Can I cross the 288 driver under 500Hz in a proper horn

**Jimmy DIY** · January 21st, 2009, 12:19 AM

Can I cross the 288 driver under 500Hz in a proper horn?For Example, if I connect it into a WE15A horn, will it work down to 150 Hz as well as the WE555 diver do?

**Horn Savant** · January 22nd, 2009, 04:33 PM

If you look at 555 diaphragms, they appear to be similar in size & construction to Altec 802
(see pictures here: audio pag speakers - as you can see by these pictures, there's nothing special with the 555. Some 555s have vented backwave (555W I think) for lower resonance (and fullrange service ?)

The 288 must have an even lower resonance than an 802 or 555 , so if you can provide enough horn loading, then you can go down to bass. I have listened to a 16A with 555 and heard bass of around 70 or 80 HZ. I want to try this with 802s & 902s that I have once I construct a monster horn.

I once listened to a repro pre-war RCA compression driver running down to below 100 Hz on a suitable horn (picture)(best low midrange I've ever heard)

GM · January 22nd, 2009, 07:54 PM

As noted, the WE15A is designed for a 1" throat, so you'd have to truncate it to fit a 1.4" driver to it, raising its cut-off. Anyway, the 288's PWT performance implies a theoretical 9 Hz cut-off, so yes, properly loaded it can be XO'd well below 500 Hz if the horn is long enough with a large enough mouth to protect it, i.e. for a 2nd order XO it ideally needs to load an octave below the XO point.

GM

**Horn Savant** · January 23rd, 2009, 03:15 PM

Also, delicate headphone 'phragms - be they mylar or metalized - run full range no problem, The reason: low power drive. I just quick tested a 902-8B (for a theater today) full range by hooking it to an amp and listening close to the ear with minimal drive it sounded good on a talk radio program but had lots of natural bass rolloff.

**Jimmy DIY** · January 24th, 2009, 02:45 AM

Hi Horn Savant,
That's what I think if you can provide enough horn loading,why 288 can't down under 500Hz as well as WE555? Thank you very much for your answer!

I found a WE22A horn replica that can help to provide enough horn loading to 288 or 802s & 902s(with modify adaptor), the manufacturer use it in a RCA MI-1428 replica that down to 150Hz,if you interested in it,please PM me and I send you the link.

Rgds

Jimmy

**Jimmy DIY** · January 24th, 2009, 03:00 AM

Originally Posted by GM

As noted, the WE15A is designed for a 1" throat, so you'd have to truncate it to fit a 1.4" driver to it, raising its cut-off. Anyway, the 288's PWT performance implies a theoretical 9 Hz cut-off, so yes, properly loaded it can be XO'd well below 500 Hz if the horn is long enough with a large enough mouth to protect it, i.e. for a 2nd order XO it ideally needs to load an octave below the XO point.

GM

Hi GM,

I think no people will truncate the WE15A horn to fit the 288 driver because the WE15A much more expensive than the 288! I found a cheap WE22A horn replica that provided 1" and 1.5" throat to fit various drivers. The size is small enough to go through the door in normal apartment! That's the reason why I consider it.

Rgds

Jimmy

**Horn Savant** · January 26th, 2009, 02:09 PM

In tests I did, I found the Altec 1" drivers had better LF performance than the bigger 288s.
I used a larger rear cavity (lower resonance)(a long polypropylene pouring jug stuffed with wool for no back wave reflections and crossed over at 250 hz (4th order) to 511s (tho a bigger horn would have been better I suppose). A whole new world of lower midrange magic.

**valhallax** · January 26th, 2009, 09:43 PM

i saw an add one time only for a horn setup for ale drivers. it was a mono job, but the horn mouth was huge, as was the length. it was on the bay and only the horn was for sale. havent seen anything like it since, but the guy claimed pure bass bliss. i cant imagine this being a full range system tho. anyone with more pics? anyone ever run a 288 through hornresp? i just downloaded hornresp, and, i think i need a crash course or maybe lots more free time.

**bfish** · January 26th, 2009, 10:37 PM

Originally Posted by valhallax

... i just downloaded hornresp, and, i think i need a crash course or maybe lots more free time.

I doubt if there is such a thing as a crash course.

The newer help files are greatly improved, but from my experience, you need to already have a full grasp of all the elements (and I don't). The program just saves lots of recalculations every time you change a parameter.

A good primer would be to simulate a well-documented, existing system until you get results that approach the real thing. Even that ain't easy.

I'm known for being stubborn, but I gave up on that one. (The wheels fell off and burned).

May the force be with you.

GM · January 27th, 2009, 02:02 AM

FWIW, the various 'wizards' makes it pretty easy to use now. WRT inputting a compression driver into a simming program, accurately measuring its specs is no trivial pursuit due to it being so well damped with a tiny Vas and ultra low Qes, not mention measuring the front chamber's volume and effective throat, so good luck with that.

GM