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Post subject: Hum/Buzz from Supersonic 22 power supply
Posted: Thu Feb 22, 2018 11:57 am
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Hi,

Been having this hum and/or buzz (can't really tell the difference) from my amp for years but it has now gotten to the point that it stops me from recording with the amp.

The amp is a Supersonic 22, famous for it's noisiness I know, but trust me, I owned this amp since 2010, it hasn't always been this bad, altough a bit $@!&#* most of the time.

I swaped the tubes and biased the amp just for good measures but that didn't help at all.

Today I took the amp apart, trying to find any obvious faults. Nothing seems to be broken (except some so-so solders all across the board) but I did find one thing, a buzzing noise coming from the power supply PCB. The same buzzing noise I hear when the speaker is plugged in. I tried to locate it to a specific component, but it proved to be harder than I hoped.

Some quick facts:
- The buzz/hum only starts sounding in the PCB and speaker when the stand-by is switched off
- The buzz/hum isn't really effected by the volume control altough the gain controles (espacially gain 2) makes it more intense
- The reverb control really enhance the noise (even though the tank is not hooked up) and with NO volume
- The noise is NOT coming from the power transformer

Anyone that have the slightest idea what could be causing this?

PS. Here's some audio files https://drive.google.com/open?id=1YTdh1CRgOvGbTZw1Cpz8EJbYEGOQhdBk


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Sun Feb 25, 2018 3:01 am
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To hear you audio file I need to download something , I wish not.

Hum/ buzz is most of the time coming from filter caps ; bad caps or bad solder


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Sun Feb 25, 2018 5:54 am
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stratele52 wrote:
...filter caps ; bad caps or bad solder


+1 stratele52, my first thought as well.

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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Sun Feb 25, 2018 8:26 am
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While you easily could need repairs to the amp as Stratele and Shimmilou suggest, the hiss/hum has just been a two year distraction for my SS22 particulalrly when mic’ed recording and low volume playing.

I am finally satsified by emplying the following. I dropped an MXR M-135 SmartGate in the fx loop with a Morley volume pedal after the MXR. The SmartGate is set for “hiss” and dialed in at the marked sweet spot. The Morley is cocked about 50%. For living room volume I crank the volume knobs at about 1:00. This eliminates the idle noise and the amp sounds great with the 6V6’s cooking with the extra power.

I do not need any of this for gigging as the ambient noise of the room coupled with the higher volume masks the idle noise.

HTH

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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Sun Feb 25, 2018 1:28 pm
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Hey all,

Thank you for the replies!

@strattele52, that's odd, for me it plays in a web-player. I uploaded it to Soundcloud so you (or anyone else) won't have to download it: https://soundcloud.com/jacobthebluesman/sets/supersonic-22-noise

Yeah, caps usually seems to be the culprit. I could however not locate the buzz coming from any of caps on the power supply PCB, but that doesn't need to mean anything. I did also go trough the solders and they all seemed good. Anywho, I guess I'll just need to desolder the caps and measure them to see if they seem alright.

Started looking for suitable replacement caps to buy here in Europe and only came across an Ebay-seller selling caps from "JJ-electornic" (http://www.jj-electronic.com/en/contact. Anyone know of this brand and if it's any good?


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Sun Feb 25, 2018 2:07 pm
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JJ made good tubes, I will trust their caps

Did you check bias circuit filter caps too , If filtering is wrong you will have buzz / hum at the speaker

How much AC volts ( yes AC not DC ) do you read at each main power supply filter caps
C78, C80, C83,C84

Do same reading at Bias circuit filter cap

Report


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Sun Feb 25, 2018 2:59 pm
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flygandejacob wrote:
...Started looking for suitable replacement caps to buy here in Europe...


F&T are made in Germany, and are some of the best caps made.

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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Mon Feb 26, 2018 2:06 am
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shimmilou wrote:
flygandejacob wrote:
...Started looking for suitable replacement caps to buy here in Europe...


F&T are made in Germany, and are some of the best caps made.


+1, I mostly use them with Sprague Atoms,


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Mon Feb 26, 2018 3:03 am
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"but I did find one thing, a buzzing noise coming from the power supply PCB. The same buzzing noise I hear when the speaker is plugged in."

The answers you've been getting seem to be ignoring that. Focusing on typical types of hum/buzz problems that are purely electronic in nature, and only become audible when the speaker turns electrical energy into acoustic energy.

Other than transformers, I've never heard anything inside an amp chassis hum/buzz.

Is there a choke or inductor inside the amp?
----------------------
Reading that quote, I can interpret it as saying you were testing the amp with no speaker connected. If so, don't ever do that again.

For silent testing rig up a dummy load. Or make a really long speaker cable and put the speaker in another room.

(With no input signal, a healthy tube amp with no speaker load isn't quite as harmful as generally thought. But a hissy amp or an amp with a loud hum/buzz is creating its own signal -- no speaker equals a lot of stress on the tubes and output transformer.)


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Mon Feb 26, 2018 3:07 am
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strayedstrater wrote:
"but I did find one thing, a buzzing noise coming from the power supply PCB. The same buzzing noise I hear when the speaker is plugged in."

The answers you've been getting seem to be ignoring that. )


Wrong !
Buzz / hum always comes from Power Supply

Or he mean mechanical vibration ?


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Mon Feb 26, 2018 12:45 pm
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He says he hears a hum/buzz coming from the area of the power supply PCB, and the PCB hum/buzz sounds similar to the hum/buzz coming from the speaker.

When y'all told him to check the filter caps, he checked back in to say that he couldn't locate the buzzing coming from the caps, but he planned to disconnect them and measure them sometime in the future -- that suggests he listened to the caps to see if they were making the noise.
------------------
Maybe I'm taking the OP too literally, but it sure seems like he's saying there's a hum/buzz coming from inside the chassis, independent of the speaker.


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Mon Feb 26, 2018 12:50 pm
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strayedstrater wrote:
He says he hears a hum/buzz coming from the area of the power supply PCB, and the PCB hum/buzz sounds similar to the hum/buzz coming from the speaker.

When y'all told him to check the filter caps, he checked back in to say that after listening to the caps, he couldn't hear them humming or buzzing.
------------------
Maybe I'm taking the OP too literally, but it sure seems like he's saying there's a hum/buzz coming from inside the chassis, independent of the speaker.


You could be right.

Checking filtering like I write take few minutes and you will know if filter caps are good or not.


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Mon Feb 26, 2018 1:23 pm
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strayedstrater wrote:
Maybe I'm taking the OP too literally, but it sure seems like he's saying there's a hum/buzz coming from inside the chassis, independent of the speaker.

@strayedstrater, you are completely CORRECT. The buzzing noise is audible even without the speaker being plugged in. To be honest, I thought this was clear.

Now that this has been settled, any new ideas of what this could be?


strayedstrater wrote:
Is there a choke or inductor inside the amp?

Here's a schematic over the PCB :
Image
It seems like a choke can be found on the PCB with the number 022707, am I right? Could this be the villain?


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Mon Feb 26, 2018 2:20 pm
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flygandejacob wrote:
[

Now that this has been settled, any new ideas of what this could be?


strayedstrater wrote:



Yes and I answer


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Post subject: Re: Hum/Buzz from Supersonic 22 power supply
Posted: Mon Feb 26, 2018 2:24 pm
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stratele52 wrote:
Yes and I answer


Sorry, I'm not following you completely?


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