2.5" 4 ohm speakers - useable for small amps?

[graylensman]

I salvaged a pair of 2.5" 4 ohm speakers from a CD player. I'm thinking about holding on to these for a future build of a small amp like the Ruby: http://www.runoffgroove.com/ruby.html. Would these speakers work for such a build? thanks!

[bool]

low efficiency usually

[R.G.]

Define what you mean by "work".

They will make sound. The quality of that sound, especially as regards bass and high treble response will be... open to debate.

[Mark Hammer]

The frequency response will not likely be complimentary to guitar tone.  That doesn't mean it can't be, just that it wasn't as deliberately designed to complement guitar as something intended to be a guitar speaker.

As RG notes, there will be no inspiring bass from it, on its own.  You would need to design a cab that enhances bass specifically, in order to get a more pleasing sound.  So, a larger cab, with perhaps a tuned or quasi-tuned port.

That said, peole of reknown have had great fun and interesting tones, over the year using a Pignose.  And if you're going to pervert the sound with pedals anyway (which is, I assume why you're here), then the "natural" sound of those speakers isn't really an impediment to providing a usable mini-amp.

Just appreciate that it won't/can't be very loud.

I have some 2.5" 64-ohm speakers, pulled from old Mac Classics, that have a foam surround AND a big honking magnet, more typical of what yo might find on something at least double the diameter.  If you ever used one of those computers, those were damn impressive little speakers.

[R.G.]

One of the projects in the semi-infinite stack is a 1/3 scale Thomas Vox Super Beatle. I noted that if you divide the dimensions of everything about the Beatle by three, you come up with easy-to-find materials: 1/4" thick plywood and 4" speakers among those. Even 1/4" diameter rod/tube for the trolley.

I'll probably have to embroider/cross stitch the grille cloth, though. I did a test piece about 4" by 4" back when. Looked like a scale replica.

Some day.

[graylensman]

Thanks for the responses, folks! So, judging from comments, it seems like they'd work, but certainly won't put my Bugera V22 out of work. But that's ok - just looking to do a little learning and a little building. Similar to R.G., this will go on the semi-infinite stack.

[PRR]

> a 1/3 scale Thomas Vox Super Beatle. ...divide the dimensions of everything ...by three, you come up with easy-to-find materials: 1/4" thick plywood and 4" speakers among those.

I had the same thought, except about Altec A-7 and similar Theater Speakers. (Maybe 1/4 scale.)

As a fine fillip, the Fostex FE-104 is very nearly a 4" version of some fine 15" speakers like JBL D-130.

A *real* theater speaker has 3" or 4" diaphragm for highs. 1" domes are easy. (But tin-smithing 18 tiny horns for a proper multi-cell array seemed tedious.) 

If you don't look close, a 12AU7 is "kinda sorta" two WE 300B power triodes on small scale. (Not really...)

I did put two 3.5" *car* speakers in a box the rough proportion of a Fender Twin (two 12"). Worked good as a room music-speaker but was no tiny-Twin. Open-back (like a Twin) it was gutless. Closed-back it lacked the midbass throw of a real Twin. Can't beat sheer SIZE.

[tca]

I salvaged a pair of 2.5" 4 ohm speakers from a CD player. I'm thinking about holding on to these for a future build of a small amp like the Ruby: http://www.runoffgroove.com/ruby.html. Would these speakers work for such a build? thanks!

I wonder if it will go under 200Hz... and as soon you hit it with a distorted signal it will buzz and rattle, intermodulation will make a lot mechanical vibrations. But maybe it will sound "good"

[DDD]

I think the low-effective PC speakers (90 dB and less) with decent low-frequency performance are quite acceptable for the low-wattage amps.
Those tiny amps are especially good for home use, so they have to be quiet rather than loud.
All you need is to cut some high-frequency portion of the signal.
So, the said speakers do this work good.
Here's the sound of the heavily overloaded 2-watt SS output stage through Hi-Fi Yamaha NS-C125 2-Way 40(120) Watts Center Speaker (86 dB sens., 3" woofers, 0.8" tweeters).
Recorded with cheap Samsung GT-S5282 mobile phone.
http://zalil.su/529993
http://zalil.su/839076