2" Tractrix Wood Horn + BMS 4590 listen

[D-MAN]

Rick (3dzapper) was extremely kind to send a pair of wooden Tractrix horns to me that he built. They were built to Bruce Edgar's specs from the Tractrix midhorn article which was intended for a cone midrange driver, if I remember correctly.

I had to do some hardware shopping to get my 4 bolt BMS 4590 compression drivers to mount, but I finally did.

The BMS drivers are coax, so that means that the tweeter is also going to propagate through the midrange horn along witht the midrange. Since very few midrange horns with a low flare rate can pass high frequencies (most attenuate above 15K), it was a question whether the Edgar Tractrix could do it also.

The Tractrix DOES do something quite delicious in the lower mids - the only way I can describe it is the strange-yet-wonderful "damping" that a fine piece of tube gear can do in the mids. That was the sound.

However, it attenuated the highs. I would have to guess somewhere around 9 or 10K. There could be a couple of reasons for this... one being that the throat was square, not circular. The driver throat is circular, and high frequencies are quite unforgiving of discrepancies in the throat area. Remember that the horn was intended for a cone driver.

The other reason would have to do with the Tractrix flare rate - there are no tweeters that use a tractrix flare that I know of. Evidently there is a reason for that - who knew!

The P-Audio horns that I'm using are very close in mouth size with the Edgar Tractrix horns, they are virtually the same area and proportion. The P-Audio horns are shorter in path length, though. They also have a "squeeze" of the throat (to extend the horizontal dispersion characteristic) which the Tractrix does not. The Tractrix had a wider midrange dispersion characteristic than the P-Audio but tended to beam on the upper end and THEN attenuated the highs. The P-Audio's that I use are 90x40. I don't know what the Tractrix is, but it is definitely much wider than that.

Now, granted, the Tractrix wasn't intended to be anything other than a midrange horn, and I was using it in a coax configuration - but what the heck - it needed to be tried anyway. So it really isn't very suprizing that it doesn't work very well with a coax. I thought it would work well enough to make it worth trying, but I was wrong on that account.

If I could get horns that do what the Tractrix does on the lower mids AND retain the high frequency capability of the P-Audio horn for using a coax, I could take over the horn world!

My opinion is that as a MIDRANGE-ONLY horn (as it was intended), the Tractix is going to be very hard to beat. The tendancy is to beam, so keep the upper frequency limit fairly low, 5 or 6K would be a good guess.

It has a deliciousness to the low-end (I crossover at 600 Hz) that frankly, I haven't experienced before. It is palpably delicious! That's the right and only word for it, too. You have to hear it to know what I'm talking about. I think it has something to do with "damping" (whatever that is), but it has a "tube-like" quality to it (in the best sense of the word "tube"). I'm using quality SS gear, too.

I think that it has something to do with the trailing edge of the waveform - it just starts and is full-bodied and ends naturally - but there is something else there, too. I think it has to do with the way the sound ENDS. It's trailing edge is the difference lies, I think. It has a bit of a "suction" to it, if that makes any sense at all. It stops in a manner that can only be described as full "black space" - no overhang, no ringing, and not truly dead air either - more like an extremely large volume of space would respond, the quiver is there. It's more like a natural decay response in a really BIG space with no residuals or reverberation. Silver - it sounds a bit like silver cabling!

So for coaxial use, don't use them - however, for a "straight" midrange, going to be very hard to beat.

DM

[Guest " "]

Intresting report. I have this on my list of things to try someday.

[jwc]

Dana. Please post a pic.

I was going to hold on posting this stuff as my project is a little on hold because of the jubilee build which is off to a slow start.

However, I too have put together the templates to make wood horns. Mine also follow along with the Edgar Article except these are 2" driver 225Hz tractrix horns. The mouth is 24" wide by 12" height. The intent was for a three way setup with jubilees or the Khorn.

I'm glad to hear of your low mids with good results as I was going to shoot for crossing down to 300Hz (with the appropriate driver of course). Yes I realize a jubilee can be crossed over higher.

The picture below shows the tools to make the horns. The far right is the template to make the flare....reuseable. The bottom trapezoid thick piece is for mounting the flared and nonflared sizes. The two stacked flares are one finished product for the top and bottom. The sides will be layered veneer.

I had put this on hold but was dug out of the back of my mind with this thread. May get around to finishing them after the jub.

Any suggestions on a driver?

jc

[3dzapper]

Thanks for the fair review Dana. The word is "bubble".

I can't envision how to constrict the horn throat of that horn to provide the missing highs. That is above my pay grade.[]

Fritz, If you would like to give these a taste, let me know. Be fore warned, that pair is nowhere near as nice looking as Al K's.

Rick

[freddyi]

FWIW thought LE5 sounded decent on 250Hz tractric with old LE5 on K-horn but didn't have compression driver for comparison. newer ferrite JBL 5" are no good on these horn past ~3K.

I'll guess throat and throat length is critical to get HF EQ (?)

[D-MAN]

Rick, again, thank you. I took some pics of the setup in place.

I hacked up the 2" mounting board that you had attached. It now has 2 big holes for mounting 2 of the 4-bolts on a 2" driver (the 6 you had are not used). It also mounts kitty-corner in order to clear the driver mounting bolts. I took some pics of the setup in place and you'll see what I mean, but I'll have to remember to download them.

I re-glued one of the side pieces as one came off and set a couple of screws from the side that should be permanent to help hold them (the drivers weigh 20lbs each!). The mounting board with the driver in place is then attached with 4 angled screws from the front of the "side flange pieces", 2 per side. Worked great.

Let me know who gets them next.

JC, I like BMS, so try the midrange-only 2" version - I guarantee you will like what you hear, especially in the Tractrix. Also, the output is rated at 113db, so that is also going to be in keeping with the potential of a Jubilee bass bin.

Another reason I like the BMS is that they are rated to 300Hz @ 150watts! That alone ought to sell you on them!

Dana

[Daddy Dee]

D-Man,

Thanks for your post and explanation, in some lay terms, too which make sense to me.

These horns do indeed sound sweet in the mids. I have also had the privilege of listening to a pair of Rick's horns. I've used them with K55 and have found the mids intoxicating.

I'm also impressed with Ricky's DIY skills. Great job. Thanks Rick.

[3dzapper]

Ricky?

Ba-ba-loo

Ba-ba-loo

Thanks Dee.

Ricky

[D-MAN]

Here's some picks of Ricky's horns in action...

[D-MAN]

Another.

[D-MAN]

3 of 4, these pics make them look alot worse than they actually are in real life, and even so, behind a grill cloth, who is going to care?

[Jay481985]

D-man I am probably taking this out of context but:

"The other reason would have to do with the Tractrix flare rate - there

are no tweeters that use a tractrix flare that I know of. Evidently

there is a reason for that - who knew!"

did you just mean midrange that can do traxtrix or others? All reference series models use Tractrix for midrange (to some extent) and tweeter.

[D-MAN]

My understanding is that the Tractrix flare is not particularily good at high frequencies due to the extremely short wavelengths employed, i.e., too short to make an effective difference between conical flare rate and tractrix, for instance. For example, make a tractrix flare tweeter horn that is less than 1" in overall path length, see what I mean? Not possible. Extremely short horns like that are all basically conical in expansion and effect.

Bruce Edgar also reported the Tractrix to be bad at low frequencies below 100Hz. It seems to be relegated to the midrange frequencies, and I can attest to the fact that it is quite effective there.

DM

[Jay481985]

I don't deny the fact they make a better midrange horn but as with the statement above, the tractrix is employed in basically all the reference series models sans some satellites which use a conical type something horn. But have you listened to any of them??? There not bad and my rf-83 goto 21-22000 hertz which is above most exponential horns of the heritage which until the revision of late was only good to around 17000 hertz?

[D-MAN]

I haven't heard any of them but I suspect that they are likely too small and too limited in bandwidth for my needs.

I'm going to play around with some cheap-and-dirty horn baffle extensions to see if I can approach the 90 deg. terminus of a true Tractrix flare on my horns.

DM

[mikebse2a3]

Hey guys Klipsch is using a new Tweeter in the Heresy III and Cornwall III and its a Tractrix Design.

mike tn[]

[Jay481985]

I haven't heard any of them but I suspect that they are likely too small and too limited in bandwidth for my needs.

I'm going to play around with some cheap-and-dirty horn baffle extensions to see if I can approach the 90 deg. terminus of a true Tractrix flare on my horns.

DM

I say just try them, I think you won't be disappointed.

Don't knock them and sound like an audiophile now....... []

[Jay481985]

mikebse2a3

did you take a picture on a digital camera from the monitor and post? []

just hit print screen next to scroll lock and paste in mspaint.

[3dzapper]

Dman, How would you rate those trackhorns vis-a-vis a 511 as a mid-range horn?

Rick

[mikebse2a3]

mikebse2a3

did you take a picture on a digital camera from the monitor and post? []

just hit print screen next to scroll lock and paste in mspaint.

Jay481985 thanks!

Actually Dr.Who told about that last week.

In this case I just copied/croped and resized a brochure I got from the Hope Pilgrimage because it was simple and quick at the time. I didn't bother to even see if Klipsch has this info posted on their website yet.

mike tn[]