Can't catch a break, I've been struggling getting the Aquaboy deluxe to sound clean, so I put it aside and built the Dirtbaby. Everything seems to be working but I get a white noise on the repeats.
Audio probe on PT2399 pin 15 signal is clean, but white noise on the delayed signal on pin 14.
Reflowed solder, tried different ICs before I used the audio probe and found the noise is coming out on pin 14.
I must have had beginners luck with delays when I built the Zero Point SDX a few months back, fired right up with no issues. It's been a frustrating week with these other two...
Sorry, forgot to post the voltages
VD 7.8v
VC 8.14
VB 3.87
PT2399
1 - 4.96
2,6,9 thru16 - 2.48
3,4 0.0
5 - 2.97
7 - 0.57
8 - 0.61
FWIW, the PT2399 sounds better in the moodring, has some white noise on pin 14, but less noticable
Is the noise present in all settings of the delay pot or just toward the max delay?
Thanks for the help!
It's there, but less noticeable on short delay, worst sounding with delay knob all the way down, then cleans up quite a bit the 1st 1/8 turn, then progressively gets louder as the pot is turned up.
I'm using the 50k Lin for the delay pot, in fact all values are per the build doc except the 2u2 NP caps, I'm using 2-1u NPs in parrallel for each.
Best thing I've tried so far was 25k Lin for delay pot and 68k for R35. Kinda minimizes the white noise but max delay is much shorter. I tried lower and higher values for R37, stayed with 220k.
Hope there is something else to try.
Mike
Well, the white noise/hiss is still to much even with the 25k delay pot.
Is there something else I could try?
There's going to be some noise, but you really should not have any with the delay pot all the way down and very little with it in the first half. So, possibly something is awry in the filtering. Have you double checked to make sure all your resistors and caps are the correct values?
If so, here is something else you can do: Increase C9 and C10 to 2n2 and C19 to 47n. Socket these while you are at it. This should clamp down that noise quite a bit. If it goes too far, back off C19 to 22n. Let me know what you think of the results.
Also, have you put in the correct LED on D2? I found this made a huge difference in my build.
Quote from: madbean on March 10, 2015, 06:13:43 PM
Also, have you put in the correct LED on D2? I found this made a huge difference in my build.
Found the same here.
Cody
I do have a 5mm green diffused LED and all the cap values have all been verified. I also checked all the resistors around the PT2399. I have a few more LEDs, I could swap it out just to be sure.
I have noticed something with the delay pot today. When turned all the way down, there is a wierd noise coming through when not playing. When I turn the knob to about 8 o'clock the noise disappears, and as long as I'm not playing it stays quiet when maxed out. When playing, the repeats have the hiss. The noise with the delay turned down almost sounds like RF noise.
I've got to assume something is out of place or not soldered well.
Once I re-flow solder again, and double check everything around the delay pot, if no change I will then try the value you noted above.
Would the delay pot noise be related to just that part of the circuit? i.e. C3, R37, R38, PT2399 pin 6 and ground? The depth pot didn't have any affect on the noise I was getting when the delay pot was turned all the way down.
How critical is C3 value? I have 2 1u NP in parallel measuring just under 2u. Can a regular 2u2 electro be used, if for nothing else but troubleshooting?
C3 can be 1uF, no problem. I made it 2u2 since there was already one for C33. In fact, the LFO will work even with C3 jumpered but it's there for potential noise isolation between the delay and modulation.
What you are describing with the delay pot is definitely not kosher. You might have a jinxed pot. Some contact cleaner would be my first step before replacing it (if you have it). So, my guess is that the noise and pot issue are somehow related. Having just boxed my own DB build up today I can tell you for sure that noise should not be much of an issue in this build except for the unavoidable artifacts you get when running the PT2399 over 400ms.
Your voltages looked pretty good and I assume that they are stable on the PT. Your VC/VD/VB are a bit on the low side, though. You might want to just jumper out R42 while you are at it. And last but not least, try a different power supply when noise is a problem (goes for any build).
I have the same problem, sounds amazing but I can't get past the "hiss", and I don't even use very long delay settings. I haven't done the cap changes yet but I will soon. Will things improve once it's boxed up maybe?
*UPDATE*
Did the cap changes, (socketed all the listed caps), and I stuck with just putting 2n2 into C10. Got all the hiss down to where I barely even hear it, like hardly at all, and it's totally acceptable. This is definitely going into a box now.
I haven't been so fortunate, even with 2n2s and 47n for C19 still to much hiss to my liking. (when letting the notes ring out)
I'm having the same issue with a Zero Point Mini I just built today, tried 4 new PT2399s, all sounding the same. Powered with 9v, 15v and a 9V battery. Same results.
Maybe it's supposed to sound this way with PT2399s?
To be clear, with delay 1/2 way up, mix 1/2 up, feedback minimum, no modulation, if I play a chord and hold it, there is a hiss that appears and lingers as the notes decay. It happens on single notes too when I let the notes ring out. If I cut the notes or chords short, you can't really tell, but the hiss is there. The hiss reaches "unacceptable" levels with the resistance on the Delay knob above 16k. Gets worse as the knob is turned up further.
I doubt it supposed to work/sound like this. I don't recall the Zero Point SDX sounding this way.
I get this, too. But I would describe it as distortion as the notes decay. I wasn't sure if that was supposed to be that way or not. I tried the cap swaps, but it sounds the same.
Where are you guys getting your PT2399 chips from?
I got mine from Tayda and Paul's store. The one I got from Paul was cleaner sounding than any of the tayda ones. I've still got noise though, just not as bad after the cap changes. Running it at 18v also.
Is there a store that sells these tested and with low noise?
I have chips from different sources, but I have a couple from smallbear that are low-noise which I keep for evaluation purposes. It's good to have one or two around so you can benchmark other chips against them. They are basically all over the place in terms of specs and Tayda ones may very well be out of spec (just a hunch).
Still, I do not understand why a few people are getting so much noise. It is a pretty quiet circuit by PT2399 delay standards. I'll think on it a bit.
Yeah, I got mine from Tayda as well. I have quite a few of them from different batches, but I've only tried 2 so far. Same results with both. I'll pull the ones from my Multiplex tomorrow and give them a try.
I did sub tl072's for the tl062's because that's what I had. Not sure if that would matter.
I've been getting my 2399s from Tayda, I must have gotten lucky on my 1st order as the Zero Point SDX sounded great. That was a few months ago.
I'm convinced the ICs are the issue as the only constant between the 2 Dirtbaby's and the Zero Point Mini is my guitar, patch cables, and the solder. I'm pretty sure none of those are causing the problems with all 3 builds. Also, the other constant is the 5 PT2399s I have, have all been purchased from Tayda.
For now I did all the C8, C9, C10 and C19 cap changes, didn't really change much, but it may have taken the edge off the white noise a bit. I also added a 220k across the Delay pot bringing it's value down to 40k. This seems to allow acceptable, or less noticeable, noise up to about noon on the pot.
One other thing I noticed is when feeding the Dirtbaby with a Boss CE2 Chorus clone, the noise wasn't so apparent on the repeats.
Anyway, going to try another source for more 2399s.
I grabbed a bunch of PTs from MKlec and had great luck with them. Worth a try.
Cody
Just received 10 PT2399s from Nooelec , no improvement. I also tried them in a Zero Point Mini, same noise issue.
Going to give MKlec a try before I give up on these builds. Very frustrating!
Here is a reply I received from NooElec about the noisy PT2399s I received from them.
"We are an ISO certified facility and purchased these parts directly from the factory. We have sold thousands from the lot that was shipped to you. There is about zero chance you received 10 defective parts. Please send full details of your testing methodology, thank you. Kind Regards, Sarah NooElec Inc."
Does anybody have a sound sample of a Dirtbaby or single chip Zero Point you can post? I'd like to hear how yours sound with Delay knob at noon, Feedback down, Mix up and you hold a note or chord and let it ring out.
Both my Dirtbaby and Zero Point mini have an annoying white noise on the repeat.
Thanks,
Mike
I wouldn't deal with them much longer if I were you...
A common tactic with these sellers is to string you along with requests, messages, and chit-chat until the return period passes. :-\ Besides, I highly doubt that Princeton knows or would appreciate that their patented design is being sold out of the factory back door.
If you truly feel that the products are defective, you should just file a claim now.
Quote from: Maoriente on March 27, 2015, 04:53:28 PM
Does anybody have a sound sample of a Dirtbaby or single chip Zero Point you can post? I'd like to hear how yours sound with Delay knob at noon, Feedback down, Mix up and you hold a note or chord and let it ring out.
Both my Dirtbaby and Zero Point mini have an annoying white noise on the repeat.
Thanks,
Mike
I'm sorry you are having so much trouble with your builds. I am going to a demo of the ZPSX2 soon so I will hook up the Dirtbaby too and do one for you. That should give you a basis for comparison.
Thanks Brian, appreciate all that you do.
It has to be the PT2399s. Still waiting on the ones I ordered from mklec.
I was able to record a sample of my Zero Point Mini. It's essentially the same noise issue with the Dirtbaby. All 15 PT2399s sound about the same. 5 are from Tayda, 10 from NooElec.
Mix is all the way up, feedback off, no modulation.
Recorded strait sound, slap back, delay knob 1/2 way, then full on.
Sounds a little dark because I recorded with an Air Zone neck pickup and have 2n2 for C7 & C17, and 47n for C18. I also used a dual gang pot for the delay and tone control, as the 50k delay is turned up, the simulated 25k tone is turned down. Was hoping this would help. Seemed like a good idea, but didn't do much. Haven't had a chance to reverse all the changes yet.
I'd be curious if this is the same issue as the others who have been having noise on the repeats.
I received 3 PT2399s from mklec, 2 have no delay at all and the 3rd is noisy.
Another $12 down the drain.
Dang, I was waiting to see how you did with mklec. Sorry man. I think I may have to give up on PT2399 stuff. Maybe when dr tweek's site is back up, (if it's not already),he'll have some tested ones to sell
I had decided to throw in the towel a couple times as I've spent more hours troubleshooting these 2 Dirtbaby's and a Zero Point Mini than it took me to build the last 10 pedals! But I'm re-determined (is that a word?) to get them acceptable.
Some success, turns out my Zero Point Mini locked up the PT2399s. I've since added an LED to pin 7 and tied the other leg to both pins 3 and 4, thus grounding pin 4. The new PTs came back to life.
One of the mklec PT2399s is tolerable in the Dirtbaby, until the Delay pot resistance is about 25k and as long as I keep the mix volume low. Sounds really good with all the stock cap values...until the noise creeps in on the longer delay times or if I turn the mix up to loud.
I'm going to replace the Delay pot with a 25k and limit the Mix volume with the trimmer to see if both the noise and the delay times are acceptable. And if that works, I may also increase the 1n caps to 2n2 to see if that will allow for a little more delay before the noise is irritating.
I think I screwed something up on mine. I swapped the pt2399 from my Multiplex Jr. and got the same distortion. Conversely, the PT2399 from the Dirtbaby sounded great in the Multiplex.
I'll have to come back to this one when I have some more time to troubleshoot it.
Major improvement!
C13!!!
I noticed C13 is a much higher value in other circuits such as DBD and Multiplex. Swapped in a 33n and for the 1st time the noise is greatly improved! I almost don't want to touch it anymore. :-\
Can't believe it took me 3 weeks to stumble on this, especially considering I knew the noise began at pin 14 of the PT2399. I had tweaked C8, C9, C10 and C19 but completely overlooked C13.
Going to try a 47n and 56n tomorrow.
I don't know if this CAP change takes away from the intent of the Dirtbaby's DMM-like sound, but my main goal is to reduce the noise and it appears C13 is the key.
May actually wrap this up tomorrow ;)
All I know is PT2399 chips are the bane of DIY existence. They seem to be in the middle of several ongoing issues. I do know the first time I built a PT based delay I was a bit disappointed and had to except that the drawbacks that are apparent with this chip are just the way it is.. Isn't there a different digital chip that sounds better?
As far as I know, not with the PT2399's market saturation, or with it's ease of use (you can pretty much keep the soldering tech level at the analog op-amp phase, not the SMD LQFP48 oh-god-what-have-I-started phase.