Echo Base - a new PT2399 delay

[Cenzoru]

Thanks for yours answers guys.
So far my scheme looks like a football camp, it's growing bigger and bigger and it's really complicated, because I couldn't divide for example the TL072 symbol in 2 different/independent pieces, so all the routes are really messy. Anyway I've started to learn some PCB components layout so this way it will be much easier to finish the board.

Hi Cenzoru,

Firstly, I should mention that I am not familiar with this particular schematic, but I have built the full version, with delay time modulation, so I may be of help.

Any chance to get that scheme or PCB layout for the full version ?

Thank you!

[garcho]

Any chance to get that scheme or PCB layout for the full version ?

did you see my post directly before yours?

here it is again:

^ yes, no need to look at that schematic, look at the original:

http://www.musicpcb.com/documentation/

find the Echo Base link at the bottom of the list and you'll open a PDF with not just the original V2 schematic but also the BOM, some mods etc.

[p_wats]

Hey folks,

I'm trying to clear out some old, half-finished projects and came across an old Echo Base PCB I had mostly populated eons ago. I've finished it now, but it's clear my soldering and quality control have come a long way in the last 8 years or so, so I've been re-doing portions of the board and re-checking components.

Suffice it to say, the delay now works, but I'm getting no love from the modulation. Here's what I know:

- The LFO LED lights up solid, no matter the position of the pots
- I can hear a faint ticking that changes in time with the mod speed pot
- My voltages are in line with those Slacker posted ages ago (here: http://www.diystompboxes.com/smfforum/index.php?topic=60662.msg498824#msg498824) except for pins 8 & 9 of the 4066.

Anyone have any experience similar to this?

The PCB I've got is an old one (not one of Taylor's). It's an older layout from Anonymousfacelesscoward:


I'm not too bothered, as I've also got one of Taylor's PCBs kicking around that I figure I'll build up while troubleshooting this one, so I have a comparison.

[Oolooloo]

Hey Paul,

From what I can gather from the layout, it's expected that the LED would light up solid. It's hooked to V+ and not the LFO.

Since you hear the ticking rate change with the pot, the LFO itself should be working. I would look for look for connectivity/wiring issues around the PNP transistor and Mod Depth pot. Remember to check transistor orientation (check the pinout if you subbed it for a different part).

I also noticed that this layout is missing the 10uF cap that is in series with the 240k resistor coming from the LFO, in more recent versions, which I believe serves to prevent the depth modulation from interacting with the delay time too much.

[p_wats]

Hey Paul,

From what I can gather from the layout, it's expected that the LED would light up solid. It's hooked to V+ and not the LFO.

Since you hear the ticking rate change with the pot, the LFO itself should be working. I would look for look for connectivity/wiring issues around the PNP transistor and Mod Depth pot. Remember to check transistor orientation (check the pinout if you subbed it for a different part).

I also noticed that this layout is missing the 10uF cap that is in series with the 240k resistor coming from the LFO, in more recent versions, which I believe serves to prevent the depth modulation from interacting with the delay time too much.

Thanks! I had heard of various different layout options out there with older ones having an LED that doesn't blink with the rate, so that makes sense. I do believe this board is from long before things like Taylor's were ready.

It's interesting you mention the 10uf cap, as I was curious about that too. The mod depth pot does seem to have a small effect on delay time in this version.

It sounds like the LFO might actually be working then (the voltages around the TL072 in that area read as though everything is fine), but the actual signal isn't being modulated for some reason. I'll revisit it and scour that area. I may end up not spending too much more time on this, as I do have a brand new PCB from Taylor as well and this old board is starting to show the signs of too much monkeying around.

[p_wats]

Got it sorted.

Turns out my BC560 isn't working (could have been fried somewhere in the process, I suppose), so I swapped for a 2N3906 (and switched the orientation based on pinout) and now it's great.

Thanks for your help!

[p_wats]

For anyone who has done the dub madness switch, do you find it doesn't work when the feedback knob is set to a single repeat?

[mastad]

That adapter board is great.
Do you have a layout for that?

I think this does it, was along time ago and i messed up trying to upload...

A short stubby 47uf cap would fit normally, the one i had was too tall so needed to be flopped over.

http://www.aronnelson.com/DIYFiles/up/EchoBase_Buffer_Pcbdoc.pdf

dave

Hi Dave, Hi Everybody.
could you help me to understand why on some schemes in TL072 pins 1 and 2 are connected together and on the other 6 and 7?

http://jonandtina.net/static/images/echobaserev2-changes.png
and your's example:
http://www.aronnelson.com/DIYFiles/up/EchoBase_Buffer_Pcbdoc.pdf

Thanks:)

[bluebunny]

Hi mastad - welcome.

There are two independent op-amps in a TL072.  You can use either of them in whichever combination suits you.  Here's a picture to illustrate:



When you tie the output pin to the inverting input, you make a buffer.  So the first example you mention is making a buffer from the 2nd op-amp in the package - pins 5, 6 and 7.  The other buffer circuit is using the 1st op-amp - pins 1, 2 and 3.

[sugonidamaso]

Hello everyone. It's been a while since my last visit to this great forum. Thank you for all your countless efforts helping all newbies like me to build again. I would like to ask again for your help based from this layout: https://blogs.yahoo.co.jp/anonymousfacelesscoward/19192939.html. Adding a momentary foot switch for those infinite repeats. My plan is to put 2 delays in one box. The other is the rebote 2.5 which I will put the momentary foot switch based from build notes of the said pedal. Thank you so much in advance!

Sent from my ASUS_X008D using Tapatalk

[BetterOffShred]

I'm about to build the Echo Base from Taylor's board and I just had a few quick questions if anyone knows. 

There were reports of distortion with humbuckers so the recommended fix was to put 2x27k in place of the 2x47k as shown in the mod document, but there is also a diode lift option to reduce distortion, are these basically the same fix? Just two different approaches ?  The diode lift indicates that it also changes the character of the repeats, would this be worth putting a couple sets on an on-off-on ? 

The dub madness mod, puts a 27k in series with a switch, is it worth putting a pot in series with a switch to tweak/tame the runaway ?

I realize these are experimental options, but with damn near 80 pages of info I figured someone may have tried these things. 

I was planning on putting the input gain values in series with a double gang pot so I could trim it depending on how hot my guitar signal is.

Thanks for looking

[garcho]

if you're up for having a large enclosure, with at least 2 foot switches and many pots, then just go ahead and add everything, almost nothing rewards knob wiggling and switch flicking like a delay, even one made with a PT2399.
otherwise i would breadboard it and tweak to fit your pickups and playing style and then hard wire whatever you can.

i would add the N.O. foot switch "punch in" option without any second thought, the most used "option/mod" of any pedal i've ever made, i can't understand why anyone would build a delay without that feature.

[BetterOffShred]

Yeah I usually add all the options with most stuff, as I'm not a gigging musician worried about board space.  I built a ruthenium reverb to box with this in a DD sized box.   

By the Punch In mod do you mean the dub madness?
Thanks

[garcho]

By "punch in" i'm referring to having a N.O. momentary foot switch in parallel with the normal latching foot switch. This way, when you actuate the momentary switch, you only have delay for as long as you hold it down. When you lift your foot off of the switch, the echoes trail off and your dry signal is unaffected. This only works in "tails" mode, if you have your delay wired in "true bypass" as soon as you lift your foot off the switch you'll hear an awkward, abrupt end to your delay echoes.
Why anyone would chose to not use "tails" is a complete mystery to me. Is it the cult of true bypass? If you care that much about your precious "tone", you might as well forget about using a PT2399 delay.
Anyway, with "punch in" you can select a brief moment to get delay-ed and the echoes finish off in a way that sounds natural. It's nice for when you want some echo but don't need a constant wash of delayed notes à la U2. It can be a very nice effect for say, the last few notes of your solo, or one staccato chord, or a pick scratch, etc. If you had to click the latching switch twice in a row quickly, things can get sloppy and clumsy, and if you had too much to drink, you'll fall over.

[BetterOffShred]

Ok yeah that makes sense with tails    thanks for the idea, I always forget about tails and buffered effects typically only needing two poles..  I'm having some troubles with my Ruthenium so this may just end up in an XX by itself.   Lots of room for all the mods and a momentary on switch.   

[KurbadsLV]

Hi, everyone. I just ordered DIY Echo Base kit and I'm wondering is it useful at all to include 9V battery as an alternative power source to DC input or would this pedal drain the battery too quickly and it's not worth the trouble to add it to the circuit? It seems this could be the case...

Also, as I'm still a DIY newbie, where should I connect the 9V battery clip so the battery is used when there's no plug in DC jack? The bypass in this circuit is not what I'm used to see in my previous (and very simple fuzzbox etc.) builds. (See pic)

Any help will be appreciated.

[BetterOffShred]

I have honestly never run a delay off a 9V battery, but I'd imagine that it will tap out a battery pretty quick.  You'd hook it up just like every other offboard wiring including a 9V battery,  battery and dc jack grounds connected, and the battery power attached to the Battery lug on the power jack. 

[lzj]

Hello, I've used the Echo Base v2 schematic to design my own PCB, I've soldered everything but I can't get it to work properly.
What happens is:
- when it's not bypassed and I turn the feedback knob up it self-oscillates quite loudly
- when it's bypassed I can't hear anything, if I pluck a string I can hear a single sound, but it's very distorted and it's more of a sound that an amp might make when turned on, or if you unplug your cable from the guitar and knock on the jack plug

I got the following voltages from PT2399 (measured when it's bypassed):
1   5.31
2   2.58
3   0
4   0
5   3.03
6   2.56
7   4.88
8   4.88
9-16   2.64

I also took oscilloscope screenshots of input and output signals, using a function generator as input - 440 Hz, 2 Vpp sine and square wave. Yellow is input, green is output. The screenshots are:
- sine input when it's bypassed
- square input when it's bypassed
- square input when it's not bypassed and I set the knobs randomly. If I fiddle with the knobs the output signal does change with square wave input and it does change in the way I would expect it to.
The output signal looks the same bypassed and not bypassed with sine input, which is why I didn't bother to make another screenshot. So overall it looks like it does something when the input is square but with sine it just doesn't work? Any ideas guys? Thanks in advance.

[thomasha]

sounds like a problem around the first opamp stage.
The fact that it has a loud feedback means that the rest is probably working.

Check around the opamp/ input stage. Some pictures would help. You could try to use an audio probe and follow the signal path. That would definetely show where the signal stops or has a bad connection.

[lzj]

Thank you very much! It turned out to indeed be due to the input op amp, but it was a mistake on my part. I had connected the 1M resistor at the positive input to ground instead of Vref. I ran some wires to get around this bug and it seems to be working well, judging by waveforms. I will do some testing with the guitar later and modify this post.

About the battery question that was asked here before - I tried supplying the circuit from a 9 V battery, but it got drained very quickly -the voltage dropped to about 8.5 V (from 10.5) in like 20 minutes of testing.

Edit: I finally got around to test it with a guitar. I must say I am VERY surprised. This effect sounds really, really good. I can't seem to get anything good out of modulation, but I will find a knob setting that works for me I'm sure.