Building the Echo Base PCB

[wizardsofzen]

THANKS! rock on! are there products you also have on the interwebs? i'd be interested in building anything!

[djaaz]

Hi Guys,

I've been living with the echo base for a few time now.
I have a few thing / issues:

1. I have a permanent hiss as soon as the pedal is on the board, whether it's on or off. It's annoying enough to be a show stopper, i don't know if it's my build or a design thing. Anyone can tell?

2. The repeats seems to be all in the same very short frequencies window: no bass / low medium. all medium and not so much nice highs.

There's nothing in there that make this pedal a crappy one, but there's enough to make it one i very much don't like.

Is it a taste thing or are these things stuff i can try to improve?

[slacker]

It might add a small amount of hiss, but not enough to be a show stopper. Possibly you have a problem with your build.

Here's a couple of videos that give a good idea what it is supposed to sound like. They might give you an idea if you have a problem with your build or if you just don't like how the pedal sounds.

[StarGeezers]

 Wow!!  Just like the old "freak out" days ...      Sure a Lot of possibilities ...   What a COOL pedal ....   

[wizardsofzen]

thanks for all the help ! with out you guys i wouldn't have had the courage to get this far.
sound/video soon enough.

[Taylor]

Nice!

[djaaz]

It might add a small amount of hiss, but not enough to be a show stopper. Possibly you have a problem with your build.

Thanks for the videos links.

Here's a mp3 sample i made from the pedal. The first seconds are the echo base, the last one are a memory toy.
http://djaaz.free.fr/echobase.mp3
They illustrate two things:
1. The hiss is quite obvious
2. The lack of bass

Is there anything that i could/should check?

Thanks in advance!

[slacker]

That sounds like it is either a bad PT2399 or you have a bad connection or wrong components round the PT2399. If you turn the level to zero does the hiss stop? If it does it is definitely coming from the PT2399.
I would check all the components and connections down the left and right sides of the PT2399.

[djaaz]

Thanks for your answer.
I should have mentioned a few points:

The hiss comes wether the effect is off or on, maybe a minute or so after the pedal is powered.
If i turn the level pot to from zero to full clock, i have noises & sometime the hiss stop for a few seconds.

Only mod is "dub madness" with the resistor soldered directly from the board to the spdt switch. Tested before boxing.

I did not notice that hiss with the pedal out of its box but i do not focus that much on small noises as long as a board is not in its enclosure.

This sample is with the effect off, turning the level pot from an end to the other.

http://djaaz.free.fr/hiss.mp3

As the pedal is boxed, i will need an hour to unbox it, check the board & components and try another PT2399 i have lying around.

[deeptubez]

Hey all, just finished up my build and everything is working and sounding great EXCEPT.....I set this pedal up with true bypass wiring, clean kill switch, LFO switch and tails switch....all of which work perfectly fine, BUT, when I switch from bypass to the effect I get about an 80% volume drop.....I know this can't be normal.  The effect sounds good, no distorting or hissing...all the pots work fine, but to me it sounds like there's a resistor that needs to be changed somewhere or something. I've checked and double checked my connections and everything seems to be good....any suggestions would be greatly appreciated.  THanks!

[Taylor]

The circuit is not designed, as is, to be true bypass. Modding it to be true bypass is the kind of mod that will involve some tinkering, since you're making it do something for which it wasn't designed. I've never tried TB on the EB, but I wouldn't be surprised if there was a volume drop and it could be quite normal.

If you increase the value of the 10k resistor that's directly to the right of pin 4 of the TL072, you will raise the gain of the output stage. You might put sockets there and try a few different values, or put a pot there and you can have an overall volume knob.

[deeptubez]

I know it's not designed to be TB, and I figured it might need a little tweaking, but the volume difference is HUGE   
I thought I would just put in a 250K trimpot and adjust it till i find the sweet spot...
Which 10k resistor exactly...in that row there's a 100K on top followed by 3 10K resistors.....1st, 2nd or 3rd one down? (Looks to me it would be the 2nd one?)

[Taylor]

Yes, the second one down. 250k is probably going to be way more than you need, so all the useful adjustment will be bunched up in a tiny area, but it will work if you don't have anything smaller.

[deeptubez]

Have a 100K right here....I'll give it a go and keep you posted....Thanks!!!

[deeptubez]

Ok, so I took out the 10K resistor, replaced it with a 100k trimpot and found that only around the 25k range and the 0-10K range would pass any sound.  The 25k range was overdriven, almost fuzz-pedal like, but the best volume/sound improvement was setting the trimpot to 0....so I just put a jumper in that space.  Would there be any other values of resistors I could try lowering/raising to try to get even more overall volume?  What I did did improve the volume a bit, but the sound difference between on and bypass is still pretty significant.

[Taylor]

Are you sure you swapped the right one? Lowering that resistor below 10k should lower the gain of this amplifier, not raise it. I'm trying to figure out how you might have gotten the results you did. You're saying that the sound cuts out from 10k to 25k? Possibly a bad trimpot?

[deeptubez]

I'm sure I got the right one....Don't think the trimpot is bad, it's brand new...plus I already took it out and jumpered it....it's definitely louder than it was, but still only about 50% of what it should be as when bypassed.  As I turned the trimpot from 0 clockwise, the volume would slowly lower till it got kinda fuzzy, like it was a bad range?  Then right around 25-35K it would hit another sweet spot, but this time with ALOT more gain, not so much more volume....like I said, it sounded like I just added a fuzz feature to the echo    As I got passed 40K, the sound mostly went away and I could tell was out of range or had too much gain.  With it turned all the way down, it was nice and clean, and louder than it was with the 10k resistor there.  Is there possibly another resistor I could change near the input/output that might further increase the overall volume?

[deeptubez]

And just to make sure:

               100K
               10K
(TL072)    10K  <---- This is the one I took out
               10K
               1M5

[slacker]

There shouldn't be any volume drop if you true bypass it, so trying to fix it by making it louder isn't the answer. How have you wired it for true bypass? My guess is it's a problem with how you've done it, especially as you say the tails switch works and this shouldn't do anything if it's true bypassed.

[deeptubez]

I've bypassed it correctly....I've built well over a dozen of these things and the TB is something I ALWAYS add to whatever I'm building.  I've wired the cancel switch in to the 3pdt switch, basically to just turn the LED on and off when I switch back and forth from bypass to on (and of course to turn the board on when not bypassed).  Why wouldn't the tails switch work when the pedal is on with true bypass?  I don't know what else to change or test....It honestly sounds to me like the pedal is just a major volume/tone sucker.  The effect sounds good....all the switches/knobs work fine.  I'm going to add an output buffer circuit to it to get an overall volume boost....I've now triple and quadruple checked everything and don't think it's any of my solder points or wrong values/components....I'm gonna give the output buffer a go and see what happens....