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EV Horns

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Posted on September 26, 2014 at 06:56:05
ACMINC
Audiophile

Posts: 25
Joined: April 13, 2012
 I currently own a 3-way EV system with T-350 and 1823M w/ 8H horns. I want to remove the “Stock” exponential metal horns and replace them with wooden horns that I will construct. I want conical horns designed to maximize on the intended range that EV intended the drivers to perform. What would be the dimensions (throat, length, mouth, etc.)? Thanks in advance

 

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RE: EV Horns, posted on September 27, 2014 at 08:13:58
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 ACMINC

I run 1823's with square DIY tractrix horns which are 14.5" long with 11" X 4 square mouths. Conical horns can sound good, but they tend to not load the driver in the lower end as well as typical curved wall horns, unless you use EQ and/or oversize the conicals to compensate. This having been said, I once tested one of my horns with a JBL 175 and it went down to 400 Hz, so if you're using the EV 800 Hz crossover, similar dimensions may work for you. It would be a good idea to make some prototypes and test them before going to wood, as test conicals are easy to fabricate from cardboard.

Good luck, and let us know how it goes

Paul

 

RE: EV Horns, posted on September 30, 2014 at 17:06:09
ACMINC
Audiophile

Posts: 25
Joined: April 13, 2012
 Paul

Thanks for your reply. I am crossing my 1823M over between 800Hz and 3500 Hz. I plan on upgrading my 3-way passive system to a 4-way active system, therefore I want the 1823M frequency range to stay just were it is at. I might be reading something into what you wrote, so I’ll just ask for clarification. Are you saying that a tractrix horn allows for a shorter length horn relative to a conical for the same results? And if I wanted to use a conical horn, it would just have to be “oversized”? I read that most mid-bass (120-800Hz) horns are exponential. Is this just for length consideration also?

Ken

 

RE: Ping The Conical Crew, posted on October 1, 2014 at 19:54:05
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001



Ken

Take a look at the pic attached here, it's from Elements of Acoustical Engineering by Harry Ferdinand Olson (recently reprinted in paperback, in the public domain, and very highly recommended). Note that the slower expanding exponential horn has the best bass extension of the group, as it's more "pipe like" than the conical or parabolic. Conical horns quickly become unpractical for bass horns, but in the midrange where spacial considerations are less of problem they have now become contenders along with some oversizing/EQ "dirty tricks" (to paraphrase P.W. Klipsch).

It would be nice to have a rule of thumb for designing a conical mid horn (which is not really my dept.), and perhaps one of the conical guys will be attracted by the subject line here and step forward. In the mean time, an exponential horn (for example) is most efficient when the length of the horn is equal to 1/2 of a wavelength at the lowest target frequency, and the area of the circumference of the mouth is equal to 1 wavelength, where 13500/(Freq. in Hz.)= wavelength in inches. As should be obvious from the graph, you will have to oversize the conical horn considerably to get it to load the bass as well as the exponential horn, and/or use some EQ. You don't mention what you are intending using below the conical mid horn for the bass. If it's a direct radiator box woofer, then EQ may work as you will have to pad the 1823 down relatively to match the level of the woofer anyway. An exponential horn is a rather specific thing, going from the 1 inch or so mouth of the 1832 to the horn length and mouth area dictated by the sound waves, and following an exponential curve. However a conical horn just has to be cone shaped, and this could mean quite different things in practice. At any rate, some "cut and try/cowboy engineering/see what happens" is ahead for you.

Paul

 

RE: Ping The Conical Crew, posted on October 2, 2014 at 08:49:53
Inmate51
 Paul, dude! You have "Elements of"?! Wow!

I have "Acoustical Engineering", the 1957 'update' to "Elements of".

Both of these books are quite rare, and I'm glad to see that "Elements of" has been reprinted!

I also have "Music, Physics and Engineering", which is more approachable for the layman and covers some other topics.

Olson was quite the engineer AND writer!

:)

 

RE: Ping The Conical Crew, posted on October 2, 2014 at 19:28:02
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 I.

The large hardback 1957 version of Acoustical Engineering was reprinted in the late 90's by Ed Dell's Old Colony/Speaker Builder group. Prior to this, many is the story of people lending the original book out, and never seeing it again. One of the greatest audio discoveries of the 70's was the existence of this book, and you're a brave man for admitting that you actually own it. Until the paperback reprint of Elements of Acoustical Engineering came out, I would have said "maybe I have it, and maybe I don't". Most of the important horn stuff is in the Elements version from 1937, and there's no excuse for anyone not owning the paperback version now. The reprint of Acoustical Engineering cost $80, but that's undoubtedly the best audio book value ever. I've had the Dover paperback reprint of Music, Physics and Engineering since the late 70's and it's also incredible. For the ultimate Olson opus read Dynamical Analogies, now available as a download from Pete Millet's site. It's an utterly staggering Rosetta Stone of analogies between the electrical, mechanical and hydraulic disciplines.

Harry Olson was the Nicola Tesla of audio!

Paul

 

RE: Ping The Conical Crew, posted on October 3, 2014 at 07:32:35
Inmate51
 10-4 on all of that!

Yeah, my "Acoustical Engineering" is the brown hardcover. My "Music, Physics and Engineering" is the Dover paperback edition, with the blue and green cover - and, being a musician, I've darn near worn it out. :)

I don't know what your audio emphasis is, but mine is sound, acoustics, psychoacoustics, recording, and loudspeakers. I suck at electronics and couldn't find my way through an amp circuit if I had to, but I know a thing or two about rooms. ;) So, a couple of the other vintage texts I have are "Music, Acoustics & Architecture" by Leo Beranek, and "Acoustical Designing in Architecture" by Knudson and Harris, and a few others.

I think it's so cool to have these landmark works! What an awesome body of knowledge they contain!!

Sorry, OP, didn't mean to hijack your thread, but when Paul posted that pic, I couldn't resist blabbering.

:)

 

RE: Ping The Conical Crew, posted on October 3, 2014 at 14:17:35
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 It sometimes seems like more things have been forgotten in audio than have been discovered in the last 40 years or so. BTW thanks for the heads up on the Beranek Music, Ac. & Arc., I just ordered a used copy from amazon. You should definitely check out Dynamic Analogies where many electrical concepts are explained with mechanical analogies like gears, levers and springs.

Paul

 

RE: Ping The Conical Crew, posted on October 4, 2014 at 09:09:08
Inmate51
 "It sometimes seems like more things have been forgotten in audio than have been discovered in the last 40 years or so."

That's a very insightful point.

Pretty much everything we need to know was all known by 1965.

Btw, I look at Olson's electrical analogies to various things like musical instruments, voice, etc., and think: He really GOT this stuff!

I'm reminded of having lunch with John Hilliard. He, Olson and others had all of this figured out, and paved the way!

:)

 

RE: EV Horns, posted on October 4, 2014 at 17:52:35
SpeakerScott
Manufacturer

Posts: 16
Location: Texas
Joined: September 17, 2014
 I've never worked withe either of those drivers. Based on the limited specification information from the EV datasheets available online I think you might be able to get satisfactory operation from the 1823 on a conical horn, though with lower maximum output than on the 8H horn. The T-350 though, I'm not sure. They go to great length with the original lens to provide a longer path-length, supposedly for phase purposes. From the drawing though it looks like it also provides a higher acoustical load...

You may find that T-350 isn't up to the task on a conical lens, though you might get away with it for home use where the volumes needed just aren't that loud.

If you try it, take frequency response plots with distortion measurements (REW is great for this) and post them. I'd be curious to see the results.

Scott


Scott Hinson
speakerscott.tumblr.com
www.etsy.com/shop/SpeakerScott

 

T-350, posted on October 5, 2014 at 07:05:52
Inmate51
 Thanks for posting that data sheet! I have T-350s in my system, but have long ago lost the data sheet.

With regard to their output, while it's true that they can be crossed as low as 3,500 Hz, that will limit their output due to excessive diaphragm excursion at those lower frequencies. Trust me, you do NOT want to have to replace that diaphragm! It's a bugger! I had eight T-350s (four per side) in a sound reinforcement system a long time ago. When I had the "opportunity" to repair one, I said "never again!", and raised their x-over frequency.

Even in a home hifi, it's better to cross them higher. Mine are crossed at about 5,500 Hz, high enough so that I can crank the system without concern for over-excursion.

ACMINC, I would advise you not to mess with what is an excellent design. If you look at the data sheet diagrams, you'll see that the horn/phase plug assembly is much more than simply a diffraction horn that you can easily replace with a home-built conical horn. Further, as Scott pointed out, the conical horn won't properly load the diaphragm, increasing the possibility of damaging it. Lastly, the T-350 is a classic high performance driver, and it would be a shame to negatively impact its value by bastardizing it. If you'd rather have something else, I'd consider buying them from you.

:)

 

RE:More T350 lore, posted on October 5, 2014 at 11:13:25
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 I agree that it's unlikely that a beginner could design a horn and phase plug to replace the one on the T350, and have it perform as well as the original. The original post here concerned a conical horn for the 1823M to replace the 8HD, and that's certainly feasible.

I don't want to alarm anyone, but I cross my T350's first order at 2500 Hz. My 1823 mid drivers have copper voice coils and the highs roll off lower than the 1823M (or 1824M) which have aluminum voice coils. So the non-M 1823's work better in my application with a lower XO point. For me the forte of the T350 is it's ability to cross this low. I've never blown a T350 diaphragm, but I've been running a Dyna ST70 for a couple of decades, which is currently triode wired with 16 WPC. So your milage on the T350 phrams may vary if you have a very large listening room and big SS amps, and listen at live rock concert levels frequently.

I have'nt found the T350's particularly difficult to work on, however getting good replacement diaphragms has become a problem (see DJK's recent comments here). Great Plains Audio got the tooling to make them from EV, but apparently they are having trouble sourcing the phenolic base which the coil is wound on, at least that's what a friend told me who spoke to GPA and also Bob Crites a while ago. If the weight and/or compliance of this phenolic base is out of spec it can throw the freq. response off. Problems seem to arise in the lower end, and a higher crossover point may become necessary to avoid this. BTW some guy has been rephraming T350's by putting glue on the driver side of the phram so that if you take the driver apart the voice coil leads will break when you separate the horn from the driver! The phram is press fit into the horn assembly and you don't need any glue! It should stay with the horn and terminal assembly when you separate it from the magnet. I have an ST350 which was thusly treated, and I was able to repair the broken leads with Radio Shack wire wrap wire, and it performs as well as it's twin which was not glued. It's hard to tell if this gluing is being done out of ignorance, or to purposely have the diaphragm self destruct if someone decides to disassemble a T350.

Paul

 

RE:More T350 lore, posted on October 6, 2014 at 07:07:29
Inmate51
 "I cross my T350's first order at 2500 Hz"

I didn't sleep last night... that sentence just kept replaying in my head.

You must like living on the edge. lol

Tell us you're using the STR tweeter protector!

:)

 

RE:More T350 lore, posted on October 6, 2014 at 11:07:47
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 My STR's went in the parts box a couple of decades ago. I never heard one switch a tweeter out even when I was playing the Stones loud through a Hafler 200, though I did use 2nd order crossovers back then. The spec sheet warns about not playing test tones below 3500 Hz, and not exceeding 5 Watts RMS continuously with a test tone. They added "Naturally, sustained signals of this kind are never remotely approached in program material". Power handling is further listed as 50 Watts program; 100 Watts peak. A test tone is about the only way I could see blowing a T350 in the average listening room, and it would exceed 120 dB! Two of them driven this way would become painful very quickly. Now you are one up on me, as you've actually heard a T350 blow. I assume it was in an outdoor PA setting, Dyna ST70's were not the amps, and the music being played was not a string quartet ; )

Ken, you still there? The 3500 Hz crossover (EV X36) will work fine with the 1823M/T350 as long as you observe the above cautions.

Paul

 

RE:More T350 lore, posted on October 6, 2014 at 13:03:29
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001

Would an Eminence APT-80 do or is it too fragile?

Dave

 

RE:More T350 lore, posted on October 6, 2014 at 15:34:48
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 Dave

Probably not as it's 104 dB verses the T350's 107 dB. The Eminence 2002S-8 looks interesting with 106 dB, but it is a big 1" driver. It's interesting that the replacement diaphragm for the ABT 80 is phenolic and looks similar to the T350 phram except that the lead outs are on the same side. Anyone know if the diameter of the voice coil is the same as the T350? If so it might be possible to modify the ABT 80 phram as a T350 replacement. Perhaps this is expecting too much of a lucky coincidence.

Paul

 

RE:More T350 lore, posted on October 7, 2014 at 12:43:05
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 The Selenium ST350 Super Tweeter is 111db@1w/1m, & 50 degree dispersion but I have not heard it.

 

RE:More T350 lore, posted on October 7, 2014 at 15:50:25
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 That's an interesting tweeter which I also have not heard, but Selenium's specs have tended to be rather unreliable in the past.

Paul

 

RE:More T350 lore, posted on October 17, 2014 at 07:39:36
ACMINC
Audiophile

Posts: 25
Joined: April 13, 2012
 I guess I'm going to leave the stock horns on the T-350's. But I am going to change out the stock horn on the 1823M. Most likely a conical tractrix design. I too have been thinking of raising the OX to 4000 or 4500 Hz. What are your thoughts on a mid-bass horn design? Straight conical, tractrix, exponential? I have the room and 100% WAF.

 

RE:More T350 lore, posted on October 17, 2014 at 08:04:01
Joseph Crowe
Audiophile

Posts: 53
Location: Ontario
Joined: February 19, 2014
 I made a conical horn to replace the B&C ME20 horn and the improvement was well worth while. I think conical is the way to go for hifi use. It doesn't have any 'horn' sound and provides a flat response up to 45 degrees off axis. Make sure you radius the baffle and transition nicely on the horn exit. I would avoid a round conical horn in open space as this focuses too much boost at one frequency due to edge diffraction. Mounted to a square baffle will give you a smoother frequency response. Also, pay special attention to the compression driver itself, noticing the geometry coming out the unit and making sure your horn matches with no abrupt changes in horn profile. Using digital EQ you can compensate for any loss in output near the cutoff.

 

Re: Conical horns, posted on October 17, 2014 at 08:59:11
Inmate51
 Obviously, you have not studied the characteristics of conical and exponential horns.

Conical horns suck.

 

Re: Conical horns, posted on October 17, 2014 at 10:06:43
Joseph Crowe
Audiophile

Posts: 53
Location: Ontario
Joined: February 19, 2014
 Here are my findings. Please post your horn builds with measurements.

http://croweaudio.blogspot.ca/2013/05/oblate-speherical-waveguide-diy-project.html

http://croweaudio.blogspot.ca/2014/06/oblate-spheroidal-horn-completed.html

http://croweaudio.blogspot.ca/2014/07/frequency-response-measurements-for.html

 

RE: EV Horns, posted on October 17, 2014 at 10:22:56
geezerrocket
 Try Daves fastlane Audio.

He has several horn, both finished and DIY.

Tweeter horn.



 

RE: EV Horns, posted on October 17, 2014 at 10:25:28
geezerrocket
 And mid horn.






 

Re: Conical horns, posted on October 17, 2014 at 17:34:13
Inmate51
 I don't build horns. I leave that to the pros.

All you have to do is to look at the data to know that conical horns aren't hi-fi.

 

RE:More T350 lore, posted on October 18, 2014 at 14:07:20
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 Conical horns and tractrix horns are two different animals, though hybrids incorporating features of each are possible. I prefer tractrix horns on compression drivers for the midrange, but I've heard some good conical mid horns. The selection of a different high crossover point with the 1823M should be based on data from measurements. The 1823M does not have a phase plug and subsequently just can't go all that high compared to mids with phase plugs. Raising the crossover much beyond the 3500 Hz point spec'd by EV will tend to result in a hole in the response between the 1823M and T350. In the meantime you've got some work ahead prototyping some conical mid horns. You can quickly fabricate a functional conical mid horn with poster board and duct tape which will show you if you are on the right track. BTW the 8HD is a diffraction horn and will have a broader horizontal coverage pattern if the long dimension of the horn is vertical, though this may seem counter intuitive. Ditto for the T350. You should set them up this way for comparison to anything you may build.

Paul

 

Re: Conical horns, posted on October 19, 2014 at 17:56:37
Joseph Crowe
Audiophile

Posts: 53
Location: Ontario
Joined: February 19, 2014
 Look up earl Geddes OS horns and reviews. Stop being so obstinate and insulting.

 

RE:More T350 lore, posted on October 19, 2014 at 23:52:07
quirck
Audiophile

Posts: 213
Joined: December 23, 2006
 hi Paul. The 1823M does have a phase plug.
You can see it when you open it up.

 

RE:More T350 lore, posted on October 20, 2014 at 18:59:26
Mr_Steady
Audiophile

Posts: 2042
Location: North Florida
Joined: August 19, 2014



ACMINC,

Your first instinct is correct. Getting rid of the fifty year old PA horn, and dropping in something better. It's the best first step for vintage horns.

Building horns and going four-way active is very ambitious, but while you are learning horn theory, and the art of horn construction, let me make a suggestion that you just go ahead and buy a decent pair of horns to listen to while you master all that.

Why do you want conical horns? Ultimate sound quality? Do you prefer a definate sweet spot all the time, or do you want to fill the house with music?

I posted a link below. It's not what you want, but it's just to show you what's out there. $550 and a week, and you could really do a lot for the sound quality of your speakers. Also, you could never build these, so when you build, it will be something different than this. If you want to talk about this horn, or other possibilities that's cool.

Learn what the difference is between hyperbolic, exponential, and conical, and what theoretical cutoff is, and you will be a long way to understanding audio horns. It will help you decide what you want, and what you are able to do, and the trade-offs, always with the trade-offs.

Jamie


Big speakers and little amps blew my mind!

 

RE:More T350 lore, posted on October 21, 2014 at 10:20:00
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 Quirck

The EV data sheets for the 1823 and 1824M make no mention of a phase plug or loading plug. Neither do the data sheets for the similar 1824S. A loading plug is promoted in detail as an important feature in the data sheets for the T350/T35 however. One could argue that the volume and geometry of the air chamber in front of the diaphragm in a driver like the 1823/1824 is designed to minimize destructive cancellation in the sound waves, and that this is the same task a loading plug would be put to. However they are quite different things. To be honest I have'nt currently disassembled any of my 1823's or 1824M's to examine this area, but a picture of something resembling a phase/loading plug in one of these drivers would make me a believer.

Paul

 

RE:More T350 lore, posted on October 22, 2014 at 00:47:07
quirck
Audiophile

Posts: 213
Joined: December 23, 2006
 Hi, I have sent you two pictures, cannot post them here.

 

RE:More T350 lore, posted on October 22, 2014 at 08:51:35
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001



Quirck

Thanks for the correction and the pix! There was probably a patent concern for the reason that this was not mentioned in any of the data sheets. I have never replaced a diaphragm on any of my 1823/1824's but I did open an 1823 up some years ago, and if you don't remove the diaphragm then you won't see the plug. Also there's a metal screen obscuring a view of the plug from the mouth of the driver. BTW the pix came through fine (I've attached one here) but the two text attachments were blank, maybe because I'm running a Mac.

Paul

 

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