Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Danilewicz on January 30, 2013, 03:02:57 pm

Title: Strange sound in my amplifier
Post by: Danilewicz on January 30, 2013, 03:02:57 pm
Hi!
Actually I'm making my guitar amplifier. It has 2 channels + booster. Clean - Bandmaster, Overdrive - AC30 and booster - EF86. I've wired ?power amplifier? (I'm sorry, but I don't know how to call it in english), phase inverter, tremolo and booster. The problem is that sometimes amp makes strange sound, even if booster is unconnected. I've recorded it:
http://w991.wrzuta.pl/film/6y4KHOpvUgM/wzmak (http://w991.wrzuta.pl/film/6y4KHOpvUgM/wzmak)
When I disconnect jack on the back of amp i turn tremolo off. Guitar is connected. Do You know what is the reason of this problem?
Sorry for my english ;)
Title: Re: Strange sound in my amplifier
Post by: stratele52 on January 30, 2013, 05:50:19 pm
You build an amplifier ?

You have schematic ?
Title: Re: Strange sound in my amplifier
Post by: smackoj on January 30, 2013, 06:11:34 pm
sounds to me like the tone killer called "motor boating" . Does the amp have a Negative Feedback Loop? Might try disconnecting NFB and see if she quits?

Good luck      :icon_biggrin:
Title: Re: Strange sound in my amplifier
Post by: stratele52 on January 30, 2013, 06:20:11 pm
Wiring lead dress ?
Title: Re: Strange sound in my amplifier
Post by: Danilewicz on January 30, 2013, 06:37:37 pm
Problem solved :icon_biggrin:
It was dry joint in power supply. It was strange, because I could hear this sound not only from the speakers, but from the circuit too. It was tiny electric arc  :laugh:
Thanks for reply.
Title: Re: Strange sound in my amplifier
Post by: plexi50 on January 30, 2013, 08:21:40 pm
Wow! Good eyes and quick fix.
Title: Re: Strange sound in my amplifier
Post by: stratele52 on January 31, 2013, 03:49:07 am
And about my 2 questions ?
Title: Re: Strange sound in my amplifier
Post by: Danilewicz on January 31, 2013, 09:49:33 am
1. I'm really sorry, but I don't understand what "Wiring lead dress" means  :/ Could You explain? Then I'll answer Your question ;)
2. Yes, I buid amp, but i don't know if I upload schematic.
Title: Re: Strange sound in my amplifier
Post by: Willabe on January 31, 2013, 11:21:42 am
Quote from: Danilewicz on January 31, 2013, 09:49:33 am
1. I'm really sorry, but I don't understand what "Wiring lead dress" means  :/ Could You explain?

Lead dress is how and where you run the wires to/from the tube scokets, pots, resistors, caps, switches, etc.


          Brad      :icon_biggrin:
Title: Re: Strange sound in my amplifier
Post by: stratele52 on January 31, 2013, 02:10:17 pm
Bad lead dress bring lots of problem , noise.........
Title: Re: Strange sound in my amplifier
Post by: John on January 31, 2013, 03:11:40 pm
Quote from: Danilewicz on January 30, 2013, 06:37:37 pm
Problem solved :icon_biggrin:
It was dry joint in power supply. It was strange, because I could hear this sound not only from the speakers, but from the circuit too. It was tiny electric arc  :laugh:
Thanks for reply.

 :icon_biggrin: