Resolved: standalone buff n blend : no sound out of the send jack

[Anonymous]

Hi all !!

I’m a complete newbie in diy pedals, but already totally hooked to this hobby 😉

I already finished some arcadiator kit from parasit studio, and wanted to add some clean bass sound to it. Hence the standalone buff n blend idea.

Why standalone ? To make it the most versatile possible, and be able to use it with any pedal / setup.

However, it appears my build doesn’t
work as expected :
1/ true bypass is ok
2/ return is ok, as the blend pot : using a looper, I clearly hear the recorded riff, and I can mix between full level with blend full CW, or no level when blend fully CCW.
But :
1/ using my bass, or the looper as input, when the BNB is on and blend pot set fully CCW, I hear no sound. Using my combo at full volume level (usually I’m using it at levels 1 or 2, here I put it at 10), I hear my original signal at a very tiny level (as if the level was set to 0.5 on my combo), plus some noise.
2/ whatever I plug between the send and return, blend pot set fully cw returns absolutely no signal. I acknowledged the phase inversion problem, so I tested the following :
– arcadiator only, on and off
– looper only (boss rc1), off and on
– arcadiator + looper in serial, whatever their order, both on
– direct link with a patch cable
None of the above worked. At least one of them should have worked. The patch cable should have worked whatever the blend position.

I’m guessing either a problem around the mpf102 (which looks fine using my multimeter, checking value between base and source / gain, on both directions, using the diode mode : both values were similar, and one direction gave higher values than the other : to vs from base..), or around the first capacitor of the circuit..
I got a problem with my audio probe, but I guess this is my best chance to clearly isolate the problem so far..
I also checked the +9v, all ground and all input/output/send/return parts, without finding any problem..

Do you have any hints of clues about my problem ? Any hints on how to check the transistor or whatever ?
My best guess from now is to fix my audio probe setup and check my signal path from the input.. but any help would be greatly appreciated !

Best regards, and thanks in advance for your support !!
Gus.

[Barry]

You are correct about the audio probe.

You can check the voltages of the transistor but that wouldn’t be my first guess.

This really sounds like a project for the Paramix which will also handle phase inversion.

[Anonymous]

Does the arcadiator work by itself?  Battery voltage?  Voltage at the drain of the MPF102?

Try to reflow all solder joints with the transistor removed.  You DID use a socket for it?

Check orientation of the transistor.  Without pictures we cannot tell much.

 

[Anonymous]

Hello Barry & Wilkie, thank you very much for your quick feedback !

I’ve been a bit away from the computer these days, hence the delay in my response..

To answer to Wikie’s questions :

Yes, the arcadiator works by itself.

There is no battery in my build, only a power plug (a RockPower 9V, 1300mA). The voltage is a bit above 9V (9,29V)

I checked the transistor position (according the picture on the BnB board, plus I checked with the specs). The voltage on the Drain (the leg nearest the foot toggle switch, am I correct ?) is 9,29V.
I got the same voltage on the opposite leg, but middle one show up lower voltage (8,93V). I’m not sure if that’s relevant, though.

I’ll triple check the soldering joints, I’m clearly not happy with a bunch of them. (And yeah, the transistor is socketed ;-))

Barry : Got the point about the audio probe !

For the time now, I’ve got very few spare time to spend on my build, but I’ll get back with more info as soon as possible.

Some important note : I did NOT wired the LED circuit. As it’s separated from the audio one, this shouldn’t have any impact, am I correct ? I plan to do this once the audio part is OK.

Again, thanks for your support !

Cheers,
Gus.

[Anonymous]

Hi again,

I dug further, and here are my latest discoveries :

when the power plug is removed, the Buff’nBlend works perfectly ! Send/Return plugged to the Arcadiator, I clearly can mix up the clean signal and the Arcadiator Fuzz using the potentiometer : hooray \o/
So, almost all my circuitry seems ok at this point.

However , once I plug the power, I’ve got no sound at all.
After audio-probing the PCB starting from the input, I lost its signal just after the C1 (at the junction of R2, R3, and the G leg of the mpf102). I inverted the MPF102, with no results.

So far, I’m completely lost with this build … My best chance now is to order another MPF102 (or any replacement , like the J113) and cross my fingers ?

Cheers,
Gus

[Cybercow]

If it works with no power, that’s a hint that something is likely wired wrong. The +9v is ONLY there to light the LED. Let’s see some good clear photos of the PCB (both sides) and the wiring please.

[Anonymous]

Hi Cybercow !

Doesn’t “Buff’n’Blend” stands for “buffer” and “blend” ? What about the +9V on the left topmost part of the circuit, connected on R2 and on the Drain gate of the MPF102 ? 😉

Anyway, I made some pictures, and for sure there will be a lot to say about my soldering skills :-S
Here they are : https://photos.app.goo.gl/AHTn12b7MTBHYAoH9

(I’m not sure the image will show up to you, hence I put the shared album link)

 

Cheers, Gus

[Barry]

Inverting the MPF102 could have ruined it. Try another JFET. MPF102, 2N5457 or J201 all have the same orientation as the silk-screen on the board.

[Anonymous]

Hi Barry,

Thanks for the tip, I just ordered another transistor.

TBC.. 😉

 

Cheers, Gus.

[Anonymous]

Hi again !

Just received my new MPF102, replaced it, and tested it.

the Good : the sound level is way much audible than before.

the Bad : now, when mixing the channels, I barely hear nothing from the Send/Return effect. My clear channel takes almost all the room on the output signal. I tried with and without phase inversion (I’m using a Lehle P-Split to achieve this), with no audible effects.
I did not put any resistance on R5 (I just soldered a straight connector in place), so the signal should be louder, am I correct ?

 

And yeah, now I understand why the paramix is a best solution 😉

I’m thinking about this buff-n-blend build as a test to check what exact components I would need to integrate it among a future Arcadiator build. 😉

 

Cheers !

Gus

[Barry]

+1 on the JFET. You can actually start a fire or at least burn your finger with those with only 9v by inserting them backwards. For me there are some unknown elements. The other circuit, not being able to see everything clearly as well as the P-split.

I highly suggest using the right tool for this particular job which is the Paramix.

[Anonymous]

You can actually start a fire or at least burn your finger with those with only 9v by inserting them backwards

Dully noted ! I wasn’t even aware of this ;-/

I completely agree with paramix, which I’ll order from musikding asap 😉

About the buff’n’blend, however, what do you suggest to me ? I don‘t want to completely throw it away 😉
I can either post the arcadiator schema + pictures of my build ?
Maybe would that fit better a completely new thread ? (since the original problem , aka “no sound” is now over) ?

Br,
Gus

[Anonymous]

I fixed it !!!

wow… just spent almost 2 hours checking what was wrong with my build.

I checked again everything with the audio probe, and just recently noticed that plugging / unplugging the output jack was causing the problem… A bit of investigation further, I discovered the tip of my out socket was bending over, making contact with one of the legs of the blend potentiometer…..

I rotated the socket, and now, it works perfectly fine, and does exactly what I wanted : buff, and blend my signal 😉

woohoo ! \o/

Thanks again a LOT for your support. That helped me 😉
Next time I’ll directly think about the paramix ;p

 

Cheers !

Gus.

[Anonymous]

We are glad you got it solved Gus! I’ll mark it as resolved.

[Author]

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