Ruby amp just wont work, PLEASE HELP!

[peps1]

Iv been trying to get a Ruby amp to work for weeks now!

Even ordered all new components, just incase......but all i get out of it is a VERY quiet fuzzed output?

Im using this breadboard layout:
http://www.beavisaudio.com/bboard/projects/bbp_Ruby_Rev_1_1.pdf

And here is my breadboard.







here are the +V at the chip pins

1: 1.36
2: 0
3: 0
4: 0
5: 1.36
6: 4.78
7: 9.54
8: 4.69

[PRR]

Transistor voltages please. Should be 9V, 1V-2V, and zero V.

I don't see a resistor/pot at LM386 pins 1 and 8. This thing should work without it, but odd that you do not mention this change?

The plan is in three halves: JFET buffer, volume pot, LM386 booster. Test each part separately.

Lift the wire from hole 12-e. Lift the wire from hole 25-a and put it in hole 12-e. Does it pass signal? (Should be unity gain.)

Put wires back.

Lift the wire from hole 20-c. Lift the wire from hole 1-a and put it in hole 20-c. Does it play? (Should be loud.)

[peps1]

Thank for the help.

Transistor voltages please. Should be 9V, 1V-2V, and zero V.
9.52v - 0.94v - 0v

Lift the wire from hole 12-e. Lift the wire from hole 25-a and put it in hole 12-e. Does it pass signal? (Should be unity gain.)
No signal

Put wires back.
Lift the wire from hole 20-c. Lift the wire from hole 1-a and put it in hole 20-c. Does it play? (Should be loud.)
Yes it plays, not very loud (but louder then before) but a lots of distortion.....FUZZZZZzzzzzz

[Brymus]

You can also try swapping pins 3 and 2 into the 386 if your output isnt floating this might help.
Also try taking your input straight into the 386 skipping the MPF102,to eliminate that.
The first thing to consider is your spkr you are going to get the best results from a high efficient guitar spkr 8-16 ohms the best.
This alone could explain the lack of volume.
I was using a 5" Jensen MOD spkr once with a 386 and it had almost no volume sounded awful then I put it in an enclosure and it sounded great,really great.
You really shouldnt get alot of fuzz until the gain is dialed up or you are overdriving the input,at higher volumes without ODing the input the 386 has a nice breakup,why IMO it has such a following.

[peps1]

You can also try swapping pins 3 and 2 into the 386 if your output isnt floating this might help.
Still have to put my ear to the spkr to hear it

Also try taking your input straight into the 386 skipping the MPF102,to eliminate that.
will try that and report back

The first thing to consider is your spkr you are going to get the best results from a high efficient guitar spkr 8-16 ohms the best.
Yep its a 8ohm and work well with the first ruby i made (worked perfectly, but i gave it away!)

[tiges_ tendres]

Jumper pins 1 and 8.  Or put a 10 uf cap between pins 1 and 8.  Do you have any volume now?

[Mugshot]

change your IC. i have experienced the very same problem before (the very low, fuzzed output). i had to buy a bunch of them LM386 and out of the 9 ICs i had, only one actually worked.

during my last visit to the parts store, i bought the last two left. only one of them worked. must be the IC then

[Scruffie]

Is your output pot connected properly? I find occasionaly when placed into bread boards they don't connect quite right and I have to push them in or attach seperate wires to the legs, just an idea.

[PRR]

> 9.52v - 0.94v - 0v
> No signal

DC voltages look OK, not going through pot, yet no signal.

> Yes it plays

Then in and out jacks are working.

It seems to be the blue cap in row "d", or just plain bad contacts in the protoboard.

> not very loud

It should be much louder. You may have more troubles.

[peps1]

Jumper pins 1 and 8.  Or put a 10 uf cap between pins 1 and 8.  Do you have any volume now?

More volume, but the background noise renders it unusable (with both jumper & cap)

change your IC. i have experienced the very same problem before (the very low, fuzzed output). i had to buy a bunch of them LM386 and out of the 9 ICs i had, only one actually worked.

tested 6 ICs now.....more in the post 

Is your output pot connected properly? I find occasionaly when placed into bread boards they don't connect quite right and I have to push them in or attach seperate wires to the legs, just an idea.

gave that a go, same results.

> 9.52v - 0.94v - 0v
> No signal

DC voltages look OK, not going through pot, yet no signal.

> Yes it plays

Then in and out jacks are working.

It seems to be the blue cap in row "d", or just plain bad contacts in the protoboard.

> not very loud

It should be much louder. You may have more troubles.

Switched the blue cap in row "d" and still the same, even built another on on a new breadboard with box fresh components.....same issue, low volume, and a tone of background noise with fuzzy output.




Even made a huminator from beavis http://www.beavisaudio.com/projects/Huminator/index.htm but still no good.

[stcook111]

Sounds like your 386 is running away. Try putting a 220uf electrolytic directly across pins 3 and 6 of the 386. If you used Radio Shack's LM386's this will most certainly solve the problem. They seem to be very susceptible to parasitic oscillations. This one gets me every time I use those darn things.

[Brymus]

Yes and a 10n as well,I always filter my power supplies this way now out of habit.
Two 220uf caps in series with a 100r in between them,and the 10n in parallel with the 220 connected to the V+ pin on the IC wouldnt hurt.
It has to be right at the pin though,there was a thread awhile back where the guy had it to far away and was having problems.
Now that it was mentioned I remember having a similiar issue resolved this way.
You should get good usable volume(for a quiet bedroom) without anything connected to pins 1 and 8,then adding a pot or 10uf cap will give you a big boost and lots of overdrive ability.
Check the ROG page for more on 386 stuff,Grace ,Big Daddy,Little Gem MK II, Ruby > all good designs with the 386.

[peps1]

Sounds like your 386 is running away. Try putting a 220uf electrolytic directly across pins 3 and 6 of the 386. If you used Radio Shack's LM386's this will most certainly solve the problem. They seem to be very susceptible to parasitic oscillations. This one gets me every time I use those darn things.

This made a huge difference, but only when the tone pot was add....but still a real improvement.

Yes and a 10n as well,I always filter my power supplies this way now out of habit.
Two 220uf caps in series with a 100r in between them,and the 10n in parallel with the 220 connected to the V+ pin on the IC wouldnt hurt.

any chance of a diagram to show how that would look 

[Mugshot]

i breadboarded one for the nth time this weekend and found out that the non-working 386 i had worked when volume pot is raised to 100k or higher. on mine, it works best with the output of the buffer stage directly plugged to the input of the 386 without the volume pot. and gain is open (i.e., leave pins 1 and 8 open).