used 1uF snubber resistors on the filament pins, but that its probably not necessary either.

I don't get regulating filament voltage. Filament voltage can be +- a volt and still be just fine.

Despite being somewhat more complex than most circuits, this is easily built point to point. No need for PCBs.

Here is my version, using input and output transformers and octals:
http://boozhoundlabs.com/microphone-preamp-aikido/

jsn

 

[JojoD818]

I use AC on my Aikido. It works well. I do not like the sound of regs in the heater circuit.

Thanks, my tube amp has AC heaters and is dead quiet. Its just that most I read here use DC heaters.

I used simple unregulated DC filaments on my aikido microphone preamp. Just a couple 1000uF caps with a 1 ohm resistor between them. I also used 1uF snubber resistors on the filament pins, but that its probably not necessary either.

I saw that one last night while I was researching on the net, very nice implementation.

Did you diy your rack mount chassis?

Thanks guys,
JojoD

 

[jsn]

Thanks.

The chassis is a BUD chassis from Mouser. Part #563-CH-14400

It uses standard system holes, so it will be easy to have a nice frontpanel made with frontpanel express. It isn't very heavy-duty, but for something like this, it's fine - and easy to work with.

As for AC vs. DC, I would use AC on everything but phono and mic stages. And just use simple unregulated DC. Some popular and very quiet circuits use a single large cap and a dropper resistor for the filament filtering.

I use a stack of zener diodes fed from the B+ via a large resistor as a sort of shunt regulated phantom power supply fir microphones. If you must have regulated filaments, that might be a good way to do it. I think you can get 6.3V zeners.

jsn

 

[JojoD818]

jsn,

I'm set on using AC then, I hope everything works out ok.

Thanks
JojoD