DIY Attenuator - Treble Switch Doing Nothing

TobyZ28

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Vancouver
Hi all, wondering if anyone has tried building this circuit and had issue with the treble switch:
https://guitar.com/guides/diy-workshop/diy-workshop-build-your-own-attenuator/

I built the attenuator a year ago and have been using it just fine, however I never finished up the Treble switch. I've finally got my hands on some bipolar caps to test out and I've tried alligator clipping in some in to test. So far I can hear ZERO difference when I A/B them. I've tried 6.8uF and 8.2uF Bi-Polar caps, both significantly higher than the two caps shown in the link above.

Has anyone built anything similar also found similar results? My Circuit appears to be wired fine, i've checked and rechecked it many times. I've cranked the attenuator way "up" bringing the volume way down to the speaker to try and maximize the effect but still have no noticeable change.

Thoughts or tips welcome!


upload_2021-9-8_20-24-39.png
 

Suproman

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Ottawa, ON, Canada
The schematic you linked to shows the switch connected between lugs 3 and 2 of the L pad, not 1 and 2 as in your picture above. Did you maybe confuse lugs 1 and 3 on the L pad? it's easy to do when looking at it from the back.
 

TobyZ28

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The schematic you linked to shows the switch connected between lugs 3 and 2 of the L pad, not 1 and 2 as in your picture above. Did you maybe confuse lugs 1 and 3 on the L pad? it's easy to do when looking at it from the back.
Thanks Suproman, I think you may have hit the nail on the head! Looking at the pictures in the original article (Specifically the one about 4/5ths down the page) they show the black wire connected to the "top most" lpad lug which im assuming Lug 1 and I appear to have my ground wired up to the bottomost lug which is actually Lug 3 - also meaning my hot wires are wired to Lug 1 instead of Lug 3!

I'm curious, what exactly is my circuit doing if its wired in reverse this way? The attenuation has worked just great as i mentioned, what are they bypass caps actually doing? Allowing high frequency to pass through to the negative side of the circuit instead of on the signal going to the amp(I'm tottaly guessing at this!)

I'm going to begin rewiring this to see if it makes a difference anyhow.

Thank you!
 

Suproman

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Lug 1 is connected to ground, so if one side of the switch is connected to ground instead of lug 3 it means one side of the caps will be connected to ground and not function as treble bypass caps.
 

TobyZ28

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I rewired the attenuator last night and the treble bypass now works! I used 4.7uf + 8.2uf caps and am quite happy with the results so far! Thank you!
 

DarkMatterSound

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Jan 12, 2022
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Montreal, Canada
Hi there! I’m currently building the exact same type of attenuator following the same instructions but the treble caps have absolutely no tonal effect at all when engaged…
My caps are non-polar (2.2 and 4.7uf).

The attenuator itself works great though, I first wired the 1-3 in the opposite way and the volume control was acting the opposite way (“full volume” started at 0 but was much lower in db when engaged compare to the normal wiring (with the ground wire to the #1). The proper wiring kept my amp at it’s volume when engaged this time.

But still the brightness switch is not changing anything. I tried with many different EQ and my ear stuck to the speaker wile turning the switch but nothing. Hope my explanations are clear enough. 😂

Here is a photo of my wiring. The L-Pad tags are 1-2-3 from left to right exactly as seen on the photo.

Any help would be much appreciated! 😉
 

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