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Very low sound coming through δ1

delta1

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Very low sound coming through δ1

Postby astrouk1 » August 19th, 2012, 4:28 pm

Hi,

I've just built a 3 channel B22 using the backplane, but when I connect the headphones, I'm getting barely audible music, the volume doesn't change as I adjust the δ1 (Att 24.5K).

I'm thinking it's the way I'm connecting to the backplane. Both JP4's are in and I'm using the INOUT. Using the Right channel as an example: the GR is connected to the left-mostpin on the backplanes J7, the OR is connected to the middle pin on J7 and the IR is connected to the right-most pin on J7 (next to the text "Right Volume" on the backplane).

The relays click fine, matched by the LED indicators.

Any help much appreciated.
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Re: Very low sound coming through δ1

Postby linux-works » August 19th, 2012, 6:13 pm

even when the atten is at 0db, you still get nothing?

if you connect a normal pot to the 3 pin vol headers on the b22 backplane, that does work ok?
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Re: Very low sound coming through δ1

Postby astrouk1 » August 19th, 2012, 6:16 pm

Even at 0db it stayed the same volume, very low.

I don't have a normal pot to try it with, I do have a variable output on my DAC, but I've been using it's line out.

I swapped IR and OR on the backplane and nearly blew my head off, it was very loud.
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Re: Very low sound coming through δ1

Postby astrouk1 » August 19th, 2012, 6:22 pm

Just to clarify the signal path:

RCA - D2 input Port - D2 input Bus - D1 Input - D1 INOUT - Backplane Volume J7/J6 - "Headphone out" on Backplane - E12 DC Protect in - E12 DC Protect Out - D2 Output Bus - D2 Output Port - Headphone Jack
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Re: Very low sound coming through δ1

Postby astrouk1 » August 19th, 2012, 7:05 pm

I've just tried bypassing the E12 & D2 output side by running a wire on one channel directly to the headphone jack from the spare headphone out on the backplane, no change in volume.
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Re: Very low sound coming through δ1

Postby linux-works » August 19th, 2012, 7:18 pm

it would be good to just look at the d1 in isolation. have you done that?

not using d2 and not using a strong b22! ;)

I would plug a signal source (dac output or similar) to the input jack on the d1. then run the d1 output into a home stereo that has a 'safety' vol control so that at d1=max, you still won't blast anything.

then vary the d1 on the lcduino and hopefully it will work smoothly and with no big jumps from 0 all the way down to -127.

the system is big and complex. for me, I would go smaller steps at a time.
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Re: Very low sound coming through δ1

Postby astrouk1 » August 19th, 2012, 7:30 pm

OK, I'll give it a shot on my DVD player (it has RCA aux inputs) first thing tomorrow morning, I won't do it now, the wife'll kill me!
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Re: Very low sound coming through δ1

Postby astrouk1 » August 20th, 2012, 7:51 am

I've just done the test. The only component from my setup was the delta1 I had exactly the same result, barely audible sound coming through the speakers, it didn't change volume as I changed the volume on the delta1. The only thing I think it can be is perhaps a faulty relay somewhere in the system (NB I've been known to be wrong)? One on the lower value resistance end that's leaking most of the signal to ground? I'm not too sure on how to check for this. Ralph.
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Re: Very low sound coming through δ1

Postby astrouk1 » August 20th, 2012, 7:57 am

I've attached a jpeg showing my resistor setup.
You do not have the required permissions to view the files attached to this post.
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Re: Very low sound coming through δ1

Postby astrouk1 » August 20th, 2012, 8:26 am

I've just checked for shorts on the harness between the driver board and attenuator section (powered down) using the audible checker on my DMM and found none.
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