LM386 headphone amp questions

[wsgarner]

OOOPS! Posted in the wrong place to start with!!

:icon_question:Well, I built my first Headphone amp. Used the GEM schematic but I have 2 questions.
1. The distortion isn't really that good. I'd like it to be more like a FUZZ, but not sure what to do. I put the 10uF cap between pins 1 & 8. Can this cap be eliminated or changed to differnet value to get a better distortion?
2. I'd like to add an AUX IN jack for my MP3 or CD player. How would this be done?

Thanks,
Scott
PS: as you guessed, I'm new!

[Steben]

OOOPS! Posted in the wrong place to start with!!

:icon_question:Well, I built my first Headphone amp. Used the GEM schematic but I have 2 questions.
1. The distortion isn't really that good. I'd like it to be more like a FUZZ, but not sure what to do. I put the 10uF cap between pins 1 & 8. Can this cap be eliminated or changed to differnet value to get a better distortion?
2. I'd like to add an AUX IN jack for my MP3 or CD player. How would this be done?

Thanks,
Scott
PS: as you guessed, I'm new!

You can only get distortion, if the LM is pushed to its limits, and that must hurt in your ears! or is there a pot in front of the headphones (rheostat)?
You cannot make an overdrive unit sound like a fuzz, (unless you boost the highs maybe...)

If you connect a hifi source, you cannot expect the amp to distort only your guitar; So putting guitar and CD together is possible, but only if you use the LM386 as a clean amp (with tone shaping in front of your headphone amp.

[wsgarner]

Steben,
Actually the way I built it is with 2 LM386's (Right and Left). I put a dual pot at the output to cut the volume (yes I didn't to start with and my ears are still ringing). What I wanted to do was just bridge the cd (aux in) to the output channels (R/L) then I would control the cd volume with the cd player and the guitar volume with the output pot. My concern though is that I can't just bridge across without damaging either amp or the cd player by applying the 2 outputs directly together??

OK, distortion. So, I would need to build a distortion (FUZZ, OverDrive,......) at the guitar input (pre lm386) and only use the lm386 clean (which sounds great clean by the way)? If I did that, I would want to do something very simple. Maybe 2 trans. fuzz or overdrive another opamp. Any suggestions??

Thanks,
Scott

[lethargytartare]

I built the EZ headphone amp because it was...well...easy!  Really, I just needed to crank one out in a big hurry, and that worked out.  And I thought the distortion (which is the 10uF cap across pins 1-8) was pretty good in light of how simple the circuit was.  So my opinion is that the next step up would be a proper fuzz or fuzz-like circuit.  Look up something called the "GES Bad Trip" -- designed by someone here, I think (I can't get at the original files because my work proxy blocks so many sites now).  I think that was a LM386 distortion circuit, and I was able to build it without a board -- it was very simply and very very nasty! Might be some ideas in there.  Or just whip up a fuzz.

As for the CD player, one thing you could to to test your idea is to just use a set of alligator clips, put an 1/8th to 1/8th cable in your CD player, and use the alligator clips to connect that cable to the output jacks of your pedal -- I can't imagine anything can get hurt since you're pretty much just putting an extension on the CD's cable.  If it sounds good, wire it up properly :-)  I wonder, though, if the CD player will have enough output to compete with the headphone amp -- if not, you'd be stuck keeping the headphone amp section down very very low.  There are plans floating around for a headphone amp with an aux input, I'm pretty sure -- if I see them again, I'll ping ya.

ltt

Steben,
Actually the way I built it is with 2 LM386's (Right and Left). I put a dual pot at the output to cut the volume (yes I didn't to start with and my ears are still ringing). What I wanted to do was just bridge the cd (aux in) to the output channels (R/L) then I would control the cd volume with the cd player and the guitar volume with the output pot. My concern though is that I can't just bridge across without damaging either amp or the cd player by applying the 2 outputs directly together??

OK, distortion. So, I would need to build a distortion (FUZZ, OverDrive,......) at the guitar input (pre lm386) and only use the lm386 clean (which sounds great clean by the way)? If I did that, I would want to do something very simple. Maybe 2 trans. fuzz or overdrive another opamp. Any suggestions??

Thanks,
Scott

[wsgarner]

Dang Proxy servers. Mine at work is getting bad too!

I think I will build the 2 transitor distortion. I have the parts and should be able to knock it out pritty quick.

CD player??? Not sure what to do. I just biult (tonight) an effects loop box with a blend pot and switch for the in signal to blend in with the effects loop signal. It works great except that I can't hear any blend. If I get the blind up high enough to be heard in the mix, I get a crazy high pitched tone. The point I'm trying to make with this is that the 2 signals aren't playing together well. I suspect I would have the same kind of result with my cd/aux in idea. I think I would have to mix the 2 signals with a couple of opamps or transister circuit to get the mix to play together.

For know, I'm going to eleminate the cd/aux idea from my project; add a 2 trans distortion to the input and have fun. I don't like the Altoid box as the case, things got too cramped, so I'm moving it to an electrical box tomorrow (a light mount box/junction box from Lows). More room and it will be different.

As a side note; I used the lm386 headphone amp tonight to test my effects loop box. I just love the tone from that thing with a clean signal (no overdrive pins 1 and .

It's late and I'm going to bed!!
Later: thanks,
Scott

[Steben]

My idea? Some CMOS (4049 chips etc...) overdrive really tubes it up you know!