Role of 10K Resistor on input? - diyAudio
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Old 10th July 2009, 12:23 AM   #1
gychang is offline gychang  United States
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Default Role of 10K Resistor on input?

can someone explain what the role of the resistor on the t-amp clone?

thanks,

gychang
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Old 10th July 2009, 10:46 AM   #2
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Hi gychang,

It is normally only needed if you don't use a volume control in the same case. As in a Power Amp.
It is there to drain the charge from the input caps. 20k, 47k or 100k could be used.
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Old 10th July 2009, 11:14 AM   #3
Pafi is offline Pafi  Hungary
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It's in series with the input, so it can't be the discharge resistor.

I don't know that amp, but it can be the part of a low-pass filter, needed to avoid interference.
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Old 10th July 2009, 12:07 PM   #4
Ian444 is offline Ian444  Australia
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gychang, maybe more information is needed to answer that question. Does the signal go from the 10K resistor to a volume pot, if so, what is the pot rated at 10K, 20K, 50K? Or do you have a schematic to share that would help answer the question. I guess it is TA2024? Another approach to answer this question is to download the datasheet for the particular Tripath chip that you have, and scroll down to see the manufacturer's suggested circuit, and read the fine print. To find the datasheet I usually put "TA2024 data" (as an example) into google and look for a pdf file to download, but there may be easier or better ways, i.e. a site that has all the Tripath datasheets on it. On the TA2020 schematic there is no reason for any resistor on the input except a 20K after the input cap, all the required parts are usually on the PCB

Ian.
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Old 10th July 2009, 01:25 PM   #5
gychang is offline gychang  United States
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Quote:
Originally posted by audio1st
Hi gychang,

It is normally only needed if you don't use a volume control in the same case. As in a Power Amp.
It is there to drain the charge from the input caps. 20k, 47k or 100k could be used.
thanks audio1st. the unit came assembled (SMDs are too tiny for my old eyes) with ALPS RK097,10 KΩ volume pot and input caps. I subsequently added 3 RCA input selector with all 10K resistors.

I am wondering if I should leave them on? or since it came with volume control whether this is redundant.

gychang

Quote:
Originally posted by Ian444
gychang, Does the signal go from the 10K resistor to a volume pot, if so, what is the pot rated at 10K, 20K, 50K? Or do you have a schematic to share that would help answer the question. I guess it is TA2024? Another approach to answer this question is to download the datasheet for the particular Tripath chip that you have, and scroll down to see the manufacturer's suggested circuit, and read the fine print. To find the datasheet I usually put "TA2024 data" (as an example) into google and look for a pdf file to download, but there may be easier or better ways, i.e. a site that has all the Tripath datasheets on it. On the TA2020 schematic there is no reason for any resistor on the input except a 20K after the input cap, all the required parts are usually on the PCB

Ian.
The picture is amp32, with Tripath TA2021B chip. The signal goes to volume pot as stated above.

gychang
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Old 10th July 2009, 03:11 PM   #6
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Quote:
Originally posted by Pafi
It's in series with the input, so it can't be the discharge resistor.

I don't know that amp, but it can be the part of a low-pass filter, needed to avoid interference.

Thanks, I didn't look properly.
As it is in series with a 10k pot I suppose it is just so the source sees a 20k load.
Will cut the volume down though. Just what you don't want with a low power amp.
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Old 10th July 2009, 04:59 PM   #7
gychang is offline gychang  United States
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should I just try it with resistors out? I am interested in maximizing the amps output while retaining the good sound.

gychang
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Old 11th July 2009, 07:57 AM   #8
Ian444 is offline Ian444  Australia
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I would try it without the resistors.
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