Morning glory question, a mod with strange results....

Started by ShadSunsCrash, September 13, 2020, 06:33:25 PM

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ShadSunsCrash

TL;DR Why is the middle position quieter than the 4.5k and 12k positions? It seems like the middle position would be the loudest but its the quietest which is actually perfect cause now the middle position/"off position" is just like a blues breaker and the 12k position is like a morning glory(louder than the middle position) but not as loud as the 4.5k position which is like a boosted morning glory (loudest). Just trying to wrap my head around why the "off" position is quieter? I ended up using a J113 JFET cause the 2N5457's i have all resulted in a much quieter pedal, not bad just not as good as with the J113. I tried a few other JFETs but the J113 was the best.

I just built the Morning Glory Vero Layout from Tagboardeffects and i wanted to do something akin to the extra gain stage that the V4 morning glory has. I wasnt able to figure out how they do it despite having a few hypothesis. Anyways what i ended up doing was removing the 12k resistor thats connected to Source on the JFET and the positive side of the 100uf cap. I figured i could boost or buck the circuit by changing the voltage at the JFET. So after removing the 12k i put wires running from each space where the 12k leads used to be. Then i connected those wires to the middle lugs on a DPDT on off on switch. On one side of the switch i put the stock 12k resistor that i just removed and on the other i put a 10k trim pot (i have that trim pot set to about 4.5k which gets me the boost i was after). So heres where im getting results that im having a hard time understanding. And i should mention that i only used an On Off On cause i didnt have an on on. So when the switch is the the 12k position im getting the stock output level, no surprise there. And when im in the 4.5k variable resistor side im getting a boost thats louder than stock(more resistance on the variable resistor = less of a boost, less resistance = more of a boost). All of that is well and good, but in the middle position where the two wires are not connected since its the "off" position im getting a drop in output that brings the pedal to almost exactly what youd get from a stock blues breaker. I honestly love it like that, the middle position being less output/more like a stock blues breaker makes the pedal very versatile and i actually have been finding i prefer it in that position. But i cant wrap my mind around whats causing the level to drop when the connection is severed in the "off" position rather then boosting it. I keep thinking that in the middle "off" position i should be getting a boost louder than the 12k position and the 4.5k position since its seems without that connection there would be less resistance? I must be missing something, possibly something obvious. Or i could have a fundamental misunderstanding about what im really accomplishing with this mod. I havent seen anyone else do this mod so im kind of on my own to figure it out. To be clear its absolutely excellent how it is so it turned out to be a happy accident. But i need to know why its working as it is. Anyways ill add a picture of the layout below. Thanks for your help!


PRR

4.5k gives most gain. 12k gives less gain. Infinity (open) is even less gain.
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ShadSunsCrash

Quote from: PRR on September 14, 2020, 01:08:17 AM
4.5k gives most gain. 12k gives less gain. Infinity (open) is even less gain.

SMH, your absolutely right! I truly think myself into stupidity sometimes. As simple an answer as it was i really do appreciate it. I think the real question is how i confused myself to the point of not seeing that right away. I knew it was open in the middle position but every time i was thinking of that position i was thinking "0" as if it were connected/jumpered without any resistance rather than it being open/"infinite" since the center position isnt connected. Honestly thank you for your help!

PRR

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