Very small high efficiency speaker for Ruby

[Heemis]

Hey everyone,

I recently came across a great little transistor radio in which I'm going to house a Ruby amp.  The radio has a 3 inch speaker which actually works with the circuit, but i'm thinking a higher efficiency speaker, or a speaker that is made for a guitar would be better.  Anyone have a source for a high efficiency or guitar specific 3 inch speaker??

Thanks in advance!

PS the radio has two 2SB77 transistors in it... could these be used for anything useful?

[JKowalski]

You'll have to search around. All you should look for is one that has a frequency range that covers all the guitars notes - which goes from about 80hz (low E) to a 25th fret F (1500hz). You are definitely not going to find one that is made for guitar specifically, considering the size.

This one looks fine:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=102-1179-ND

I was going to do the same thing! Twas looking for a transistor radio to use. I was planning on getting/making one of those leather carrying cases for it too, to make it a super portable amp   




If you are looking for a louder speaker, you really have to get a bigger speaker. More surface area = Higher power/output efficiency. And keep in mind - guitars simply do not sound as good on small speakers - ther is a limit to what you can do here. You may want to just stick with the one you have. But I suppose it cant hurt to spend $2.50 to try another one out.


Af for the transistors:

I looked them up

http://www.datasheetcatalog.org/datasheets2/38/38116_2.pdf

And they are PNP germanium. People enjoy using them in fuzz pedals and distortions due to germanium's unique response to clipping (which IMO is not that noticable). In most other applications, I would use a silicion modern transistor instead of a germ as germaniums are noisy, leaky, and temperature sensistive. The most common use for PNP germaniums is in the fuzz face.

[Rob Strand]

You can only go so far with increased efficiency, there is a limit to what you can make and buy.   A bigger speaker is usually the best way to increase efficiency.  The other is to use stronger magnets (bigger), or make the cone lighter - a lighter cone generally means the bass response is chopped off more ie. the resonant frequnency increases as a result of the lower cone mass.   There is usually limited technical data on small speakers but site I'd be looking at the ones with the larger magnets.   As to the sound they are all over the map and the sound doesn't have much to do with the efficiency.

[Heemis]

Thanks for the replies.  I actually built up the amp last night and it sounds pretty good using the original speaker.  I was only thinking that I would be able to get a bit more volume out of a higher efficiency speaker, because that has been the case in previous ruby builds I've done.  I'll probably pick up a new speaker just for the chance that this one blows... it looks a bit frail.