DC Filament Supply question

deepcmd · 2033

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Offline deepcmd

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on: March 28, 2016, 03:33:34 PM
Finished and op checked the unmodified Kaiju and then installed the DC filament kit. Everything went well and final voltages checked out at 4.88/4.96. The last instruction on page 17 says "you may want to confirm the hum pot settings for minimal noise performance".

I took that to mean to run the Hum Balance steps in the main Kaiju manual, page 71. When I did so, the voltages across the speaker terminal posts were 0 no matter what the hum pot setting, and I couldn't tell any difference in noise by listening and turning the hum pots across their full range (only that noise overall was much smaller than without the kit installed).

The Kaiju works fine, sounds awesome. Was just not sure if I was supposed to do the same voltage adjustment on the hum pots, or if that is something that doesn't work with the DC kit installed? My meter autoranges, and it picked up the unmodded voltages just fine, but manually setting the range is something I didn't think to do till just now.



Offline Paul Joppa

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Reply #1 on: March 28, 2016, 04:48:57 PM
Many posters on other forums claim that regulator chips "sound worse than AC heaters in spite of the hum". Using a hum pot should in theory make it possible to null out most of any noise or distortion in the chip. This theory comes from Jac at EML (he even makes some tubes with center taps on the filament itself for this reason). So that's reason number one reason to make this possible.

Reason number two is that it's less work to add the filament supply board.  :^)

If you don't hear any difference other than less hum, then don't worry about it. Listen again in a year when everything is well broken in and you are more deeply acquainted with the sound of the amp; you might pick up on something subtle then. Or not.

Paul Joppa


Offline deepcmd

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Reply #2 on: March 29, 2016, 04:50:49 PM
Sounds good, I'll let it be and listen awhile.   8)

Thanks!