stepped attenuator pop

Ted205 · 17th July 2008, 10:04 AM

I'm just testing out my 24 step stepped attenuator to the front of my chipamp gainclone. http://cgi.ebay.ie/Attenuator-24-Step-10K-A-Dale-resistor-Stereo-NEW_W0QQitemZ220247489309QQihZ012QQcategoryZ73369Q QtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262

It's wired up on my bench with crocodile clips and running from a bench supply.

I'm getting a small 'pop' when the pot is turned. Is there anything that can be done to remove this ? (I know it could be just the poor connections - the croc clips)

thanks

Ted205 · 17th July 2008, 10:46 AM

well it turns out it was a dodgy ground

i do have another newbie question though.

I'm using a 10k volume control with a 25Vac input per channel (so around 32Vdc once rectified and with diode losses ?)

The 10k has a very bad scale. The first click is a big step while the other 23 make very little difference to the volume.

Do i simply need a larger input pot resistance to adjust the scale? Or can i use maybe an in series resistance to help set the volume scale ?

Nuuk · 17th July 2008, 02:20 PM

What amp and other equipment are you using it with?

Ted205 · 17th July 2008, 05:04 PM

Its a chipamp.com lm3886 amplifier kit i'm currently running one channel from a bench supply.

The chipamp manual schematic shows a 25k pot at the input but i couldn't find a step attenuator rated at the same value.

Ted205 · 17th July 2008, 05:04 PM

i forgot to add. Input is from my laptop (which has a volume control of its own) and the output is a 6 ohm hifi speaker

Nuuk · 17th July 2008, 06:57 PM

Still that attenuator should work OK. Are you sure that you have it wired up correctly? A picture would help!

Ted205 · 17th July 2008, 10:22 PM

well it does attenuate the signal so i'm assuming (

) it is wired correctly, its just not very linear and most of the 'steps' i can't hear the attenuation (though i can see it on the scope).

A normal 10k pot does a better job to be honest. Would you suggest i try the 50k or the 100k 24 step ?

Nuuk · 17th July 2008, 11:19 PM

I'm not sure a different value would change things. A lot depends on the steps that the designer of your attenuator chose.

Peter Daniel · 18th July 2008, 03:34 AM

Are you sure it's 10k attenuator? Looking at the picture, the resistor values (100k, 140k, 200K) could indicate 250K attenuator (even the pic name says it)

Ted205 · 18th July 2008, 09:43 AM

its Definitely 10k.

A normal 10k pot does the job but the stepped attenuator doesn't. The first step is like an on/off switch. The steps in the middle are inaudible. Its not until the last 3 or 4 steps that you can hear the difference

17th July 2008, 10:04 AM	#1
Ted205 diyAudio Member Join Date: Jun 2008	stepped attenuator pop I'm just testing out my 24 step stepped attenuator to the front of my chipamp gainclone. http://cgi.ebay.ie/Attenuator-24-Step-10K-A-Dale-resistor-Stereo-NEW_W0QQitemZ220247489309QQihZ012QQcategoryZ73369Q QtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262 It's wired up on my bench with crocodile clips and running from a bench supply. I'm getting a small 'pop' when the pot is turned. Is there anything that can be done to remove this ? (I know it could be just the poor connections - the croc clips) thanks

17th July 2008, 02:20 PM	#3
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	What amp and other equipment are you using it with? __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

17th July 2008, 06:57 PM	#6
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	Still that attenuator should work OK. Are you sure that you have it wired up correctly? A picture would help! __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

17th July 2008, 11:19 PM	#8
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	I'm not sure a different value would change things. A lot depends on the steps that the designer of your attenuator chose. __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

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17th July 2008, 10:46 AM	#2
Ted205 diyAudio Member Join Date: Jun 2008	well it turns out it was a dodgy ground i do have another newbie question though. I'm using a 10k volume control with a 25Vac input per channel (so around 32Vdc once rectified and with diode losses ?) The 10k has a very bad scale. The first click is a big step while the other 23 make very little difference to the volume. Do i simply need a larger input pot resistance to adjust the scale? Or can i use maybe an in series resistance to help set the volume scale ?

17th July 2008, 05:04 PM	#4
Ted205 diyAudio Member Join Date: Jun 2008	Its a chipamp.com lm3886 amplifier kit i'm currently running one channel from a bench supply. The chipamp manual schematic shows a 25k pot at the input but i couldn't find a step attenuator rated at the same value.

17th July 2008, 10:22 PM	#7
Ted205 diyAudio Member Join Date: Jun 2008	well it does attenuate the signal so i'm assuming ( ) it is wired correctly, its just not very linear and most of the 'steps' i can't hear the attenuation (though i can see it on the scope). A normal 10k pot does a better job to be honest. Would you suggest i try the 50k or the 100k 24 step ?

18th July 2008, 09:43 AM	#10
Ted205 diyAudio Member Join Date: Jun 2008	its Definitely 10k. A normal 10k pot does the job but the stepped attenuator doesn't. The first step is like an on/off switch. The steps in the middle are inaudible. Its not until the last 3 or 4 steps that you can hear the difference

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