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Runt too dark

Started by studiodunn, October 26, 2012, 11:42:45 PM

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studiodunn

Runt
Not bright enough, need more high end/treble
tried various guitars and amps - side by side to a Rat i own....still dark
No substitutions

Can someone lease advise me on what parts to start messing with to get some more treble in a stock Runt.

Thanks

gtr2

hmm.. I think you may have something incorrect in your build.  There is plenty of treble with the runt/rat.

Josh
1776 EFFECTS STORE     
Contract PCB designer

studiodunn

Thanks Josh, and I would have to agree that every rat or like pedal I've had has had tons of treble. Too much!
The pedal sounds great and works as it should I would just like to open it up some more. Is there a specific resistor I can change to do this?

gtr2

I would really double check your component values.  The runt is the exact same circuit as the rat.  I've built the runt as well.  With the stock values there is ALOT of treble available.  Also double check that there are no solder joints etc at R4, R5, C5,C6  This is the main area for low frequency roll off.

The cut potentiometer, R7, and C8 are also a low pass filter.

At stock values this places the corner frequency from 47 to 3216Hz depending on your potentiometer setting.  If something is wrong here it could make it seem dark as well.

Josh
1776 EFFECTS STORE     
Contract PCB designer

studiodunn

Quote from: gtr2 on October 27, 2012, 11:59:20 AM
I would really double check your component values.  The runt is the exact same circuit as the rat.  I've built the runt as well.  With the stock values there is ALOT of treble available.  Also double check that there are no solder joints etc at R4, R5, C5,C6  This is the main area for low frequency roll off.

The cut potentiometer, R7, and C8 are also a low pass filter.

At stock values this places the corner frequency from 47 to 3216Hz depending on your potentiometer setting.  If something is wrong here it could make it seem dark as well.

Josh

Thank you. I will check the mentioned components and go from there.

Gristlepig

The time has come for me to quit lurking and post something...

I'm having the same problem with my Runt build. I just finished it a couple days ago and it sounds great. Added a DPDT to switch between 1N41's or LED's. Love it. Used Barry's Guitarpcb DPDT wiring board. Mint.

AB'ed the Runt with my early 90's Rat it's almost spot on, except the sweep of the tone/filter knob.
I have to turn it almost entirely counterclockwise to get the same amount of treble response as my ProCo Rat with the filter set at noon.
As I turn the filter clockwise it just gets bassier and muddier. Past 10:00 or so, the sweep of the tone knob is pretty useless.

I double checked my cap and resistor values and and they're spot on with the BOM... I even checked my capacitors on the DMM before soldering them in.

Could the pot taper type be responsible for this? The BOM calls for 3 100kA pots, and I used 100kB for Filter and Distortion and a 100KA for Volume. I dunno... I can't imagine THAT much of a difference between Audio or Linear pots...

Also, I've also noticed the Runt is significantly louder than my ProCo RAT. ...not that this is a problem!

That said, I built this for a buddy in a punk band who could care less about the tone control. He just set it about 7:00 and said "f*cking perfect!" He's using the LEDs to boost the front end of a JCM800. Sounds sweet.

studiodunn

Well, I went back over the board and then went over it again. I couldn't find anything wrong. No substitutes, DMM on everything...nothing.
So I had resolved to it being a little dark, and with the bacon bits in front it was still a great sounding pedal for those tones.

Move forward a week and several new mini boxes later and I am rewiring the board and i decide to do each of my new builds solo to listen for tone suck. I plug in the Runt and BAM! There is the sizzle, over the top treble that I was expecting. Come to find out a couple patch cables I had made were killing the high frequencies...............DOH!!!!!!!!!

Now on to my snarkdoodle issues ???

Om_Audio

Hah!
good to know- I just ordered a few Runt boards.

I was testing a build recently and learned a lot after trying it with different amps, cables, wall sockets, etc.
good job
C
Sent via soup cans and string.

BraindeadAudio

Quote from: Gristlepig on October 29, 2012, 02:27:16 PM
The time has come for me to quit lurking and post something...

I'm having the same problem with my Runt build. I just finished it a couple days ago and it sounds great. Added a DPDT to switch between 1N41's or LED's. Love it. Used Barry's Guitarpcb DPDT wiring board. Mint.

AB'ed the Runt with my early 90's Rat it's almost spot on, except the sweep of the tone/filter knob.
I have to turn it almost entirely counterclockwise to get the same amount of treble response as my ProCo Rat with the filter set at noon.
As I turn the filter clockwise it just gets bassier and muddier. Past 10:00 or so, the sweep of the tone knob is pretty useless.

I double checked my cap and resistor values and and they're spot on with the BOM... I even checked my capacitors on the DMM before soldering them in.

Could the pot taper type be responsible for this? The BOM calls for 3 100kA pots, and I used 100kB for Filter and Distortion and a 100KA for Volume. I dunno... I can't imagine THAT much of a difference between Audio or Linear pots...

Also, I've also noticed the Runt is significantly louder than my ProCo RAT. ...not that this is a problem!

That said, I built this for a buddy in a punk band who could care less about the tone control. He just set it about 7:00 and said "f*cking perfect!" He's using the LEDs to boost the front end of a JCM800. Sounds sweet.



Yes. A/B pots have a different taper. Switch B pots to A100k and that should fix it. The taper difference is causing it to bunch up at a different position than it would is you used a 100ka.