adding tweeter to amp

[ndxs]

what I'd like to do is add a tweeter to my guitar amp that is swtchable, (on/ off) for playing my acoustic thru it, presumably making it sound better, like when it's played thru the PA.
this way I can still use the built in effects of my amp on the acoustic gtr.
So my questions would be
1. do I need to wire a capacitor in between the 12" speaker and the tweeter.?
2. what value should the capacitor be.?
3. does the tweeter get wired in parallel w/ the 12" speaker?
4. do you actually think it will make the acoustioc sound better thru the amp by doing this?
thanx, I appreciate any educated input.

 

[Major Tom]

Yes, adding a tweeter will make it into a passable acoustic amp. (the purists will disagree) I do this with a little 20 watt tube amp I have, and for what little I use it it works great.
If you use a conventional tweeter, you will need a crossover capacitor - non-polarized electrolytic. Guitar speakers freq. response starts dropping off around 5000 hz, so you will want the crossover point somewhere in that vicinity. You can do a search on the net for crossover cap and find the value, it will vary according to your amp's speaker impedance. Yes, it would be wired in parallel, with the capacitor wired in series. Adding a tweeter will not affect your overall speaker impedance enough to matter. You can wire it into a 20 watt L pad, which is like a tweeter level control on a stereo speaker, when you turn it down all the way, it will be off, so no need for a switch. Guitar speakers are usually pretty efficient, so use a tweeter with a fairly high efficiency rating, so that it will be loud enough.
What I use is a lot cheaper - I had a Motorola-style Piezo horn tweeter laying around, so I used that with test lead clips on the ends of the tweeter's leads. I think you can get these for $10 or less. When I want to use it, I clip it onto the speaker's terminals and set it on top of the amp. The piezo tweeters don't need a crossover, they only reproduce frequencies starting at around 5000 hz or so, a good match for your amp's speaker.
Either way, you will need to connect the tweeter so that it is in phase with the amp's speaker.
It won't sound as good as a dedicated acoustic amp, but it works pretty well as an acoustic guitar monitor, the tweeter adds the high end sparkle that's missing in an electric guitar amp.