Echo Base - a new PT2399 delay

[mth5044]

That two in one delay almost sounds like a multihead delay.

[doc_drop]

Or a multi-tap delay.

I took a look at the box I want to put these guys in, and I don't think they will fit. Besides I am kind of bored with the PT2399... So, the new plan is to put a Noisy Cricket in the box, and make a practice amp with a psuedo reverb/delay. I'll be perfing it up tomorrow.

Does anybody know why on the Beavis site, the schematic has different cap values than the breadboard diagram?

[Auke Haarsma]

I'm in the process of creating my own pcb for the EchoBase. Since I want to use 9mm alps pots and my supplier only has 10k or 100k pots... I need to change the LFO.

My guess is that the LFO is scalable. But, could someone point me in the direction on how to arrange the values if I use an 100k pot for the LFO section?

Much appreciated!

[D.O.O.H.H.]

So,increase the cap in integrator of LFO to 10 uF and decrease the resistor 27k to 2k.

[Auke Haarsma]

Ah thanks for the pointers. I'll give it a shot in my testrig!

[Valoosj]

Auke, just buy from Banzai... They have everything except for 2K, which is not used in this pedal.

[Auke Haarsma]

yeah, I may have to do that if scaling the LFO does not work out. However, I do not like banzai, so I prefer to use the pots I have at hand.

[slacker]

Making the changes D.O.O.H.H. suggested will work fine. Technically the cap needs to be non-polar but instead you can use two normal 10uF electrolytic caps, connect the negative ends to the opamp pins and connect the positive ends together, that makes a non-polar cap.
It'll probably work fine with just a normal 10uF electro though.

[kierc]

Just wanted to say I've got the tiny layout the right size now!

Printed it at 200.25 DPI to get the right size, as with all diylc traces 

[Barcode80]

anybody have any ideas about what i posted earlier? about how to increase highs on the repeats without changing that cap near the feedback pot? when i lowered it down it caused quite a bit of distortion and I was wondering where in the circuit a different change could be made cap wise or maybe even a good place to install a high pass filter...

[Auke Haarsma]

I've also been caught by the Echo Base virus!
I designed my own pcb, which is currently being tested. Added a tempo-led mod (by André) which works nicely (makes use of a PIC).

I'd like to mention (repeat) a couple of things which I solved with the help of this thread, which I think could be common issues:

LFO ticking
This can easily be solved by putting a 2.2uF elco from pin 7 of the LFO IC (U1b on Slackers schem) to ground.

Distortion on repeats, especially with hot pickups/humbuckers
Just leave the two diodes in the feedbackpath out. Did the trick for me.
I tried with two yellow LED's, but they didn't do anything. The LED's are rated to conduct at 2.1V, the diodes I used (1n914) at 1V. Something in between would be nice (~1.5V).

Feedback pot causes too loud feedback too soon / oscilliation
There is  a resistor to tweak here. Focus on the 20k resistor running from the middle lug of the feedbackpot. Raise this value to tame the feedback pot. I swapped in a pot and dialed my 'perfect' value. Turned out to be 135k. No resistor with that value in my stash ofcourse. 120k would still cause oscilliation before reaching the end of the feedbackpot, so I put in 150k. Does the trick. I'd would probably be a good idea to replace the 20k resistor with a trimpot (say 150k or 250k).


There are plenty of great layouts posted already, which are probably easier/better than mine. But if there is interest, I'll gladly share mine once I finish verifying it.

[Barcode80]

i'd like to see yours posted. you never know, someone may have an easier time trimming a board to fit with a different layout.

[Auke Haarsma]

I'll upload the layouts. In my multi-fx thread I posted a couple of pics already. Just a repost here:

I'll upload two version. The one above (with boardmounted pots and footswitchs) and another one, with the offboard stuff really offboard (so the pcb is a bit smaller).

[slacker]

Nice looking board, thanks for the report as well. When I get some spare time I'll change the schematic and my vero layout to include the extra 2u2 cap, and maybe make a few other tweaks based on the information different people have posted here.

[mikemaddux]

Ive built my echobase from a board I got from John Lyons, populated it according to the anonymousfacelesscoward ?? layout and I cant get anything out of it.  My audio probe only gets sound out of the first couple solder terminals.  Anyone else have this problem?  Ive looked for solder bridges all over and I cant find any.  Im hoping someone else has had this same problem and can tell me where to start looking on such a big board.  (this is my most complicated build to date)

Thanks in advance.

Ill follow up with pics and pinout voltages.

[Auke Haarsma]

Hi, pics and voltage readings will help!

Can you read the schematic? If so, use that as a guide to follow the audiopath. check it from input to the first IC, out of the first IC, into the next etc.

[mikemaddux]

pin voltages to come

[Auke Haarsma]

I do love them blue boards!

I could be optic-illusion, but from the pics I'd say look at the area's I marked below:


I looks like there are some shorts there. There may be more, I did just a quick scan.

[fegg]

Making the changes D.O.O.H.H. suggested will work fine. Technically the cap needs to be non-polar but instead you can use two normal 10uF electrolytic caps, connect the negative ends to the opamp pins and connect the positive ends together, that makes a non-polar cap.
It'll probably work fine with just a normal 10uF electro though.

hi, is this mod in order to use a 100k pot instead of the 47k delay time pot?
if so which cap is being changed (is it c25 on the vero layout?)
it would be useful to me as I have only 100k spare for the delay time pot
..if not would using the linear pot trick work ok http://www.diystompboxes.com/analogalchemy/emh/emh.html

excellent project btw 

[Auke Haarsma]

the mod mentioned was just for the 1M LFO pot.

However, I am using only 100k lin pots for all the pots in the echbase.

For the delay-time, just throw in a 100k pot. You'll get the possibility to get longer delays, no adjustments needed.