|
#1
05-01-2010, 09:26 PM
|
|||
|
|||
|
Technical question about amp buzz . . .
Well, I have managed to make several improvements in my new (used) Hiwatt DC40 combo over the past several weeks, including reducing the noise level through re-tubing and proper biasing. But there is still one noise in the amp that I have been unable to solve. Details:
1. It is a "buzz" type noise (not a hum -- it's more "staticky" with no "low end") -- almost like one you would hear in a music store from nearby lighting fixtures, or from single coil pickups. 2. The buzz is present even with both master volume and gain at zero. The buzz does not get any louder as either gain or volume is turned up. 3. The buzz does not vary with different guitars, cables, etc. 4. The buzz seems only seems to be present when the amp is in "pentode" mode (full power -- 40 watts). When I switch to "triode" mode (12 watts), the buzz seems to go away. 5. The buzz becomes very clear with the amp's presence knob way up. When you back the presence knob down, you can still hear the buzz, but it is masked a little by the overall darker tone. (PS -- I like to dime the presence on this amp.) Does this sound like it could be a grounding issue? A possible problem with the pentode/triode switch? Something else?
__________________
KRAMER: Come on, did you ever read one of these [Penthouse Forums]? GEORGE: It's not real. They're all made up. KRAMER: Ohh, it's real. GEORGE: Well you know there is an unusual number of people in this country having sex with AMPUTEES! Last edited by WienerDog; 05-01-2010 at 09:52 PM. 
|
|
#2
05-02-2010, 09:05 PM
|
|||
|
|||
|
anyone?
__________________
KRAMER: Come on, did you ever read one of these [Penthouse Forums]? GEORGE: It's not real. They're all made up. KRAMER: Ohh, it's real. GEORGE: Well you know there is an unusual number of people in this country having sex with AMPUTEES!
|
|
#3
05-02-2010, 09:17 PM
|
|||
|
|||
|
Sounds like a ground issue. Have you tried this in other rooms in your house to rule out a bad socket ground? If you turn away from the amp, like it's behind you with a full band and you're facing the crowd, does it buzz?
|
|
#5
05-03-2010, 08:07 AM
|
|||
|
|||
|
Quote:
__________________
KRAMER: Come on, did you ever read one of these [Penthouse Forums]? GEORGE: It's not real. They're all made up. KRAMER: Ohh, it's real. GEORGE: Well you know there is an unusual number of people in this country having sex with AMPUTEES!
|
|
#6
05-03-2010, 09:18 AM
|
|||
|
|||
|
The first thing I'd do is remove the NFB loop and see what that does.
__________________
If nobody laughs at your dreams they aren't big enough :)
|
|
#7
05-03-2010, 09:23 AM
|
|||
|
|||
|
Quote:
__________________
KRAMER: Come on, did you ever read one of these [Penthouse Forums]? GEORGE: It's not real. They're all made up. KRAMER: Ohh, it's real. GEORGE: Well you know there is an unusual number of people in this country having sex with AMPUTEES!
|
|
#8
05-03-2010, 09:55 AM
|
|||
|
|||
|
could be the lead dress
__________________
www.HipKittyProducts.com
|
|
#9
05-03-2010, 10:16 AM
|
|||
|
|||
|
Based on your description and the fact that the sound goes away in pentode mode, I would be looking at a failed electrolytic at the screen supply.
__________________
Disclosure: I operate a small, tube only repair shop in Ft Wayne, IN. Note: I've "parked" my website in case anyone has been searching for it.
|
|
#10
05-03-2010, 01:47 PM
|
|||
|
|||
|
Quote:
I don't completely disagree with Jerry, but I think the problem is elsewhere.
__________________
If nobody laughs at your dreams they aren't big enough :)
|
 |
| Thread Tools | |
| Display Modes | |
|
|
Linear Mode
