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Rothwell Attenuators

Ian Austen

pfm Member
Has anyone tried or is using Rothwell attenuators and what effect they have on the sound? I'm thinking of using a set to attenuate a variable level DAC directly into a power amplifier. The DAC has a maximum output of 4.8v via its class A output amplifier.

attenuator.JPG
 
There are a few discussions here - have a search.

The main thing is to use them at the right end of the IC.

A common use is to bring a DAC/CDP ouput down to something compatible with a phono and/or tuner level.
 
I've tried them but prefer to have it integrated into the cable. Not sure who's doing them though now that we don't have Flashback.
All they do is give you more travel in volume control and better input matching.
 
They do a job but it’s better to not need them; I had gain reduced in my preamp after trying some and that was preferable.

Not sure if they’re still around but Goldenjacks offered a near identical product at a much more reasonable price.
 
I've used a couple of pairs to improve the usability of the volume control on an amp. They work fine and I couldn't hear any drop in sound quality.
 
I use them between my valve supposedly 40dB MM phono stage and Sugden A21se input. It allows me to set volume at or around the 12 o’clock midway position as opposed to “twenty odd minutes to”. Just feels better and easier to fine adjust. A bit like slipping into overdrive in the old days on a flat road and when conditions allowed. Turns a super amp into classy with it if you get my gist.
 
Goldenjacks offered a near identical product at a much more reasonable price.

Yes, they're good. I have a pair of -6dB from CDP to pre (at pre. end, of course). I was surprised that my 3.4V output needed so little attenuation (I have meters on my pre.). Tried -10 and -15 previously but too much, and my friend and I could hear a degradation in s.q. with those, but not with my -6dB. I concluded (and this has always been controversial) that the higher the attenuation, the greater the effect on s.q. Seems logical to me, but not to engineers; there y'go !
 
One annoying point is that the level of extenuation is not marked on them. The two sets I have are different attenuation and I can't remember which is which. Or in fact how much attenuation they provide.
 
One annoying point is that the level of extenuation is not marked on them. The two sets I have are different attenuation and I can't remember which is which. Or in fact how much attenuation they provide.
If you have a multimeter you can measure the value of the two resistors and hence calculate the attenuation.

I believe (as I've never had a set in my hands) that its a potential divider something like this:-

input--- R1---output---R2---common (gnd)

Measure the values of the two resistors (input to output/output to common) and the attenuation will be 20Log(R2/(R1+R2))dB

Cheers,

DV
 
Just thought I’d ask where I might source these male/female adapters WITHOUT any attenuation resistors fitted. Instead of using Y leads and loading plugs may be I could adapt them to fit caps and reach the 400pF that my A&R P77 is said to favour.
 
Just thought I’d ask where I might source these male/female adapters

If you Google image search, "male female RCA adapter", you will find a few (image enables a quick sorting from the far more irrelevant finds).
 
Instead of using Y leads and loading plugs may be I could adapt them to fit caps and reach the 400pF that my A&R P77 is said to favour.

You are going to struggle to get small 400pF cap's, but if you use two 180pF in parallel, to give 360pF, or a 180 and a 220 to give exactly 400, there are plenty of tiny options that would be easily soldered across the contacts inside most ordinary RCA plugs.

180pF Leaded Ceramic Multilayer MLCC Capacitors | Farnell UK

220pF Leaded Ceramic Multilayer MLCC Capacitors | Farnell UK
 
@Chris won't be needing 400pF caps, @Vinny. He's aiming for 400pF total, including Rega tonearm and phono input.

We ran the numbers recently, but I can't recall what we came up with. Chris?
 
Hi Craig. Not sure of phono input so I’m thinking of trying, say, 180, 200, 250 . It’s just that I fancied copying the neat Rothwell solution using a look alike adapter blank but with the caps inside rather than resistors.
 


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