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Post by mr_sooty on May 19, 2009 4:47:56 GMT -5
Hello, me again. So I run approximately 12 pedals on a board, all powered with a Godlyke PA9 power supply. It's a 9v regulated switchmode type thing, 1700ma capacity which is plenty for my board. My rig has been super quiet lately, no unwanted noise (I'm also using Dimarzio noiseless 'single coils').
Today I replaced 2 of my boost pedals with a modified Boss CS3 compressor. Did the mod myself, done heaps of these for other people, and used one myself for years. But I noticed that this pedal added a bit of noise to my chain in bypass mode, including a faint high-pitched whistle. I really like the sound of the pedal, and I want to keep it.
Thing is, the noise goes away if I use a battery instead of the power supply. But the supply handles the rest of the board including the two pedals I removed, without the whistle. If I take out the CS3 and replace it with another pedal, no whistle. This is all with bypassed pedals. All three of these pedals are buffered.
Any bright ideas? Time for a new power supply? Or is there something I can do to the pedal?
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Post by newey on May 19, 2009 5:18:13 GMT -5
Hmmm.
One more test- Try running just the CS-3 alone off of the power supply, without any other pedals connected., see if you still get the whistling. If you do, your attention should then be directed to the pedal.
If it's quiet with just the CS-3, then it's either an interaction between the Boss and another pedal, or perhaps a power supply problem (doubtful). I would then try putting the CS-3 elsewhere in the chain, see if that helps (I know, ultimately you want it to be where you have it in the chain, but we're testing here . . )
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Post by ashcatlt on May 19, 2009 11:29:02 GMT -5
I think newey's suggestions are good ones. Always a good idea to try different things to narrow it down. I suspect, however, that the solution to this issue might be similar to the one we came up with for your wah. Remember that? |
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Post by mr_sooty on May 19, 2009 15:16:57 GMT -5
Yes I remember the wah one very well. Still working great. Think with this one though is that I'm not using a battery connector, so that solution would have to be somewhat modified. Will test it in different spots and with just the CS3 in the chain today.
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Post by mr_sooty on May 19, 2009 18:39:13 GMT -5
Ok guys, I did some more tests. Odd results.
Firstly, doesn't seem to make a difference where I put the CS3 in the chain, whistle is the same.
If I have the CS3 as the only pedal in the chain, and power it from the Godlyke PA9, I get really wierd results. The LED is faint, and the signal distorts, like I'm running a fuzz pedal next to the CS3, or running it with a really flat battery. If I take the PA9 out and put a battery in, fine, no noise, clean signal, bypassed or not, LED comes on strong.
Add the pedal back to the chain, perfectly good strong LED and no fuzz when powered by the PA9. But still the faint whistle. Battery in that position, perfect operation. (Don't really want to use a battey though.
Another thought, I suspect the whistle may be in the chain whithout the CS3 as well, but it's very faint and hardly audible. With the CS3 it's more noticeable. That would make sense if the pedal was on, given that it's a compressor, but it's there when the pedal is bypassed too.
Thoughts?
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Post by newey on May 19, 2009 19:13:59 GMT -5
My guess would be that the 9V power jack is bad, sounds like you're not getting full power through it, and getting weird behavior as a result. If it works ok with the battery, and the daisy chain plug works ok with other pedals, that leaves the jack as the likely culprit.
I can't explain why it would be ok with other pedals on the chain and not by itself. We're talking about the same plug off the daisy chain in both cases right? If so, the only explanation is that it's an intermittent problem of some sort, but that's an admittedly weak explanation.
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Post by mr_sooty on May 19, 2009 19:58:35 GMT -5
We're talking about the same plug off the daisy chain in both cases right? Doesn't make a difference which plug. Wierd huh. This is with the guitar straight into the pedal, pedal straight into amp. As soon as the pedal goes back in the chain it behaves normally (apart from this faint whistle. Oh, forgot to mention, when it's making this low powered fuzz, there's no whistle. The whistle only exsists when in the chain. |
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Post by newey on May 19, 2009 20:31:46 GMT -5
No, that would make sense if the problem lies in the power jack, as I suspect. But it does seem as if the whistling is a separate problem altogether.  |
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Post by ashcatlt on May 19, 2009 23:03:03 GMT -5
Random question: Does the amp have a safety ground? You know, like a 3 prong plug?
I had worked up this completely unfouded theory, but upon further investigation I think I was completely wrong.
I now have another theory. Please do check that DC jack.
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Post by mr_sooty on May 20, 2009 3:22:59 GMT -5
What should I be looking for with the DC Jack? All the wires seem to be soldered on properly. I haven't touched them during the mod.
I gotta point out, this is not an "oh my God, this pedal is stuffed!" situation. I will proably use the pedal how it is. It's bearable, just slightly irritating.
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Post by ashcatlt on May 20, 2009 15:03:06 GMT -5
we'd like to know that there is in fact continuity between the two terminals on the jack and the places they are supposed to attach on the board. Sure they look fine, but you might test with a meter just to be sure.
Here's another question (since my last was ignored): What happens if the compressor is the only thing connected to the PA-9, is not connected to the amp, but a cable is inserted into the input jack? Obviously you won't be able to tell us anything about how it sounds, but what does the LED do?
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Post by mr_sooty on May 20, 2009 15:29:21 GMT -5
Sorry Ash, I did answer your question, but then I lost my post in an internet connection glitch, and forgot to retype the bit about the amp. All amps in New Zealand have the earth prong, it's apparently really dangerous not to have that here, so yes, it has one of those.
Haven't tested the continuity yet, but I tried the pedal being the only thing on the PA9 with just a jack in the input, no output. Same faint glow with the LED.
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Post by mr_sooty on May 20, 2009 17:45:54 GMT -5
OK, I did some tests, and the results are, well, kinda bizarre, to me anyway, maybe they make sense to you.
The readings are taken from the DC Jack, red wire to circuit board, blue wire to circuit board. The measurements were taken both at the jack terminals, and at the circuit board connections, same results. The pedal has two 'states'.
With the light glowing bright, the readings are:
Red: 8.99v, Blue: -0.00.
With the light glowing dimly, the readings are:
Red: 6.5v, Blue: -2.54v. (There are slight fluctuations here among the different scenarios, the Red going as low as 6.44v, but I put this down to the accuracy of my measuring. Basically, all the 'dim light' scenarios were in this ball park).
Now the interesting thing here was that there was only one scenario where the light glowed bright. That was: Pedal shares power with other pedals, pedal in signal chain with other pedals.
With boss pedals, the input normally activates the pedal. It did, but faintly. I had to put an output into the pedal to get it glowing bright, and that output HAD to be connected to the next pedal. If I pulled the patch lead out from the next pedals input jack the light went dim.
So I'm thinking: "maybe there's a ground issue, and the next pedal is acting as a ground." If the CS3 was the only pedal being powered, it was dim regardless of whether there was an output jack or not. It seems the next pedal needs to be powered for it to work as a ground?
The other thing is that the amp isn't a good enough substitute, meaning if I power the pedal by either means (dasiy chain or direct from adaptor), and have an input plugged in and an output straight to amp, it's dim. Seems the amp won't do the job of the next pedal in the chain.
So to get full lights, the next pedal must be powered, and the output jack must go into the next pedal. Of couse, in this scenario, I get the faint whistle.
Another point of note is that during this testing, the blue wire came off the DC jack, obviously it was working loose. "Great", I thought, "maybe that'll explain it." However I fixed the connection and still got the same results.
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Post by newey on May 20, 2009 18:56:01 GMT -5
Ok, I'll admit to being stumped.
What I was earlier suggesting you do with the jack was to wiggle the plug a bit in the jack, pull it out and push it back in again, see if you can replicate the dim condition. I might also swab out the inside of the jack with a bit of contact cleaner.
But your latest post implies a much more complicated problem, and I'm out of ideas.
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Post by mr_sooty on May 20, 2009 19:16:33 GMT -5
OK, so further progress. I figured the pedal wasn't grounded or something (remember, I am an electronics doofus, and don't really have a clue what's going on), and that the next pedal in the chain was grounding it. I also noticed that with the 'dim light' scenarios, I could make the light bright again by touching the ground lug of the DC plug against the chassis of the pedal. So I figured it needed some kind of better ground. I ran a piece of hook up wire from the groung lug of the DC Jack, and attempted to solder it to the chasis. Couldn't manage that, wouldn't stay stuck, so I soldered it into one of the screw holes the bass plate screws into. Managed to get it to stay there, and the bass plate is holding it a bit (no screw in that hole).
Hmm, just occured to me that I could have soldered it to the bass blate itself - may have stuck.
This has fixed the 'dim light, fuzz box sound' scenario. Unfortunately though it hasn't stopped the faint whistle. So I guess it's just 'noisy pedal disease'.
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Post by ChrisK on May 20, 2009 19:47:40 GMT -5
What frequency is the whistle?
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Post by ashcatlt on May 20, 2009 20:05:05 GMT -5
Yay!
I was right about that part, though I never stated it cause I thought I might be nuts. Then again, aren't we all?
So, two seperate issues. Answer ChrisK's question. I think it's now going to be a matter of filtering the power supply a little better than what Boss or Godlyke have done for you, much as we did with that wah.
PS - I figured that thing about the 3rd prong out by looking at where you are. Everything should have the 3rd prong no matter where you are in the world. Unfortunately, our government (the greatest in the world, of course) isn't as caring as yours. Over here, that Godlyke thing sells without the 3rd prong too.
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Post by mr_sooty on May 20, 2009 20:29:52 GMT -5
Dunno man, I don't have a frequency generator or measurer. It's pretty high, high enough that sometimes you don't really notice it. Just within the range of my hearing I suppose. For what it's worth, this problem isn't half as bad as the Wah issue was. This is pretty 'nit-picky', a barely audible whislte. But it's noticeably absent when I replace the pedal with a more expensive one.
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Post by mr_sooty on May 20, 2009 20:32:43 GMT -5
Actually, we do have some appliances without a 3rd prong. The Godlyke has no third prong. Neither does my coffee grinder. But the guitar amplifiers all do.
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Post by ashcatlt on May 20, 2009 22:15:33 GMT -5
...The Godlyke has no third prong... Really? From what I googled, the ones sold in the UK do. I guess independence has some disadvatages?  |
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Post by mr_sooty on May 25, 2009 4:01:50 GMT -5
Wow, major revelations here: indyguitarist.com/forum/index.php?PHPSESSID=6131dc8407e3b642b6e7eb10aec93660&topic=145.0Apparently my CS3 is an older one that needs an ACA adaptor has an 'ASA' adaptor. If you read this you'll see it will work if it's running on a daisy chain with a common ground, and there's another 9v pedal in the chain. Man, that explains alot. It says if you run it with a normal 9v PSA type adaptor the light will be dim. I just bought a brand new PSA version, and then found this out. By the way, the new one still whistles. |
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