DIY line attenuator

[woodturner-fran]

Hi All,


Anyone out there able to instruct me or point me to a good recipe for making a line attenuator for my CDP? From what I can read there seems to be 2 resistors needed, but I'm in the dark with respect to values and the config within the cable. Are they 2 resistors of teh same value in series from hot to hot and ground to ground or is the arrangement mroe complex?


I'm using a CDP with an output of 2v into an audio innovations integrated valve amp, don't know the input sensitivity of the amp.

Reason for looking at this issue is that there is too much gain, volume pot starts at 7 oc and by 9 its LOUD!

thanks in advance!

Fran

 

[moamps]

Hi Fran:

You're on the right track. The picture below shows two 20dB attenuators - one is RCA-RCA and the other is XLR-XLR. The mixer out in the picture is in fact your CD out so don't let that confuse you. Should the attenuation be too high for your purposes, just use a greater value for R2.

Regards,
Milan

 

[woodturner-fran]

Jumpin Jesus, its as simple as that!


OK, so are ordinary carbon films OK or what should I be looking for - money really isn't an issue as I'm only making one set of these.

Also from subsequent reading around it seems I should shoot for something in the order of 11 - 14dB reduction. So if I keep R1 at the 10K shown below, what would be a good value for R2?

thanks again,

Fran

 

[AndrewT]

Hi,
put the resistors INSIDE the RCA plug at the receive end.
Mark it so that you don't accidently reverse it.

 

[moamps]

OK, so are ordinary carbon films OK or what should I be looking for - money really isn't an issue as I'm only making one set of these.

I'd recommend using resistors with 1% tolerance. Any type should do, really.

Also from subsequent reading around it seems I should shoot for something in the order of 11 - 14dB reduction. So if I keep R1 at the 10K shown below, what would be a good value for R2?

Reduction(dB)=20*log(R2/(R1+R2));
for R2=2k2, reduction is 15dB.
Using this formula you should be able to calculate resistors for desired reduction.

Regards,
Milan