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Author Topic: Noisy Cricket problems!  (Read 17618 times)

dan6896

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Noisy Cricket problems!
« on: February 02, 2011, 12:01:20 AM »
Ok, so i built a noisy cricket following the schematic on beavisaudio.com,turned it on and plugged my guitar in it sounded pretty good. but when i turned the volume up and started playing it made this horrible fuzzy sound, same with the gain pot. :grr  when i turned the boost switch on it sounded absolutely terrible :grr :grr. its really hard to describe the sound that it makes. Whenever i play a note it makes the same fuzzy farting sound but it is dead quiet when nothing is being played. I have checked the schematic to my layout and it is all connected fine. i have tried many different speakers and it all sounds the same

any ideas on how to fix this.

in advance thanks for the help, ;)




DJPhil

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Re: Noisy Cricket problems!
« Reply #1 on: February 02, 2011, 04:20:29 AM »
I'm not entirely sure what your trouble is, but I have something you can try. I made a Ruby (similar 386 amp) for a friend, and he found that it sounded horrible if his guitar's volume wasn't turned down a good bit. He's got an axe with an (my opinion) absurd amount of pickup options on it, and it ran a bit hot for the Ruby.

The Ruby's volume and gain controls are very, very interactive and require a lot of tweaking. In the Ruby we'd often turn the volume up, the gain down, and slowly bring up the gain until it started breaking up at about 1/3. With the volume at half the gain would go to about the same. Exceeding that brings the clipping on hard and the sound gets horrible.

If you dink with it a while and have no luck you might consider trying to post a sample of the audio, as it'd be really useful if it turns out to be a bugger.

Hope that helps. :)

joecool85

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Re: Noisy Cricket problems!
« Reply #2 on: February 02, 2011, 05:53:10 AM »
I haven't built the Noisy Cricket, but I did build the Little Gem which is a more basic LM386 design at runoffgroove.com.  The only time mine got "farty" was when the batteries were low or I had a grounding out issue.
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J M Fahey

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Re: Noisy Cricket problems!
« Reply #3 on: February 02, 2011, 07:51:23 AM »
Please post the schematic here, so we all refer to the same one.
A picture would also help, to see your layout.
Never built a Noisy Cricket , but the simple 386 one (similar to the Smokey), and had no farting problems.
Yes, it overdrives easily, but in a pleasant way.
In fact there even is a distortion pedal based on it.

dan6896

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Re: Noisy Cricket problems!
« Reply #4 on: February 03, 2011, 01:59:39 AM »
ill try and post a picture in a couple of days. i was gonna post a sound sample but my mic screwed up :grr

schematic attatched:

ps: im using an lm386N-4

thanks everybody :tu:


J M Fahey

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Re: Noisy Cricket problems!
« Reply #5 on: February 03, 2011, 10:58:44 PM »
Well, with no volume and minimum gain, what's the DC voltage on LM386 pins   6 and 5?
What's Q1 (Fet) source voltage?
In that schematic, C3 should be 10uF and don't know what C4 is supposed to do.
I would not use it at all.

dan6896

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Re: Noisy Cricket problems!
« Reply #6 on: February 03, 2011, 11:21:38 PM »
from what i believe c4 is  switchable to get extra grit.

ill post the voltages soon.

i tried it on 12v power and it sounded much better but it has the same kind of farty sound

Alexius II

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Re: Noisy Cricket problems!
« Reply #7 on: February 04, 2011, 03:04:43 AM »
Have you tried it with a battery?
By your description, this could be caused by a "bad" power supply (and/or a ground loop), as joecool already stated.

Try a battery or another power supply  :tu:

dan6896

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Re: Noisy Cricket problems!
« Reply #8 on: February 04, 2011, 03:15:31 PM »
i used it with a 12v power drill battery which had about 13.8 volts

Dimi Pana

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Re: Noisy Cricket problems!
« Reply #9 on: October 25, 2011, 05:39:16 PM »
Well, with no volume and minimum gain, what's the DC voltage on LM386 pins   6 and 5?
What's Q1 (Fet) source voltage?
In that schematic, C3 should be 10uF and don't know what C4 is supposed to do.
I would not use it at all.

Hello, JMF !!!

Are you absolutely sure this C3 should be 10μF instead of 100nF ? What is the reasoning behind that? I am not questioning your input -on the contrary- I am just curious why, just want to learn.

Also, when jumpering pins 1 and 8 of the LM368, should n't a capacitor be in there as well? I read somewhere about this but unfortunately do not remember any specifics.

Thank you!

joecool85

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Re: Noisy Cricket problems!
« Reply #10 on: October 26, 2011, 02:01:22 PM »
Also, when jumpering pins 1 and 8 of the LM368, should n't a capacitor be in there as well? I read somewhere about this but unfortunately do not remember any specifics.

On all three LM386 amps I've built I jumpered 1 and 8 directly, no cap or resistor.
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J M Fahey

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Re: Noisy Cricket problems!
« Reply #11 on: October 26, 2011, 05:25:42 PM »
Fact is, LM386 was designed with *extreme* simplicity in mind.
So much so, that it includes the gain setting negative feedback resistors.
To provide you an option, one of them is connected between pins and 8.
Open: "normal" gain, good for most uses.
Shorted: quite a lot more.
But there is some DC voltage betwen those pins, so if you add a pot there to vary the gain, you need a cap in series with it or it will scratch.
If you add a gain switch, it will pop when activated.
If the connection is fixed, no problem, can use or not the 10uF cap at will.
a 100nF cap is too small and, best case, will work as a bright control.

Dimi Pana

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Re: Noisy Cricket problems!
« Reply #12 on: October 26, 2011, 11:20:18 PM »
Also, when jumpering pins 1 and 8 of the LM368, should n't a capacitor be in there as well? I read somewhere about this but unfortunately do not remember any specifics.

On all three LM386 amps I've built I jumpered 1 and 8 directly, no cap or resistor.

OK, I am getting a little confused, but that's normal for a novice, right?

So, the LM386N-1 datasheet http://www.national.com/ds/LM/LM386.pdf says:

"With pins 1 and 8 open
the 1.35 kΩ resistor sets the gain at 20 (26 dB). If a capacitor
is put from pin 1 to 8, bypassing the 1.35 kΩ resistor, the
gain will go up to 200 (46 dB). If a resistor is placed in series
with the capacitor, the gain can be set to any value from 20
to 200."

First the 1.35 kΩ resistor from the datasheet, where is it on the NC schematic?

Second, regarding the pin1-8 gain thing, what is the difference between the two approaches? What are the benefits or simply the rational behind each design?

I guess if I want max gain without a gain pot I do it like you Joe, otherwise if I want to vary the gain from 20 to 200 then the original NoisyCricket design is correct right? But there is no capacitor in the NoisyCricket. So what's going on?

Also, that C3 cap is connected to pin 7 which is labeled as "bypass". Bypass, of what? The way I see it pin 7 is also connected to pin 5 (Vout) via the the "grit" switch and C4. I mean pin 7 is there for a reason, so why is it labeled "bypass".

So that C3 what is it doing there and is the NC value correct or should it be changed to 100nF instead of 10μF and why?

Thanks!
« Last Edit: October 27, 2011, 12:21:13 AM by Dimi Pana »

Dimi Pana

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Re: Noisy Cricket problems!
« Reply #13 on: October 26, 2011, 11:38:51 PM »
Fact is, LM386 was designed with *extreme* simplicity in mind.
So much so, that it includes the gain setting negative feedback resistors.
To provide you an option, one of them is connected between pins and 8.
Open: "normal" gain, good for most uses.
Shorted: quite a lot more.
But there is some DC voltage betwen those pins, so if you add a pot there to vary the gain, you need a cap in series with it or it will scratch.
If you add a gain switch, it will pop when activated.
If the connection is fixed, no problem, can use or not the 10uF cap at will.
a 100nF cap is too small and, best case, will work as a bright control.

In my case, the 386 being simple is good.

So since I do want a Gain control, do I follow the NC design exactly or do I add the extra 10μF cap in series with the variable resistor between pins 1 - 8? And what designation do we give that cap so I do not confuse it with C3. And what is the purpose of C3 ???

Thanks!

 
« Last Edit: October 27, 2011, 12:20:53 AM by Dimi Pana »

J M Fahey

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Re: Noisy Cricket problems!
« Reply #14 on: October 27, 2011, 09:34:05 AM »
This Forum tries (and does !!) help, but it's not Electronics 101.
We try to answer most questions, but when *every* part of a circuit has to be explained, the effort does not justify the result, mainly because we try to offer answers which are useful for as many users as possible.
Explaining in great detail *one* circuit to *one* user is not the idea.
What about the thousands others who follow us?

Am I implying everybody has to be an Electronics Engineer to participate here?
Not at all, quite the contrary, the Forum is based on "regular" musicians which have depeloped an interest on how the Electronics they use all day long happen to work.
You do not *need* to know any Electronics theory to build one of these projects, such as the Noisy Cricket, just need to follow building instructions, play, and be happy.

The published circuit and instructions *do* work, the project is popular and has been built by thousands, just build it as-is , play, and then share your experience with us.
After that, you can continue advancing, the Sky is the limit.
Meanwhile read datasheets, suggested application notes, they provide a wealth of information.
Good luck.