Wirewound Pot Law Fake with Wirewound Resistor

[wrenchone]

I was lucky enough to grab a pair of old Clarostat 75k wirewound pots on E-pay. I'm thinking of using them in my preamp law-faked with a high qality 15k resistor. I happen to have a pile of old bobbin-wound ultraprecision resistors that I picked up years and years ago from Poly-Paks (remember them?). Has anyone ever used this type of resistor in audio? I wonder how they sound.

[mlloyd1]

thanks for mentioning poly-paks. now, i don't feel so old by myself


to answer your question - never used 'em, no idea how they sound.

mlloyd1

[beeger]

I can't speak for the Clarostat controls, but I have used wirewound controls with law faking resistors with great success. In fact, I like them more than most stepped attenuators I have tried. I used a 50kOhm pot with a 6K8 Ohm law faking resistor. Your control would permit a higher input impedance. Hope you got a good price on the wirewound controls.

[AndrewT]

Hi,
I wonder if these would respond to a liberal dose of switch cleaner and lots of wiper moving to clear away any contamination of the contacts?

[wrenchone]

Anderw, what are "these", the pot or the switched attenuators? As far as I can tell, the pots I have are not gunked up. If I need to clean up the wiper/element, the rear cover simply snaps off. Not bad, for a pot that may be almost as old as I am. To beeger - I got the pots for $12.99 the pair. They have the old Navy anchor stamp on the back.

[AKSA]

Depending on impedance, some of these wirewounds can exhibit very high inductance which pulls back HF response.

I've seen worse than 3dB at 20KHz on a British wirewound 100K, and it's highly audible, but if yours are 20K or less you'd probably be OK.

Cheers,

Hugh

[wrenchone]

I took one of my 75k Clarostat wirewound pots to work today and subjected it to a 100Hz-100kHz scan on an HP 4194A analyzer. If anything. there was a very slight drop in impedance at the high end of the scale, indicating that stray capacitance is more of a factor with this particular pot than inductance. The next thing I'll do is to try a scan on one of the Daven 17.83k wirewounds I've chosen as a lawfake resistor. It'll be interesting so see if they used a non-inductive wind technique.