Jubilee 2-way Horn Question

[BiggerIsBetter]

Greetings,

I have not posted in awhile but have been lurking, I had trouble with my password around the time of the site migration and never took the time to get it worked out until now.

I believe I have completed the path with my super corns and am now in the processing of moving on to the next bestest thing ever.

I have my base bin, rear loaded scoop with JBL 2240 drivers, and have decided on BMS 4590 drivers which I am in the process of ordering.

I have a 400hz Tractrix (supossedly, looks more like a 500-600 to me) mid horn, but I want to get the cross over down to somewhere between 200-300. I have already convinced myself that the driver will go this low in my application so please don't try to ruin my fantacy on that.

There seems to are very few options for horns that large.

First, we have the very nice looking bentwood 200hz exponential horns for a rather attractive price ($495).

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=002&item=120029495060

Having performed the highly scientific human voice (i.e. mine talking through it) test through like size tractrix and exponential horn, and adding in what I have read, I really done want to invest further in an exponential horn

Next, we have a VERY large 140 hz round tractrix, also at a reasonable price ($1000).

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9718926978

This horn is too large, never thought I would say that, (approx 36") and by the way shipping alone is around $1200.

Last, we have the new ORIS 250hz horn, it does not say whether it is tractrix or not, that has been specifically tested with the BMS driver. Cost, not including assembly or painting is around ($1200). More at http://www.bd-design.nl/

With that long winded intro, my questions related to the Jubilee horn are:

1. It is obvious that the KPT-402-HF is a large horn, what is the expected cutoff? Will it go to 200hz

2. I read that they may be available for sale, Roy POC, but can't find that thread. Is so, any price on the horn only?

3. Any input on the Jubilee horn versus the other options stated, in this application, are greatly appreciated.

4. Other options, besided build my own...

Thanks!

[DrWho]

So your bass bin is the fixed variable? What is its directivity and

frequency response in the 200Hz region? This will ultimately determine

the necessary performance for your top-end. I'm pretty confident that

with today's technology you'll never achieve 200Hz - 20kHz with a

single driver without severely sacrificing other aspects of the

performance.

Also, the coax design of the 4590 will require some fancy phase-plug action to achieve smooth controlled extension into the higher frequencies.

Are you absolutely sold on the concept of 2-way, or is 3-way an

optional alternative? Can you crossover at a higher frequency? Say

above 500Hz?

I don't mean to be negative, but there are some serious hurdles that

will need to be jumped over - and to the best of my knowledge there are

no such solutions yet available.

[BiggerIsBetter]

I have not tested the bass bin and expect them to be significantly flawed and would not considered them a fixed point. I am fairly sold on the BMS driver, give the single source point and ability to get down to near 200hz (several sucessful reports of that in "high end' audio now). The bins are way undersized, not sure if they even qualify as a horn, for an 18' driver at approx 2'x2'x3+'. There is only one "fold", like a larger (and back loaded) LB76 (I thnk I got that number right)

I am triamping and expect to be using a digital crossover/EQ. As such, I expect to be able to use the parametric eq to resolve most of the nasties. I am not looking for the last word, my priorities are "big" immediate sound that can reproduce the bass with enough energy to provide a "realistic" experience. In comparison, I love my Corns but the bass in no way come close to meeting that criteria.

Besides, if I build the "perfect" speaker I would not have the opportunity to continue to play around....what fun would that be?

[Duke Spinner]

I have my base bin, rear loaded scoop with JBL 2240 drivers, and have decided on BMS 4590 drivers which I am in the process of ordering.

Well ...

Ya already got the Scoops ....

getsum 2360's, cross at 600-800 hz, an be done with it ...

(check my Sig....[] )

[jwc]

Are you a DIY guy. I would just read Edgar's midhorn article and use the same principles to build a tractrix horn with a lower cutoff.

I made the templates for a 223Hz Tractrix horn for 2" driver. The mouth is 24" x 12". It is pure tractrix down to the millimeters but have not put it together yet as other projects in my way right now.

[DrWho]

Here's an interesting PDF:

http://www.eaw.com/Docs/AX/AX_whtppr_L.pdf#search=%22ring%20radiator%20polar%20response%22

The EAW AX series are very nice sounding too.

They mention some of the concerns that I'm talking about. No design is perfect - just trying to spotlight the trouble areas cuz that's where the compromises come into play (see sig).

[BiggerIsBetter]

Excellent reference, thanks!

In the equation f min = 1129 ft/sec / (D/4)

where D is the horn mouth dimention, intuition would tell me that D should be in feet. The answer I got (i.e. around 1200 hz for a 40" wide K402 in the horizontal) does not seem right. Should D being in inches?

Regarding the challenges of a coaxial, it seems the challenges they are addressing are related to a cone mid with a compression high. The BMS is a compression driver for both the MF and HF.

Looks like it's not too bad as long as I sit within 10 degree off axis, I can live with that.

I would hate to even see the temporal alignment of the scoops I have. Good thing I only paid $750 for the pair of cabinets with JBL 2240 drivers (reconed with non-JBL parts of course for that price...)

[D-MAN]

Try

wavelength = 13200 / Fc (13200 = speed of sound in inches per second)

circumference = 1/3 wavelength

diameter = circumference / pi

which gives diameter in inches.

Also MOST designers use 1/3 of a wavelength instead of 1/4 which gives a much smaller mouth size.

Keele, Edgar, Leach, etc. formulas are all based on 1/3 wavelength of Fc=circumference of mouth. 1/4 can be a little small and would require very accurate reactance annulling to prevent "peaking".

To calculate mouth area the formula is pi * (r * r) or radius-squared where r=radius (1/2 of diameter).

DM

[bodcaw boy]

Greetings,

I have not posted in awhile but have been lurking, I had trouble with my password around the time of the site migration and never took the time to get it worked out until now.

I believe I have completed the path with my super corns and am now in the processing of moving on to the next bestest thing ever.

I have my base bin, rear loaded scoop with JBL 2240 drivers, and have decided on BMS 4590 drivers which I am in the process of ordering.

I have a 400hz Tractrix (supossedly, looks more like a 500-600 to me) mid horn, but I want to get the cross over down to somewhere between 200-300. I have already convinced myself that the driver will go this low in my application so please don't try to ruin my fantacy on that.

There seems to are very few options for horns that large.

First, we have the very nice looking bentwood 200hz exponential horns for a rather attractive price ($495).

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=002&item=120029495060

Having performed the highly scientific human voice (i.e. mine talking through it) test through like size tractrix and exponential horn, and adding in what I have read, I really done want to invest further in an exponential horn

Next, we have a VERY large 140 hz round tractrix, also at a reasonable price ($1000).

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9718926978

This horn is too large, never thought I would say that, (approx 36") and by the way shipping alone is around $1200.

Last, we have the new ORIS 250hz horn, it does not say whether it is tractrix or not, that has been specifically tested with the BMS driver. Cost, not including assembly or painting is around ($1200). More at http://www.bd-design.nl/

With that long winded intro, my questions related to the Jubilee horn are:

1. It is obvious that the KPT-402-HF is a large horn, what is the expected cutoff? Will it go to 200hz

2. I read that they may be available for sale, Roy POC, but can't find that thread. Is so, any price on the horn only?

3. Any input on the Jubilee horn versus the other options stated, in this application, are greatly appreciated.

4. Other options, besided build my own...

Thanks!

Hi betterisbigger,

the 402 horn loads to about 250 Hz. it has a 2" throat. i can see if we sell it separately but it is highly unlikely. i do know that if you buy the 402 with 69, you also get a mounting bracket and bottom board to let you mount it horizontally.

i don't much about the bms driver but i take it that it is a coaxial driver. because of the improper match of the tweeter to the horn, the horn might not be able to do much except provide some loading gain, typically about 3 to 5 db.

will let you know.

berryboy roy

[D-MAN]

Roy makes a good point. There is no horn made that does both low-end and high-end equally well. You have to choose.

I am running the BMS 4590 on a P-Audio 4525 (400Hz fc) horn and it works satisfactorily...

Attached is the frequency response curves for the BMS in the horn, you will have to look far and wide to do better than this (entirely possible, but very likely more expensive).

DM

[BiggerIsBetter]

Dana,

To leverage the capabilities of the BMS driver, I would choose a larger horn capable of close to 200hz in order to get the voice out of the bass bin. I am sold on the need/advantage of EQ and will be using a digital crossover with a PEQ, likely a Behringer.

I already have a 400hz fc round tractrix. I have not purchased the BMS driver yet. I am still waiting for assistance audio to send me a PO so I can pay for it.

Sounds like Roy may not be able to sell the horn separately, which I completely understand. That would leave me with quite a choice.

I still don't have my bass bins up yet, so my next step is to put the BMS purchase on hold and see how they respond/sounds between 200-500 hz. If they do OK up to 500, I am seriously considering the K402/K69....which would leave me with a Jubilee migration path.

Any thoughts on how the BMS would work on the K402?

[D-MAN]

The BMS is only rated to 300Hz. I've not heard one below 600.

And you certainly don't need to go that low, seems to me.

It is really pushing the hardware to cover that territory.

The BMS I have is a 2" throat. I haven't hear the smaller versions, but I would question the value of attempting to use a coax on a smaller size throat.

DM

[BiggerIsBetter]

I'm looking at the same 4590 driver you have. There are lots of reports of using it down to the 200s in home audio application.

There is a guy that reportedly modified the driver and uses it with a 250hz horn, crossed over at 220.

Here's a thread discuss the driver mods

http://www.bd-design.nl/forum/forum_entry.php?id=10736

And here's the specific product that crosses over that low

http://www.bd-design.nl/forum/forum_entry.php?id=10719

[D-MAN]

Ah-ha! I went the other way - extend the coverage of the bass horn.

Our ideas are directly opposed, yet we choose the same gear to do it!

That ought to say something about the BMS driver!

Dana

[Deang]

I think the lowest useable crossover point for that driver is 400-450Hz. 300Hz is really pushing things, and any lower is definitely asking for trouble. There's no derived benefit from a lower crossover point if you've doubled your distortion levels.

The non-coax version of that driver looks killer for the Klipschorn.

We need that big Trachorn Al.

[BiggerIsBetter]

Yes, we really need a large Tractrix horn!

As originally posted, there are very few options. I would love to have that K402 and find our how this driver does 200hz for myself...

I'm betting it would with no problem at all (in home audi application that is) and sounding very good doing it. I talked at length with the US importor (a pro audio guy) and expected him to laugh when I mention 200hz. His reply was should be no problem at those levels with a steep crossover.

[D-MAN]

One problem I noted on using the "stock" version of the Edgar Tractrix was that it had a much wider dispersion characteristic than my "normal" 90x40's, which I found hard to control.

The soundstage therefore became indeterminate, the opposite of what the coax BMS driver can do in my "other" horns. However, the tonality was exceptional.

If somebody finds the "right" horns, let me know!

DM

[DrWho]

Interesting plots. Is that divided by 10dB on the vertical and 2kHz linear on the horizontal? I must confess that looks better than I imagined - and that's the first off-axis data I've seen too. Any idea how the measurements were taken?

[D-MAN]

I would like to mention that the use of a lower-frequency midrange horn in a corner MAY BE sort of a bad idea. Here's why...

The lower cutoff of the mid-horn is going to be determined by how far the horn is from the nearest reflecting surfaces. That is because the LF is going to be reinforced by reflections, and the mid isn't due to shorter wavelengths not "fitting" in the space between source and reflector. The normal cutoff ios

The use of large (i.e., lowER frequency mid-horns) being discussed are going to introduce their own set of problems when placed in a corner.

Something to think about! These issues are typically not in play with the "normal" setup of 4 octaves or more on the corner-style bass horn.

DM

[DrWho]

That's exactly why Roy prefers to use such a insanely huge horn for the Jubilee top-end...by maintaining coverage control down into the lower registers you don't have as many corner reinforcement issues. Gotta keep the "sound bubble" moving forward away from the walls.