Smokey amp in a pedal

[BulletBill]

I want to take the dirty sound of my Smokey amp and put it in a pedal now that the cigarette box it came in has disintegrated. I can solder well enough but I'm a complete novice at putting together stuff like this.

Could take off the 9v battery input and swap it for a DC power input? How easy is this?
Can I just disconnect the speaker or would I need to put a resistor in?
I've read that I'd need a 10k pot to control the level, where would I connect this?
How easy to achieve is true bypass in something like this?

There's a schematic here but I'm ashamed to admit that it means very little to me. As such, I would be extremely grateful for any help or advice I can get.

-BB

[MikeH]

I want to take the dirty sound of my Smokey amp and put it in a pedal now that the cigarette box it came in has disintegrated. I can solder well enough but I'm a complete novice at putting together stuff like this.

This explanation may sound complex, but it is pretty easy.  You'll need an enclosure, a switch (3pdt or dpdt), a DC jack, and possibly some different input and output jacks.

Could take off the 9v battery input and swap it for a DC power input? How easy is this?

Yes, you can actually use both if you wish.  The + wire (probably red) on the battery snap can be connected to the DC jack.  Check out #2 on this page here:

http://www.tonepad.com/getFile.asp?id=76

It shows a diagram to wire up a typical fx board.  You can just leave off the battery snap connections if you dont want to use one.  If you remove the snap part, connect the + wire from the board to the appropriate connection on the DC jack shown in the diagram.  The - connection will connect to the large lug on the DC jack

Can I just disconnect the speaker or would I need to put a resistor in?

No resistor is necessary.  Since the smokey amp is advertised as being able to drive a speaker or connect directly to an amps input, you can hook it up as if it was driving an amps input.  Just remove the speaker- that is where your volume control will go.

I've read that I'd need a 10k pot to control the level, where would I connect this?

Take the positive lead that went to the speaker (or attach a lead to where the tip of the output jack is connected), connect it to lug 3 (left most lug, looking at the back of the pot with the lugs pointing down).  Lug 2 connects to the bypass switch.  In the tonepad diagram "out" on the circuit board is the same as lug 2 on this pot.  Lug 1 connects to ground.  You can probably use anything from 10k to 100k.  Make sure you use an audio taper pot, as opposed to linear.

How easy to achieve is true bypass in something like this?

The tonepad diagram shows several different true bypass methods.  If you want to hook up a status LED, the easiest method would be number 5, using a 3pdt.  If you don't need/want an LED, then number 2 would work best for you using a dpdt bypass switch (it incorporates the DC power jack).  My guess is that the input and output (aka speaker) jacks on that smokey are mounted directly to the pcb; in this case you'll have to remove them from the pcb in order to do the bypass switching.  You'll then have to hook up leads to where the tip and ring were for the input jack, these will be the "IN" and "GND" connections on the board in the tonepad layout.  You might be able to use the jacks you removed for your input and output jacks, but soldering to pcb pins instead of lugs in a little harder, and prone to failure.


Now... that all being said.  This is an incredibly simple circuit, and to be honest, I think it would be easier to build one from scratch, as opposed to disassembling this one and putting it all back together.  Just my 2 cents.  You may want to have a look at something like this:

http://www.runoffgroove.com/grace.html

If you compare the schematic you posted to the schematics in this article, you'll note they're actually pretty similar.  These will have the same character as a smokey, but will sound much, much better.  And the perf layouts they have there are really easy to follow.

[BulletBill]

Thanks a lot for your reply, it's very helpful. I'm still a little unclear as to how to incorporate a volume pot.

Could I just put one before the output connection and keep a bypass connection? I don't know if that makes sense.

I prefer the Smokey's sound to the audio demos on that site your posted. It's a bit warmer and I like that.

[vendettav]

ok see this pic?


basically what you need is that
the wire that goes to speaker's + and this is your Signal In in the diagram showed above
the wire that goes to speaker's - is your ground (you know what a ground is i am sure )
the Signal Out going from the pot is your output. hook it back to your bypass switch and there you go

[BulletBill]

Thanks a lot, that makes it all clear.

Well, I've got all the bits and pieces coming in the post and I'll post my results when I'm finished/get completely lost.

[vendettav]

haha at the /get completely lost

good luck man 

[FiveseveN]

I prefer the Smokey's sound to the audio demos on that site your posted. It's a bit warmer and I like that.

A lot of the "Smokey sound" comes from the limited frequency response of its tiny speaker. This is not news. Check out this video to compare the sound of its internal speaker vs. the Smokey run through a Mesa 412 (toward the end of the clip): http://www.youtube.com/watch?v=iqbe69nxd-U
Using the same circuit as a "pedal" (i.e. before another amplifier) would not provide the same sound, though it wouldn't be terribly difficult to get close.

[BulletBill]

I prefer the Smokey's sound to the audio demos on that site your posted. It's a bit warmer and I like that.

A lot of the "Smokey sound" comes from the limited frequency response of its tiny speaker. This is not news. Check out this video to compare the sound of its internal speaker vs. the Smokey run through a Mesa 412 (toward the end of the clip): http://www.youtube.com/watch?v=iqbe69nxd-U
Using the same circuit as a "pedal" (i.e. before another amplifier) would not provide the same sound, though it wouldn't be terribly difficult to get close.

I mean I like how it sounds when driving my amp

[deadastronaut]

as mike said, just build another, and experiment....it'll only cost a couple of quid..whoops dollars etc...

very easy to build...it'll take ya an hour or so really max...

[LucifersTrip]

Can I just disconnect the speaker or would I need to put a resistor in?

No resistor is necessary.  Since the smokey amp is advertised as being able to drive a speaker or connect directly to an amps input, you can hook it up as if it was driving an amps input.  Just remove the speaker- that is where your volume control will go.

mine did not work properly unless I had an 8 ohm resistor across the output jack

[MikeH]

Wouldn't an 8 ohm resistor across the output jack pretty much ground the signal?  That doesn't sound right to me.

[PRR]

> Wouldn't an 8 ohm resistor across the output jack pretty much ground the signal?

The amp is basically a LM386, made to drive 8 to 16 ohm loads.

A simplified "Ruby Amp".

It does not need a load to function, though in some cases the sound will change, and in some layouts an unloaded '386 may be unstable (jiggle at radio frequency, which screws with the audio response).