I just tried reversing the polarity at the 9VAC end of the adapter, also did not help unfortunately.

FYI, here's the Eden.  You can see a divider in the feedback loop to lower the maximum JFET drain-source voltage.

I tested all the units separately before installing in the rack. There definitely was no hum on the wah unit, but I forgot if I used that 9VAC adapter currently installed, or a different one I had laying around which was actually 12VAC, yeah risky heh but it worked well during the isolated test.

Quote from: Esppse on Yesterday at 04:49:46 PMTomorrow I will try an EBTech Hum X on the adapter. I actually have had success before using one of those HUM X things on 2 prong units, even though it takes 3 Prong units.

Unlikely to work.  As far as I'm aware these work by breaking the ground cable and inserting a network into the ground to stop loops, similar to what is done inside of equipment.   An AC wall-wart is already isolated and the 3rd pin, if it has one, usually goes nowhere.

You could check if there's any connection between the ground pin and the output.

I agree with Antonis.   You could try flipping the low voltage AC.
It certainly wouldn't hurt to try another power supply.

Do you get the problem if you use that pedal alone?

Quote from: Esppse on Yesterday at 04:49:46 PMdoes it matter if the adapter is plugged in upside down?

In theory, NO..

In practice, Yes (sometimes..)

Quote from: Fancy Lime on Yesterday at 04:30:04 PMInteresting design but it looks to me like there is a considerable portion of the full output swing across the 5457 at high sensitivity settings, no? Curious choice, if the limiter is supposed to be power amp protection rather than a tone shaping device (which may or may not be the case, I just always assume that when I read "limiter" rather than "compressor").

Most designs suffer from that in some way.

For the SWR when the sensitivity is low it raises the threshold but at the same time reduces the AC voltage at the JFET.   When the sensitivity is high it lowers the threshold and increases the AC voltage at the JFET.   *However*, the rectifier is sensing the voltage at the JFET so at any Sensitivity setting it tries to prevent (by design) the AC voltage at the JFET getting too high.    During transients and before the attack time is met it can reach higher voltages.   This same process/issue is present on the Squeezer/1176 designs.

The main trick of the SWR is how the control signal on the gate feeds the control current down the low impedance path via the 100 ohm.   That reduces the control feed through.  (The way the user threshold is variable using a fixed threshold across the JFET is also a good feature.)

To be honest for gain control based compressor/limiters I don't really distinguish between compressor and limiter.   A limiter tends to have a fast attack but you can set a compressor for fast attack!   In theory you can set the output limit of a limiter and it doesn't exceed that level but that means infinite compression.   In most cases we want the compression curve to have a knee and most circuits have a knee hence there's a fine line between compressor and limiter.

I recently assembled a rack system and located the source of hum. My Prostage Wah module is the only unit that uses 9VAC. When I shut power to that adapter the hum stops. I made sure when designing this. there was no ground loops, and nothing is physically touching any unit.

All the units in the rack are plugged into the same switched power strip.

I am using this power supply:
https://www.amazon.com/dp/B00B886DEA?psc=1&ref=ppx_yo2ov_dt_b_product_details

Is it this specific brand adapter that is causing the issue?
 
Also, does it matter if the adapter is plugged in upside down? It is AC after all, that shouldn't matter right?

Tomorrow I will try an EBTech Hum X on the adapter. I actually have had success before using one of those HUM X things on 2 prong units, even though it takes 3 Prong units.

Quote from: rundgrenrules on Yesterday at 04:21:26 PMWould that happen to be the job of Q4/Q5 on the CE3?

Q4/Q5 on the CE3 only switch in the effects mode, not unlike Q6 on the PH-1R.

The thing that tweaks the gain on the CE3 is Q2 and R18.  For the PH-1R you would place that type of circuit at R5 or R33.

FYI, on the web will see people taking about R18 on the CE-3.   You will also see people complaining about the volume *drop*.   It's all to do with what you expect and not resolvable across all people.   If you compare a CE-3 against a CE-2 the CE-3 sounds lower in level.  However, if you compare the dry and effects levels the CE-3 does seem more balanced, perhaps a tad low at times.    It's very hard to get an exact value.  I'd suggest going a tad higher in level than the CE-3.

Hi Rob,
thanks fir the hint about SWR. Found a few schematics of preamps and even an extracted limiter schematic:



Interesting design but it looks to me like there is a considerable portion of the full output swing across the 5457 at high sensitivity settings, no? Curious choice, if the limiter is supposed to be power amp protection rather than a tone shaping device (which may or may not be the case, I just always assume that when I read "limiter" rather than "compressor").

Quote from: Rob Strand on Yesterday at 03:46:30 PM

Quote from: rundgrenrules on Yesterday at 12:16:10 PMI just went back and put some alligator leads in place of R32.  I experimented with this value until I felt like I wasnt getting the gain boost that was there with the stock 22k, and arrived at 47k.  Now, isn't this resistor post the Q6 transistor that flips the effected path on/off, and wouldn't changing this value also change the bypass volume as well?  Either way it seems easier on the ears and dealt with the clipped/pushed sound.

R32 only affects the effects mode.

With R32=47k the overall should be perceived about equal (as much as can be expected).

The key point to keep in mind it using R32 isn't really the "technically correct" way to change the level as it changes the phaser characteristic as well.   A slightly better compromise might be to use 39k as it gives deeper notches, ie. affects the phaser characterisic a little less, with only a small increase in level on 47k.   I'll admit there's not much in it.

If you were to set the gain using the technically correct method it would *only* affect the gain and not the effect.  The use of R32 is a compromise to get around changing the actual level since changing the level alone requires more extensive mods. 

QuoteOnce this was done I was able to revisit paralleling R9 with a cap and detected a more noticeable improvement in filtering the high-highs.  I played with that value until I arrived at 47nf.  That seemed just enough to take the harshness out of the upper range without robbing too much up there.

All good.

QuoteI think the order of how I did things before didn't allow for me to land on the combination of tweaks in it now.  I'm pretty satisfied with the overall sound but

I'm pretty sure now your issue is mainly due to the slightly perceived volume increase.

QuoteI AM curious about R32 and if/how it does/doesn't affect the bypassed volume.  I understand that it is setting the gain of IC1, coming into the Inv Input of side A from the effected path, and that the clean signal is coming into pin 3 on the non inv input of side A and thats where the two are combining.  It is my understanding that Q6 is acting to turn the wet signal of and on, so I would think R32 being downstream of this transistor would affect the bypassed volume?

It definitely doesn't affect the bypass volume.

The opamp IC1 at the output is configured as an inverting mixer.   The dry signal input at R31 is completely independent of the effect signal input at R32.   What happens in this feedback connection the inverting input (pin 2, IC1) looks like it is shorted to ground and that prevents interaction between the two signal paths;  it's called a Virtual Ground.

Thanks for all the help!  I might try out 39k again. 

Quote from: Rob Strand on July 25, 2024, 11:44:26 PMThere's no easy way to fix that issue since it needs another JFET to knock the gain down in effect mode.  One way to tackle the issue is the way CE3 chorus does it.

Would that happen to be the job of Q4/Q5 on the CE3?