Search found 6 matches
- Tue Jan 02, 2024 10:15 am
- Forum: Attenuators
- Topic: Bias output stage via AVC
- Replies: 1
- Views: 7395
Bias output stage via AVC
Hi All, I'm thinking of using fixed bias and kill two birds with one stone, volume and bias. Been experimenting with SIT transistors, a simple 2SK79/2SK60 SET. 2SK79 has 2K rp, loaded with 18K, the AVC at the output helps to lower the impedance. 2uf coupling capacitor for the equivalent 25K reactanc...
- Tue Jan 02, 2024 10:00 am
- Forum: Attenuators
- Topic: How have the auoformers changed over the years
- Replies: 4
- Views: 8940
Re: How have the auoformers changed over the years
Is this figure frequency dependent especially at the low end? So 200H at 20Hz etc?
- Tue Feb 23, 2021 10:31 pm
- Forum: Attenuators
- Topic: Bal to SE and AVC
- Replies: 5
- Views: 7399
And because you've pointed me in the direction of a new 600:600 input transformer a crazy idea came about. A 600 1:1+1 input transformer capable of doubling the input voltage to 40Vpp max, apply a negative voltage for a fixed bias 3W PX4 amp without caps, standard 40H 5K gapped OTP. My DAC has a cla...
- Tue Feb 23, 2021 10:15 pm
- Forum: Attenuators
- Topic: Bal to SE and AVC
- Replies: 5
- Views: 7399
The sketch is looks good and what I've been using, I guess if the DAC wasn't to BAL specs it wouldn't see the expected impedance and start humming. Also took your advice from a 2005 post on a bifilar choke setup and it works surprisingly well. Hooked up a Magnaquest cobalt 10K otp with headphones an...
- Sun Feb 21, 2021 5:22 pm
- Forum: Attenuators
- Topic: Bal to SE and AVC
- Replies: 5
- Views: 7399
Small mistake in the schematic, pins 1 and 3 are reversed, I need to tattoo this on my arm, 1- Ground, 2 - Positive, 3 - Negative Didn't take long to make the changes as suggested with the floating AVC. Just for the hell of it I left the existing grid leak and gave it a try, a bass tilted signature,...
- Sun Feb 21, 2021 9:20 am
- Forum: Attenuators
- Topic: Bal to SE and AVC
- Replies: 5
- Views: 7399
Bal to SE and AVC
Hi all, Been using a 28 step AVC with great success for a 10Y preamp/driver setup. However the input transformer placement is bugging me and thinking of redoing it. Current setup: 20Vpp balanced source into a 15K bridging transformer for SE conversion with a 15K load, AVC to the tube grid with a 100...