mxr distortion+ low volume

[rhdwave]

Just wondering if anyone has built this (mxr distortion +).  I breadboarded it and when i turn the effect on there is a huge drop in volume.  The distortion works, but drops the sound.  I'm using an lf351 opamp.  Wondering if anyone has run into this problem.  I checked the circuit for continuity, and everything seems to be connected properly. 

thanks for any help!

[Mark Hammer]

How loud is it wiithout the diodes?

[rhdwave]

I'm not at home right now, but i will check that tonight.  The other curiosity i had about the circuit is that it calls for a 10k volume pot.  I tried it with such and then decided to give it a shot with a 100k volume pot, it did get a little louder, but is still way below the volume when i bypass the effect. 

[Mark Hammer]

Well, one thing seems to be working right.  Just keep in mind that it is not a ridiculously loud pedal unless you changed a number of things.

If you have a meter, set it for AC millivolts, plug in and measure the AC voltage at the input to the op-amp and the output.

[rhdwave]

Thanks for the quick responses! I will check that as well this evening.  Now a hypothetical question: if i remove the diodes and it gets a lot louder, would there be a fix for that situation? Also, are there any ways to modify that would give a volume boost? I know these are a lot of questions, but also, if i used a different opamp, would that possibly affect the volume or use two opamps, for example say an lm386 for a boost and then a switch to the mxr distortion + circuit?

[LyleCaldwell]

Sure you have the Distortion knob wired up correctly?  If you have it backwards it gets quieter as its turned up.

[rhdwave]

I believe it is correct, however i will check this as well.  The picture i was looking at had lug 1 (as far as i know this is looking at the pot, with the lugs on the bottom the right most lug) and lug 2 wired together, with lug 2 going to ground and lug three going to the circuit.  At least this is the way i wired it.  The other thing is, if it were wired incorrectly, would the level raise if the pot were turned in the opposite direction, or would the level just drop for everything?

[LyleCaldwell]

If you have it backwards the dist and level will come up when you turn the knob all the way counterclockwise.

[Mark Hammer]

Thanks for the quick responses! I will check that as well this evening.  Now a hypothetical question: if i remove the diodes and it gets a lot louder, would there be a fix for that situation? Also, are there any ways to modify that would give a volume boost? I know these are a lot of questions, but also, if i used a different opamp, would that possibly affect the volume or use two opamps, for example say an lm386 for a boost and then a switch to the mxr distortion + circuit

Don't start making radical changes at the moment, including switching chips or adding chips.  The main thing to do right now is figure out what it *isn't*.  That will help narrow down what the problem IS.

It *will* get, or rather *should* get a lot louder without the diodes.  How loud it gets, relative to bypass should provide some clues to people here.  So far, it sounds like you have simply encountered one of the many commn building problems every one here encounters.  The question is: which one/s?

[rhdwave]

Okay, i'm not sure if i did this correctly, i'm new with the multimeter.  I measured the voltage at pin 2, pin 3, and pin 6:

pin 2: 1.259 millivolts
pin3: 1.259  millivolts
pin 6: 6.27 millivolts

[rhdwave]

Thanks for everyone's help, just got all working (3am).

seems that a resistor wasn't making the proper connection.  Now it's very loud withthe 100k pot, testing different diodes and combinations.  This is so addicting, haven't gotten much sleep lately, but happy.  Thanks again all for your help, this forum is amazing.

[Mark Hammer]

Sounds like you not only acquired a new pedal, but you got smarter too.  Congratulations!  That's what it's all about.  Well, that and the adulation and easy sex.