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Old 7th December 2007, 01:01 AM   #1
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Default Replacing 50K pot with 10K pot

Hello,

I am replacing a 50K pot in my integrated amplifier with a DACT 10K pot.

The pot I am replacing is one of those fake Chinese Alps stepped pots that was on E-bay a couple of years ago, the ones with individual resistors.

So, I imagine I will not have the range I need with the new pot and my music will be too loud even on the first couple of clicks of the new DACT pot.

Now to correct this, could I just add a 40K ohm resistor on the output side of the new pot? Is it that easy?

There is already a resistor on the pcb at the output of the pot, it feeds a capacitor. Should I series the 40K resistor with this resistor? Or just replace this resistor with one of its value plus 40K ohm?

Any advice would be appreciated.

Also is there anyone that has some good quality resistors in the 40K range for sale?

Thanks

Kevin
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Old 7th December 2007, 05:03 AM   #2
gootee is offline gootee  United States
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Why don't you just replace it with a 50K pot?
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Old 7th December 2007, 05:27 AM   #3
es44 is offline es44  Denmark
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Default Re: Replacing 50K pot with 10K pot

Quote:
Originally posted by KevinLee
Hello,

I am replacing a 50K pot in my integrated amplifier with a DACT 10K pot.

Kevin
Someone smarter than me propably have a better explanation than i can give, but Your pot is just a voltage divider.
Then, a 50K and a 10K will ( theoretically ) give the same results.

But... There might be an issue with the impedance at the place Your pot belongs. I guess there's a reason the manufacturer put in this value.

best regards
Ebbe
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Old 7th December 2007, 06:11 AM   #4
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See if this is useful:

http://www.goldpt.com/mods.html
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Old 7th December 2007, 06:49 AM   #5
Gasho is offline Gasho  Croatia
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Why did you remove "fake" Alps pot? It is better than original Alps and almost same as DACT.

If you put a 10K instead of 50K, you will probably have a lower input impedance of integrated amp becouse integrated amps are almost always designed as power amps with selector and passive pre (atenuator) in front of power section.

Very small number have a buffer stage before attenuator.
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Old 7th December 2007, 08:33 AM   #6
AndrewT is offline AndrewT  Scotland
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Hi,
we really need more detail of the source electronics and the input stage of the integrated to give useful information.
Otherwise, we will try to cover all the options and leave you mesmerised with data.
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Old 7th December 2007, 01:53 PM   #7
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Hello,

My current source is a Quad 99CDP CD player.

The integrated amplifier is a modified Rotel RA930AX. I have the input going into the pot then into a small pre-amp section which is based on BB OPA627, from there the signal goes into the power amp section. I will try to post schematic of the pre-amp section.
Kevin
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Old 7th December 2007, 03:00 PM   #8
AndrewT is offline AndrewT  Scotland
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What's the output impedance of the source?
Is it DC blocked?

What's the input impedance of the receiver (BB opa627)?
Is it DC blocked?
Does it have RF attenuation?
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Old 9th December 2007, 12:02 AM   #9
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So, I have been doing some more thinking on this, It would probably make the most sense to put a resistor at both the input and output of the pot?

Any thoughts?
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Old 9th December 2007, 12:25 AM   #10
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Quote:
Originally posted by KevinLee
So, I have been doing some more thinking on this, It would probably make the most sense to put a resistor at both the input and output of the pot?

Any thoughts?
It will work in a way that you will increase input resistance, but you will loose gain. Adding 10k resistor before the 10k pot will lower signal by 6dB.

Depending on your source, you may not need any adjustements at all and 10k pot will work equally well as your 50k.
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