Need info on alternative speaker for cheap amp design

[Roshihyde]

Hi I'm working on a project amp and I'm trying to spend as little money as possible. I took 2 sets of speakers out of an old stereo system and the smaller ones are 8 ohms while the bigger ones are 6 ohms. the instructions I have call for the 8 ohm speaker but what I want to know is will two 2'' speakers put out enough volume or will I have to use the bigger ones, and if I use the 5'' ones what do I need to change in the design?


Here is a picture of the speakers


And the is where I got the instructions
How To make a Guitar Amp (Cheap)!!!

And here is the site with the written schematic
http://runoffgroove.com/littlegem.html

[Chuck H]

If this is in regard to a guitar amplifier I doubt you'll get much feedback (pun intended). There are too few precedents for 5" and 2" speakers WRT guitar amps to expect advice. Speakers may be where the $$$ needs to go for this project. 8", 10" and 12" speakers are where it's at for guitar amps. Unless this isn't a serious project.

[Roshihyde]

Im really just trying to do this as my first full DIY project and I'm using as many materials I already have as possible.

[J M Fahey]

Use the larger one; the smaller one is a TWEETER.

[Roshihyde]

Can I use it without changing anything other than the speaker?

[scrimpus]

Yes, You can use it without changing the design.

[Roshihyde]

Awesome. Can I also use 2 speakers without having to alter anything except adding the extra speaker?

[Brad1]

Be aware that home stereo speakers are not really suitable for electric guitar amplifier usage. The design and construction are different, as are the frequency responses and other factors that guitar amp speakers need to respond properly and sound good.

Using home stereo "woofers" in a guitar amp will yield, at best....mud. Indistinct, bass and low-mid heavy sound, with no high mids. Guitars are all about midrange.

If you want to build more of a "full-frequency" acoustic/electric guitar amp, though, those may be suitable for experimentation. AE amps will generally have a low/mid driver and a tweeter. It's to reproduce an acoustic guitar sound.

To do that, you'd need to have a crossover to separate the highs and lows, and send the lows to the woofers and the highs to the tweeters.

You also have impedance issues in what you state. Two 6 ohm speakers in series will add up to 12 ohms. Two 6 ohms in parallel will divide to 3 ohms. You state your amp wants an 8-ohm load.

Is it a solid-state amp, or a small tube amp? That needs to be considered.

This is not a serious project, if you are looking for usable, good sound. If you are just experimenting, though, if your amp wants 8-ohms, then one of the 6-ohm speakers should be close enough to goof around with. Just don't expect it to sound like a good electric guitar amp.

You need guitar amp speakers, designed for that. They are voiced more appropriately, and generally have stiffer surrounds. The surrounds on your stereo speakers are likely fairly "spongy" and loose. They are that way to allow for more excursion to better reproduce bass, and thus, are not stiff enough to produce tighter mids and highs that are in the full range of an electric guitar.

Brad1

[Jazz P Bass]

Being that this is a solid state amplifier, the output wattage of the LM386 iC is dependant on the power supply voltage & the load.

Also there are different versions of the IC.
The LM386 'N' has the highest dissipation rating.

If you are using one speaker, I would not go much lower than the 8 ohm rating stated in the ic's datasheet.

If you go for more than one speaker, wire them in series, not parallel.

Link: http://www.ti.com/lit/ds/symlink/lm386.pdf

[Roshihyde]

Its a solid state. Heres the design for it. http://www.instructables.com/id/How-...tar-Amp-Cheap/ Yeah this is kind of a goof around and see what we can do project but its more of a learning experience. I've been enjoying this as a small hobby repairing my own guitars and I've been wanting to learn more about it so I can build and design amps and guitars one day.

[g1]

If you are using one speaker, I would not go much lower than the 8 ohm rating stated in the ic's datasheet.

If you go for more than one speaker, wire them in series, not parallel.

Jazz: I gave up looking for a minimum load spec in that data sheet, where did you find it? Page 5 shows a graph with power output into 4 ohms?

Regardless, as you stated, if he wants to use the two 6ohm speakers they need to be wired in series.