From: moskowit@panix.com (Len Moskowitz)
Subject: Re: DIY bass cabinet notes
Date: Thu, 17 Dec 1992 14:27:14 GMT
Organization: PANIX Public Access Unix & Internet, NYC


Ralph Gonzalez writes:

>Speaker Builder is PO Box 494, Peterborough, NH 03458. Phone:
>603-924-9464. I've seen one project for a big bass cabinet (I
>think it's in the the 1990 backissues) which was pretty
>ambitious, but most of the articles are for hi-fi systems.

If I recall, it was a a 15" in a large sonotube (round reinforced
cardboard tube), with an array of Dynaudio midrange and tweeter domes in
another enclosure on top of the tube.  Looked like a transportation
nightmare to me.  I can't imagine those things surviving a steady
gigging schedule.

>For bass guitar it's nice to have the speaker flat down to
>80 Hz or preferably 40 Hz. You won't find any full-range driver
>which is really good for that. When you say you want the cabinet
>to emphasize the highs, I assume you're talking about the mids
>(200 Hz-1000 Hz), since no bass guitar I know of puts out any
>signal in the range where a tweeter is active (above 2-3 kHz).
>Try it -- if you put your hand over the tweeter while playing
>your bass, the only difference is you hear less hiss from the amp.

I've played with amps that have equalizers up to about 5 kHz and found
that there is a small amount of information that's lost if you cut off
below that.  You lose a bit of the sparkle and clarity on pick attacks.

>What I've done is to use a single largish (only 12" - should be
>15" I guess) woofer and a horn midrange to take over up to about
>2-3 kHz.

Eden and SWR use that approach, sometimes adding more woofers (and not
necessarily getting better bass response).  Eden quotes +/- 2 dB from 63
to 13 kHz for their D-210T cabinet (2 - 10's and a horn tweeter), and
down 6 dB at 30 Hz.  The D-410T (4 - 10's and a tweeter) is rated at +/-
2 dB from 80 to 13 kHz, and "usable" from 30 to 15 kHz.  The D-110T ( 1
- 10" and a tweeter) is rated +/- 2 dB from 60 to 13 kHz, and down 6 dB
at 31 Hz.

>If you only need to go up to about 2-3 kHz, you probably can do it
>with a single driver or an array of the same driver. I've seen a
>10" SEAS (25F-EWX) driver which has a very nice response up to
>2 kHz and a gentle rolloff above this. I think this would fit the
>bill for you. It has decent power handling and has a gradually
>rising response which emphasizes the midrange. If you put it in
>a properly-vented cabinet you can get bass down to 50 Hz. I would
>suggest an array of 2 or 4 to get more power handling.

I wouldn't use the Seas 25 F-EWX for bass guitar.  Yes, it has a good
extended high end (my Dynaco A-25 speakers use its cousin) but it really
only handles 50 Watts (perhaps a bit more), and it's rather inefficient.
It also doesn't go down much below 50 Hertz in a reasonably small
cabinet.  Perhaps a better choice in a hi-fi speaker (read that as "low
efficiency") would be the Peerless 831727 or the 831759, both 10"
drivers and part of their premium CC line.  The 4 Ohm 831759 is somewhat
more efficient (91.4 dB SPL for 2.83 volt input), and both are rated at
220 W max power.  They can provide some seriously low bass in small
cabinets too (~1.5 cubic feet).  They'll go up to 2 kHz or so on axis.

>Another good source is Madisound Speaker Components, 608-831-3433.

Madisound carries Peerless, but as you suggest, they no longer carry
Seas.

Enjoy!

-- 
Len Moskowitz
moskowit@panix.com
Newsgroups: rec.music.makers.bass