I have a TC Electronic G-Force and Eventide Eclipse in the parallel effects loop of my amp and use a rack mixer to keep them in parallel with each other, and so allow me to use them both 100% wet and so avoid having to digitize my dry signal. I do have OCD about keeping my core dry signal out of the digital domain completely.
But I also have an Eventide Pitchfactor and would like to put this in too, and although the rack mixer can accomodate 4 in and 4 out, adding the Pitchfactor to an already limited rack space would be a pain, so I wanted to make a little 3 channel utility splitter/mixer to use instead of the rack mixer to save 1U and allow me to put two pedal trays in my 6U rack.
I used the splitter scheme you can see at Paul in the Lab, and a generic mixer circuit I found so that everything can be done with one quad opamp. I may even make this with 3.5mm jacks for the send and returns, make up my own high quality cables and then this will all fit comfortably in a 1590B. It would pretty much be a set and forget utility for me so I suppose I could even use trimmers instead of pots, set the levels and tuck it away somewhere. So I thought I'd add it here and it may be useful for others to adapt for their own uses.
I have a feeling this will be extremely useful, and it's a heck of a lot simpler than a lot of the other mixers. As a bassist, you really want a dry signal underneath a lot of your effects, and this may be easier than incorporating a boatload of JFET blenders into all the things I build.
ReplyDeleteNICE! This is going to be my next build!
ReplyDeleteIncidentally, you can of course omit the channel level controls if you wish. If this is being used to put effects in parallel, and those effects each have their own level controls then an additional one may well be superfluous for your use. In which can just take the return jack straight to the board.
ReplyDeleteIf I wanted to use this for a clean blend could I just link one of the send-returns for the clean part or does this circuit rely on there being some kind of buffer in between? I'm thinking of adapting this to add a ckean blend to a fuzz pedal.
ReplyDeleteYes you could do that no problem
ReplyDeleteI was going to do the 4 channel mixer until I saw that people were having problems with it.
ReplyDeleteI think I'll trust this one and just go for it!
One person. And it is verified...
Delete+m
Could this be adapted to suit an a/b/y pedal?
ReplyDeleteYes but you wouldn't need any of the mixing components or the returns, and obviously only two sends. Probably the easiest way would be to connect two of the sends to their own stomp switch. Only a SPDT would be required, or DPDT if you want LED indication. Like this:
Delete1 - From Board
2 - To amp
3 - Ground
So with two stomp switches you can turn each amp on and off independently, or both on of course. And amps bypassed with have the connection to the amp grounded to prevent noise.
Has |v|ark or anyone else successfully built this? I've given it a couple of trys and I can't figure out why there's no signal getting through any of the channels. I may get around to troubleshooting it on a breadboard and will update if I figure out what I'm doing wrong.
ReplyDeleteI'm a long time listener, first time commenter, so I want to get in a thanks to |v|ark & Mirosol & the regulars for sharing & verifying.
Can you post the IC pin voltages
DeleteI've tried a couple of different TL074's and they both show about the same voltages. I just realized pin 13's v changes with the master volume pot. This is with the master volume pot all the way turned up:
Delete1: 4.45v
2: 4.45v
3: 3.09v
---
4: 8.86v
---
5: 3.09v
6: 4.45v
7: 4.45v
---
8: 4.45v
9: 4.45v
10: 3.09v
---
11: 0.0v
---
12: 0.0v
13: 7.95v
14: 7.95v
The voltages on the non inverting inputs of the splitter channels don't look right to me on pins 3, 5 and 10. The two 10M resistors create a voltage divider there which should be closer to 4.5V.
DeleteForgetting the mixing channel entirely for the time being, are you getting nothing at all from any of the Sends?
Can anyone verify this?
ReplyDeleteI finished it, but output volume is about the half of the bypassed volume.
ReplyDeleteAlso each channel pot works, but even with 0 position, I can still hear the effects I plugged in.
Ivlark mentioned about the voltage on pin 3, 5, 10. I got 3.2, 3.1 3.1v.
i built one, but only hear hum sounds. Do I have to connect the gnds together?
ReplyDeleteYes, all grounds must connect to the negative pole of the power supply.
DeleteThanks
Dave
After a discussion on FSB I've updated this layout to what I believe will now do the trick. I think the problem with the last version of the layout was that I grounded the non inverting input of the mixing opamp channel, this now connects that to a half reference voltage. Changes have also been made to the input and so the new board is slightly larger and you're probably going to have to start again with a new board. Sorry to those who have already built this.
ReplyDeleteHas this been verified by anyone??
ReplyDeleteDid you build the first or second revision?
DeleteIvlark,
ReplyDeletePlease help me.
I made the second revision, channel 1, and 3 works fine, but ch. 2 pot is not working right.
Also when I turn the master pot, the sound goes off after 9 o'clock.
I checked my build several times, but I can't seem to find any faults.
The second revision got me very close to where it should be. Even with the master pot problem, right before the volume goes off, the amount of output volume is the same as input volume.
ReplyDeletech 1 works good, ch 2 gives click sound around 9 o'clock and the volume curve is a bit strange than ch 1 and 3.
ch 3, I shorted send and return jack for dry signal.
Are you sure the opamp isn't damaged? Post all your pin voltages to see if it gives any clues about a problem area (other than the obvious one around ch2).
Delete1- 4.64v
Delete2- 4.64
3- 4.22
4- 9.29
5- 4.22
6- 4.64
7- 4.63
8- 4.64
9- 4.64
10- 4.22
11- 0
12- 4.64
13- 3.53
14- 8.61
I don't have an extra opamp at the moment.
DeleteAlso all the pots made crackle sound when I turn them. :-(
The voltages don't look too bad actually, until you reach pin 14 which is far too high and I can't see anywhere obvious that may be coming from. Crackles may signify a faulty pot or probably a poor connection somewhere. Can you post a front and back pic of your board
DeleteIvlark,
DeleteHere is the link of the pictures.
http://weplaymusic.co.kr/187
I do love this small box.
This is the best utility box since I made loop box.
I just need to make it 100%.
Just built this and am having very similar problems as Jaemin. Wondering about a possible error... Mark, in your post from May 2013 you mention the "10m resistors" and in the Paulinthelab layout he specifies 10m resistors but the layout above calls for 10k resistors everywhere and I built off of that. What are the odds that swapping up for the higher values will fix these issues?
ReplyDeleteYes originally I did it based on Paul's splitter and a generic mixer circuit, but someone on FSB mentioned that it wouldn't work like that and posted this correction
Deletewhich the layout is based on. So instead of 2 x 10M resistors making a voltage divider directly at the non inverting input, two 10K resistors were used and then the non inverting inputs connected to it via the 1M resistor after the input cap.
And yes you're right about the number of tracks, that happens sometimes when I make a layout I've already finished slightly more compact but forgot the change the note.
Also, the layout calls for a 16x12 vero, but my count has it at 16x11 (I caught it befor I started making cuts and ended up with an extra row. No biggie obviously...
ReplyDeleteJust quadruple checked my build, track cuts, off-board, etc. Can't find anything obvious. Here are my voltages:
ReplyDelete1: 4.66
2: 4.66
3: 4.23
4: 9.33
5: 4.23
6: 4.65
7: 4.65
8: 4.66
9: 4.66
10: 4.23
11: 0.0
12: 4.66
13: 4.66
14: 4.66
Please let me know if there is anything I can do to problem-solve this further.
Your voltages look pretty much text book to me, exactly what you would hope to see. But there is obviously an issue which is why I've now marked this "on hold" and so put it to one side for a while and let me look into it a bit deeper to see what could be amiss.
DeleteHi all! Long time lurker, occasional builder here.
ReplyDeleteI've built this with the original layout last summer, but only the splitter part worked, so I've used it as a splitter since. I really needed a small mixer, so I managed to make it work, though I have no idea why it works.
SOLUTION: Put a 33k resistor from pin13 of the opamp to ground. The 47uF cap is also necessary (it was missing on the first version).
This gives you the mixed output of the 3 returns. It seems to be a bit higher than unity, on full volume I get some nice overdrive on the low B of my bass, but it is fine on lower volumes. I've soldered my resistor from the master pot to the ground lug of the output jack, as I was too lazy to pull the whole thing out of the box. As soon as I get my hand on a scope, I'll debug this properly.
Anyone care to enlighten me why my solution works? I'm not real big on theory, and this makes no sense to me. Used my sick bending skills to stumble upon this solution :P
Thanks for the info. That would make the schematic something like this:
Deletehttp://oi62.tinypic.com/10x57bc.jpg
and I still can't see why it would be required. It really does my head in that I'm fine with much larger effect circuits, but something as simple as this has caused problems and I don't know why! :o)
I solved Jaemin Choi's problem by putting a B25K for Master instead of B100K.
ReplyDeleteReally helpful tool. Thanks a lot, IvIark.
Hello, I´m a beginner here, I just finished this building, this my 3rd one but wanted to give it a try because it seemed to be perfect for some sound I was looking for. After finishing it had the same problem than Jaemin Choi so did as nicolas.lesage suggested, using a B25K instead of the B100K. After that it just works perfect, keeps the sound of volume and every channel works perfectly well, no noises, simply fine. By the way I switched channel one straigth to keep always one dry signal, and use channel 2 and 3 to connect effects. Also added a DBDT switch to cut the dry signal and leave only the sound of channel 2 and 3, and a 3DBDT switch to bypass the entire thing. Plus one led on each switch to know its position. So from my point of view you can remove the ON HOLD tag to VERIFIED ;) Thank Ivlark for your job and dedication here and everibody else for their contributions, this is just great!
ReplyDeleteCould some one explain what you would use this for?lol.
ReplyDeleteYou can use it for split the signal feg. one guitar to 2 or 3 amp. Or mix 3 instruments to one amp. Or making fx loops on the channels, cant controll more fx pedal with a footswitch. But the most common use is that make solution to fuzzy, overdrived, distorted bass sound. When u use this pedals you lose the dynamic and power of the dry sitnal. More distortion more inarticulate, spongy, fluid sound. But you mix the original sound in this fluff, you get back the carractered, ballsy sound
DeleteIs this still ON HOLD?
ReplyDeleteyes
DeleteThanks!
DeleteHello, I hope this thread is not dead because I have been looking over a schematic I drew up of this in order to understand what the problem is. I have a few questions and maybe some insight.
ReplyDeleteI am curious why the mixing stage is an inverting amplifier. You could have done another voltage follower (like the splitter stages), only with higher gain. It might look like: 100nf capacitor coupled input straight to pin 12, 22k from pin 13 to GND, 100k pot from pin 13 to pin 14.
I am also curious as to why 10k resistors are used on the return. They make a voltage divider with the 100k. The 100k master pot, when divided by the 10k resistors, will give the stage a gain of 10, whereas if you replace the 10k's with 1k's, you would have a gain of 100 when the pot is cranked all the way.
This might explain why someone earlier stated that a 33k to ground worked out for them, only that is not a good way to execute that. I would think it creates motorboating.
I've thought about it, and the input impedance of the inverting op amp is divided between three channels, so perhaps lower the 10k input resistors --I think you could get away with something like 470R. Or you could increase the gain as I said before... you might do better with a 1k or 10k from pin 13 to ground. I have not bread boarded this. I bread board circuits like this all the time and its not difficult to find which values to swap out.
ReplyDeleteHi Guys. For any of you who have made this, is there any bleed through from channel to channel like the split 'n' blend? Or are all 3 channels independent.
ReplyDeleteRookie mistake, didn't ground the pots. Works perfectly now, Great Layout.
DeleteI connected the first send and return directly to a pot so I would be my clean blend, and I added phase invertor's on the returns of what are now my Loops 1 and 2.
https://imgur.com/wRUq0Ma
Hi everyone, it seems I'm arriving at this party quite late but I wonder if there is anyone watching this who might be able to offer some insight.
ReplyDeleteI built this over the weekend, and am having an issue with the master pot. I'm using the 25K Lin pot suggested above, and it seems to basically work. When I turn the master up from 0 (about 7 oclock) it starts silently and increases in loudness until about 2 o'clock, when it suddenly cuts out. There is no sound from any of the channels if the master is turned up above that point.
I am getting some weird voltages around pins 12-14, they are in the 7.0. to 7.5 range. Seems way too high.
Any ideas what I can check?
This comment has been removed by the author.
ReplyDeleteThis comment has been removed by the author.
ReplyDeletePLEASE HELP ME!!!
ReplyDeleteDoestn work correctly., but I really need this pedal for everyday use.
the ic pins voltage with the B100K Master pot:
0% volume. 100% volume
1. 4.7. 4.7
2. 8.78. 4.7
3. 4.7. 4.7
4. 0.83. 4.7
5. 4.27. 4.27
6. 4.7. 4.7
7. 9.43. 9.43
8. 0.0 0.0
9. 4.27. 4.27
10. 4.27. 4.27
11. 4.7. 4.7
12. 4.7 4.7
13. 4.7. 4.7
14. 4.7. 4.7
tried A25K Master, caused another problems
0% volume. 100% volume
1. 4.7. 4.7
2. 4.7 8.67
3. 4.7. 4.7
4. 4.7 2.62
5. 4.27. 4.27
6. 4.7. 4.7
7. 9.43. 9.43
8. 0.0 0.0
9. 4.27. 4.27
10. 4.27. 4.27
11. 4.7. 4.7
12. 4.7 4.7
13. 4.7. 4.7
14. 4.7. 4.7
Really thank you for your help!
Maybe get rid of it and build jet parallel looper?
Hi there, have tried building this one, but unfortunately, I get a high-pitched whine that changes in frequency when the pots are adjusted in certain ways. I do not get any guitar at the output with all three send/return jacks connected together, or even disconnected.
ReplyDeleteI will measure and post Voltages as soon as possible.
I disconnected all three channels and the noise persists, no issues seen with the soldering so far.
Added a LED for power indication, don't know if this would affect anything.
Thanks, and all the best
Padster
So, I redesigned this circuit to use +/-9V (using a 7660S) for the Op Amp Power since the problem seems to be with the biasing, based on my Voltages posted. I added an LED which may have caused issues with the original circuit, but not sure.
DeleteThe new circuit omits the two 10k biasing resistors, but I left the 1M in (now going to ground), and the output Op Amp is referenced to Ground. The actual output still has the 10k going to ground. The board ended up being 16x16 but it may be possible to reduce this.
The result is that the circuit works well, with a significant boost in Volume at the output, however, there is a background 'whine' whenever the guitar starts playing, but this is not very noticable when the guitar gets louder.
If anyone wants to see the circuit, let me know and I'll figure something out. Also, if anyone knows what may be causing the 'whine', please let me know so I can get this circuit perfect, as it's very close.
Voltages measured and looks weird:
ReplyDeleteIC1: (TL074 Inserted)
1 8.8 14 8.8
2 8.8 13 8.8
3 8.8 12 9.2
4 9.25 11 0
5 8.8 10 8.8
6 8.8 9 8.8
7 8.8 8 8.8
IC1 TL074 removed
1 0 14 0.028
2 0 13 0.028
3 8.4 12 9.24
4 9.25 11 0.06
5 8.4 10 8.4
6 0 9 0
7 0 8 0