Author Topic: C-1 channel imbalance  (Read 1767 times)

Offline treos33

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C-1 channel imbalance
« on: December 09, 2012, 01:31:38 PM »
Has anyone noticed this with other C-1s? At low volumes there is a significant volume imbalance with the left channel being much lower than the right. It evens out at about 1/8 rotation of the volume knob but my speakers are efficient enough and amp powerful enough that this is quite loud.

Do you think some deoxit could fix this or is this just characteristic of the volume pots Carver used?
Desk:
ObjectiveDAC, Technics SL-1500 w/ Grado Black Cart -> NAD 1000 pre -> Emotiva Airmotiv 4
Bedroom:
Creek 4330R -> DefTech StudioMonitor 450
Home Theater:
Onkyo TX-NR809, Rotel RB-981 -> Boston Acoustics VR-40, VR-12 Center, Soundware surrounds, Velodyne VRP-1200

Offline Kingman

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Re: C-1 channel imbalance
« Reply #1 on: December 09, 2012, 01:33:17 PM »
I would think oxidation.
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Offline Slim-Shaddy

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Re: C-1 channel imbalance
« Reply #2 on: December 09, 2012, 05:21:12 PM »
I had a problem similar to this and it turned out to be a dirty speaker switch on the amp.
I am confident that an SL-1200 is capable of outperforming turntables of much higher expense with minor modification.

Offline OCCD

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Re: C-1 channel imbalance
« Reply #3 on: December 11, 2012, 05:19:02 PM »
Most of the time it is dirt. 
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Offline treos33

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Re: C-1 channel imbalance
« Reply #4 on: December 11, 2012, 07:38:00 PM »
Alright, I'll try some contact cleaner this weekend. It could possibly be the amp, still need to change the speaker relays on my NAD 2200 but that problem manifest differently. Thanks for the replies.
Desk:
ObjectiveDAC, Technics SL-1500 w/ Grado Black Cart -> NAD 1000 pre -> Emotiva Airmotiv 4
Bedroom:
Creek 4330R -> DefTech StudioMonitor 450
Home Theater:
Onkyo TX-NR809, Rotel RB-981 -> Boston Acoustics VR-40, VR-12 Center, Soundware surrounds, Velodyne VRP-1200

Offline treos33

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Re: C-1 channel imbalance
« Reply #5 on: January 16, 2013, 08:24:19 AM »
Tom, after some reading this seems to be a known issue with the Carver volume pots. If you and Anders can't fix it with some contact cleaner then don't worry about looking for a replacement pot.

Refer to:

http://www.audiokarma.org/forums/showthread.php?t=55854

Specifically:

"According to a service bulletin put out by Carver in 1988 there were numerous complaints about non-linear tracking and preamp noise(hiss) at lower volume knob setting, say below the 8:00 position. For example: my C-1 would lose volume on the left channel before the right channel when trying to listen to it at very low volume levels, say late at night when everyone was sleeping and I didn't want to disturb them. At the other extreme, It would play at unbelievably loud levels at ~10:00 on the volume control. I would guess that it would max my amp out at ~12:00 volume setting.

In order to correct the problem it was necessary to lower the gain of "MAIN OUT 1" (which is programmable) in order to get away from the non-linear portion of the volume control and also to operate the preamp away from its noise floor. This would also allow the end user to get the best possible signal to noise ratio at normal or optimal listening levels."
Desk:
ObjectiveDAC, Technics SL-1500 w/ Grado Black Cart -> NAD 1000 pre -> Emotiva Airmotiv 4
Bedroom:
Creek 4330R -> DefTech StudioMonitor 450
Home Theater:
Onkyo TX-NR809, Rotel RB-981 -> Boston Acoustics VR-40, VR-12 Center, Soundware surrounds, Velodyne VRP-1200

Offline treos33

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Re: C-1 channel imbalance
« Reply #6 on: January 16, 2013, 10:28:45 AM »
I found the service bulletin so I'm just going to change the resistors myself to reduce the output gain on Main 1. Don't even bother opening it up.

If anyone is interested in this mod, the service bulletin can be found on the last page of this PDF:

http://thecarversite.com/manuals/mandir/Carver%20C-1%20service%20manual.pdf



P.S. Tom, looks like it was the volume pot itself, so suck it.   O0
Desk:
ObjectiveDAC, Technics SL-1500 w/ Grado Black Cart -> NAD 1000 pre -> Emotiva Airmotiv 4
Bedroom:
Creek 4330R -> DefTech StudioMonitor 450
Home Theater:
Onkyo TX-NR809, Rotel RB-981 -> Boston Acoustics VR-40, VR-12 Center, Soundware surrounds, Velodyne VRP-1200

Offline OCCD

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Re: C-1 channel imbalance
« Reply #7 on: January 16, 2013, 11:57:24 PM »
lol  you prob broke that cheap ass pot... >:D >:D >:D >:D >:D
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