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This can't be right???
Old 23rd January 2013
  #1
Gear Nut
 
NUVMUSIC's Avatar
 
🎧 10 years
This can't be right???

Hi guys
I have an Avalon AD2022 Pre and, when set to identical gain levels, channel 2 seems to be around 4dB lower in volume than channel 1. This is really starting to get frustrating and defeats the object of having stepped controls when matching levels. I've swapped out leads etc., to no avail. The pre works perfectly fine and there appears to be no issues with noise or distortion as a result.

The problem has persisted since I bought the unit, which is over a year ago now.

Is this normal with such pres, even though it's built around discrete symmetrical boards? Are there any other users experiencing a similar problem?

Can any techs among you suggest what the problem may be?

Any help would be really appreciated.
Old 23rd January 2013
  #2
Gear Guru
 
Drumsound's Avatar
 
🎧 15 years
It sounds like there's something not quite right, to me. Have you contacted Avalon. I don't doubt that it is something simple to fix. There may even be a simple calibration pot inside the unit.
Old 24th January 2013
  #3
Gear Nut
 
NUVMUSIC's Avatar
 
🎧 10 years
Hey Drumsound
Thanks for the response

Quote:
Originally Posted by Drumsound ➑️
Have you contacted Avalon. I don't doubt that it is something simple to fix.
Very hard to make contact with them from here in the UK and the UK authorised service tech guy didn't appear to be helpful, particularly when he tried to quote me several pounds for a replacement bulb(!!)

Quote:
Originally Posted by Drumsound ➑️
There may even be a simple calibration pot inside the unit.
I've opened it up but not quite sure where to find this.

Come on guys. Only one taker in this?
Can any techs among you point me in the right direction. I appreciate it's difficult to pinpoint, particularly when you haven't got the unit in front of you but any help is appreciated.
Old 24th January 2013
  #4
Lives for gear
 
gyraf's Avatar
 
🎧 15 years
Finding a schematic would be the first step in solving something like this.

Nearly impossible without one.

Jakob E.
Old 24th January 2013
  #5
Lives for gear
 
🎧 15 years
Hi
Be more persistent trying to contact Avalon or your dealer.
It could well be a calibration issue but if you have had it from new why didn't you comment to the dealer then?
Of course it is not 'normal' for what you say is around 4dB difference in level between channels, but it is not necessarily that serious a job to check calibration.
It should be looked at by someone with reasonable skills to determine whether it is just calibration that was not done properly of if there is an actual fault.
Matt S
Old 24th January 2013
  #6
Lives for gear
 
Lotus 7's Avatar
Sometimes it's easy to overlook the simplest solution. Please don't be insulted by this, but have you checked that the input gain switch knobs are correctly positioned (the same) on both channels. I only mention this since the gain steps are each 4 dB (same as your gain "error"). When you turn both switches fully CCW or fully CW are the knob indicators each on the first or last step?

If so, then something is clearly not right and as suggested, call Avalon.
Old 24th January 2013
  #7
Gear Nut
 
NUVMUSIC's Avatar
 
🎧 10 years
Thanks for taking the time to reply, guys.
@gyraf: I've no hopes finding an Avalon schematic, as I've looked for one previously, but I agree with your point hence...

@lotus7: I have checked alignment of the gain dials, as I know this is easy to overlook and yet it's a simple fix, but all seem fine.

@MattSyson: I bought the unit from a private seller who owned it from new. Of course, it was out of warranty when I purchased it.
Contacted the UK Avalon repair tech again today and his rates appear to be more reasonable.

Just thought I'd put it out here to see if anyone had a similar experience or could advise withe regards a DIY fix.

Thanks again for your replies
Old 26th January 2013 | Show parent
  #8
Gear Guru
 
Drumsound's Avatar
 
🎧 15 years
Quote:
Originally Posted by NUVMUSIC ➑️
Hey Drumsound
Thanks for the response
you're welcome
Quote:
Originally Posted by NUVMUSIC ➑️
I've opened it up but not quite sure where to find this.
Look for a small white plastic pot that needs to be adjusted with a small screwdriver. The ones I've seen are in a dark grey housing. There would be two, one for each channel. Are there markings on the PC boards? I'd look for something that says cal, output or hopefully output cal.
Old 27th January 2013
  #9
Gear Nut
 
NUVMUSIC's Avatar
 
🎧 10 years
FIXED!!!

I popped the lid (again) and it appears that there was excess solder bleeding onto contacts on the reverse of the pcb. Funny because all this time I had been looking for the problem on the surface of the board. All that was required was a simple clean up to remove the thin strands from the small circuit board in the centre and around the area to the bottom left of the image posted.

Still testing, but all appears to be well.
Feels like a new pre )

This can't be right???-imageuploadedbygearslutz1359272794.023219.jpg
Old 28th January 2013
  #10
Gear Guru
 
Drumsound's Avatar
 
🎧 15 years
Good Job!
Old 28th January 2013
  #11
Lives for gear
 
Lotus 7's Avatar
Great that you were able to find the problem. You're lucky that the "solder bridge" only caused a gain reduction and didn't short a power supply rail.

Solder bridges can cause expensive mic pres like the Avalons to loose all of their electronic smoke and once released, it's very hard to compress it back into the circuit boards! It's almost as hard to work with as Lucas smoke on British sports cars! Please don't ask me how I know.
Old 29th January 2013
  #12
Gear Nut
 
NUVMUSIC's Avatar
 
🎧 10 years
Quote:
Originally Posted by Lotus 7 ➑️
Great that you were able to find the problem. You're lucky that the "solder bridge" only caused a gain reduction and didn't short a power supply rail.

Solder bridges can cause expensive mic pres like the Avalons to loose all of their electronic smoke and once released, it's very hard to compress it back into the circuit boards! It's almost as hard to work with as Lucas smoke on British sports cars! Please don't ask me how I know.
How do you know?



Just testing.
Yeah I feel VERY lucky in this instance, Lotus.
Thanks for all replies (and the subtle pointer to the correct terminology!)
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