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Oakley TSL - normal to be louder/bigger sounding in 2pole?
MUFF WIGGLER Forum Index -> Oakley Sound Systems  
Author Oakley TSL - normal to be louder/bigger sounding in 2pole?
bananeurysm
Hey guys - I just finished my build of the Oakley TSL, when I have the response pot at 0 the filter sweeps sound louder (bigger?), than when the pot is fully clockwise.

Is this normal or could I have done something wrong?

Is there a test I can do to verify that I'm getting full 4-pole operation?
Synthbuilder
Two pole will usually be louder than four pole. This is simply because it allows more upper harmonics to pass as its filter slope is less steep. With a sine wave input it should not sound appreciably louder than the four pole output.

One way to test that your TSL is working correctly is to see whether you get a bandpass response when the slope control is at its middle point. The calibration section, for trimmer BPA, in the User Manual tells you how to check this.

Tony
bananeurysm
I did go through all the calibration steps - and I definitely get bandpass at the 12:00 on the slope control - so it sounds like everything is working right!!

I was a little confused during calibration - when doing off1, U1 pin7 was giving me a waveform on the scope when I expected a steady voltage. Is that normal? Like a lopsided sine kinda thing.

Also after calibrating off1 and off2 as best I could with a scope - the filter actually didn't sound quite as good to me - so I ended up just playing with the trimmers till it sounded right.. ha.

At any rate - it's probably all good - since the filter sounds great!!!

Thanks Tony!
Synthbuilder
bananeurysm wrote:
I was a little confused during calibration - when doing off1, U1 pin7 was giving me a waveform on the scope when I expected a steady voltage. Is that normal? Like a lopsided sine kinda thing.

No you shouldn't have that. U1 pin 7 is the output of the input mixer. It should have no audio on it unless you have an input connected to a VCO or something.

bananeurysm wrote:
Also after calibrating off1 and off2 as best I could with a scope - the filter actually didn't sound quite as good to me - so I ended up just playing with the trimmers till it sounded right..

Only OFF2 should have an effect on the sound. OFF1 simply controls the amount of CV breakthrough from the resonance CV. OFF2 can upset the balance of the ladder and thus the sound. OFF2 is really about minimising the offset generated by the VCA that controls the resonance. It's best to do it by ear I find but only by using the method given in the user manual.

Tony
bananeurysm
Thanks! I went through and calibrated it again last night. You were right - I must have had something plugged into the input when I was getting that waveform on U1 pin 7. It behaved as expected this time.
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