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Post subject: HRD hiss from reverb
Posted: Sun Oct 23, 2016 2:30 pm
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Aspiring Musician
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There is a hiss (noise/static) coming from my HRD. Did some troubleshooting and I believe the problem has something to do with either the reverb tank or the reverb circuit. With nothing plugged into the amp, the hiss is present only when the Reverb is on. The higher the reverb level the louder the hiss.

Before I take the amp to a qualified tech, I'd like to know if there is anything I could try.

Thanks and Cheers!
BM

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Post subject: Re: HRD hiss from reverb
Posted: Sun Oct 23, 2016 5:27 pm
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Try pulling the connecting cables to the reverb tank. Cleaning and re-connecting them. A little contact cleaner may help.

Good luck!


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Post subject: Re: HRD hiss from reverb
Posted: Mon Oct 24, 2016 2:27 am
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BMW2002Ti give the best answer. Be sure you know how to clean connector. Contact cleaner and plug in and out connectors many times to clean them.

1-You can use any stereo cable for test.
2-Remove the reverb tank from the cab, keep it connected, listen....No hiss, try to relocate tank in the cab, few inches can stop the hiss.
3- Remove tubes V1,and V2 power amp ON and listen ; no hiss, try new tube(s)

Amp reverb circuit is all solide state, nothing you can do yourself.


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Post subject: Re: HRD hiss from reverb
Posted: Mon Oct 24, 2016 11:17 am
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Thanks for the feedback. As always, very much appreciated.

First chance I get I'll give a try and let you know the results.

Thanks!
BM

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Post subject: UPDATE: HRD hiss from reverb
Posted: Mon Oct 31, 2016 12:48 pm
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Aspiring Musician
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A while back I installed some LEDs underneath the amp which give a cool sort of Blues glow. It turns out that the transformer that powers the LEDs is the culprit. I don't understand why this wasn't an issue before. Obviously something changed.

Thanks and Cheers!
BM

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Post subject: Re: UPDATE: HRD hiss from reverb
Posted: Mon Oct 31, 2016 1:53 pm
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Bluer Monkey wrote:
A while back I installed some LEDs underneath the amp which give a cool sort of Blues glow.

Thanks and Cheers!
BM


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Post subject: Re: UPDATE: HRD hiss from reverb
Posted: Mon Oct 31, 2016 2:33 pm
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Bluer Monkey wrote:
It turns out that the transformer that powers the LEDs is the culprit. I don't understand why this wasn't an issue before. Obviously something changed.


That tranny is probably heading south now.

Arjay

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Post subject: Re: UPDATE: HRD hiss from reverb
Posted: Mon Oct 31, 2016 9:23 pm
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Retroverbial wrote:
Bluer Monkey wrote:
It turns out that the transformer that powers the LEDs is the culprit. I don't understand why this wasn't an issue before. Obviously something changed.

That tranny is probably heading south now

Quite possibly, but not necessarily. There could be noise from somewhere else in the building that's new, and that the transformer always has been badly shielded and amplifying the EM noise. It just might not have been noticeable before if there wasn't a strong noise source before.

I have a pedal like that[*]. It's usually fairly quiet, but if a dimmer is on at the other side of the room, and that particular pedal is close to the amp and turned on, the amp hisses. Move the pedal away from the amp, and it quiets down. Turn the lamp off or to full, and it quiets down too. Putting a ferrite bead on the lamp cord helped, but didn't stop it completely. I just wonder how the heck the EM signal gets from the metal enclosed pedal based on vicinity. The knob?

[*] A Phase 90. For the songs that absolutely need one.


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Post subject: Re: UPDATE: HRD hiss from reverb
Posted: Tue Nov 01, 2016 8:07 am
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Aspiring Musician
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Thanks for the detailed reply, arth1. The reverb/hiss was present when I moved the amp to the garage so I'm thinking it's not the outlet or circuit in my office/studio. There are no dimmers anywhere in the house nor have there been any changes to the electrical system since the LEDs were installed. Could it be the transformer itself? Not sure this will help but here is a picture:

Image

I know very little about what happens inside the amp and how interference works (btw I had to look up ferrite bead) but is it possible that my little LED project caused damage to the amp's transformer? :shock:

Cheers!
BM

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Post subject: Re: UPDATE: HRD hiss from reverb
Posted: Tue Nov 01, 2016 9:57 am
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Bluer Monkey wrote:
...but is it possible that my little LED project caused damage to the amp's transformer?


Doubtful.

Arjay

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Post subject: Re: UPDATE: HRD hiss from reverb
Posted: Tue Nov 01, 2016 2:48 pm
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Bluer Monkey wrote:
Not sure this will help but here is a picture:

Image


Oh, it helps. "Be Well" is, from what I can tell, a cheap copy of the more reputable Mean Well power supplies, and it's quite likely the culprit here. Give a company like Mouser or DigiKey a call, and say you need a replacement for a 12V 600mA power supply, plus on tip. (Can't see the connector, so measure the size - there are a couple of different sizes). They're cheap enough, especially if you need less than a couple of ampere. Less than $20, I would think.

Bluer Monkey wrote:
but is it possible that my little LED project caused damage to the amp's transformer?

As Arjay said, it's highly doubtful.


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