I was looking through some schematics of my favorite fuzz pedal the Ibanez TS9. Looking at the diodes in the feedback path I would think being identical this would promote 3H distortion from the symmetrical clipping. I like asymmetrical clipping and the more 2H sound so I want to change one of the diodes to something other than the 1N914. All I have on hand are 1N4148 which I believe are the same thing, I also have some 1N4001's. I was thinking of going with 1N4148/1N4001 combo. Will that give asymmetric clipping? Another idea was to just add another diode in series on one side so there is two diode drops, but this might be too much. I guess the only way to tell is do it but if anyone has any experience doing this or if doing the first option isn't going to yield any results I will just jump right to the second option. I am thinking the conduction knee will be in different spots with dissimilar diodes hence trying the 1N4148/1N4001 combo first.
I have some test equipment like sig gen and scope so if there is interest I will do a little write up. Or if this has been done please share or link me the details, I don't feel like wasting my time🙄
Schematic: http://www.muzique.com/schem/ts808.gif
Thanks in advance🙂
-Bird
I have some test equipment like sig gen and scope so if there is interest I will do a little write up. Or if this has been done please share or link me the details, I don't feel like wasting my time🙄
Schematic: http://www.muzique.com/schem/ts808.gif
Thanks in advance🙂
-Bird
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1N4148, 1N914, 1N4001 are all silicon diodes and so all have the same forward voltage drop of around 0.65 Volts.
To try out asymmetric clipping you will want to change one of these to something other than Silicon.
Either:
1) go lower forward voltage drop, schottky diode, try a BAT85 at about 0.4 Volts
2) go higher froward voltage drop, LED, RED LED lowest voltage of around 1.4V, Green at 1.8 to 2.0 Volts and BLUE LEDs above 3V.
I'd try the BAT85 first.
Cheers,
Ian
To try out asymmetric clipping you will want to change one of these to something other than Silicon.
Either:
1) go lower forward voltage drop, schottky diode, try a BAT85 at about 0.4 Volts
2) go higher froward voltage drop, LED, RED LED lowest voltage of around 1.4V, Green at 1.8 to 2.0 Volts and BLUE LEDs above 3V.
I'd try the BAT85 first.
Cheers,
Ian
Hi, I did some snooping around on the internet and people said they heard a difference with the 1N4148/1N4001 combo and that it gave enough asymmetry. I didn't give a listen after I tried that combo but nothing looked different on the scope so I didn't feel confident that I changed anything.
I agree I need a completely different diode with a completely different forward voltage drop. I had no LED's so I took the two original diodes and strung them in series for one side and then I used a 1N4148 for the other. So theoretically I should have 1.2v voltage drop on one side and .6 on the other.
Here are some pics. Clean input. Normal distortion. Then modded distortion.
Controls are set to the same setting. 440Hz input @ 200mV.
I will plug it in and report back on the sound analysis.
I agree I need a completely different diode with a completely different forward voltage drop. I had no LED's so I took the two original diodes and strung them in series for one side and then I used a 1N4148 for the other. So theoretically I should have 1.2v voltage drop on one side and .6 on the other.
Here are some pics. Clean input. Normal distortion. Then modded distortion.
Controls are set to the same setting. 440Hz input @ 200mV.
I will plug it in and report back on the sound analysis.
Attachments
get out your meter, set to diode test, and measure the drop of each candidate diode. You may find enough differences to matter to you.
No LEDs? Have you no dead electronics stuff in your shop? Everything has LEDs in it these days. VU meter in an old cassette deck, power indicator in some device, heck the IR LED in the nose of an old remote control from a TV. It is still an LED even if you cannot see the light it makes.
You can also try just eliminating one diode, that is about as unbalanced as it gets.
No LEDs? Have you no dead electronics stuff in your shop? Everything has LEDs in it these days. VU meter in an old cassette deck, power indicator in some device, heck the IR LED in the nose of an old remote control from a TV. It is still an LED even if you cannot see the light it makes.
You can also try just eliminating one diode, that is about as unbalanced as it gets.
The problem is that the amount of asymmetry is a matter of personal taste, so it is on you to find out. I expect one single si-diode, anti- parallelled by 2 Si-diodes in series, could be a starting point.
Boss SD1 has an aysmmetrical set of 3 silicon diodes. So its an arrangement that has been well liked for a long time. I tried symmetrical and also a silicon/germanium pair, but then left it as it was.
Yes this is where I started because the two diodes with slightly different forward voltage drop wasn't if at all any different than stock. I measure the anti-parallel diodes at .6 and .64 so the asymmetry wasn't enough. The three diodes is a good starting point indeed, but I like it enough to leave as is for now. Maybe I can scrap up some LED's form junk electronics as suggested and go for more asymmetry in the future.
http://www.hobby-hour.com/electronics/s/schematics/boss-sd1-super-overdrive.gif
Yes it appears I did exactly the same diode arrangement that's in the Boss SD1. I played it last night for a short period of time and I can easily notice the difference, I am digging this sound a lot🙂 Thank you for sharing that info.
I loved the TS9 but now it's even better. People swap opamps and I have tried that but didn't notice a huge difference. I left a BB OPA2134PA because it felt the warmest, maybe the true FET input?
I have band practice this evening so lets see how it cuts through the band noise.
I have found that the combination of 2 series diodes antiparallel with 3 series diodes works really nicely as a mod for the Big Muffs. It also works really nice as hard clipping (when you place this between output and ground). With the TS, you may need to adjust the gain to get the same amount of distortion.
It's also definitely worth trying different combinations of diodes. Germanium diodes drop about half the voltage of silicon diodes, and LEDs are about 2V. Also apparently MOSFETs work really well as clipping diodes although I'm not an expert on all the different connections.
It's also definitely worth trying different combinations of diodes. Germanium diodes drop about half the voltage of silicon diodes, and LEDs are about 2V. Also apparently MOSFETs work really well as clipping diodes although I'm not an expert on all the different connections.
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