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Old 27th June 2012, 07:41 PM   #11
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yeah

every time I dismantled DAC chip with ladders , I found several relays in there

in fact , I'm not buying relays anymore - have enough DAC chips as donors

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Old 24th February 2015, 06:01 PM   #12
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Hi,

instead of opening an new thread I think this will fit in here.

Ive also got a loud popping sound using an 6bit r2r volume control (1.5dB steps) with my X-BOSOZ.

There are only two positions where the pop occurs, going from -46.5 to -48dB (very loud) and from -48dB to -46.5 dB (loud). So from 011111 to 100000 and back.

The problem seems to be the 48dB jump (theres no DC and no pop when there's no input signal)
The very loud pop could be avoided by changing the order of the relais switching (first switching the -48dB relais) but Ive got no idea how I can avoid the loud pop as there will always be a 48dB jump in loudness regardless of when I switch the relais.

The volume control had 1dB steps before I changed it to 1.5dB and Im not sure the pops where there before (occurring from -31 to -32dB) as I wast in the range very often.
I changed it because -63,5dB was still too loud with some sources.

Any ideas if these pops are normal and how to avoid them without using a mute relais or making the steps smaller using 7 or 8 relais?

William
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Old 24th February 2015, 07:02 PM   #13
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useful trick is to find specific relay position and solder 470-1000uF in parallel to coil , to slow it

sometimes simpler than changing software
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Old 24th February 2015, 07:18 PM   #14
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Hi,

I wrote the software myself so that would not be the problem. It has to react differently depending on going up or down so slowing it down would only help one way.

William
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Old 24th February 2015, 10:51 PM   #15
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Relay resistor configuration can do this even with no DC. What is the schematic like and type or relays?
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Old 25th February 2015, 05:09 AM   #16
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Hi,

relais are miniature 5V relais from F.T. type B4A4.5Z. Schematic is as in the pic.

William
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Old 25th February 2015, 05:37 PM   #17
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Do look for any DC coming in. Relays like this work well because they make contact quicker than break.
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Old 26th February 2015, 02:10 AM   #18
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Hi Wayne,

Like i mentioned before, no DC and no noise when switching without a signal. I think I will try to change the 48dB step into 2x 24dB steps.

William
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Old 26th February 2015, 06:23 AM   #19
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two step volume change.
first switch attenuating relays, then switch un-attenuating.
somth like that. helps.

the idea behind is to always have less volume than required during switching transition.
So if you want to go from -47 to -48, you want to go thru -47, -?99?, -48. Currently you get -47, -?5?, -48.
**numericals are imprecise **
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Old 26th February 2015, 01:17 PM   #20
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First switching the attenuating relais is what happens going from -48!to -46.5dB. Here the pop is not as loud as the other way round but still too much.

William
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