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DIY Stompboxes => Building your own stompbox => Topic started by: tenser75 on October 22, 2016, 12:02:11 AM

Title: how to add a mid boost?
Post by: tenser75 on October 22, 2016, 12:02:11 AM
during last year building pedals, and as a newbie in electornics I understood the concept of capacitors and their propery of cutting lows or highs... but what about boosting the mid? is it maybe actually a cut in low and high at the same time that make us perceive it as a mid boost?

thanks
Title: Re: how to add a mid boost?
Post by: bluebunny on October 22, 2016, 05:17:02 AM
A capacitor by itself doesn't cut anything: it needs to work with a resistor. And it certainly doesn't boost. But the perception thing holds: if the rest of the front rank on the parade ground steps back, then you've just volunteered.  ;)

Sent from my GT-N8010 using Tapatalk

Title: Re: how to add a mid boost?
Post by: GibsonGM on October 22, 2016, 06:54:01 AM
Quote from: tenser75 on October 22, 2016, 12:02:11 AM
is it maybe actually a cut in low and high at the same time that make us perceive it as a mid boost?

thanks

Yup :)
Title: Re: how to add a mid boost?
Post by: Derringer on October 22, 2016, 09:52:17 AM
glad this came up

how about taking one of those mini Xicon transformers
http://www.mouser.com/Search/Refine.aspx?Keyword=xicon+transformer
and making a RLC network in the inverting feedback loop of an opamp for a mid boost?

I'm not sure what that network would look like exactly though, my breadboard is full at the moment


The inductance ratio goes something like this
(primary impedance / 1000)(3/8) = inductance in henries
ex, the 42TM018-RC has primary impedance of 10K (you could use either side it's 10k:10k)
so (10,000 ohms / 1000)(3/8) = 3.75 Henries.
You could center tap this one and also get just short of 2 henries.
Title: Re: how to add a mid boost?
Post by: GibsonGM on October 22, 2016, 04:52:22 PM
You COULD do it that way, Derringer, altho L's tend to be pretty noisy for stompbox work.

Most people prefer something like a Twin T, they are easy to work with...   http://www.geofex.com/article_folders/eqs/paramet.htm (http://www.geofex.com/article_folders/eqs/paramet.htm)
Title: Re: how to add a mid boost?
Post by: Derringer on October 22, 2016, 05:15:25 PM
yup, familiar with the twin T

just have inductors on my mind since working on my Acoustic 320 and then modding a Windsor to be more Orange-like
Title: Re: how to add a mid boost?
Post by: mac on October 22, 2016, 05:40:13 PM
What about an active filter?

(http://www.circuitstoday.com/wp-content/uploads/2009/10/Multiple-Feedback-narrow-bandpass-filter.jpg)

mac
Title: Re: how to add a mid boost?
Post by: robthequiet on October 22, 2016, 05:44:32 PM
Maybe it's worth looking at a specific application?

If you put at high-pass filter ahead of a low-pass filter you end up with a mid-heavy tone. Or vice-versa. The Tube Screamer is a mid-heavy effect.

The thing to keep in mind is passing enough signal in the process, as you're removing highs and lows. The remaining signal has to be boosted back up in most cases. As Marcello posted, active circuits give you some flexibility with less power loss. If you look at the early Fender amplifier tonestacks, you may get different ideas.

Is this helping?
Title: Re: how to add a mid boost?
Post by: D.C. on October 23, 2016, 02:05:17 AM
OP: Consider this frequency booster circuit: http://www.muzique.com/news/frequency-booster/ (http://www.muzique.com/news/frequency-booster/)
Title: Re: how to add a mid boost?
Post by: smallbearelec on October 23, 2016, 04:25:27 AM
Check out the sound clips in this article:

http://diy.smallbearelec.com/Projects/WMouse/WMouse.html (http://diy.smallbearelec.com/Projects/WMouse/WMouse.html)