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DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  100k vs 500k output volume control 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: 100k vs 500k output volume control  (Read 1142 times)
Posts: 2826

100k vs 500k output volume control
« on: March 03, 2012, 10:38:22 AM »

Simmed a LPB like circuit with a 100K and 500k output volume control
Think about the added output series resistance when the volume control is not at max

left side is a simple guitar sim and cable
LPB like circuit
.1uf output cap, changing this will change the low end
output of wiper to 390pf, 10 feet of 39pf a foot cable and I picked a 470K as the simple input resistance of the next stage you can change this to 1 meg etc.

Also the high pass will change with different C1 values

Now sim a FF like circuit and try different output control values, coupling cap values, cable length, next stage input resistance loading...

100k control

500k control
Posts: 2826

Re: 100k vs 500k output volume control
« Reply #1 on: March 10, 2012, 12:45:39 PM »

I have noted that over the years people have asked about 100k vs 500k volume controls in circuits like a FF.

The circuit used in the sim is a one transistor gain stage.
The left side to C3 is a simple guitar/cable sim.  2.5H, 7K pickup, 250K volume and tone controls at max resistance, .022uf tone cap, 10 feet of 39pf a foot cable.
R10 and R5 are the single volume control with a log like curve .step param GSET part.  What happens is the different GSET number is placed in the simple math for R10 and R5.  Green curve is .1, Blue curve is .25, Red is .50  etc.  The wiper is the node of R10, R5.  The screen shot is for a 100K if you want a 500K change the 100K for 500K at R5 and R10.

C4 is the cable cap between the output of the effect to the next stage, this change with length and type of cable.   R11 is the input resistance of the next stage this changes with different circuits.

High pass means it lets the highs pass and blocks the lows(left side of the curves)
Low pass means it lets the lows pass and cuts the highs (right side of the curves)

Note the changes with the high end with the volume control change.

The above is from using LT spice.
Posts: 2458

Re: 100k vs 500k output volume control
« Reply #2 on: March 10, 2012, 01:19:24 PM »

Cool.  It's nice to see things with LT Spice.  Wink

Stomping Out Sparks & Flames
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