Building the Echo Base PCB

[slacker]

Great advice Tom

[grilojoe]

Hi everyone. First post, first pedal project. 

I've looked around, but haven't found an answer yet. My Echobase is working as it should (as far as I know). When I crank up the feedback it starts this crazy oscillation (which I expected) that then gets really really loud (which I did not expect). Is this supposed to function this way? I've already had to troubleshoot this to get it working in the first place, but I'm just wondering if perhaps I need to work with it some more.  Thanks

[tombaker]

Hi everyone. First post, first pedal project. 

I've looked around, but haven't found an answer yet. My Echobase is working as it should (as far as I know). When I crank up the feedback it starts this crazy oscillation (which I expected) that then gets really really loud (which I did not expect). Is this supposed to function this way? I've already had to troubleshoot this to get it working in the first place, but I'm just wondering if perhaps I need to work with it some more.  Thanks

Hi,
Increasing volume on runaway feedback is normal. If you have the runaway feedback mod or if you just crank the repeats to full the signal will get louder and louder pretty quickly until a point, but at that point you'll probably have the effect volume down quite low to compensate.
I believe this to be true as it happens with mine and has happened one a few other pedals i've used which weren't diy.

[grilojoe]

Okay. Another question:

When the tails switch is on, the effect is on. The bypass switch does nothing at all except turn on the LED. If the tails switch is off, then the footswitch functions as normal. I know I'm not great at troubleshooting, and this one's got me scratchin' my head.

[slacker]

It is probably a problem with the tails switch or the wiring to the switch. Double check that it's wired correctly.
Do you have a multimeter?

[grilojoe]

Cool. Thanks, I'll double check the wiring to that switch. It wouldn't surprise me if I screwed that up. I get anxious to finish and make mistakes.  Anyway, yes. I'll look again. Thanks for the help.

Yes, I have a multimeter, no it's not awesome. It works passably well until I can get something better.

[grilojoe]

Yep. Tails switch wiring was the culprit. Thanks for pointing me in that direction. I'd gotten a couple wires switched even though I checked and rechecked them before soldering them in. Thanks for the help.

Some other things came up, but got those ironed out on my own. Everything's working now, including the waveshape mod, which produces some sounds weird enough, I'm thinking real hard about a clean kill switch. We'll see.

[slacker]

Cool, I like it when debugging is that easy.

[grilojoe]

Me too!

I scoured this thread when the other problems popped up. I replaced the 4066 and had a faulty connection on the waveshape pot. After fixing those two things, it works like a charm.

It's a great circuit (thank you, slacker) and a great pcb (thanks taylor). 

[soggybag]

I just built two of these. The first worked with no trouble. The second is giving me problems. I dry audio all the way to the output. When I probe the PT2399 I get the dry signal at pin 15. I also get audio at pin 9. But there's no delay and I don't here anything when I probe pins 10, 11, 12, 13, and 14.

Should I be getting a delay signal at pin 9?

If I get audio at pin 9, I should be getting audio at pin 11? What would prevent the signal from getting getting from the first filter section to the second filter?

[slacker]

Yeah you should get signal at pin 9, have a look at this post for voltages and what to expect on the PT2399 pins http://www.diystompboxes.com/smfforum/index.php?topic=60662.msg498824#msg498824
Not sure what to suggest if you're not getting signal on pin 12 except to check solder joints and components around those pins. Maybe compare voltages and audio probe results with the working one.

[9aul]

Hey, I was wondering if anyone knew if a 2n3906 would be an OK replacement for the BC560?? Its a PNP and I know the pin layout is the opposite way round but would it work? (as long as the emitter is where the emitter should be and collector where it should be)

[slacker]

Yes that will work fine.

[9aul]

Great thanks!

[electricmimesis]

Hey All,

I hope this is the right place to post for questions. I've just built the echo base and everything seems fine except that the dubmadness mod is not working as it should. I purchased the board from music pcb and followed the instructions provided in the manual. What happens is that when the toggle is on I get heaps of feedback as expected, but when it's off, the feedback pot is not working at all and I only get one slap-back. When I remove the dubmadness mod the feedback pot works just fine.

Any ideas on where to start?

Thanks.

[electricmimesis]

oops i realized i posted in the wrong area! please delete.

[9aul]

Hi, I'm still wrestling with getting this one to work (stupidly I had a few of the caps at the wrong value  but thats all sorted and double checked now). Anyway I've finaly got some echo out of it, although the LFO side of things dosent seem to be working and i cant get a short delay time, only fairly long ones. On top of that there is also some noise when turning up the level of the effect. Also is the  dub madness mod just meant to act exactly the same as turning the feedback right up?
I cant work out whats wrong, I've replaced the opamps with fresh ones just in case, but to no avail. Ive posted a pic of all the values for my ICs. Any ideas on where I might have messed up would be much appreciated! I used a BC558c in place of the BC560, hope thats OK?.

Thanks

[garcho]

On the phone on train, but just glancing over your voltages, did you notice your base of the 2N5089 is at 0V while the emitter is at 0.04? Also, the TL072 at the far right has a ground pin that's not at ground.

[slacker]

Does the LED flash? Does the Voltage on pin 1 of the opamp under the speed pot fluctuate or is it a constant 5 Volts. Does the Voltage on the wiper of the LFO depth pot go to zero if you turn it all the way down?

Yeah the dub madness mod is supposed to be the same as turning the feedback all the way up.

Great idea putting the Voltages on the PCB like that

[9aul]

Thanks Garcho. I really should have noticed the ground pin wasn't at 0! I've just had a double check and I cant see solder bridges going to earth, I'll have a nose around the 2n5089 and make sure any components leading to it are def the right value.

Hi Slacker, Yes the LED flashes at different rates as I change the LFO speed pot. The voltage on pin one does fluctuate around 5v. And yep when the wiper on the depth pot is turned all the way to the left the central lug of the pot reads 0, when all the way to the right the voltage fluctuates from – 0.12 to + 0.12.