OKAY! Built!!! Works and sounds AWESOME! However - J175 jfets are DGS, not DSG. I went ahead and did the layout as you drew it, and tried out just about every jfet I have with that pinout. The octave down is apparently GREATLY affected by that bit, so the one I settled on was a BF245C. I twisted the legs on a J175 to see if it would work, and it did, however, the octave would cut out whenever I would dig into the strings. Also - TL062s work fine but tracking is WAY better with TL072s. Like almost digital/POG tracking perfect. Way better than I would expect from a 4013. This is an awesome circuit and is going on my board as soon as I box it up!
I test my builds with a baritone guitar tuned to B Standard. Also I must mention, sockets on all the ICs are worth it. Had to try a couple flip flop chips and dual op amps (settled on a mix of 4558s and TL072s) too. This effect is unity gain but tracks better than any analog circuit I've built so far.
I built it and it works but somewhat weak...tried the suggestions Chris made above and it is better but not powerful enough. And, there is no difference when I remove IC4... still sounds the same, could that be a hint to the weakness?
I could use some help. I built this following Chris’s suggestions except I only used TL072s as I was not sure what order the different ICs would go in. It sounds good and tracks really nice.
The problem I am having is when I turn it on only the dry signal comes through, then I have to play pretty hard for the octave to kick in (like it’s gated and needs the volume to hit a certain threshold to activate) After that it works really good as far as I can tell (I’ve never actually used an octave before) But after awhile if I play to fast or hard or a combo (haven’t quite figured out the cause) the octave cuts out again and I have to repeat the process.
The two things I know is 1: that I accidentally connected the power in reverse at first but it was only -0.03v thanks to the Schottky. I looked up the ICs and Transistor and they should be fine. 2: this was my first strip bored project (second pedal build) I needed to extend the border so I staked another piece over lapping with row Z but I for got to add the cuts to the lower level of strip board. I realize now that I could have just butted them together and the components would keep it together.
Would greatly appreciate any help! (I’m pretty green at all this) Thank you.
sometimes when i experience that i really have to play very very hard, it turns out i had a bad (cold) solder, or wrong connection, so double check all your solders, check for jeff bridges! and check that your wires are connected at the correct points. ( i have not build this one (yet)
I have looked over the solder joints and connections and they all looked good, but it doesn’t hurt to triple check. I will look over it again and maybe I should go ahead and fix the over lapping strip board. Thank you for such a fast reply!
with layouts as large as this one it is best to get larger stripboard ( which is not fun since it is much more expensive) but then again, buying the effect itself is akways more expensive then buying larger stripboard!
Also - may I commend your bravery for choosing something as large and relatively complicated as this for your first strip build. I think my first was the tagboard layout of the original Interstellar Overdriver. Building on this stuff can be fraught with errors - some that may be practically invisible. A tiny fleck of copper left on a cut or a minuscule solder bridge can wreck the functionality of the circuit. Don't give up! Getting one of these designs to work is an achievement and totally worth multiple attempts!
Okay. I’ve narrow it down some what. First of yes, I will definitely look in to getting big strip bored next time. And thank you for the encouragement! So, what if found, first I was missing the 220k resistor. Adding this made the problem more consistent. So that was exciting! Then a made an audio probe to track my signal through the circuit. The dropping in and out seemed like it was stemming from somewhere where it enters IC2. I pulled Q1 and the signal was steady but very weak and didn’t really have the octave. Then I realized that since I was using the BF245C and that the pin out on the bored has been updated I needed to twist the legs. So I did that, but still pulsing in and out. (But cleaner sounding) I listened with the probe on pin one of IC2 and put my positive lead off my multimeter on leg G of Q1 and saw that the sound drops as the Gate is closes on the transistor. The the Gate opens (up to about 4.7v) and the sound is back. I also noticed that the gate is opening with a higher pitched and louder note, and closes with a lower softer note when I playing a MIDI bass with my phone. When playing a real bass if I play with consistent medium loud notes it would have the octave pretty much every other note regardless if I played fast, slow, legato, or staccato. So that seems like a some useful information! But, I don’t really know what to do with it. 😅 If anyone hade any ideas of what to do or look for, it would be greatly appreciated! Also (lasting thing I’ll say for now((sorry if this is to long winded)) For the brief glorious moments that it works, it sounds KILLER!!! Thank you fuzzhead for the design!
I haven’t had a chance to do that yet. But I will. I thinking maybe the BF245C is not biased correct. (As the bored was laid out for a J175) do know what resistor(s) are biasing Q1?
check the pinouts from your transistors, bf245c has different pinout then j175 https://www.componentsinfo.com/wp-content/uploads/2023/04/j175-fet-transistor-pinout-equivalent.gif https://files.easybom.com/blogimg/20220328/16484505262282.jpg
j175 is dgs , in the layout its gds so with a j175 you'll have to twist the legs to make it work and with a bf245 the pinout is gsd (still have to twist the legs) or change the layout
Hey all - as someone who has done multiple builds of this with the exact same results, I'm not posting to argue about what is "right" or "accurate" according to schematics. Just sharing what I have done.
First, in this FSB thread: https://www.freestompboxes.org/viewtopic.php?t=4160&start=120 there are two documents. 1st is the ORIGINAL ampeg schematic, 2nd is a REDRAW by the FSB user - BOTH clearly show a P CHANNEL Jfet. However, when I build this (I'm currently making my 5th one) if I use a P-channel jfet (I've tried multiple different ones, correcting the pinout when necessary by twisting legs) the octave barely works. It sputters and cuts out.
However, when I use an N-channel jfet which is clearly wrong according to the schematic, the octave is present, full, and tracks quite well. I don't care enough to lose sleep over why. To anyone attempting this monster of a layout, all I can say is USE SOCKETS for the jfet and be ready to try a bunch of different ones.
And if you want to use a jfet that is (from top to bottom) G-S-D, you can move the jumper from pin 5 of IC2 up one row, and move the jumper that goes from "direct 1" underneath IC1 up one row as well in order to connect to the Source. The jumper that goes from pin 3 of IC2, as well as the leg of the 47k resistor will need to come down one row in order to remain connected to the Drain.
thx for the info! will use sockets (like you said before) and see what's best, but since you've built this like 5 times, i will do what you said and try it with a n channel jfet first.
that's awesome! lol thats cool you posted a small vid as proof of concept! Im waiting for my stripboards to be delivered ( hope next week) and then will try this layout with the wrong jfet
Thanks Magus! I use a lot of stuff that I built from layouts on here. Some folks will tell you that 9v guitar pedals ruin the fidelity of drum machines and synths but I happen to love how "crappy" it makes everything!
very original and experimental to make tunes like that, I like it! also like your nicargua pedal and dire pedal! if i was in the us i would have bought them from you instantly!
i was eyeballing this layout and noticed it was mentioned that there is a cut at d6? do i need a new set of glasses , cause there's no cut at that position?
I had no J175s!!! However, they just showed up yesterday so...
ReplyDeleteBuilding this one up now. Haven't fired it up yet. But you should update the layout to say "51 cuts, 31 links"
ReplyDeleteOKAY! Built!!! Works and sounds AWESOME! However - J175 jfets are DGS, not DSG. I went ahead and did the layout as you drew it, and tried out just about every jfet I have with that pinout. The octave down is apparently GREATLY affected by that bit, so the one I settled on was a BF245C. I twisted the legs on a J175 to see if it would work, and it did, however, the octave would cut out whenever I would dig into the strings. Also - TL062s work fine but tracking is WAY better with TL072s. Like almost digital/POG tracking perfect. Way better than I would expect from a 4013. This is an awesome circuit and is going on my board as soon as I box it up!
ReplyDeleteChris! You are awesome, great job and many thanks!
DeleteThe J FET pinout is now corrected (easy fix!) and it is TAGGED.
Did you use it with guitar or bass?
DeleteI built the Multiplexer Octave some years ago, but I never made it works properly (volume and hiss issues).
I test my builds with a baritone guitar tuned to B Standard. Also I must mention, sockets on all the ICs are worth it. Had to try a couple flip flop chips and dual op amps (settled on a mix of 4558s and TL072s) too. This effect is unity gain but tracks better than any analog circuit I've built so far.
ReplyDeleteShouldnt Q1 be DGS for a J175
ReplyDeleteI built it and it works but somewhat weak...tried the suggestions Chris made above and it is better but not powerful enough. And, there is no difference when I remove IC4... still sounds the same, could that be a hint to the weakness?
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteI could use some help. I built this following Chris’s suggestions except I only used TL072s as I was not sure what order the different ICs would go in. It sounds good and tracks really nice.
ReplyDeleteThe problem I am having is when I turn it on only the dry signal comes through, then I have to play pretty hard for the octave to kick in (like it’s gated and needs the volume to hit a certain threshold to activate)
After that it works really good as far as I can tell (I’ve never actually used an octave before) But after awhile if I play to fast or hard or a combo (haven’t quite figured out the cause) the octave cuts out again and I have to repeat the process.
The two things I know is
1: that I accidentally connected the power in reverse at first but it was only -0.03v thanks to the Schottky. I looked up the ICs and Transistor and they should be fine.
2: this was my first strip bored project (second pedal build) I needed to extend the border so I staked another piece over lapping with row Z but I for got to add the cuts to the lower level of strip board.
I realize now that I could have just butted them together and the components would keep it together.
Would greatly appreciate any help! (I’m pretty green at all this) Thank you.
sometimes when i experience that i really have to play very very hard, it turns out i had a bad (cold) solder, or wrong connection, so double check all your solders, check for jeff bridges! and check that your wires are connected at the correct points. ( i have not build this one (yet)
ReplyDeleteI have looked over the solder joints and connections and they all looked good, but it doesn’t hurt to triple check. I will look over it again and maybe I should go ahead and fix the over lapping strip board.
DeleteThank you for such a fast reply!
with layouts as large as this one it is best to get larger stripboard ( which is not fun since it is much more expensive) but then again, buying the effect itself is akways more expensive then buying larger stripboard!
DeleteAlso - may I commend your bravery for choosing something as large and relatively complicated as this for your first strip build. I think my first was the tagboard layout of the original Interstellar Overdriver. Building on this stuff can be fraught with errors - some that may be practically invisible. A tiny fleck of copper left on a cut or a minuscule solder bridge can wreck the functionality of the circuit. Don't give up! Getting one of these designs to work is an achievement and totally worth multiple attempts!
DeleteOkay. I’ve narrow it down some what.
DeleteFirst of yes, I will definitely look in to getting big strip bored next time.
And thank you for the encouragement!
So, what if found, first I was missing the 220k resistor. Adding this made the problem more consistent. So that was exciting!
Then a made an audio probe to track my signal through the circuit. The dropping in and out seemed like it was stemming from somewhere where it enters IC2. I pulled Q1 and the signal was steady but very weak and didn’t really have the octave. Then I realized that since I was using the BF245C and that the pin out on the bored has been updated I needed to twist the legs. So I did that, but still pulsing in and out. (But cleaner sounding)
I listened with the probe on pin one of IC2 and put my positive lead off my multimeter on leg G of Q1 and saw that the sound drops as the Gate is closes on the transistor. The the Gate opens (up to about 4.7v) and the sound is back.
I also noticed that the gate is opening with a higher pitched and louder note, and closes with a lower softer note when I playing a MIDI bass with my phone.
When playing a real bass if I play with consistent medium loud notes it would have the octave pretty much every other note regardless if I played fast, slow, legato, or staccato.
So that seems like a some useful information! But, I don’t really know what to do with it. 😅
If anyone hade any ideas of what to do or look for, it would be greatly appreciated!
Also (lasting thing I’ll say for now((sorry if this is to long winded))
For the brief glorious moments that it works, it sounds KILLER!!! Thank you fuzzhead for the design!
check the links you made are at the right spots maybe ? 21 links are a lot so it would not be weird if you misplaced one?
Deletei mean 31links
DeleteI haven’t had a chance to do that yet. But I will.
DeleteI thinking maybe the BF245C is not biased correct. (As the bored was laid out for a J175) do know what resistor(s) are biasing Q1?
check the pinouts from your transistors, bf245c has different pinout then j175 https://www.componentsinfo.com/wp-content/uploads/2023/04/j175-fet-transistor-pinout-equivalent.gif
ReplyDeletehttps://files.easybom.com/blogimg/20220328/16484505262282.jpg
Yep, the drain and source are reversed compared to the J175?
ReplyDeletej175 is dgs , in the layout its gds so with a j175 you'll have to twist the legs to make it work and with a bf245 the pinout is gsd (still have to twist the legs) or change the layout
ReplyDeleteBut the J175 is an P channel & the BF245C is an N channel.
ReplyDeletethe bf245 would be the better choice but the layout is with a j175 so either way, jimbo57 is going to have to do a little twist(ing)
ReplyDeleteHey all - as someone who has done multiple builds of this with the exact same results, I'm not posting to argue about what is "right" or "accurate" according to schematics. Just sharing what I have done.
ReplyDeleteFirst, in this FSB thread: https://www.freestompboxes.org/viewtopic.php?t=4160&start=120 there are two documents. 1st is the ORIGINAL ampeg schematic, 2nd is a REDRAW by the FSB user - BOTH clearly show a P CHANNEL Jfet. However, when I build this (I'm currently making my 5th one) if I use a P-channel jfet (I've tried multiple different ones, correcting the pinout when necessary by twisting legs) the octave barely works. It sputters and cuts out.
However, when I use an N-channel jfet which is clearly wrong according to the schematic, the octave is present, full, and tracks quite well. I don't care enough to lose sleep over why. To anyone attempting this monster of a layout, all I can say is USE SOCKETS for the jfet and be ready to try a bunch of different ones.
when i have a new batch of large and normal sized stripboard i will give this one a go!
DeleteAnd if you want to use a jfet that is (from top to bottom) G-S-D, you can move the jumper from pin 5 of IC2 up one row, and move the jumper that goes from "direct 1" underneath IC1 up one row as well in order to connect to the Source. The jumper that goes from pin 3 of IC2, as well as the leg of the 47k resistor will need to come down one row in order to remain connected to the Drain.
Deletethx for the info! will use sockets (like you said before) and see what's best, but since you've built this like 5 times, i will do what you said and try it with a n channel jfet first.
DeleteJust to reassure you - this works with the "wrong" jfet: https://youtube.com/shorts/YAliCggvfcI?si=u_dwGe3HX_b85x4i
Deletethat's awesome! lol thats cool you posted a small vid as proof of concept! Im waiting for my stripboards to be delivered ( hope next week) and then will try this layout with the wrong jfet
Deleteso cool! you have a lot of equipment! i subbed on your channel man!
DeleteThanks Magus! I use a lot of stuff that I built from layouts on here. Some folks will tell you that 9v guitar pedals ruin the fidelity of drum machines and synths but I happen to love how "crappy" it makes everything!
Deletevery original and experimental to make tunes like that, I like it!
Deletealso like your nicargua pedal and dire pedal! if i was in the us i would have bought them from you instantly!
i was eyeballing this layout and noticed it was mentioned that there is a cut at d6? do i need a new set of glasses , cause there's no cut at that position?
ReplyDeleteahh , there's a cut under DIODE d6 ok, problem solved!
Delete