Volume Control for 100watt input

The Oracle · « **on:** 29 May 2003, 08:39 am »

Guys - I've searched and I've searched, but I'm blowed if I can find! What value is recommended for direct input (ie no pre) - 20k or 50k?
Also - why should'nt I use an ALPS 27mm square blue for this? I'll use a pre eventually, and then select the non-adjustable input.
Thanks
Stevo

JohnR · « **Reply #1 on:** 30 May 2003, 09:30 am »

Looks like the full answer is here:

http://www.aksaonline.com/faqs/faqs_general.html#gq4

Personally, if I had a 20k log pot, I would just use it.

JohnR

The Oracle · « **Reply #2 on:** 4 Jun 2003, 10:27 am »

Quote from: JohnR

Looks like the full answer is here:

http://www.aksaonline.com/faqs/faqs_general.html#gq4

Personally, if I had a 20k log pot, I would just use it.

JohnR

Thanks JohnR - but I don't have a 20k pot, have to buy one!
The FAQ didn't help, wouldn't 20k be some risk of loading?

Stevo

JohnR · « **Reply #3 on:** 4 Jun 2003, 01:11 pm »

Hm, well, what the FAQ specifically recommends is a 100k *linear* cermet pot, with a 15k resistor connected from each wiper to ground.

JohnR

AKSA · « **Reply #4 on:** 4 Jun 2003, 01:31 pm »

Hi Steve,

A 50K pot in this role is just fine, but will be ever so slightly noisier.

10K is dead quiet but loads down the source pretty hard. 50K is noisier but gives a light load. 20K is an excellent compromise.

If you have a 50K log pot, Steve, then use it. The RK27 is a good pot, and should not be discarded.

The idea of a 100K linear pot is a good one IF it's law faked with a 15K resistance. This is not the perfect solution, but the parasitics of a linear pot are superior to a log and the sonics of the pot are swamped by the sonics of the fixed wiper to ground resistor.

Cheers,

Hugh