Building the Echo Base PCB

[NQbass7]

I try to support SmallBear as much as possible, but since they are out of stock, does anyone know of a Mouser part number for the PCB 50k pot?

I searched, but they don't seem to carry that type of pot.

I emailed them, and they said they wouldn't have the pots in stock until around July 1st.  Huge bummer.  Part of the point of this board was to avoid wiring pots.

[defaced]

Buy the long legged ones and cut them down.  http://www.smallbearelec.com/Detail.bok?no=710

[ibodog]

I think[i/] that all you need to do is connect a SPST momentary stomp to the Bypass pads and it will do that. My only hesitation is that I'm not positive whether the effect is on when the pads are connected (this is what you want) or when they are disconnected. I'm pretty sure it's set up the way you want. You can even connect the momentary switch in addition to the standard latching switch so you can have both regular bypass and dub punch-in.

So what I'd want to do is wire up the momentary switch "in parallel" to the latching one?  Then when the latching one is shorting it's lugs the delay is always on.  If the latching one is not shorting it's lugs (eg OFF) then the non-latching switch can be used to punch in the guitar sound to the delay line while the switch is held down.  That would be ideal for what I was envisioning. 

[slacker]

Yep that's it

[Taylor]

So what I'd want to do is wire up the momentary switch "in parallel" to the latching one?  Then when the latching one is shorting it's lugs the delay is always on.  If the latching one is not shorting it's lugs (eg OFF) then the non-latching switch can be used to punch in the guitar sound to the delay line while the switch is held down.  That would be ideal for what I was envisioning. 

Yep, pretty much.

Now regarding the 50k pot, that is indeed a bummer. Cutting down the long pin pots would not work because you would be cutting off the pin that goes in the board. What I'd suggest is getting Small Bear's 50k reverse audio taper pot. The taper's wrong, but IMO this isn't a big deal, it would just give you more precision at longer speeds and less precision at shorter speeds, which is fine since usually longer times are meant to be rhythmic and shorter times aren't as time-specific. You could also use a 100k pot and put a resistor across it to change it to 50k, but this would shift the taper to be like a reverse audio anyway.

Finally, you could also just use a 100k. It will give you longer possible delays (which are noisier).

[jacobyjd]

Or you could use a 100k with a 100k resistor across the lugs, giving you 50k, but with a slightly less severe reverse taper than a 50k rev log.

I love the idea of having a momentary bypass switch in parallel on this--slam a chord that'll tail while you superimpose leads overtop? Yes please! hah! Gotta build this sucker 

[Taylor]

Or you could use a 100k with a 100k resistor across the lugs, giving you 50k, but with a slightly less severe reverse taper than a 50k rev log.

Hmm, I feel like I've seen that somewhere else on this page...  

You could also use a 100k pot and put a resistor across it to change it to 50k, but this would shift the taper to be like a reverse audio anyway.

Yeah, the momentary on switch is a cool idea, and an easy mod on this PCB. What a neat project, I always want to give it up to Slacker but I know he's tired of it. I keep finding new ways to use it all the time.

I'm really liking my dual-use stomp switch, mentioned earlier in this thread. It can either be a modulation on/off or a "max feedback" stomp, both of which are very useful. Put the time all the way up, play a note, then stomp it in max feedback mode, and you get a feedback note similar to an ebow or real guitar feedback (or like the Boss Feedbacker pedal). You can play little feedback melodies rather easily this way. The modulation kill is equally useful.

[jacobyjd]

Or you could use a 100k with a 100k resistor across the lugs, giving you 50k, but with a slightly less severe reverse taper than a 50k rev log.

Hmm, I feel like I've seen that somewhere else on this page...  

You could also use a 100k pot and put a resistor across it to change it to 50k, but this would shift the taper to be like a reverse audio anyway.

Yeah, I totally got ninja'd there. That's what I get for leaving the reply window open for too long, then ignoring the 'someone else has already posted' warning. 

[Taylor]

That's ok, I do that all the time. I often click to reply, then realize, "I am going to need a cup of coffee to give this reply the thought it requires." and start a-brewin'.

I'm wondering if it would be possible to get the LFO section to go faster. I kind of like the weirdo delay-ring-modulation thing I get at high speed and depth, but it would be cool to get it a little faster. One problem is that the PT2399 has an inherent "portamento" when changing times, so that at a certain point it won't change time any faster, and it starts losing depth as a result.

http://www.diystompboxes.com/smfforum/index.php?topic=77966.0;prev_next=prev

[frequencycentral]

Reducing the value of the 1uF cap just above U1A in the schematic should make the LFO go (twice as?) faster. You could actually use two 1uf in series (= 0.5uF) for fast speeds and short one out with a switch to get normal speeds.

[slacker]

Here's a couple of shots of mine. It was a very easy build, I have to say I can now see the appeal of PCBs for bigger circuits.





As you might be able to see on the second photo I used a 100k linear pot with a 100k resistor across the lugs instead of a 50k. It works fine the taper doesn't feel weird or anything.

If you want to mess with the LFO speed changing the cap like Rick suggested is probably the best way if you want big changes in speed. If you just want to make it go a bit faster then reduce the 27k resistor, that will affect the top speed without really changing the slower speeds. I'm not sure how much faster it will go though, especially now it's got the decoupling cap on the output. Worth a shot though.

[malrock75]

Hey Slacker..Nice build. Just wondering where you got those pots from??
Thanks Mate.

[slacker]

The pots and just about everything else are from Rapid.

http://www.rapidonline.com/Electronic-Components/Resistors-Potentiometer/Control-Potentiometers/Miniature-16mm-potentiometers/65225

Welcome to the forum

[malrock75]

Thanks and thanks!

[jessej]

I'm planning to fit my Echo Base on a 4U rack panel and wonder if I can fit 5 knobs above each other?

It would be nice if someone could tell me the dimensions of Taylors PCB (metric if possible)!?

Plans are there's going to be other gems in the same rack too. Kinda like a 9V modular with guitar effects.

[Taylor]

10.16 centimeters x 4.318 centimeters (4 x 1.7 inches). I believe 1 rack space is 1.75 inches so 4U would be 7 inches. Plenty of room to spare putting the knobs vertically, so you could add a few mods and still fit it all.

[jessej]

10.16 centimeters x 4.318 centimeters (4 x 1.7 inches). I believe 1 rack space is 1.75 inches so 4U would be 7 inches. Plenty of room to spare putting the knobs vertically, so you could add a few mods and still fit it all.

Thank you for that info!

The build pdf suggests boxed metal film caps, but I mostly have ceramic caps in stock.. (and electrolytic for larger values of course)

I'm interested in finding more info about the benefits of using metal film caps here, is it a noise thing or has it to do with the sound character of the delay (dielectric absorption etc) or something else?

EDIT: Aha! I see it's more a matter what will fit the given space.. No problem, but If someone likes to still answer the "sound character" question above, please feel free to do that..

[Taylor]

The sound of capacitors is something that is debated as hotly as the existence of god, the viability of free market principles, etc.

My personal stance is that I hear no difference in different cap types. My Echo Base uses a mixture of ceramic and box film caps in the signal path, and I like it. I believe that when people say they hear a difference between two caps of the same nominal value, the difference is mostly because of the tolerance of the caps, so 2 caps labeled .1uf could be 20% different in actual value.

And since that discussion has a habit of turning into a long-winded argument, let's just leave it there for this thread. 

[hoyager]

Hi there, noob of a question but which 10k resistor is the one after the level pot on Taylors PCB?

Many thanks

[Taylor]

It's the one right next to pin 1 of the 4066. What are your plans with it?