madbeanpedals::forum

Hi guys,

I just finished building my KingSlayer using MabBean PCB.
First build but it went smoothly overall. I just soldered Pot for tone and volume in the wrong way and I can't desolder them  I guess it's not too much of a problem.

I gave that bad boy a test run and it works pretty well but I noticed a couple of problems:

When I engage the OD switch to activate D2 and D3 (BAT46s) and it works most of the time except when I give a hard strum, the audio disappears and is replace by a stuttered hum. When I disengage the OD switch, everything returns to normal.

Also, I can't hear much of a difference when I engage D4, D5 and D8, D9.
I went for red diffused LED for D8 and D9. Should they glow by the way engaged ?

By the way I could not find any TC1044SCPA or MAX1044SCPA but I used an ICL7660SCPA. Other than that I didn't switch any other components beside a 390k resistor in place of 392k.

I build the buffered bypass version.

Any advice ?

Thanks.

Readings on IC1:
1: .3mV
2: 1.2mV
3: .3mV
4: 8.99V
5: .3mV
6: .7mV
7: 8mV
8: .5mV
9: .5mV
10: .5mV
11: -8.71V
12: .4mV
13: .5mV
14: 1.3mV



Readings on IC2:
1: 8.9V
2: 4.53V
3: 0V
4: -4.29V
5: -8,71V
6: 4.53V
7: 6.83V
8: 8.99V




Could you guys tell me if that's what's expected?

Thanks

C.

Pictures of the project if that helps:

https://www.icloud.com/photostream/#v2;2;0A455935-71CB-47F8-BF4B-B1E07FE399B9;v1CAEQARoQOOc7Fh8VwZ2uUT0Qcf5lNg (https://www.icloud.com/photostream/#v2;2;0A455935-71CB-47F8-BF4B-B1E07FE399B9;v1CAEQARoQOOc7Fh8VwZ2uUT0Qcf5lNg)

I can post more if needed.

Thanks a lot for your help.

You have your IC readings backwards. Look at the schematic drawing of IC2 you will see pins5-8 are bottom to top, not top to bottom as you listed here.

So, you should read 8.9v on pin8 and -8.71 (or so) on pin5.

You should also be reading that -8.71v on pin 11 of IC1, but you've listed it as -8.71mV. Is that a typo or the actual reading?

Yes you are right, I'm sorry. I fixed it on the original post.

-8.71mV was a typo indeed, it's actually -8.71V

Any great insight ? :)

Thanks.

C.

Quote from: Neurowork on September 16, 2012, 12:16:45 PM
When I engage the OD switch to activate D2 and D3 (BAT46s) and it works most of the time except when I give a hard strum, the audio disappears and is replace by a stuttered hum. When I disengage the OD switch, everything returns to normal.

That's probably backwards, if it's the same thing as in mine. Is this only happening when you have the gain cranked? You also shouldn't get it if you engage any of the hard clippers. The oscilaltion is from the chip freaking out from too much gain. It's similar to how a dual op amp can be turned into an LFO.

Brian suggested reducing the 1M if you want to avoid it entirely. Someone else suggested that a different chip might help. My personal take is that there's op amp distortion with the diodes lifted way before it oscillates, so there's no reason to really worry about it.

What do you mean by backwards? I double check the diode polarity and they are fine.

I tried, this only happens when the gain is almost all the way up, no matter if the hard clippers are enabled or not.

I could not find any post related to that but I guess I did a lousy search if that's the case.

Quote from: Neurowork on September 16, 2012, 06:41:57 PM
What do you mean by backwards? I double check the diode polarity and they are fine.

I tried, this only happens when the gain is almost all the way up, no matter if the hard clippers are enabled or not.

I could not find any post related to that but I guess I did a lousy search if that's the case.

By "backwards" I meant when the diodes are LIFTED, whereas you said it happens when the diodes are inm the circuit and not when they're lifted.

Maybe it's different from what happened with mine. Mine only oscillates when all diodes are lifted with the gain cranked. Here's the thread with Brian's and jubal81's replies with advice for curing it:
http://www.madbeanpedals.com/forum/index.php?topic=6102.0

Right, when the soft clippers are engaged, you should have some signal drop from the clipping. When lifted (and with the hard clipper switch in the middle position) no diodes are clipping. So, at max gain on this setting you might get some motor-boating or oscillation. You don't want to use it at max gain without any diodes for this reason. You can eliminate this by reducing that 1M resistor in the feedback path...470k-750k. This will also reduce max gain overall with the diodes clipping, too, so take that into consideration since you may not like that.

Thank you guys.
I double checked and indeed I had it backwards. The problem happens exactly as you described, when none of the diodes are clipping.
I might try lowering 1M to see what happens. I agree I'm not likely to push the gain while none of the diodes are clipping but I wouldn't want that motorboat thing to happen during a gig :)

The good news is, my first build worked right away :) pretty neat. I'm just waiting for my drill bits to arrive and I'll box that baby.

Thanks again for providing this project and for your support, I'm already considering what my next project will be.

However, I didn't get that whole business about putting the diodes symmetrically or asymmetrically. I just followed the schematics. Could you guys shed some light over this ?

Thanks.

I would leave the hard clipper as symmetrical. For asym clipping in the feedback path, you can a second diode in series with either one---doesn't matter which.

I think I will add a note in the BOM to socket that 1M. It is a pretty big departure from the Klon, which uses a smaller value.

same thing is happening to me at full dirt settings fwiw.  stuttering that won't stop in the center position until the switch is thrown the other way.  not a huge deal but it is something that is likely to reoccur.

Ah, well I guess I'll socket 1M and try different values.

Thanks a lot again for your help. I'll send pictures of my final build once the painting is done.

Cheers to you guys.

Hi guys,

I just mounted everything on the enclosure and I have a weird issue.

Out of the enclosure, the pedal works just fine but when monted in, I loose most of the treble and I can't figure out what I did.

I noticed that that happens when I touch the pot enclosure with my finger also and since they are mounted to the enclosure I'm guessing that might be the cause of the problem.

Any idea how to fix that?

Thanks

Quote from: Neurowork on September 22, 2012, 01:22:14 PM
Hi guys,

I just mounted everything on the enclosure and I have a weird issue.

Out of the enclosure, the pedal works just fine but when monted in, I loose most of the treble and I can't figure out what I did.

I noticed that that happens when I touch the pot enclosure with my finger also and since they are mounted to the enclosure I'm guessing that might be the cause of the problem.

Any idea how to fix that?

Thanks

Sounds like a grounding issue.

1) All the pots or just one? If it's just one, then it's probably a stray piece of wire making contact with the case, or possible broken internally.

2) Are your jacks isolated? Use your multimeter to make sure one of the tips didn't ground out on the enclosure. Also, consider grounding the case if the jacks are isolated, but that's usually to correct loud humming.

3) Potentially relevant: True or buffered bypass?

4) Just to make absolutely certain ... your power jack is isolated, right?

Thanks for the advice.

It turned out to be a Tone Pot solder issue.
I also realized that my DC plug was NOT isolated which is obviously an issue with negative pin.
Besides that, the build works great.

Cheers to you all

C.

I have the same issue with all clippers lifted and gain cranked.  No biggie as I'd never crank the gain past noon.

A couple of things I'd like to verify.  I have LEDs in D8 and D9 and they and not lighting unless the gain is pretty high or I strum REALLY hard.  Definitely a higher threshold than I have seen on other circuits.

EDIT: Scratch the part about the opamp distortion.  This thing has a heck of a lot of output and was saturating my preamp and that's what I was hearing.

Have the same issue with the stuttering sound at full gain. Besides that the pedal sounds great..

But i also noticed that there is no difference in sound between middle position and left position of the clip switch..
Any idea what's causing that?

THX!

From the build doc:

Quote09.17 Update: A couple have people have pointed out that running the Kingslayer at the max gain
setting with both the soft and hard clipping diodes lifted caused some motor-boating and/or
oscillation. This is due to the higher gain produced by using 1M for R11. For the most part, you do not
want to use the max gain setting with no diodes, but it does sound pretty good up to the half-way
point (before harsh op-amp clipping sets in). If you want to avoid this situation altogether, socket R11
and try some lower values, something between 470-750k. Keep in mind that this will also reduce the
max gain when the clipping diodes are engaged, so it may require testing a couple values to find the
best balance for your needs.

Ok! I wont crank it all the way up anyway so thats cool..

But do you know what might cause the behaviour of the clip switch?

THX!

any suggestions please...  :'(

Quote from: ringleader on November 07, 2012, 01:28:51 PM
any suggestions please...  :'(

Check continuity on your switch to the diodes, and double check your soldering on the diodes or make sure they're making good contact with the sockets if you used sockets.

If you used LEDs and that's the position you're talking about, LED clipping is very mild and you might just not be noticing it. Does it stutter in the LED position?