Author Topic: Rothwell RCA In Line Attenuator -10db  (Read 174 times)

Offline stereosane

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Rothwell RCA In Line Attenuator -10db
« on: January 11, 2018, 12:17:56 PM »
I'm looking for an RCA based attenuator for my amp or Dac, there's a serious voltage miss match and I can only get the volume to around 9 o'clock and then it's already very loud and shouty..

Something like this would be perfect..


Offline chrisc

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #1 on: January 11, 2018, 01:47:51 PM »
Not difficult to make.  However, what is the input impedance of the amp and what is the output impedance of the source?

Assuming that these values are 100kOhm, then looking at this diagram, the Shunt In resistor is 192.495 ohms, the Shunt Out also 192.495 ohms and the series resistor 142.302 ohms.

Obviously you cannot buy these specific values so must choose the closest higher



Source:  http://chemandy.com/calculators/matching-pi-attenuator-calculator.htm

Offline stereosane

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #2 on: January 11, 2018, 02:14:26 PM »
Shooo I have no idea, the amps I can find but the Dac doesn't have any info, not even online..

Offline chrisc

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #3 on: January 11, 2018, 02:18:03 PM »
What DAC is it?

Offline stereosane

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #4 on: January 11, 2018, 02:26:32 PM »
Renaissance Amplification RD01

Offline Hi-Phibian

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #5 on: January 11, 2018, 02:30:45 PM »
Output impedance shouldn’t be as high as 100 k, wouldn’t be great design I think.  The typical objective is to get it as low as possible.

Input may be 10-100k. 







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Offline Hi-Phibian

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #6 on: January 13, 2018, 09:47:33 PM »
Proprietor of Croak Audio Exploration.
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Offline stereosane

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #7 on: January 13, 2018, 10:03:13 PM »
Is that my pair?  :rubhands:

Offline handsome

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #8 on: January 14, 2018, 09:56:51 AM »
you going to struggle to drive those <1k resistances. Try just a 22k (standard value) inline - in other words ignore the shunt resistors and use 22k as the series resistor. Its not ideal (neither are the rothwells) but assuming a 10k input impedance (pretty standard) you should get ~60% reduction in level. Easy and cheap to make - just solder the resistor into the RCA plug and make sure you put that plug into the amplifier, the 'far' end of the cable. If the volume reduction is not enough just increase the value of the resistor.

Offline stereosane

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Re: Rothwell RCA In Line Attenuator -10db
« Reply #9 on: January 18, 2018, 07:03:23 PM »


Busy listening to my cable now  :dance: works like a charm, I highly reccomend this kind of thing if u not able to get past 10 o clock on the volume dial, I have a much more precise volume control now... not loud or soft only  :dance:

Thanks Hi- Phibian  :dop: