EM drive tiny debug...

[Surgeon]

Anybody who built this one gets some gated fizz in there somewhat?

I even get it at pretty much zero gain. It's not huge but it's there, on top of the tone, a little fuzz/fizz that quite gated, especially on the low strings of my telecaster (at low gain, at higher gain I get it pretty much on any string).

I went with the usual suspects: solder bridge, transistor swap (I originally had a 5088 in there but even the 222 did the same thing) so I'm wondering what else it could be. It's not on the bypass signal so it's not coming from my amp or speaker.

Any idea? Kinda ridiculous considering how low-part this tiny thing is and yet there's something wrong with my build...damn...

[Madferret]

I build both versions, the mojo and tiny one, and I have to say there was a bit of fizz on both, not gated but it was present in the decay of a note as the sound died out.  I didn't really rate this pedal I'm afraid so I didn't investigate further.  I used a 5088 too if it's any help, maybe something a little lower gain might be the answer?

[Ross]

The EM-Drive is a very hFE-dependent circuit. Higher gain transistors will help stop the gating. My build used an MPSA18, which worked really well. I would guess that Emerson selects their 2N5088s for high gain, as 2N5088s tend to be all over the place when it comes to gain.

[Surgeon]

Well, I went as low as using a 2n222 in search of lower gain, thinking it would solve it... didn't.

I didn't expect higher-gain would make it better (showing my low-comprehension of this circuit probably), so I'll give that a try. Either screen my 5088 for a higher-hfe one or a MPSA18 like you did.

Thanks for the input, I'll report back!

[Geiri]

I'm not saying the circuits are alike in any way but I made a Kay T1 tremolo on friday and I didn't have enough high-gain trannies so I used some medium-high ones and it was quite dirty so I replaced two with higher gain ones and the whole thing got a lot clearer. I guess you could think of it as headroom, if you have lower gain trannies, you have less headroom for it to be clear and nice so you need higher gain for it to get through without distorting or fuzzing.

Not saying it applies to all circuits but some at least.

[Surgeon]

Well, that didn't work either. I used MPSA18 that read about 1000 for hfe and the pedal almost didn't make sounds... just ultra gated noise when I hit the strings real hard. The 5088 that I used was about 600. Not better either.

I went the opposite way afterwards: tried one of the MPSA18 that read 260ish. Better but still a bit of noise on the low-string when hit hard, just less than with the original 5088.

The demos I've watched were all mostly finger picking and light picking stuff. Maybe that's just not a pedal that suits me well.

I think I'll just reuse the enclosure for something else with two knobs.

Thanks for the help gentlemen!

[peavey_xxl]

I ended up using a 2n2222 for this build hfe Around 240.  I put is side by side with the real thing and it sounds identical.  This was also built with the same paper in oil caps.  

[peavey_xxl]

I also measured capacitance and found a pair with a 1% tolerance.  I used CTS pots like the original.

[Surgeon]

See,I didn't like it even with a 2n222... Confirming that it's just not a pedal for me.
Thanks for confirming that they sound identical though! Cheers!

[peavey_xxl]

I guess it really depends on what you are wanting it to do.  I like it for just a slight boost for a dirty channel, but you can't dime out the gain on the real deal or the clone it just sounds like hammered dog crap