Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: isaac_teller on November 25, 2022, 11:26:22 am

Title: Steve Luckey November project
Post by: isaac_teller on November 25, 2022, 11:26:22 am

Hello. I built this exactly as per the schematic, except with diodes instead of a 5Y3. All the voltages are within +/- 5%. Sounds great except there is a slight motorboating-type buzz in the preamp. When I turn the master down it's dead quiet. What should I look for  to fix it? Thank you.
http://www.sluckeyamps.com/november/november.pdf (http://www.sluckeyamps.com/november/november.pdf)

Title: Re: Steve Luckey November project
Post by: kagliostro on November 25, 2022, 12:00:54 pm

Motor Boating may have to do with PS

As you have SS rectifier tray to increase the first filter cap

You can also revise the value of the resistors on PS

Franco

Title: Re: Steve Luckey November project
Post by: isaac_teller on November 25, 2022, 01:29:05 pm

Thanx. I'll give it a try.

Title: Re: Steve Luckey November project
Post by: kagliostro on November 25, 2022, 02:45:17 pm

I forgot to say

You can also sub the 1N diodes for UF diodes

At least, add an UF diode After the FW or FWB rectifier and before the first e-cap

K