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32 mV DC: defective or acceptable?

98.10.54.107
Posted on March 15, 2017 at 23:38:49
dave789
Audiophile

Posts: 559
Joined: September 21, 2001
 I picked up a new Onkyo M5010 stereo power amp from Best Buy ($250 plus state sales tax)?

One channel has 15 mV and the other channel has 32 mV DC at the output.

The source has DC blocking capacitor at the output. So the DC output is the power amp's offset.

Is 32 mV acceptable level of DC output on a hi-fi amp(well, that model is not really hi-fi)?

I have seen some hi-fi amp's catalogue specs such as DC less than 10 mV (Quad, Creek, BGW, etc.).

In the case of a Parasound Halo amp, the manual claims 0.00V meaning that DC offset at the output is less than 5mV.

 

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RE: 32 mV DC: defective or acceptable?, posted on March 16, 2017 at 06:41:34
reuben
Audiophile

Posts: 1639
Joined: September 28, 2004
 The Adcom GFA-1 has a protection circuit that kicks in at 50 mV. I could live with 100 millivolts.

Dark energy? Ridiculous!
We live in an electric universe.

 

Is that with no load? nt, posted on March 16, 2017 at 08:29:05
Ralph
Manufacturer

Posts: 4769
Location: Minnesota
Joined: April 24, 2002
 -

 

with speaker connected. nt, posted on March 16, 2017 at 08:35:46
dave789
Audiophile

Posts: 559
Joined: September 21, 2001
 .............

 

RE: 32 mV DC: defective or acceptable?, posted on March 16, 2017 at 09:08:20
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 Test it with no load and after it has warmed up for about 5 minutes.

Honestly even my cheaper amps can be set to 0mv. Sounds like some poor QC on the part of the factory line person doing that settings.

Check it while the stereo is "cold" and then again after it has been on for an hour. If there is a significant swing you got some problems.

 

That might be about a 1/10th of a milliwatt. I wouldn't worry about it. nt, posted on March 16, 2017 at 09:12:56
Ralph
Manufacturer

Posts: 4769
Location: Minnesota
Joined: April 24, 2002
 .

 

no DC adjustment pot on the service manual, posted on March 16, 2017 at 15:39:41
dave789
Audiophile

Posts: 559
Joined: September 21, 2001
 I saw a service manual on the internet. I could find what seems to be bias adjustment pot, but could not find DC offset adjustment pot.

 

same without load. nt, posted on March 16, 2017 at 16:02:39
dave789
Audiophile

Posts: 559
Joined: September 21, 2001
 ...............

 

100mV, posted on March 17, 2017 at 13:54:30
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 There is no DC adjust.

If the DC exceeded 100mV I would consider replacing the diff input pair for that channel.

 

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