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Old 20th December 2008, 04:34 PM   #1
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Default Strange buzz in only one channel

Hello,

I'm facing a strange problem.

I've just assembled a dual mono kit from chipamp.com and it sound great!

But only one of the channels, the right one, is very sensible to what is attached to elettric plant.

e.g if I leave on the solder station only the right channel makes a lot of noise, the left one is deadly silent... same thing when you switch on or off lights: only right channel is sensible!

Someone has any idea about it, what to check?

Thanks in advance
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Old 20th December 2008, 06:05 PM   #2
Nuuk is offline Nuuk  United Kingdom
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With these being kits, the most likely fault will be a badly soldered joint somewhere. There isn't much else to go wrong.
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Old 20th December 2008, 07:26 PM   #3
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Quote:
Originally posted by Nuuk
With these being kits, the most likely fault will be a badly soldered joint somewhere. There isn't much else to go wrong.
I've redone all solder joints in the PSU an amp boards but the buzz still there...
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Old 20th December 2008, 07:27 PM   #4
Nuuk is offline Nuuk  United Kingdom
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Is the buzz only there when the amp is close to the soldering iron?
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Old 20th December 2008, 07:42 PM   #5
Ted205 is offline Ted205  United Kingdom
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my guess would be a earthing issue.

Are you using a star ground scheme ? are all the ground leads the same length ?

Does the right channel work ok when the left channel is removed (power & ground leads)? What happens if you swap the modules?
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Old 20th December 2008, 08:40 PM   #6
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Quote:
Originally posted by Nuuk
Is the buzz only there when the amp is close to the soldering iron?
No, the amp is not close to the soldering iron.

Only branched ad turned on

Same thing happens with lights or when refrigerators starts compressing but in this case no buzz but pops.

Only to the right channel!

Quote:
Originally posted by Ted205
my guess would be a earthing issue.

Are you using a star ground scheme ? are all the ground leads the same length ?

Does the right channel work ok when the left channel is removed (power & ground leads)? What happens if you swap the modules?
No, in this moment the amp is still 'naked' and if it would happened to both channels I would have considered a grounding issue but the left channel is deadly silent and doesn't seem affected from either soldering iron, lighst or refrigerator!

Now amp is configured in dual mono (dual amp, dual PSU and dual transformer) but yesterday was connected with both amps and a single PSU and single transformer and the problem was the same...one channel ok, the other 'sensitive'.

I'm confused...
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Old 20th December 2008, 11:50 PM   #7
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Well, I've surrended.

Buzz doesn'stop, the other channel stopped working!

Amp modules gone in the trash bin, I hope I'll be more lucky with MyRef...or maybe the next Gainclone (I've saved PSUs).

Thanks to everybody tried to help.
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Old 10th January 2009, 07:37 PM   #8
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Default For whom could be interested I've found the problem! :)

I've buyed two pcbs more and rebuilt the chipamp's Gainclone and that same strange problem reappeared, in the same channel, the Right one!

But there was also a new problem: no way to have dual mono!

If both amps were connected to one single PSU they worked, otherwise the right channel made only buzz!

The only things that have not be changed are:

RCA Connectors + theirs cables
Binding Posts
PSUs
Transformers

Well I've swapped RCAs Left <-> Right and the problem moved to the left channel!

So it was a RCA connector overheated...

Changed both RCA and now it works quite fine, also with solder station switched on...

I hope that this could be helpful for someone else!
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Old 11th January 2009, 11:07 AM   #9
AndrewT is offline AndrewT  Scotland
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can you post a pic of your set up?
and the schematic of both PSU and Amp?
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Old 11th January 2009, 12:58 PM   #10
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My setup is simply based on Chipamp.com PCBs so the schematic can be found on their website.

The components used are:

Panasonic FC & Evox-Rifa MMK (PS Decoupling)
Nichicon KG Gold tune (Main PS Reservoir)
Takman REX Resistors (Signal Path)
Philips/BC PR02 (Power resistors and Zobel)
Wima FKP2 (Snubber)
Evox-Rifa PHE426 (Zobel)
Selectronic R-Core 120VA Transformers
Solid Core speaker cable
Tasker Shielded Cable
Chinese 'High-End' Binding posts
Chinese 'High-End' RCA connectors (substituted by a PCB RCA Connector from trash...)

Some photos:

Click the image to open in full size.
Click the image to open in full size.
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