Echo Base - a new PT2399 delay

[The Kebash]

YES!!! That helps an insane amount.  I really am just starting to grasp this stuff.  I have done some simple circuit bending, tube changing & biasing.  This build is going into a childrens toy piano with a contact mic (piezo transducer) as a sound supply.  Is this going to cause any problems?  Also, which brand did you use mainly on the caps but resistors too if you can remember? 

Just for some fun info, I recently brought a supro valco chicago 51 (1961) back to life (good cleaning and new tubes), my plan is to amp the setup with it.

PS- Here is a link to the piezo (http://www.radioshack.com/product/index.jsp?productId=2062402
)
     and just for fun a link to the piano (http://www.toypiano.com/product_information.asp?html_model_number=2522R)

     and amp (http://www.valcopages.com/Amps.html) scroll down to view first amp with tele in pic

[hane12345]

Hiyall!

Trying my first pedal build with the vero layout and i'm a bit new to electronics. Local electronics store didn't have 10M metal film resistor, can i substitute it with 9M9 ?
Would not like to hunt more parts, would like to solder the parts this weekend...
I have extra 100k carbon film resistors, and most of the build is carbon film due to having a box of those retma e12 series resistors, suppose would not
be good to slap one of those in series with 10M, due to difference in power rating?? But you tell. Don't really understand the circuit, just slapping the parts
together for now.

[tasos]

Hiyall!

Trying my first pedal build with the vero layout and i'm a bit new to electronics. Local electronics store didn't have 10M metal film resistor, can i substitute it with 9M9 ?
Would not like to hunt more parts, would like to solder the parts this weekend...
I have extra 100k carbon film resistors, and most of the build is carbon film due to having a box of those retma e12 series resistors, suppose would not
be good to slap one of those in series with 10M, due to difference in power rating?? But you tell. Don't really understand the circuit, just slapping the parts
together for now.

Hey part hunter!
Most resistors have a decline about +- 10% from the value that they are supposed to do...
You can use 9m9 instead of the 10m...

I don't think there would be problem if you used your 100k resistors but there is no need to do so....Don't do it!

[slacker]

Local electronics store didn't have 10M metal film resistor, can i substitute it with 9M9 ?

Hi

Yes you can use 9M9 if you have one, or a 100k will be fine. I can't actually remember why I used 10M, it could even be a typing mistake on my original schematic.

[intripped]

so, is this the last and verified TB version?



and I would also ask Slaker about the PT2399 "hiss issue" and it's probable solution reported here: http://www.diystompboxes.com/smfforum/index.php?topic=92515.0
(cutting the connection between pin 3 and 4 it is)
does it work? do you suggest this mod?

thanks

[slacker]

This is the latest version of the true bypass version http://www.eskimo.plus.com/fxstuff/tbeb2.jpg
The schematic you posted just replaces the electronic switching with mechanical switches, it's not true bypass.
I tried the hiss reduction modification, I think I posted in that thread, to me it didn't seem to have any effect, but it did no harm.

[intripped]

thanks!   

[DavidM]

Hi Slacker, I am currently in the process of compiling info previous to start building my Echo Base

Got one question: since the version 2.0 has a different input buffering stage, the final signal is phase inverted. I was thinking (with my nulln knowledge of electronics theory) if it was not possible to revert this (i.e. making the output non-inverted) by taking signal from the 10k resistor coming from the delay level pot and instead of feeding into 2 of the opamp, feeding it directly into 3 with the existing resistor from Vref (similiarly to input buffer) and substituting the 1n/10k RC from 2 to 1 with just a jumper.

Do you think this is possible?

Thanks in advance and congratulations for all your work on this.

David

[slacker]

Hi

Yes you can do that, the problem with it is that the volume of the dry signal changes depending on the setting of the delay level pot, as the delay level is reduced the level of the dry signal goes down. Using the inverting input (pin 2) there is no interaction between the pot and the dry level.
If you want to keep the signal in phase with the input the easiest thing to go is make the input buffer inverting like in version 1, but use lower resistor values say 10k instead of the 1M. Then put a buffer in front of it, a simple JFet one will do, this gives a high input impedance so the pedal won't "tone suck" but should be quieter than version 1.

Personally I don't worry about the phase inversion, it only becomes an issue if you want to run different pedals in parallel, then the fact that the dry signal is out of phase may be a problem. The delayed signal won't be in phase anyway due to the fact that it's delayed. In a normal pedal board setup where everything is in series it makes no difference.

[DavidM]

Thanks a lot, Slacker, for your explanation. Will let you know how it goes. Will be using Version 2 schematic so I will have to do some adaptations to anonymousfacelesscoward's PCB (which I have already etched). Surely I will need to mount ompamps and other components offboard.

Best,

David

[DavidM]

Hi Echo Basers,

Well I finally put together my Echo Base rev. 2 (still in my lucky cardboard box, which has served as temporary housing for my DIY Sansamp Bass Driver Clone and Boss CE-2 chorus clone already).

I managed to use the first PCB layout by An....Face...Cow... and by doing some cuts, bridging, subbing and mounting of additional components (2.2uF for ticking, 47R and cap for Vrefon the same PCB well I do have a fully functioning EchoBAse rev 2.

I am very satisfied with it so far. I tried a very basic bandpass filter (hipass RC and lopass RC, 2 resistors, 2 caps) between the 10K resistor at pin 14 of the pt2399 and the 15n/100n caps junction. I did get some change in sound but presumably due to the so basic filtering the result wasmore like a loss in volume rather than authentic Boss DM-2 like degradation of highs and lows so I took it away. Would love anyway to be able to toggle some grainy repeats at will.

I am planning to build a second parallel output (with a TL071) mirroring the outpt buffer and have a jack that will interrupt the path between IN and OUT buffers so as to have completely separate dry/wet outputs. Might also add a level pot for the Dry. I take it than mirroring the output buffer from the 10K connecting to the neg input of the opamp onwards should do the trick, rite?

Finally there is something I would like to comment. Proably this is an expected behaviour. When bypassed in "Boss" mode I still can hear a VERY faint delay. If I stomp on the Echobase it will catch the repetitions from what I was playing while in bypass. Is there any workaround for this?

Thanks Slacker and all of you guys for sharing and commenting.

Warm regards from Argentina,

DAvid

EDIT: Browsing thru the post, I found this behaviour is referred to as "flashback" Maybe it can hel to describe more graphically my concern.

[slacker]

Nice work, converting the PCB to rev2.

I am planning to build a second parallel output (with a TL071) mirroring the outpt buffer and have a jack that will interrupt the path between IN and OUT buffers so as to have completely separate dry/wet outputs. Might also add a level pot for the Dry. I take it than mirroring the output buffer from the 10K connecting to the neg input of the opamp onwards should do the trick, rite?

Yes that should work, if you just want a separate dry out you can take the output from after the input buffer. If you then break the connection between the input buffer and the output mixer you get wet only out of the output mixer.

If I stomp on the Echobase it will catch the repetitions from what I was playing while in bypass.

That is how it is supposed to work, you should not be able to hear the delay when it's bypassed though. Some people have reported a faint delay when bypassed, on mine I can only hear it if I turn the level up and the feedback so it self oscillates, in normal use I don't hear anything. You could try changing the CD4066, using a different one might solve the problem. You could also try making the 1M5 resistor after the CD4066 pin 11 smaller, try values between 10k and 100k, that might solve it.

If you don't want it to "catch the repetitions" in bypass then you can wire the tails switch so in Boss mode it connects points A and B. That will completely remove the signal from the PT2399 in bypass.

[DavidM]

Hi Slacker,

First of all, thanks for all your help. This is a beautiful project and I wonder what we Echobase fans could do for you. I am sure many of us would be willing to make at least a small donation or otherwise offer our help in whatever capacity. I am an English to Spanish localization professional so please bear that in mind should you need some translation work

Nice work, converting the PCB to rev2.

I took some notes while doing this. I worked on the "old" AnonFaceCow PCB. It took me some patient reasoning and rechecking but in the end everything worked perfectly at first start. Should anyone be interested then I would be glad to help. I added all features in Rev 2 except for the flashing LED. Anti-ticking capacitor, decoupling capacitor for Mod Depth, Vref section and improved buffers were implemented and everything on the same PCB (did some side-mounting of components and careful wiring with heatshrink but turned out quite sturdy.)

I did change the two 47K resistors and used 27K instead. This cured at once 1) the higher level of the delayed signal relative to Dry 2) the feedback pot kicking in too early.

I am planning to build a second parallel output (with a TL071) mirroring the outpt buffer and have a jack that will interrupt the path between IN and OUT buffers so as to have completely separate dry/wet outputs. Might also add a level pot for the Dry. I take it than mirroring the output buffer from the 10K connecting to the neg input of the opamp onwards should do the trick, rite?

Yes that should work, if you just want a separate dry out you can take the output from after the input buffer. If you then break the connection between the input buffer and the output mixer you get wet only out of the output mixer.

So you mean that I should be OK taking the output from INput buffer after the 10K and wire that directly without an output buffer if I wanted only dry? Please clarify since my idea is to have this option: "normal" Echobase and a second jack. When plugging into the second jack, it will break the connection from the "dry" signal coming from Input buffer. Then I would use a mirror output buffer for connecting the output of the Input buffer and thus have discrete separate ouptuts for Dry and Delay. From what I infer, your suggestion (if I understood correctly) not only makes a mirror output buffer redundant but would also provide a Dry output with the same phase as the original signal.

If I stomp on the Echobase it will catch the repetitions from what I was playing while in bypass.

That is how it is supposed to work, you should not be able to hear the delay when it's bypassed though. Some people have reported a faint delay when bypassed, on mine I can only hear it if I turn the level up and the feedback so it self oscillates, in normal use I don't hear anything. You could try changing the CD4066, using a different one might solve the problem. You could also try making the 1M5 resistor after the CD4066 pin 11 smaller, try values between 10k and 100k, that might solve it.

If you don't want it to "catch the repetitions" in bypass then you can wire the tails switch so in Boss mode it connects points A and B. That will completely remove the signal from the PT2399 in bypass.

Strangely enough today I was not able to hear the faint delayed signal in Bypass mode. Maybe it only happens when maxing all knobs. Thanks again for the tips on this and especially on the Boss/Tails mod. Will try them and for sure let you know.

Best,

David

[jan007magic]

guys! mind if you properly document this? )
include all the latest mods, revisions, versions and just put it into 1 pdf so that it would be easier to all of us.. )

[jan007magic]

and also the ready-to-print pcbs )

[egasimus]

^ by all means, please do!

[slacker]

First of all, thanks for all your help. This is a beautiful project and I wonder what we Echobase fans could do for you. I am sure many of us would be willing to make at least a small donation or otherwise offer our help in whatever capacity. I am an English to Spanish localization professional so please bear that in mind should you need some translation work

Thanks for the kind words David, my Spanish extends are far as greetings and ordering up to cinco cervezas if I ever need anything else I may call on your skills

I thought a picture would be the easiest way to show what I meant with the separate dry and wet outs.



The switch would be part of the dry out jack, which would be a switched type jack. With nothing in the dry out jack the Out would act as normal and give a mix of dry and delayed signal. Inserting a plug into dry out would break the connection giving only the delayed signal from the normal out. The extra 10k resistor to Vref is to correctly bias the U3A, I'm not 100% sure that it's needed but it will do no harm. There may be a neater way to do this but i think it should work.

[slacker]

guys! mind if you properly document this? )

It's something I keep intending to do but never get round to, nothing stopping anyone else from doing it 

[DavidM]

Hi Slacker,

Thanks for your explanation. I am glad I will not need yet another opamp for this mod

As you might have inferred by now I have no real electronics knowledge, but nevertheless I am quite intuitive (if I say so) and am keen on learning by asking and comparing. Your picture is really clear to me. Aside from the fact I don't quite get why the Vref-10K to neg input of output buffer and the 100n were added, I came up with another way of accomplishing my goal. Please see picture:


echobaserev2 dry out by **Timelord**, on Flickr

This mod needs a Stereo jack with cut for the Dry Output. The cut works as expected and the Stereo lug allows to bridge the path from the 100K resistor to ground only when a the Dry output is used. What I perceive as a benefit with this way is that the Dry Output is totally isolated when nothing is plugged into it.

Please also noticed I made a small circle with an annotation (for lack of space) regarding addition of a 100K level pot-100n combo for the Dry, which would work both in normal mode and in Dry Output mode.

EDIT: Do you think this could work?

Once again, thanks very much for all your patience.

Best,

David

[slacker]

Yes what you've drawn will work, I was going to suggest the same thing but I couldn't think how to make the Jack break the connection between the output of U3B and the 10k resistor. You don't need to break the connection between the 100k resistor and ground, the opamp will happily drive the dry out with nothing connected with no ill effects, doing so won't do any harm though.

I've thought about what I drew some more and you don't need the extra 10k resistor to vref. The reason for the 100n cap is because pin 2 of U3A will be at 4 or 5 volts DC and you don't want this getting to the output, the cap blocks the DC voltage.

You can add a volume pot like you suggest, you will need a capacitor either side of the pot, the same as the level control. Or if you use my method, you can simply replace the 100k resistor with a pot and take the dry out and the switched connection from the wiper. This would give you control of the dry volume in both modes.

I really like these mods, I'm surprised it has taken so long for someone to suggest them