So I have a quick question for you guys. I was playing this pedal last night and I used a Tele and a Les Paul. Both sounded incredible with the bridge and neck pickups. However, when using both pickups with the Tele or LP, I can hear a subtle but noticeable high frequency whine over the sound. It's not something crazy though, I can easily fix it rolling off the tone knob on the guitar, but it is somewhat annoying that I would have to do this.
Now, I've read a few people having issues with MAX1044 "whine". Is this the same issue? I have the MAX1044A from SB. Would changing this IC fix this issue, or should I look into increasing or decreasing one of the ceramic caps in the circuit?
How about grounding pin 6 on the charge pump? I know on the datasheet says that would be necessary for voltages less than 3.5V, but is it worth a shot?
Thanks guys!
-Kaleb
One thing to try immediately is a 100pF cap from pins 1/8 of the charge pump to ground. Try doing this by just touching the leads of the cap between pins 1 and 3 to see if it eliminates any whine. You could also use a bit of wire to short pins 3 and 6 to test your own hunch (all this to avoid soldering something before you know if it even helps).
If not, I would replace the pump with a TC1044SCPA or the ICL7660SCPA. That should eliminate the whine.
Awesome, thanks Brian. I'll try this when I get home tonight.
I'll also try putting the cap from 6 to 3 to see if that does anything. I will report back my findings.
Thanks man!
-Kaleb
I tried this but it didn't work. One thing I did notice was when I touched the output wire (on the insulation) some of the whine went away. I wonder if shielding the output wire would help. Maybe twisting the output and G2 wire together from the switch to the board.
Yes, shielded wire on the output might very well get rid of it. This thing is very high gain...probably one of the highest gain designs I've seen.
Hello guys,
I have just finished boneyard and it really rips, it really nails the tone I am after!!! ;D
I am experiencing the same problem, lots of whine without an obvious reason.
The whine goes away only when I turn down the tone knob or by lowering the gain or level.
It is not the max chip to blame. For testing, I altered the circuit to use double 9v batteries and
the whine is still there and very loud.
I have tried all the fixes madbean mentioned but nothing seems to make the whine go away. :'(
Any ideas?
Hey man!
In my case, I used a 150pF across pins 1 and 8 (I just stuffed it into the socket) and it took care of if.
Now, I'm not sure if we have the same problem in common though. The frequency whine I had was very subtle and it wasn't very loud. Did you do any modifications to the circuit? Also, did you try using shielded cable?
-Kaleb
real plexis whine when turned up too, sounds like the boneyard emulates them very well :D
The whine is only heard when using passive pickups, there has to be something wrong with the input section.
My strat has EMG installed and I hear no whine (all pots @10).
Note that the leds in the clipping section are lightly on when the whine occurs.
I have tried shielded cable but nothing changes.
No special mod, 2 switches (bypass and boost), just haven't used the crunch pot and
shorted the switch on the high-gain side
If not just a whine, it is an oscillation in the 2nd stage where the clipping occurs.
Here it is
My guess is that you have a problem in your power section, not in the input section. Because you've modded the power section to run with two 9V, that would be my first guess.
Jacob
Oh wow...yeah this was not my issue at all...Have you checked your capacitor values, placement, etc? I would start looking at the ceramic disk caps...
It's like some cap is grounding somewhere...
The dual battery was just a test for 10 minutes.
I reinstalled the chip and now works as before.
Not a power section problem.
The pcb is triple-checked and cleaned with isoprop,
most of the components have been replaced, just to make sure everything is ok.
There is no short circuit in the pcb.
I have a feeling that it is possibly a topology issue, due to the lack of the crunch gain pot.
The tracks around the pot are not connected or grounded, so they form an antenna or something,
that affects the clipping stage.
Still investigating....
Having the same issue, audioware. Did you ever figure anything out?
BUMP... Audio Ware did you find anything regarding this issue?
I don't have any guitars with active pickups, only passive. It works fine at lower gain, but squeals/whines at higher gains. I started a thread in the general questions section last night, but then stumbled across this thread this morning, so sorry for the duplicate. I guess I should have performed a better search.
Thanks..
Check this out:
http://www.madbeanpedals.com/forum/index.php?topic=3924.0