Potentiometer Research

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Structo
Posts: 15446
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Potentiometer Research

Post by Structo »

As a side effect of a coronary event (heart attack) I have way too much time on my hands.
So I have been researching potentiometers.
The quality of various types, fidelity of various resistance compounds, and different mechanical solutions to the lowly front panel control.

Most of you will probably think it is a waste of said time, since after all, we are dealing with low fidelity guitar amplifiers that by definition are not made for pure sound reproduction.

This has to be the most unique solution I have stumbled upon so far.

[img:235:170]http://www.goldpt.com/mv1_2_170b.jpg[/img]

[img:140:109]http://www.goldpt.com/detail3_140.jpg[/img]

[img:132:125]http://www.goldpt.com/mv_front125.jpg[/img]

This is a stepped attenuator type volume control.
It uses surface mount discrete resistors with a tolerance of .1%
Where this type of pot would shine is in a dual gang stereo pot.
With the low tolerance resistors you would be assured of equal attenuation of each channel in a stereo amplifier.
But I digress.....

This is the ultimate guitar amp potentiometer!

[img:250:157]http://www.goldpt.com/mvc_loaded1.jpg[/img]
This one uses our beloved Dale metal film resistors.
This one uses the RN60's.
24 position, "make-before-break" thick hard-gold contacts on PC boards for minimum switch bounce.
Tight mechanical tolerances and clearances on the bushing and shaft for a solid, quality feel.

And since you get to choose the actual resistance of each step you can totally control the taper of the potentiometer.
Make your own audio taper to your specs. Or a very linear taper that is accurate.
No more actual 243K for a 250K pot.

So the ultimate pot has been achieved!

Not totally out of sight price wise. $58 for a single mono pot. Of course then you have to buy the resistors.

Or if you use the SMD one, it is $79

Anyway I thought these are pretty cool.
They also make custom rotary switches to your specs.

Website:
http://www.goldpt.com/index.html
Tom

Don't let that smoke out!
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ChrisM
Posts: 1169
Joined: Wed Oct 22, 2008 11:12 pm
Location: Toronto, Canada.

Re: Potentiometer Research

Post by ChrisM »

Your pics aren't working Tom.
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rawnster
Posts: 562
Joined: Wed Feb 20, 2008 4:27 pm
Location: Northwest

Re: Potentiometer Research

Post by rawnster »

I tweaked the code to get the images to work......
Structo wrote:As a side effect of a coronary event (heart attack) I have way too much time on my hands.
So I have been researching potentiometers.
The quality of various types, fidelity of various resistance compounds, and different mechanical solutions to the lowly front panel control.

Most of you will probably think it is a waste of said time, since after all, we are dealing with low fidelity guitar amplifiers that by definition are not made for pure sound reproduction.

This has to be the most unique solution I have stumbled upon so far.

[img:235:170]http://www.goldpt.com/mv1_2_170b.jpg[/img]

[img:140:109]http://www.goldpt.com/detail3_140.jpg[/img]

[img:132:125]http://www.goldpt.com/mv_front125.jpg[/img]

This is a stepped attenuator type volume control.
It uses surface mount discrete resistors with a tolerance of .1%
Where this type of pot would shine is in a dual gang stereo pot.
With the low tolerance resistors you would be assured of equal attenuation of each channel in a stereo amplifier.
But I digress.....

This is the ultimate guitar amp potentiometer!

[img:250:157]http://www.goldpt.com/mvc_loaded1.jpg[/img]
This one uses our beloved Dale metal film resistors.
This one uses the RN60's.
24 position, "make-before-break" thick hard-gold contacts on PC boards for minimum switch bounce.
Tight mechanical tolerances and clearances on the bushing and shaft for a solid, quality feel.

And since you get to choose the actual resistance of each step you can totally control the taper of the potentiometer.
Make your own audio taper to your specs. Or a very linear taper that is accurate.
No more actual 243K for a 250K pot.

So the ultimate pot has been achieved!

Not totally out of sight price wise. $58 for a single mono pot. Of course then you have to buy the resistors.

Or if you use the SMD one, it is $79

Anyway I thought these are pretty cool.
They also make custom rotary switches to your specs.

Website:
http://www.goldpt.com/index.html
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rawnster
Posts: 562
Joined: Wed Feb 20, 2008 4:27 pm
Location: Northwest

Re: Potentiometer Research

Post by rawnster »

oops, you got it Structo. :-)
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Structo
Posts: 15446
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Re: Potentiometer Research

Post by Structo »

Yeah for some reason the hot links are not showing up right away, if you refresh it or right click and choose "show picture" they should show.
Tom

Don't let that smoke out!
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M Fowler
Posts: 14036
Joined: Wed Jan 16, 2008 2:19 am
Location: Walcott ND

Re: Potentiometer Research

Post by M Fowler »

That is a kool pot though Tom and if your going to build your self a great amp that money is not wasted if this would work good.
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David Root
Posts: 3540
Joined: Fri Aug 04, 2006 3:00 pm
Location: Chilliwack BC

Re: Potentiometer Research

Post by David Root »

I was about to post something similar Tom! You scooped me!

No problem, I have recently bought a Vishay Spectrol 20K square section pot and two 1M military spec pots for a Dumble 4x6L6GA build in a BF Bassman chassis, because they are small enough diameter to fit the Bassman faceplate without redrilling.

I will dig up the specs and post them. These are molded carbon pots, not the hi-fi attenuators you are showing.

Actually, the attenuators you are looking at are more similar to what HAD used on his SSS amps, in some ways.
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Structo
Posts: 15446
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Re: Potentiometer Research

Post by Structo »

I think they look cool and if a guy was talented in the art of machining and precision PCB construction, you can make some very nice volume pots.
The one with the RN60's looks mega cool. And like I said, you can totally customize the taper by the values you choose.

It's basically just a nice wafer switch with resistors on the switches.
Tom

Don't let that smoke out!
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