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August 19, 2022, 08:28:44 AM

Author Topic: Resistor type recommendation  (Read 181 times)

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Offline Skipperrik

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Resistor type recommendation
« on: May 06, 2022, 12:06:44 PM »
The volume on my Crackatwoa is too loud. I found this thread in the Crack forum that addresses the problem. Scroll down to the third item. I assume the same solution will work with my Crackatwoa.

https://forum.bottlehead.com/index.php?topic=4295.0

I've been looking into resistors and have found prices for a 75k to range from $0.02 at Digi-Key to one by Audio Note for $57.48 EACH! The Audio Note resistor has pure silver leads and end caps. While I'm sure the resistor will impact the sound quality I suspect the silver ones are kind of like the super fuses that also command a high price. I doubt my ears could tell the difference between those and something much less expensive.

So here's the question, what type and brand do you guys recommend? Carbon film? Metal film? Is Takman a good choice?

Thanks for any recommendations!

Offline Paul Birkeland

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Re: Resistor type recommendation
« Reply #1 on: May 06, 2022, 01:00:56 PM »
With the C2A, you have the volume and balance pots stuck together, so in some ways it's actually easier to install since the 75K resistors can just jump from the balance to the volume pot.  I would go for something with long leads for the 75K resistor like an RN55D.  May as well use the same for the 33K I suppose.

If you're going to spend $300 on four resistors, you may as well just throw the attenuator upgrade in, as it will provide very good channel balance at low volumes. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Skipperrik

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Re: Resistor type recommendation
« Reply #2 on: May 06, 2022, 03:22:12 PM »
Thanks, Paul. I assure you I won't be splurging on silver resistors. I like your idea about the long leads though. I'll probably go that route.

I would love to install the stepped attenuator upgrade but I am reluctant to give up the balance pot. I have a hearing imbalance so I find the balance adjustment to be useful. I'll play around with the resistors first and see if I still need the balance once I can increase the volume.

Looking at the RN55D I noticed it is 1/8 watt. Is that sufficient?

https://www.mouser.com/ProductDetail/Vishay-Dale/RN55D75R0FRE6?qs=GZl0KSxEb0HFl2%2FLz7%252BVQw%3D%3D

Offline Paul Birkeland

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Re: Resistor type recommendation
« Reply #3 on: May 07, 2022, 04:30:43 AM »
Yes, that will limit you to about 130V of incoming signal, which is about 60 times more than you need.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Skipperrik

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Re: Resistor type recommendation
« Reply #4 on: May 07, 2022, 08:32:00 AM »
Thanks,Paul. Do I still need the 33k resistors between the outer terminals on the volume pot? What is the purpose of these?

Offline Paul Birkeland

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Re: Resistor type recommendation
« Reply #5 on: May 07, 2022, 08:51:47 AM »
Yes, these bring the overall impedance of the pot back to around 100K rather than the 175K you might otherwise have.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Skipperrik

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Re: Resistor type recommendation
« Reply #6 on: May 07, 2022, 08:54:41 AM »
Very good. I'll report back on the results.

Thanks!