Speaker frequency response

[MetalUpYerEye]

Hi I'm building a Ruby Amp (for a bass guitar though) for a buddy of mine and he asked me to put it in a small box for portability. I asked him what size speaker he wanted, chiming in that anything under 8" would probably not yield near enough bass to sound halfway decent. He asked for a 3" speaker so I bought one for him at the local electronics store. My question is that on the package for the speaker it says that the Freq. Response is 1500-21,000 Hz, I know this has to do with the range of frequencies that the speaker will output but can someone explain it to me better? What is the basic frequency range of a guitar? Will this speaker give a decent sound or is the frequency range off too much?

[bancika]

It's very likely that it will sound very bad. I have two 3" and I tried them yesterday with my little gem mk2. It's too fizzy, distorts easily (with volume on guitar above half). The only way it doesn't sound too horible is at low volume clean and neck pickup. Even than it lacks bass, so for bass guitar it will be even worse. Get a speaker that's designed for bass.

[petemoore]

  regular ol stereo or car speaker is probably a good match for the Ruby, to get 'better', or higher spec than that might not sound more pleasing to you and might cost you more.
  Look at Jensen or Celestion specs to get an idea of where bass and guitar speakers tend to rolloff.

[Mark Hammer]

A cheap 3" speaker will typically have a frequency response of around 200hz to maybe 8khz or 10khz.  They are not intended to do much more than cover the range of the human voice and a little bit more than that.  Unless the specs of the speaker you bought are deliberately mis-stated (like those 180W "PMP" computer speakers you can buy for $10), the chances are quite good that you accidentally bought a tweeter, and not just a small "full-range" speaker.  This will obviously not work for bass, since it starts running out of fundamental tones below 1500hz.  If you haven't rendered it beyond returning, I'd suggest you bring it back and get a proper 3" speaker, if that's the size you are restricted to.

One of the things to remember about speakers is that the cone is mass that has to be moved, and it takes power to move it.  When large-cone speakers are under-powered, at least part of the tonal response is actually loss of treble, as opposed to emphasis of bass.  That is, the speaker voice coil is not being energized enough to move at the faster speeds that will allow it to produce high frequencies.  If anything can be said about the 386, it is that it is unlikely to blow your average 8-12" speaker.  While that may result in the illusion of lots of bass, the loss of treble definition is annoying.  As such, while I know some folks feel their 386-based amp sounds fabulous through their 4 x 12" stack, I suspect that all those folks are decidedly NOT aiming for a crisp single-coil sound, and are clipping the bejeezus out of their guitar before feeding it to the speakers.  If your aim is to be able to get a decent clean strumming tone, the ideal speaker may well be something in the 4-1/2 to 6" range. True, it won't sound like a 4 x 12 stack, but if the enclosure is of a reasonable size/volume, you needn't sacrifice all THAT much bass.  Consider a closed ported cab to your advantage.

The other thing is that if you intend to play a bass through it, you will absolutely need the sort of headroom and "headroom protection" afforded by a higher supply voltage (12v recommended)  and some sort of restricted gain in the amp itself and compression on the input.  Otherwise, you'll get mostly blats and farts.

[brett]

Hi.

If your aim is to be able to get a decent clean strumming tone, the ideal speaker may well be something in the 4-1/2 to 6" range.

As always, Mark is on the money.  Besides getting a reasonable size speaker (16 cm or 6 1/2 inches is common for car speakers), it is important to get an efficient speaker.  Poor efficiency means below 90 dB@1m per W.  High efficiency is 92dB@1m per W.  Many cheap car speakers sound weak with small amps because they have terrible efficiency (as low as 80dB). 

As well as having a decent speaker area, you can also boost the bass coming out of your LM386 by using a filter in the feedback loop (between pins 1 and .  See the LM386 application note for details.

cheers

[bwanasonic]

The trick to using small speakers (5") for bass is to use a lot of them in a well designed cab:

http://www.philjonesbass.com/TECH%20INFO/piranha.htm

Kerry M

[Tubebass]

Still using the Bose 800s I bought used 23 years ago, not usually for bass though. Eight 5" speakers per cab. No highs, no lows, must be Bose!

[KMS]

I've built some speakers cabs over the years...many.

That speaker you have will not work for much except high-mid-range.

Take a look at the frequency of musical notes at this web page.....

http://www.phy.mtu.edu/~suits/notefreqs.html

Low E on the Bass Guitar is about 41Hz if my memory serves me correctly.

At the most it is twice that which would be 82Hz.

You can get low tones and high db(s) from speakers that were not designed to deliver such if you build an exponential horn type cabinet.... but that is a lot of work, math, and materials and also defeats the purpose of being small and portable.

The best bang for your buck when it comes to small portable bass speaker response is to get a small PC style speaker system which will have a sub woofer that includes a small full range 4" or 5" speaker facing the back of the cab with a poly-foam insulation around the entire inside surface to help with compression and it will also incorporate a small exponential horn.  I'm looking at my 45watt GE system right now and it has real good bass response with a 6"x8"x10" cab, horn, poly-foam, and 4" full range speaker.

It was $30 at Best Buy and it would cost me about $60 to build it.