Echo Base - a new PT2399 delay

fhsueh · January 31, 2009, 09:39:59 AM

I am VERY happy to report that the circuit is working now! After double-checking the resistor and cap values around the PT2399, I also noticed some shoddy soldering around the socket, where the pads were not completely covered. I re-soldered those spots, and miraculously the effect worked. Funny, whatever I fixed also reversed the feedback knob's connections, so I had to switch those around, which means I had them backwards. After that, everything appears to be working fine. Although I do hear some faint ticking, no matter where the speed and mod knobs were set. It only goes way with guitar volume pot at 0. I will check out other folks' solution to this shortly.

Thank you Ian for the great support. IMO, this effect approaches the sound of my Space Echo, and is the better alternative for live shows.

slacker · January 31, 2009, 10:21:09 AM

Glad you got it working, hearing that it sounds good compared to a Space Echo is really nice.

Shame about the ticking, I think I'm going to have to get hold of a PCB and see if I can figure it out. If it stops when you turn the guitar volume down to 0 it sounds similar to a problem someone was having with an easyvibe pedal recently, where the tick is getting into the input.
Could you or anyone else try putting a buffered pedal like a Boss in front of it and see if that stops the ticking?
You could also try removing the 2M2 resistor that goes from the input to ground, as that might stop it.

Fuzz Aldryn · January 31, 2009, 01:05:27 PM

Hi Ian,

as I already did mentioned somewhere here before, mine does stop ticking with e.g. an engaged orange squeezer in front of it. Will try in a second if a pedal with outbuffer in front of it will solve the problem too. Only got one pedal, which is not build by my own (they're all true bypass).

Regards
Helge

bent · January 31, 2009, 02:53:04 PM

i really hope someone find the ticking... cause so far i search on mine and can't find where it came from....only know that it goes faster or slower when i turn the speed pot...

bent

Fuzz Aldryn · January 31, 2009, 03:58:35 PM

Mine does that too, so I would say it's for sure that the lfo cricuit around the BC-whatever BJT has something to do with it. Maybe it's the current draw caused by it that bleeds into Vref and therefore is noticable in the signal path? But on the other hand, if this is the reason for the ticking it should also be noticable for say in the vero layout made by slacker himself. Strange.....

slacker · January 31, 2009, 04:32:17 PM

It's definitely caused by the LFO signal bleeding somewhere it shouldn't. I don't think it can be affecting vref because that's supplied by the regulator so it should be rock solid, plus if it was that the ticking wouldn't go away when the input is grounded by turning the guitar volume all the way down.
You could try temporarily adding a big cap directly from pin 3 of the LFO opamp to ground to see if that helps but I don't think it will.

The fact that another pedal in front stops it makes me think it's basically the same issue that's being discussed here http://www.diystompboxes.com/smfforum/index.php?topic=72395.20. That's why I thought removing the 2M2 from the input to ground might solve it.

Another possibility might be to try the same bodge as John Hollis did on the easyvibe and put a large cap from pin 7 of the LFO opamp to ground, that should round off the edges of the square waves produced by the LFO which might help.

fhsueh · February 01, 2009, 12:14:47 AM

This morning I confirmed that the ticking went away by placing a Boss pedal in front of the Echo Base. Then I played with the Echo Base by itself and got to enjoy several hours of use, until I reinserted my Boss DS-1 in front, and the echo base effect suddenly turned into endless self-oscillation. The only way to get it to stop is to unplug the DC power supply. Then, when I play a note, the delay quickly self-oscillates and turns into lots of noise.

I didn't get a chance to check voltages on the PT2399 after the unit suddenly started working last night, but I checked tonight, and the trouble spots are on pins 7 and 8, which read over 3V, when they are supposed to be .5v. I'm supposed to get a new chip tomorrow, so I'll see if that's the problem. Meanwhile, will make another pass over my noob soldering joints just in case...

I also wondered whether sharing the 1Spot power supply with the DS-1 may have contributed to this?

Gila_Crisis · February 01, 2009, 11:33:48 AM

today i finally managed to do a mod i wanted to do since a while. since my echo base is True Bypass (i built it without the 4066), i took away the level pot and instead i added a blend/mix pot like in a Deluxe Memory Man.
the whole run like this:

the 10k trim on U3B sets properly the output volume of the wet sound.

fhsueh · February 01, 2009, 02:54:08 PM

So after swapping out the PT2399, and hearing the same self-oscillation, it all ended up being a simple fix: I just pushed the chip a little harder to fit in the socket better, and the Echo Base is now working again. I didn't realize a socket can be that finicky. The voltages now read correctly.

I haven't tried any of the tick fixes yet, but when it appeared this now even with a Boss pedal in front, I eliminated it by moving the pcb away from the depth/mod pots so the board wasn't directly on top of them once the back cover was screwed on. Now the tick is only there without the Boss pedal in front, and I will attempt one of Ian's fixes the next chance I get. For now, it doesn't bother me that much since I always have at least one Boss pedal.

bent · February 04, 2009, 02:33:09 AM

Quote from: slacker on January 31, 2009, 04:32:17 PM
Another possibility might be to try the same bodge as John Hollis did on the easyvibe and put a large cap from pin 7 of the LFO opamp to ground, that should round off the edges of the square waves produced by the LFO which might help.

YEAHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

IT WORK'S.....

NO MORE F**** TIC TIC TIC... I PUT A 2.2 UF TO GROUND....AND IT FINALLY GET RID OF THE TIC-TIC....
THANK'S SLACKER....I JUST FINISH PLAYED FOR 2 HOURS WITH THIS ECHO!!!!!

I REALLY REALLY REALLY LIKE IT

BENT

mth5044 · February 04, 2009, 09:19:20 AM

^^^

lol someone is happy

Slade · February 04, 2009, 09:38:30 AM

Quote from: Gila_Crisis on February 01, 2009, 11:33:48 AM
today i finally managed to do a mod i wanted to do since a while. since my echo base is True Bypass (i built it without the 4066), i took away the level pot and instead i added a blend/mix pot like in a Deluxe Memory Man.
the whole run like this:

the 10k trim on U3B sets properly the output volume of the wet sound.

Fantastic, thanks for sharing.
I think I wouldn't put the trimmer but a Level pot, for I find it much necessary (one of the features I like of the Echobase is that you can drive a higher level delayed signal than the original signal).
Greetings.

slacker · February 04, 2009, 01:21:26 PM

Quote from: bent on February 04, 2009, 02:33:09 AM
Quote from: slacker on January 31, 2009, 04:32:17 PM
Another possibility might be to try the same bodge as John Hollis did on the easyvibe and put a large cap from pin 7 of the LFO opamp to ground, that should round off the edges of the square waves produced by the LFO which might help.
YEAHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
IT WORK'S.....
NO MORE F**** TIC TIC TIC... I PUT A 2.2 UF TO GROUND....AND IT FINALLY GET RID OF THE TIC-TIC....
THANK'S SLACKER....I JUST FINISH PLAYED FOR 2 HOURS WITH THIS ECHO!!!!!
I REALLY REALLY REALLY LIKE IT
BENT

Excellent news, hopefully that will solve it for everyone. I'll add this to the documentation when I get round to doing it.

rogerinIowa · February 04, 2009, 01:41:28 PM

Quote from: slacker on January 31, 2009, 04:32:17 PM
It's definitely caused by the LFO signal bleeding somewhere it shouldn't. I don't think it can be affecting vref because that's supplied by the regulator so it should be rock solid, plus if it was that the ticking wouldn't go away when the input is grounded by turning the guitar volume all the way down.
You could try temporarily adding a big cap directly from pin 3 of the LFO opamp to ground to see if that helps but I don't think it will.

The fact that another pedal in front stops it makes me think it's basically the same issue that's being discussed here http://www.diystompboxes.com/smfforum/index.php?topic=72395.20. That's why I thought removing the 2M2 from the input to ground might solve it.

Another possibility might be to try the same bodge as John Hollis did on the easyvibe and put a large cap from pin 7 of the LFO opamp to ground, that should round off the edges of the square waves produced by the LFO which might help.

Cool trick for LFO tick

Quote from: bent on February 04, 2009, 02:33:09 AM
Quote from: slacker on January 31, 2009, 04:32:17 PM
Another possibility might be to try the same bodge as John Hollis did on the easyvibe and put a large cap from pin 7 of the LFO opamp to ground, that should round off the edges of the square waves produced by the LFO which might help.
YEAHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
IT WORK'S.....
NO MORE F**** TIC TIC TIC... I PUT A 2.2 UF TO GROUND....AND IT FINALLY GET RID OF THE TIC-TIC....
THANK'S SLACKER....I JUST FINISH PLAYED FOR 2 HOURS WITH THIS ECHO!!!!!
I REALLY REALLY REALLY LIKE IT
BENT

Dude, I think we have most all likely felt that brilliant moment of truimph when it not only works, but works quite well, Congratulations!

Radamus · February 04, 2009, 07:45:21 PM

I remember reading this at some point in the 24 pages, but can you use an effects chain in the feedback loop of the PT2399 so that, for example, the fuzz increases with each repetition?

Barcode80 · February 05, 2009, 11:00:28 PM

anyone know of a good way to brighten up the repeats just a little?

slacker · February 06, 2009, 11:48:28 AM

To get the repeats brighter you can reduce the value of the 15n cap before the feedback pot.

Barcode80 · February 06, 2009, 04:28:29 PM

thanks!

rogerinIowa · February 06, 2009, 10:53:27 PM

Quote from: slacker on February 06, 2009, 11:48:28 AM
To get the repeats brighter you can reduce the value of the 15n cap before the feedback pot.

I had originally posted in this thread looking for tone control concepts that would effect the repeats...But now I wonder if maybe the answer isnt a tone control pot so much as a series of caps on a rotary switch to allow differing shades of bright and dark repeats.....the 1P6T mini rotary that Small Bear sells (http://www.smallbearelec.com/Detail.bok?no=581) might work well for this application using a selection of caps in the 15nf to 1nf range, a person could choose the best sounding 6 from that range, or start above the 15n range (I dont know, maybe 18nf to 25nf) for some darker sounds as well....I like this rotary switch: it is well made, affordable, and hardly larger than a Zvex style 9mm pot!

I guess you might end up with a "tone control with detents" that effects the repeats across a six position range of brightness.....

Just thinking

R

Slade · February 06, 2009, 11:14:00 PM

I guess it could work, but don't really know about the range of values of the "bright cap", maybe slacker could give us a guide about it.
I was thinking about it many times before and I think it's a really good idea to have this "options" for the repeated signal

Greetings!

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Echo Base - a new PT2399 delay