Smallest amp ever?

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Smallest amp ever?

Postby allesz » 31 Jan 2010, 22:48

I had bad luck recently on my mission to build an overdrive capable of driving a speaker too:http://www.freestompboxes.org/viewtopic.php?f=2&t=8239
For this kind of thing I think I will go back to lm386 (any alternative someone?).

Anyway I built this: it is so simple and stripped down it makes you laugh... but it works great and gives a good clean sound too; no distortion was available on this IC, but the volume is very good, maybe louder than lm386.

It is now my new practice amp, I built it inside a carboard box with four small speakers (two from an old laptop and two from... I can't remember) the battery is held in place by some tape inside the "cab".
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Re: Smallest amp ever?

Postby lolbou » 31 Jan 2010, 22:53

So it runs on 9V? Any idea of the current draw?
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Re: Smallest amp ever?

Postby allesz » 01 Feb 2010, 12:53

Hallo lolbou, I noticed you changed your public image; did you recently had a baby? If so congratulation.

Yes, I power the amp with a 9V battery, but you can go as low as 3V according the datasheet. I have no idea of current draw, the datasheet don't give any direct information about it and I don't know a way to find it out by myself.

I only use it for praticing on the couch by night (the volume is quite loud when wife and babies are sleeping, so you will have to roll down a bit the guitar volume or the overdrive output) and I expect a single battery to last long (a couple of month maybe).
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Re: Smallest amp ever?

Postby lolbou » 01 Feb 2010, 13:11

allesz wrote:Hallo lolbou, I noticed you changed your public image; did you recently had a baby? If so congratulation.


Yes indeed, thanks! :D

allesz wrote:I have no idea of current draw, the datasheet don't give any direct information about it and I don't know a way to find it out by myself.


I should have gieven a look at it... :slap: But I guess you could place an ammeter in series between the 9V and the pin 1 and send a sine wave to estimate the average draw...

I have a TDA8941P from an old TV here and would like to try it, for guitar or iPod, I don't know...

The input imedance is quite low for a guitar, did you try it using a buffer to notice difference in sound?
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Re: Smallest amp ever?

Postby allesz » 01 Feb 2010, 18:27

Buffer.... well (they are misterious thing to me), I use the thing mostly by itself, but sometimes with a booster-driver made by me: viewtopic.php?f=13&t=7806; even if it is not a proper buffer I have to say that the sound does not change too much in term of volume/quality.

Compared to lm386 this IC gives you less flexibility in terms of sound, but it seems more clean, stable and reliable, and the one sound it gives is a good one.

TDA8941P seems similar to the tda7052... but it has a couple of pin I don't understand. It could be a good amp for music too (maybe the input cap can get bigger in that case) but it is a mono chip.
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Re: Smallest amp ever?

Postby allesz » 08 Mar 2010, 17:55

Yesterday I changed the first battery on the amp, the sound was getting more and more distorted and the volume was going down...
I used it quite a lot jamming almost daily on my couch with just an overdrive (boss od3, dod metal maniac, tube screamer and some other things made by myself) and sometimes a delay pedal.
So the power consumption seems to be on the low side... I think this thing will follow me on holiday :D
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