Echo base dual delay module

[Skrog Productions]

Hi

Just finished designing the panel for my 2 ECHO BASE pcb's.
I've got 1 board populated and have added the clean kill / lfo kill / lfo wave shape pot / run away feedback / cv input .
for the cv input i was experimenting where & how and got a good result with an attenuated cv connected to the wiper of the lfo shape pot mod .
My feedback pot is very tame at maximum , i'll try to get a bit more soon.
initial tests were overloading the fx when connected to my modular ...so... i built a vero board CGS stopbox adapter... works a treat now , one more to build up & get the panel done (lazer printed vinyl sticker) , should have it all running during the Xmas holidays

The wide space on the main controls is allow mounting the pots on the reverse side of the pcb to get the vertical layout i wanted

Dave.

---

Echo base delay echo dec 20th 2010 cov curves BLUE sm.JPG
Description:
Filesize:	55.46 KB
Viewed:	600 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

[slacker]

Very cool, look forward to seeing the real thing.

Out of interest what voltage are you running it off?

[Skrog Productions]

Hi Slacker

i made a small vero board circuit with 12v +/- incomer to supply the CGS stompbox adaptor then through a +9v reg to supply the echobase .

alu panel drilled & stickered , slight colour banding on the blue print on the panel but i'm glad just to get them done .

i've been trying some things for my weak feed back and realised the run away F/B mod i done cuts the 20K out the circuit till i switch the run away on , so.... tracing the connections i've used a SPDT switch with the other pole connected via a 100K res. to the old 20K board thru hole , see diagram below , now i get either controlled feedback at 70% pot travel or max feedback , fab , all will be built up over the next few days.

---

dual echo base panel.JPG
Description:
Filesize:	45.19 KB
Viewed:	25904 Time(s)

---

---

feedback echobase pcb.JPG
Description:
Filesize:	24.89 KB
Viewed:	669 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

[Skrog Productions]

Finished .... ....

i'm really happy with these delays , they work great with the usual sequency stuff i do for my music.
Also great for FX whooshes & zaps with a high pitch S&H controlled VCO run through them .

My bypass led's were dim with a 50K load res , better with a 10K but with a 2K the internal Lfo stopped working so back to 10K .

I had breadboarded another type of PT2399 delay design a few years ago with not very good results , these , however , hooked up with Ken Stones stompbox adapter circuit work well with my diy modular ( and free up my 19" rack delays for the Juno's ).

after reading previously about pots wired back to front i double checked with a continuity meter the minimum or ground legs of the pot connections and yes the pots get soldered to the track (back) side of the pcb .

listen to Epicyclus on the New Years Eve electro-music concert , Friday 19:30 GMT to hear them , i'll post some short sounds here after the weekend , thanks for having a look.
Dave W.
Epicyclus & Orchard.

---

delay1.JPG
Description:
Filesize:	120.07 KB
Viewed:	555 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

---

Delay rear.JPG
Description:
Filesize:	126.56 KB
Viewed:	596 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

[Skrog Productions]

sounds.......

Hooked a vco to a h/pass filter thru a vca with lfo's & a sequencer c.v. controlling delay time later in the mp3,

Dave.

---

vco's + lfo's thru Echobase.mp3
Description:		Download
Filename:	vco's + lfo's thru Echobase.mp3
Filesize:	2.48 MB
Downloaded:	1458 Time(s)

---

[Taylor]

Sounds and looks awesome Dave! Really pleased to see the boards in a modular environment. Slacker's circuit is so versatile that I find new fun things it can do all the time.

How have you done the CV for time mod? Just sending your CV to the base of the modulation transistor?

[strategy]

[sneakthief]

Skrog Productions: do tell how you implemented your cv control

[Skrog Productions]

Hi , i added the cv in via an attenuator to the wiper of the lfo amount pot , best results if you kill the internal lfo with the lfo kill switch mod to run the external cv on it's own , you may need a resistor in series with the attenuator ground pin (something like a 10K) as the lfo amount wiper connection didn't like the internal lfo getting grounded by the cv pot when set at lowest , counter clockwise .

experiment a little to get results you like
cheers.
Dave.

[philoop]

i see your extension board
any schematics?
and how to make feedback cv controlable
and a crossfeed?

[sneakthief]

Re. stereo Echo Base crossfeed:

Success!

I took the feedback output (CW pin of the feedback pot) of the Left delay pcb, sending it to a non-inverting opamp buffer which then goes to a 20KA pot, and finally to a 20k mixing resistor that goes in the connection between the 4n7 capacitor and the 20k resistor that's on the pcb. (And the same for the other side.)

I used this buffer schematic and biased the input with the 5V output. I also put a 100n cap after the 10uF (very important!):




http://www.muzique.com/lab/buffers.htm



Also, the CV-input works well. I put a diode between the cv-input jack and the ground to remove all negative CV voltages. I connected it directly to the base of the BC560/2N5087 with a 20k resistor.



Please note: the Echo Base will invert your audio signal because it uses one inverting opamp and a non-inverting opamp.