DVD/CD Audio Out Control ?

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Greg M

Greg M

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Joined 2010
#1
The analog audio output on my Blu-ray player is too hot and over drives my sound card. The sound card (M-Audio 2496) has no way to control input, so it clips when I feed it into Audacity for ripping tunes.
Is there a passive circuit I can build (cheap) to act as a "volume control"?
It doesn't need to come down much. Maybe a pair of pots so I can do balancing as well?
I don't want to alter or color the sound, just reduce the intensity.

Thanks
 
#2
As you suggest, a volume control or even just a pair of presets. 10k would be a good choice.

If it's just a "one off" project for occasional use then just chop an old phono lead in half and wire a pot in each (correctly using all three terminals, not just in series which won't work).
 
#7
Greg M said:
I found a schematic on a page while I was searching. Think this would work?



An externally hosted image should be here but it was not working when we last tested it.




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Click to expand...

Since it's coming from a solid state player I'd recommend keeping the resistance on the low side. I'd consider 5K the minimum and 25 K the maximum. Higher values raise the noise level and all pots form a low pass filter with the cable capacitance to roll off the top faster than the bottom. Higher value pots move the high end corner to a lower frequency.

If it were mine I'd build a fixed pad of about 6dB and see (hear) how that goes. Adjustable stuff tends to encourage fiddling. Nice thing about digital media is there is an absolute maximum well defined level the machine can put out and no amount of tweaking record levels will alter it. Hence the fixed pad.

G²
 
#8
I was thinking 10k ?

Actually While I was looking through the pile-o-parts for some pots, I found an old video/mixer from about 25 years ago. A Nady unit, that I had for trying to edit VHS tapes. I put in the output of the Blu-ray player and was able to put it down just enough to stop the clipping. The results don't sound at all bad. But I still want to try "the project" just to see what happens.

I do like to fiddle
 
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#9
Greg M said:
I was thinking 10k ?

Actually While I was looking through the pile-o-parts for some pots, I found an old video/mixer from about 25 years ago. A Nady unit, that I had for trying to edit VHS tapes. I put in the output of the Blu-ray player and was able to put it down just enough to stop the clipping. The results don't sound at all bad. But I still want to try "the project" just to see what happens.

I do like to fiddle
Click to expand...

10K is an excellent choice and it's normal to like to 'fiddle'. One of the guys I worked for wanted to get rid of the adjustments in a large video system by identifying the drift sources (poor reference Voltages and poorly temperature compensated log and anti-log amplifiers) and then calculate the proper resistor values. I too like to tweak but was paid to do it differently. His point was that the bulk of the problems were due to 'screwdriver drift'. He was right and I'm now a convert and am rather circumspect about tweaking things until verifying possible bad caps.

G²
 
#13
Greg M said:
I'm having a heck of a time finding a linear, 2 gang, 10k pot.
(Like to get a little Hammond aluminum project box too)
Click to expand...

For direct control of the audio you'd probably prefer an 'audio taper'. I didn't bother trying to find a dual pot for my mic preamp and just used 2 separate controls. I still need to add the diode clippers to protect the input to the PC.

G²
 
#18
I just got the pot from Surplus Sales of Nebraska and the top pot is DOA.
The bottom half works fine.

We'll see what happens next, but for now I would not buy from them again.
I guess it depends on how they handle this or if I have to go through my credit card co.
Bummer...
 
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