Is there a schematic for this available? Is the white led supposed to glow even with no signal going to it? I think there may be something wrong with mine, but not sure. I did use an ultra bright white LED. I did use supposedly the correct ldr. Ill take some measurements in a bit. It also seems like it has fairly low output.
SOLVED Delegate Compressor
- Thread starter ambusch85
- Start date
Chuck D. Bones
Circuit Wizard
Good to hear that it fixed your problem. Is the compression working OK? The ATTACK and RELEASE controls limits the LED current which in turn limits how much the LDR can reduce the gain. If you max out SUSTAIN, ATTACK and RELEASE, the opamp is easily overdriven. EQD likes to give their controls a LOT of adjustment range. The result is that some of the extreme combinations may not be useful.
Yep, those two trannies are pretty much interchangeable.
Yep, those two trannies are pretty much interchangeable.
Chuck D. Bones
Circuit Wizard
Should make no nevermind either way. The load on Vref is on the order of microamps. I saw one schematic on the 'net that had those resistors at 1K each. That was way wrong.
I wouldn't bother with R5. Just use a reasonable SUSTAIN setting and R5 will be fine as-is. Like I said before, EQD deliberately gave the controls a wide adjustment range. Trying to undo that will ripple all thru the circuit.
I wouldn't bother with R5. Just use a reasonable SUSTAIN setting and R5 will be fine as-is. Like I said before, EQD deliberately gave the controls a wide adjustment range. Trying to undo that will ripple all thru the circuit.
Got everything boxed up and it sounds great! Thanks Chuck for the mod idea and help. And after everything boxed up with knobs to give me a better indication of where all the positions actually are at any given time, it sounds great in all reasonable settings.
Some lessons learned:
Get the right LDR. You will chase your tail trying to tweak the circuit to sound right without the correct ldr.
Make sure your LDR is functioning correctly.
Highly recommend Chuck D's mod on this.
Use a linear taper for the volume if you have one. At least in this circuit.
PedalPCB pcbs are very durable and withstand quite a bit of abuse.
Some lessons learned:
Get the right LDR. You will chase your tail trying to tweak the circuit to sound right without the correct ldr.
Make sure your LDR is functioning correctly.
Highly recommend Chuck D's mod on this.
Use a linear taper for the volume if you have one. At least in this circuit.
PedalPCB pcbs are very durable and withstand quite a bit of abuse.
BurntFingers
Well-known member
Apologies for the resurrection but I've been reading this with interest since I have a delegate board in the mail.
would you have a photo of the fabled Chuck mod handy?
would you have a photo of the fabled Chuck mod handy?
So after playing for it for a while, I noticed something a little off... When it's been turned off for a while, and then you turn it on maybe in the middle of playing something, there is a transient boost in volume. It's from the LED being off which sets the gain of the opamp stage to a max level, and then once the LDR responds to the light from turning on, it goes back to normal operation. Seems I need to have it off for a couple minutes for this to occur. Has anyone else experienced this loud transient after the effect has been off for a while then turned on in the middle of playing a chord? Trying to figure out if this is normal operation, or something else might be wrong.
Chuck D. Bones
Circuit Wizard
What are the knob settings when this happens? Just to be clear, when you say "turn it on," you mean by hitting the stomp switch, correct? This could be normal operation because when in BYPASS mode, there is no signal going into the peak detector (Q1-Q3). So when you hit the stomp switch, it takes a brief period, depending on the ATTACK setting, for the peak detector to acquire the envelope of the guitar signal. If we want to punch in and out, then it would be better if the peak detector was tracking the signal even when the pedal is in BYPASS. There is a way to do this, it involves re-wiring the input side of the stomp switch. Do you want to try that?
Exactly... hitting the stomp switch. It is absolutely because of no signal going to the peak detector. Tried to communicate that in my previous post in more simple terms. I don't recall the settings, but if I recall correctly they were all around 12:00..ish? Maybe? Found a post on a bass forum that also describes this behavior on the OG pedal. So it sounds like it's normal operation. However, you have my interest in a potential mod... I assume the implementation would be to split the signal going effect input to output jack? Wouldn't this just load the signal (pickups or previous buffer) down unbuffered with the input impedance here (just lower than 1M and some shunt capacitance). It's pretty high but by the time it hits the next device who's input buffer is likely around 510k-1M that loads the pickup or previous buffer at 337k-500k which I would think would be a fairly noticeable loading on the signal chain. A buffer splitter perhaps? Admittedly, I also built an OTA ross/Ego type compressor with blend and tone controls that I've been digging, so the Delegate got pushed to the side...
4PDT that turns an LED off when effect is engaged is what my original thoughts were before it kinda got shelved.
4PDT that turns an LED off when effect is engaged is what my original thoughts were before it kinda got shelved.
Last edited:
Chuck D. Bones
Circuit Wizard
That's what I thought you meant, just wanted to play it back to you to make sure I understood.
It's a simple mod. You're right, the input will always be loading the guitar signal, but since the input impedance is 1M shunted by 100pF, the loading effect is less than 10ft of cable going into an amp.
The mod can be implemented the same way whether you have a breakout board on the stomp switch or not. The switch terminals are numbered like this (same orientation as shown in the build docs):
1) Disconnect the wire that goes from the Input on the board to the stomp switch at the stomp switch end (either from the breakout board or the switch).
2) Connect that end of the wire to pin 3.
3) Disconnect the wire that goes from the Input jack to the stomp switch at the stomp switch end (either from the breakout board or the switch).
4) Connect that end of the wire to pin 9.
If you're implementing this mod on a new build, you can use a DPDT stomp switch because the left column is not needed.
If you're really concerned about loading, the best place for a buffer is at the guitar.
It's a simple mod. You're right, the input will always be loading the guitar signal, but since the input impedance is 1M shunted by 100pF, the loading effect is less than 10ft of cable going into an amp.
The mod can be implemented the same way whether you have a breakout board on the stomp switch or not. The switch terminals are numbered like this (same orientation as shown in the build docs):
1) Disconnect the wire that goes from the Input on the board to the stomp switch at the stomp switch end (either from the breakout board or the switch).
2) Connect that end of the wire to pin 3.
3) Disconnect the wire that goes from the Input jack to the stomp switch at the stomp switch end (either from the breakout board or the switch).
4) Connect that end of the wire to pin 9.
If you're implementing this mod on a new build, you can use a DPDT stomp switch because the left column is not needed.
If you're really concerned about loading, the best place for a buffer is at the guitar.
Last edited:
This was an interesting read, I just finished a delegate and everything seems to work great however I used a 3mm yellow ultra bright led and whatever ldr I had laying around, the weird thing is I get a squealing sound from it which is much louder when it is 'dark' (it changes when I hold my finger over the ldr) it seems to measure closer to 1m when dark so if I figure if I find the right ldr it should sort that out
Chuck D. Bones
Circuit Wizard
Does turning the SUSTAIN knob down stop the squeal?
I don't see how the LED could possibly cause the squeal.
I seriously doubt that the LDR is the cause. This circuit should be stable even if the LDR resistance is infinite.
Something else is wrong.
I don't see how the LED could possibly cause the squeal.
I seriously doubt that the LDR is the cause. This circuit should be stable even if the LDR resistance is infinite.
Something else is wrong.
I was about to ask if it was charge pump whine or some other issue with the charge pump/power supply. The 7660 (without the S suffix) does not have the function to boost the charge pump oscillator frequency above audible range, and is stuck at 10kHz. However, the 7660 with the S suffix should. I used the Microchip TC7660SCPA that boosts the oscillator frequency to 45kHz. You can check the datasheet of your particular model to find out. I have not noticed any whine or squeal on any build where I've used a TC7660S.
Chuck D. Bones
Circuit Wizard
Success, yay!
We'll be looking for a post from you in Build Reports.
We'll be looking for a post from you in Build Reports.
