Cupcake build hum prob **REVISED**

[Haberdasher]

I've completed my orange squeezer "cupcake" build.

It is fully functional and is making nice compressed tones but the hum is always steady regardless of where the internal trim is set.  It gets louder as the volume of the pedal is increased, and much worse when another pedal is engaged simultaneously.

I've swapped out the IC with a jrc4559 and the transistors with mpf102's.  I tried these changes because I've read those parts are supposed to be less noisy.  No real appreciable difference.

I've tried different power strips, different outlets.  I've put a 220uF cap between the hot side of the dc jack and ground because I read somewhere that will filter electrical noise better.  No change.  I have not tried it with a battery, because I never installed the snap.

I'm starting to think the problem may lie somewhere in my soldering.  I have looked under magnification and I really can't see anything that is bridged.  There are a couple of spots where there might be some baked on flux or something that could be making a bridge.  I have found that the desoldering braid I got from Rat shack is pretty ineffective on the eutectic solder (63/37) I bought, so I'm having problems cleaning stuff up with it.

Sorry for rambling, but I figure giving a lot of details might help...  Does anyone have any suggestions of where I can start looking for a trouble spot?

thanks in advance

[Haberdasher]

bump....

[madbean]

If it's functioning correctly then the soldering is fine. There are a couple of things I can think of. One is where you are testing this out. Any fluorescent lights around you, or maybe a computer? Have you tried an outlet on a different circuit in your house...ie a room in a different part of the home? It's a long shot but it can be a source of hum. Second is grounding: have you made sure that the entire circuit is grounded correctly? Third, you could try using shielded cable on the output of the circuit. This could reduce or eliminate the hum.

Also, are you testing it with single coils? Could it be 60-cycle?

[Haberdasher]

If it's functioning correctly then the soldering is fine. There are a couple of things I can think of. One is where you are testing this out. Any fluorescent lights around you, or maybe a computer? Have you tried an outlet on a different circuit in your house...ie a room in a different part of the home? It's a long shot but it can be a source of hum. Second is grounding: have you made sure that the entire circuit is grounded correctly? Third, you could try using shielded cable on the output of the circuit. This could reduce or eliminate the hum.

Also, are you testing it with single coils? Could it be 60-cycle?

I've tried everything you said except for going to a different part of the house and the shielded cable.
There is a computer, a fan and a fluorescent light in this room.  Those lights are almost never turned on though.  I'll experiment around later with those things.

I tried humbuckers; still the same noise.

I've been over the wiring a dozen times.  I think everything is grounded...

Hmm, I don't know how to install shielded wire.  Are you talking about the wire that goes from the OUT on the PCB to the footswitch?  Do I have to run the shielded part to ground?  Do I need to put heat shrink on that? 

Is it possible that I could have a messed up cermet trimmer or volume pot?

thanks

[slash555]

try with battery, i had one and it wouldnt stop humming unless is on battery.

[madbean]

Some power supplies just aren't good. I have a Boss adapter that will hum like a mother, but using a PP2 I have no issues at all.

[Haberdasher]

Well, over lunch I put the pedal on a couple of different outlets across the house on my little honeytone amp and the hum sounded identical.

I may need a tutorial from some kind soul on how to connect a shielded cable inside a pedal.  I would really appreciate it. 

try with battery, i had one and it wouldnt stop humming unless is on battery.

Thanks, you're probably right.  I need to break out the soldering iron again & try that.

Some power supplies just aren't good. I have a Boss adapter that will hum like a mother, but using a PP2 I have no issues at all.

I tried the only other adapter I have, which is of the same type as my other and it didn't improve.  I was planning on buying a 1-spot which is a lot cheaper than your PP2.  Who knows if that would work any better than what I have now though...

[Haberdasher]

OK, confirmation that the noise is coming from the power adapter/AC.  The battery is dead quiet, but it seems like the effect is more subdued now; less punch.

The only solution may be the shielded wire.  Are we talking about a small wire with metal braid around it?
madbean, you have a link for the kind/size shielded wire you are referring to?


thanks again

[madbean]

Less punch? Hmm...have you tried measuring the actual voltage you are getting from that power supply? I think it might be over 9v.

As far as the shielded wire, it will be one wire surrounded by the braided shield. The way you do it is cut one end, and expose the inner wire. Solder that to the FX output on the board. Make sure you trim away the braided portion completely on that end. On the other end, expose the inner wire. That gets attached to your 3pdt. The braided part gets rolled up together. You might want to solder a small piece of wire to that and then that gets attached to ground. So, one end it grounded, not both.

You can find this stuff at most electronic supply stores.

[Haberdasher]

Less punch? Hmm...have you tried measuring the actual voltage you are getting from that power supply? I think it might be over 9v.

Right you are about the voltage.  The plug says it's 9v 200mA, but the dmm reads 14.57v.  I have been using the same type on my neutrino.  Am I going to damage anything using 14.5?

[madbean]

Probably not in this case.

[Haberdasher]

BTW, for anyone who is going to build this compressor-
Unless you prefer using a battery or you have a good quality power supply, you might plan on trying the shielded wire from the outset.
Also, re-installed the 2n5457 transistors because I wasn't feeling the mpf102's.  That made a pretty remarkable improvement in tone.  I recommend you not stray from the 5457's.   

[Haberdasher]

I also wanted to mention that the actual range through which you are able to make adjustments on the trimmer is very short.  I don't know what you could do to be able to fine-tune this better.  Maybe a multiturn trimpot would give you more room to dial in, I dunno.

[madbean]

I also wanted to mention that the actual range through which you are able to make adjustments on the trimmer is very short.  I don't know what you could do to be able to fine-tune this better.  Maybe a multiturn trimpot would give you more room to dial in, I dunno.

You could use a smaller value for the trimpot...5k.

This all has got me thinking: it would be interesting to try this thing out at 18v. I've got a project coming up called the "Glazer" which is a three-band active EQ that uses a charge pump to run the IC off +18, -9v, similar to how the Klon clean section operates. It could be an interesting modification to the Orange Squeezer...lots of clean sparkly headroom. Add in a clean blend, and then you've got something really similar to the Barber compressor. I might put that on the backburner to check out at a later date. It could make an exceptional compressor. Having built the Ross compressor from Tonepad, I do prefer the Orange Squeezer...it seems to have a little more character to it.

[Haberdasher]

I also wanted to mention that the actual range through which you are able to make adjustments on the trimmer is very short.  I don't know what you could do to be able to fine-tune this better.  Maybe a multiturn trimpot would give you more room to dial in, I dunno.

You could use a smaller value for the trimpot...5k.

This all has got me thinking: it would be interesting to try this thing out at 18v. I've got a project coming up called the "Glazer" which is a three-band active EQ that uses a charge pump to run the IC off +18, -9v, similar to how the Klon clean section operates. It could be an interesting modification to the Orange Squeezer...lots of clean sparkly headroom. Add in a clean blend, and then you've got something really similar to the Barber compressor. I might put that on the backburner to check out at a later date. It could make an exceptional compressor. Having built the Ross compressor from Tonepad, I do prefer the Orange Squeezer...it seems to have a little more character to it.

If you come up with something like that down the road I could well  be interested.