[jiggler]

I would like to suggest that we start a sticky thread where folks can post the measured DC component of the sources they use or have access to. This would serve two purposes: (1) it would confirm that most, if not all sources have no significant DC component on the signal; and (2) it would be a resource for those who cannot test their particular source.

I'll start with mine:

Sony D-FJ61 - 2-6 mV
Arcam Alpha 8 - 3-8 mV

 

[jiggler]

Bump - Come on people! I know you have measured the DC on your source outputs. Please post your findings here.

 

[Videoshielded]

Can I do it with a DVM?

 

[jiggler]

I don't see why not.

 

[jiggler]

I can't believe no one is responding to this call. Do you like caps in your signal path?!

 

[Voodoochile]

Good idea, jiggler. I'll measure my NAD this weekend.
My Kenwood PCDP is so old, I doubt anyone has it anymore. About 11 years now...

EDIT: thanks for the bump- that reminds me...

 

[jiggler]

bump

 

[meat01]

Can you explain to the DVM challenged how we do this? I will do it, but I don't exactly know where to measure.

 

[jiggler]

If you are measuring the output from RCAs, just place one probe on the outside of the jack (the ground or common) and the other in the hole in the center. If it is a portable, it is easier to use a mini-to-mini connector and measure across the tip and the shaft (the shaft is ground) and the middle ring and the shaft. Make sure to measure both channels because they can be different.

 

[stereth]

Hmm. I have an analog multimeter that can read down to 100mV, but can read down to 50uA for current. Does the DC component change with load? I was thinking about measuring the current across, say, a 10 ohm resistor and calculating voltage from that.

 

[jeffreyj]

Quote:

Originally posted by jiggler I would like to suggest that we start a sticky thread where folks can post the measured DC component of the sources they use or have access to. This would serve two purposes: (1) it would confirm that most, if not all sources have no significant DC component on the signal; and (2) it would be a resource for those who cannot test their particular source. I'll start with mine: Sony D-FJ61 - 2-6 mV Arcam Alpha 8 - 3-8 mV

Finally some sensibility! This is one of the reasons I laugh at single-ended class A designs lauded for their superior linearity... Oh yeah? How 'bout that DC blocking capacitor needed on the output. But enough ranting... Here is my strange contribution to the list; measuring the output of high quality sources is well and good, but they aren't likely to be the worst offenders.. So, I submit my favorite testing device: a Dell Inspiron 8100 laptop with the ESS Maestro chipset. My particular one has a DC offset of 1.9mV left and 8.7mV right. The left channel is admirably low but the right is a touch high. Not anything dangerous, even considering an up to 11x amplification, but stilll not excellent.

 

[jiggler]

I just built an RA-1 clone in a mint tin by taking out the huge Solen input caps. It is amazing how small the protoboard can be for this circuit if they're gone. It's about the size of a postage stamp with all the restitors tombstoned. Plenty of space left for the two 9 volts and a 50k panasonic pot. And without the input caps, this RA-1 clone is even more transparent than it's commercially-available cousin.

 

[Voodoochile]

Okay, here we go:

NAD C541i: R=0.8mv L=1.0mv
Sony DVP-NS500V: R=1.6mv L=1.8mv
Luxman D-113D: R=0.4mv L=0.9mv
Kenwood PCDP Model DPC-61: R=0.9mv L=1.5mv

Sony Vaio PCG-NV100p laptop: R=1.8mv L=4.7mv (ouch)

I also have a Panasonic DVD-RP56 and a Toshiba SD3750, but I'm not pulling them out of the rack tonight to measure. Maybe another time though.

 

[meat01]

My MZ-N707 is less than a mV. Does that mean I can lose the input caps on my CMoy?

 

[10SNE1]

Hard disk MP3 player

< 1 mv on both channels

Measured with Fluke 12 multimeter (min reading = 1 mv)