Brociner folded corner horn?

[spkrman57]

I was reading the post on the forum here and ran across Beowulf57's thread on these horns and I have a similiar pair to his.

My pair of corner horns are within a inch more-or-less to his and I plan on using either a D131 reconed with 2202H cone, 2225H or a E-130 w/paper dustcap.

I'm thinking that the 2225H would be the best candidate for the job,

I welcome and and all comments on this. And yes boys and girls, it will be powered with tubes as is always my favorite.

I thank Beowulf57 for his thread here:
http://audioheritage.org/vbulletin/showthread.php?t=20973

Regards, Ron

[Beowulf57]

This is the first time in around 50 years that I have seen any other cabinets identical to those I am using! Where did you get them...did you build them? Do you know the origin or who made them?

My left channel (D131) and right channel (D130) cabinets are identical except that the outside height of the D131 cabinet is 27.625", the D130 cabinet is 29.125". So, the larger driver has a 1.5" taller cabinet. The driver mounting method is also different: D131 is mounted to a brass ring with about 2" of mounting area all around and this ring is then screwed into the solid 5/8" hardwood ply front of the cabinet; D130 mounted to a 5/8" solid hardwood baffle that is screwed onto two metal side plates using machined decorative bolts into captive nuts.

As to which driver to use, that depends on a number of factors. These cabinets were originally designed to use extended range drivers such as the JBL D131, D130 or the EV Wolverine. That's the reason the driver feeds a back-loaded horn and also fires forwards. The crossover between the horn and the front radiation is probably somewhere around 180-220Hz, but I've never measured it precisely.

I'm assuming you want to use the extended range of a D131/D130 and depending on the exact dimensions of your cabinets, they might have been built with either 12" or 15" drivers in mind. To my ears, the D130 is more powerful and open sounding than the D131 (the driver is about 2dB more sensitive), however the D131 may have a slightly more "solid" sound in the lower bass. There is a bit of difference in the tonal character of the bass, but this does not adversely affect the sound and is not at all noticeable when listening to music.

Are you planning to extend the system with drivers such as the LE85 and 2405?

[spkrman57]

This is the first time in around 50 years that I have seen any other cabinets identical to those I am using! Where did you get them...did you build them? Do you know the origin or who made them?

I have been collecting audio gear and speakers for approx the last 20 yrs. Most of what I picked up was due more to being in the right place. I found these BLH cabs about 8 yrs ago from a friend of mine who deals audio F/T and he found no real value in these for resale, but he knew I liked old vintage speakers and he picked them up for me cheaply.

Lately, I have been working on my home repairs and found it necessary to get rid of quite a few old speaker cabs. These are part of what I kept once I started selling/pitching things to make room.

My left channel (D131) and right channel (D130) cabinets are identical except that the outside height of the D131 cabinet is 27.625", the D130 cabinet is 29.125". So, the larger driver has a 1.5" taller cabinet. The driver mounting method is also different: D131 is mounted to a brass ring with about 2" of mounting area all around and this ring is then screwed into the solid 5/8" hardwood ply front of the cabinet; D131 mounted to a 5/8" solid hardwood baffle that is screwed onto two metal side plates using machined decorative bolts into captive nuts.

As to which driver to use, that depends on a number of factors. These cabinets were originally designed to use extended range drivers such as the JBL D131, D130 or the EV Wolverine. That's the reason the driver feeds a back-loaded horn and also fires forwards. The crossover between the horn and the front radiation is probably somewhere around 180-220Hz, but I've never measured it precisely.

I'm assuming you want to use the extended range of a D131/D130 and depending on the exact dimensions of your cabinets, they might have been biuilt with either 12' or 15" drivers in mind. To my ears, the D130 is more powerful and open sounding than the D131 (the driver is about 2dB more sensitive), however the D131 may have a slightly more "solid" sound in the lower bass. There is a bit of difference in the tonal character of the bass, but this does not adversely affect the sound and is not at all noticeable when listening to music.

I see using a JBL 2225H and Altec 902/811B and crossover TBD later. Crossover building is easy enough for me to accomplish. My pair of D131/2202 recones have a fs that keeps me thinking the LF response might be a bit thin. Of course, that is always subject to change!

Are you planning to extend the system with drivers such as the LE85 and 2405?

I plan to keep it a simple 2-way if possible!



Regards, Ron

[spkrman57]

This is the first time in around 50 years that I have seen any other cabinets identical to those I am using!



Actually, yours is the only other ones I have found/seen. I tried searching many places trying to identify them.

They also look similiar to a Tannoy type back-loaded horn type(but missing additional folding).

Is there any info on the web you were able to find that gives more info about these?

Mine were built at different times according to the finish on both. One of the baffle boards had a cutout for a cone tweeter, the other did not. Both baffle boards are made for 12" driver. One of the cabs had a really lame Quam 12" with whizzer cone in it. I'm not flaming Quam as they made some really good drivers, this was the economy part of the line.

Ron sends...

[Beowulf57]

Ron: I have never been able to find any information or plans of these speakers. My father (Ross Cann) did not keep the plans and for all I know he designed them himself? The D131 version was made by a friend of our family Henry Northcote who was the head of the machine shop at Raytheon Canada (my father was the president), the D130 by my father. He completed the major construction and I did the baffle board and finish work.

The design is an exponential folded horn with a loading chamber feeding the throat of the horn.

"I see using a JBL 2225H and Altec 902/811B and crossover TBD later. Crossover building is easy enough for me to accomplish. My pair of D131/2202 recones have a fs that keeps me thinking the LF response might be a bit thin. Of course, that is always subject to change!"

The 2225H is about 6dB less sensitive than the D130, however the Altec 902 is also less sensitive than the LE85, so I would expect level matching should work out just fine. Will you be using the version of the 902 that reaches down to 500Hz, or the 1200Hz model? I have tried my LE85s with the higher 1200Hz crossover and much prefer them at 500Hz for overall system balance...but this may be a function of peaking response from the D131/130 when used up that high. Likely different with the 2225H.

Why not just pop the D131s into the cabinet and see what the response is like when the cabinets are placed in the corner? I actually listened to my speakers with just the one driver for 10 years before I added the LE85s in the mid 80s. Quite listenable...though nothing like the presence, articulation and mid-range clarity with the compression drivers on top.

Douglas

[spkrman57]

Why not just pop the D131s into the cabinet and see what the response is like when the cabinets are placed in the corner? I actually listened to my speakers with just the one driver for 10 years before I added the LE85s in the mid 80s. Quite listenable...though nothing like the presence, articulation and mid-range clarity with the compression drivers on top.

Douglas

That will be what I plan to do. I have a older Eico audio generator that I can use to sweep tones and use my ears to see what the driver does mounted on the baffle board only, and then in the cabs placed in the corners.

Thanks a lot for the info and advice!

Regards, Ron

[Beowulf57]

That will be what I plan to do. I have a older Eico audio generator that I can use to sweep tones and use my ears to see what the driver does mounted on the baffle board only, and then in the cabs placed in the corners.

Thanks a lot for the info and advice!

Regards, Ron

You are most welcome...I look forward to hearing the results of your experiments. I may set up my own Eico 379 when I have a moment and run a similar test. :bouncy:

For a chuckle: recently I was using the Eico to test one of my LE85s that had a distortion problem. I was getting all sorts of odd sounds as I swept the audio spectrum from 500Hz up...gee, I thought, there must be a real problem with the diaphragm?! Then I remembered that the 600 ohm output impedance signal generator was not really designed to drive an 8 ohm load!! I was asking an output stage capable of say 15ma to provide around 250ma. :o:

Best wishes,

Douglas

[spkrman57]

My Eico is tubed and still even though designed for 600 ohms does a adequate job of providing enough signal to tun sweeps on most medium to high efficiency cone speakers.

I'm actually working on hooking up a driver in the cabs this morning.

I will report my (less than professional) findings later.

Ron sends...

[spkrman57]

Well I could not use the JBL D131/2202 since I did not have a front gasket on it and I needed to mount the driver on the back side of the baffle board.

I found a Utah 12" that is like a poor mans version of the Altec 414. It would fit behind the baffle board with no problems.

So with the driver mounted on the baffle board I ran a sweep from 200hz to 20hz, and then did the same sweep with the baffle board installed to the horn cab in the corner.

My results of the horn loading range were approx 90hz to 180hz being the predominant bandwidth. Of course I used a bedroom to do this test as the only corner I could use in the house. I think I like this design with a powered sub filling out the bottom end.

I want to modify one of the baffle boards and try out the 2225H 15" driver as I see the potential for a more full-bodied sound might be possible.

Time to shovel some snow before I can play again. I hope to know more by next week.

Regards, Ron

[spkrman57]

I took the horn path length of (approx) 40" and using my hillbilly technical math formulas and came up with 85 hz as the bottom end cutoff(not counting the walls extending the final flair).

I can see where the corner walls would help efficiency here, but not much more in the LF section.

Still I see using a Altec 902 on a 811B horn(notice how similiar the 811B baffle size is compared to the folded horn baffle!). I will make new baffle boards for the D131/2202 drivers, and a bonus is I can locate the 12" driver up as high as possible to be close to the 811B horn.

I would use Pi crossover @ 1.6khz with att/EQ built in. Add the powered sub and sounds like a really neat 2.5 way (2 subwoofers-but in mono)

Ron sends...

[spkrman57]

This is almost like our grandparents and parents built things back in the day before computers and T/S specs were available!

Install the driver, sweep the audio generator and let your ears tell you what it's doing!!!

The driver on top of the cabinet face down is the same as the one installed for the quick test. Fs is approx 40hz. I did not test these, but I have several of this model type and they usually measure fairly close.

The cone tweeter is a sealed back and is used only to cover the empty hole. And the ashtray only holds screws/bolts and nuts since I quit smoking last Apr 2009!

Note: My horns are not pretty like Beowulf57's, but if the system ends up sounding good enough, they will be refinished!

I need more room to do these projects. I'm still working on a older EV 4-way that horn-loaded a 18" and a 8" cone drivers, then compression drivers on horns for the HF and VHF. They had a Georgian 400 crossover mounted in them, but I have not found this model anywhere on the web yet. I got the cabinets empty of drivers and crossovers, but I like to try out my own designs to see how close I can get without much computer help.

Both of the corner-loaded horns EV and BLH's are in the same bedroom. And the EV's are twice the size!

Regards, Ron

Regards, Ron



Ron sends...

[Goodwill_HiFi]

This is almost like our grandparents and parents built things back in the day before computers and T/S specs were available!

Our grandparents still had Physics....... it wasn't all trial and error.

That's a nice looking horn........ makes me want to build something.

[Beowulf57]

Quick update: I searched and searched through piles of papers and documentation going back over 50 years, and...found plans for the back-loaded folded horn! I will scan and post as soon as I have time.

[spkrman57]

Quick update: I searched and searched through piles of papers and documentation going back over 50 years, and...found plans for the back-loaded folded horn! I will scan and post as soon as I have time.

I will do more testing on different drivers in the back loaded folded corner horn system.

I'm curious of the paperwork you have on these horns...

Ron sends....

[Beowulf57]

Here's the scan.

[Beowulf57]

My Eico is tubed and still even though designed for 600 ohms does a adequate job of providing enough signal to tun sweeps on most medium to high efficiency cone speakers.

I'm actually working on hooking up a driver in the cabs this morning.

I will report my (less than professional) findings later.

Ron sends...

Ahh..my 379 is a poor little FET model and certainly couldn't provide the current necessary to drive those big woofers at low frequencies (couldn't even handle 1KHz on my LE85), let alone maintain any control of the drivers.

[spkrman57]

Well, ice dams on the roof once again are leaking into the house. :(

I just got a new roof over the last summer and thought I would not have these problems still.:banghead:

I will continue the horn testing once weather quits threatening my home.:biting:

By the way, the 12" version of those horns seem to measure the same as mine!;) Thanks for sharing that scan with us!!!:applaud:

Regards, Ron

[Beowulf57]

Well I could not use the JBL D131/2202 since I did not have a front gasket on it and I needed to mount the driver on the back side of the baffle board.

I found a Utah 12" that is like a poor mans version of the Altec 414. It would fit behind the baffle board with no problems.

So with the driver mounted on the baffle board I ran a sweep from 200hz to 20hz, and then did the same sweep with the baffle board installed to the horn cab in the corner.

My results of the horn loading range were approx 90hz to 180hz being the predominant bandwidth. Of course I used a bedroom to do this test as the only corner I could use in the house. I think I like this design with a powered sub filling out the bottom end.

Hi Ron: Interesting...I'll try my Eico to do a sweep of the same range driving my main power amps (it just couldn't handle the job on its own). Did you get much output from the front of the driver below 90Hz? Was the Utah 12" designed for use with horn loading? Also, with left and right speakers, you would have a 3 dB increase in level.


I want to modify one of the baffle boards and try out the 2225H 15" driver as I see the potential for a more full-bodied sound might be possible.

I get a very full-bodied sound with the D131 & D130...but then our ears and use of the term may differ? I do wonder about the use of the signal generator as a direct source for determining the bass response of a speaker system, but then I have no way of testing this in my setup?

I run my Linn LP12 through a heavily modified NYAL Super-it phono preamp directly into my power amps (monoblock Class A P-P triodes with separate tube-regulated power supplies) with no equalization, and also my Linn Unidisk SC directly into my power amps, again with no equalization. Listening to LPs, CDs, SACDs and DVD-Audio, there is plenty of good deep, solid bass, and lots of impact. I can hear that the deepest bass is a bit lower in level than the mid-bass, but it certainly isn't lacking...so, I wouldn't give up on getting deeper bass performance from those cabinets just yet.

When I use my system for HT (satellite viewing, DVDs, Blu-rays) I run through a Yamaha C-85 preamp and use the parametric tone controls to boost the LF approximately 6 dB below 50 Hz. This gives a satisfying low end for movie scores and special effects...but again, not subwoofer territory. The major difference between this sound and that of a subwoofer system is that the deepest fundamentals are not present, however the transient impact in the bass region is excellent.

Best wishes,

Douglas

[Beowulf57]

Well, ice dams on the roof once again are leaking into the house. :(

I just got a new roof over the last summer and thought I would not have these problems still.:banghead:

I will continue the horn testing once weather quits threatening my home.:biting:

By the way, the 12" version of those horns seem to measure the same as mine!;) Thanks for sharing that scan with us!!!:applaud:

Regards, Ron

Ohh, Rats! Fix that roof...you don't want to drown while testing speakers!;)

You're most welcome. A bit more research and I think that the plans come from "The New High Fidelity Handbook," 1955;1957. I've ordered a 2nd hand copy and will see if there is any more information provided on construction.:bouncy:

[Beowulf57]

Hi Ron,

Forging ahead...I hooked up the signal generator directly into my power amps with both channels driven simultaneously: strong response down to 40 Hz and then it rolls off. I can shake the walls at 40 Hz and there is usable response to below 30 Hz. The rolloff likely starts around 50Hz...this is of course done by ear, so I haven't got the exact figures (very difficult to measure SPLs in a room due to the peaks and nulls unless you use warble tones), but I would guesstimate that the system as a whole rolls off roughly 12dB/octave below 45-50Hz. I also get significant horn output down to 40 Hz and by the time I get to 30Hz, it's pretty much all she wrote.

This is with a left channel D131 in a cabinet roughly the dimensions of the 12" design in the plans and a right channel D130 in a cabinet 1.5" taller. The D130 cabinet is about 6" smaller in height than the size suggested by the plans...who knows why?

I really wonder what response you would get with those D131s? By the way, my cabinets are elevated off the floor: 5" for the D131 cabinet and 3" for the D130. This places the horizontal C/L of the two drivers at the same height.

[iain42]

Thank you for posting your pictures and plans. This is very cool. Do these beasties have a name?

Brociner made some early Klipschorns for PWK in the 40's.
http://lh6.ggpht.com/_NVQujPOPx2c/RdZwwYYaJdI/AAAAAAAAARo/PObr_IW-w64/s400/15.jpg

[Beowulf57]

I do recall my father referring to them a few times as "Brociner modified Klipschorns."

[iain42]

I do recall my father referring to them a few times as "Brociner modified Klipschorns."

Interesting. Klipsch licensed some back loaded horns but not usually that big. That is taking it from a shorthorn size and make it khorn sized. The enclosed back and sides are an advantage for sure. I'm a bass horn junkie and really appreciate you guys posting this stuff. I'd love to hear something like them someday.

[doucanoe]

Ok, Ron. Now I have a better idea (photos) of what you were describing to me the other day. I also was under the impression for some reason that you had a single and not a pair. Too many distractions as of late I guess.

It will be interesting to follow along and see where these take you!

RC

[spkrman57]

I seem to have the ice-dam leakage problem halted temporarily.

I have my home re-financing closing date real soon and going full bore into poverty getting new windows for my house. So I'll be too poor to do anything else but play with my audio toys.

I will have to get back to the corner horns soon in the near future after the house gets finished up.

Sorry to keep everyone waiting, but I will load the horns with either EV 12" drivers I have, or the JBL D131/2202 recones when time permits in the near future.

Regards, Ron

[Beowulf57]

Well, with a bit more sleuthing I found a Jensen technical bulletin from July 1952 which shows the plans I posted below. Interesting to note that the speaker cabinet shown on the first page is not the cabinet shown in the plans. I actually grew up with the speaker on page one in our Den; the cabinets I now have were constructed as per the plans:

[spkrman57]

That be the plans!

I hope I can play around next week and get the D131/2202's in there!

Thanks a bunch!

Regards, Ron

[Beowulf57]

Hi Ron,

I found a bit more literature on the horn design used in this back-loading folded corner horn. It's from a Jensen technical Monograph entitled "Horn-Type Loud Speakers" published in 1945. The horn flare is Hyperbolic-Exponential or "Hypex" and you can see the advantage over the other flare rates in Fig. 4. There is also further information on the Hypex flare design in the Radiotron Designer's Handbook. :D

[spkrman57]

Douglas,

I just made a down payment on new windows for my house and soon when time permits, I have checked my horns and found the throat to be 50" and JBL 2225's using a throat formula found elsewhere on the web I calculated to be approx 44"!

I think they will be a good candidate for my folded horn cabinets.

Here's more Jensen info/data I found useful while researching:
http://aafradio.org/audio/Jensen_G-610_triaxial.html

Check out the tech notes near the bottom of the page!

Regards, Ron

[Beowulf57]

Interesting link...it is fascinating to see how some of these old designs carry on. So, you'll be trying a slightly less sensitive bass driver with a lower fs rather than a full range (D131) in the cabinet? I will be interested to hear what happens in the low end as the horn cutoff is around 43Hz. What crossover point are you thinking of using and what will take over up top?

[Steve Schell]

Hi guys, really good discussion. I once had an early '50s Jensen Triplex three way system that included that back loaded corner horn and it sounded pretty darn good for something of such reasonable size. Opinions vary about the hyperbolic horns though. Dr. Edgar uses a hyperbolic 35Hz. flare in his Seismic Sub to approximate a 20Hz. exponential flare in the nine foot path length of his design. He does this for the reason indicated in the response graph; low frequency extension. Some have opined that in general a very rapid cutoff will have an attendant rapid phase shift which may sound unnatural. If there is room to use an exponential flare horn of adequate length and mouth size then a more natural sound may result. Problem is that bass horn construction is such a large undertaking that direct comparisons are rarely made.

[scott fitlin]

Basshorns! MMMM, when done properly basshorn bass is INCREDIBLE!

BTW, Steve someone was telling me they stopped by your place, and how amazing your stuff sounded!

:)

[Beowulf57]

Hi guys, really good discussion. I once had an early '50s Jensen Triplex three way system that included that back loaded corner horn and it sounded pretty darn good for something of such reasonable size. Opinions vary about the hyperbolic horns though. Dr. Edgar uses a hyperbolic 35Hz. flare in his Seismic Sub to approximate a 20Hz. exponential flare in the nine foot path length of his design. He does this for the reason indicated in the response graph; low frequency extension. Some have opined that in general a very rapid cutoff will have an attendant rapid phase shift which may sound unnatural. If there is room to use an exponential flare horn of adequate length and mouth size then a more natural sound may result. Problem is that bass horn construction is such a large undertaking that direct comparisons are rarely made.

Interesting point regarding the possibility of phase shift with rapid cutoff. I can't say I've heard anything that suggests a problem, but then what would such a phase shift issue sound like in the deep bass? Any thoughts on what sonic characteristics could be identified by the listener as "unnatural"? Perhaps the contribution of the simultaneously forward firing bass masks this possible effect?

And yes...how to compare? Let's see now where can I put those Klipschorns...? :D

[spkrman57]

Steve,

Thanks for chiming in on our thread! I value your input and knowledge of horn design and theory!


Hi guys, really good discussion. I once had an early '50s Jensen Triplex three way system that included that back loaded corner horn and it sounded pretty darn good for something of such reasonable size.

Could you comment on the bottom end LF response if you remember from back then?

Opinions vary about the hyperbolic horns though. Dr. Edgar uses a hyperbolic 35Hz. flare in his Seismic Sub to approximate a 20Hz. exponential flare in the nine foot path length of his design. He does this for the reason indicated in the response graph; low frequency extension.

I always thought the horn flare was 35hz and Bruce used EQ to extend the bottom LF response.

I never could see using EQ on a horn for lowering response. Would that not introduce quite a bit of distortion compared to using EQ for a sealed/ported system?

Some have opined that in general a very rapid cutoff will have an attendant rapid phase shift which may sound unnatural. If there is room to use an exponential flare horn of adequate length and mouth size then a more natural sound may result. Problem is that bass horn construction is such a large undertaking that direct comparisons are rarely made.

According to Jensen Technical Bulletin No 3 (1952) which I referenced in a website link previously in this thread, the theoretical flare cutoff is 43hz when corner loaded, if they are sidewall loaded, would the cutoff frequency then be approx 86hz using the 40" horn length?

Thanks from a horn rookie!

Regards, Ron

[Steve Schell]

Hey Scott! Yeah, nothing like giving a woofer a real load to work against rather than having it flail about. Horn loading is a beautiful thing. I get quite a few folks through here, glad to hear the talk is not all bad.

Beowulf57, I'm not sure what rapid phase shift at 20 or 30Hz. would sound like. Sonically it may be more an issue of loading the driver adequately to prevent an unloaded condition at driver resonance. As I see it the whole point of going to the trouble of building bass horns is to avoid bloated, boomy, out-of-control bass response. Even so, some designers yield to the temptation of placing the driver resonance down around the flare cutoff frequency. This will produce more output down low, but at the cost of some boom. I have always had better results using exponential horns of low cutoff frequency and placing the driver resonance somewhere up higher in the passband where it is swamped by the horn load.

spkrman57 (two 57s in one thread!), a horn's cutoff frequency is primarily determined by the rate of expansion along its length. The longer the horn path and the larger the mouth, the smoother the response will be down near the flare frequency. This is due to the impedance mismatch at the mouth which causes sudden unloading and reflections that travel back up the horn to affect the driver loading- both positively and negatively depending on frequency and the distances involved. Actually in the case of this rear load Jensen it may be a bit more complicated as backing the cabinet will create a dual rate of flare horn, the flare inside the box followed by the flare of the room corner.

[Beowulf57]

Thanks for the insights Steve. I haven't noted much "boom" down low, as the room resonances higher up in the mid-bass (say around 160-180Hz) are more prominent. I'm intrigued with the actual result of the corner loading continuing the horn flare particularly when the output is from a split 2-section horn and is augmented from the front-firing woofer. Frankly the physics and audio math necessary to figure out how this horn actually performs is beyond me, though Figure 2. in the PDF I posted in post #28 does show the interference effect you have mentioned around the flare cutoff.

If Jensen is specifying the flare cutoff at 43Hz (which has a wavelength of around 26'), I think this must be using the additional flare of the room walls?

Almost as if the entire cabinet is a loading chamber feeding the throat of a 1/2 horn formed by the room corner? I say 1/2 as the top of the horn is open with only the sides and bottom in place (walls and floor). Though I may be way off base (bass...:blink:) here as I don't know how much loading a horn has when one of the 4 walls is absent? However, the Klipschorn seems to work this way. I'm interested in your thoughts on the audio physics of this, since once you are out into the room or in another room, one has the impression of the whole room loading the driver. I recall as a child that my father was playing around one day and cranked the system up full with pipe organ music...he cracked open a window in our den and closed the door to the room before he stepped out into the street. I could have sworn the pipe organ was the whole house as a loading chamber playing for the outside world.

[jcrobso]

Thanks for the insights Steve. I haven't noted much "boom" down low, as the room resonances higher up in the mid-bass (say around 160-180Hz) are more prominent. I'm intrigued with the actual result of the corner loading continuing the horn flare particularly when the output is from a split 2-section horn and is augmented from the front-firing woofer. Frankly the physics and audio math necessary to figure out how this horn actually performs is beyond me, though Figure 2. in the PDF I posted in post #28 does show the interference effect you have mentioned around the flare cutoff.

If Jensen is specifying the flare cutoff at 43Hz (which has a wavelength of around 26'), I think this must be using the additional flare of the room walls?

Almost as if the entire cabinet is a loading chamber feeding the throat of a 1/2 horn formed by the room corner? I say 1/2 as the top of the horn is open with only the sides and bottom in place (walls and floor). Though I may be way off base (bass...:blink:) here as I don't know how much loading a horn has when one of the 4 walls is absent? However, the Klipschorn seems to work this way. I'm interested in your thoughts on the audio physics of this, since once you are out into the room or in another room, one has the impression of the whole room loading the driver. I recall as a child that my father was playing around one day and cranked the system up full with pipe organ music...he cracked open a window in our den and closed the door to the room before he stepped out into the street. I could have sworn the pipe organ was the whole house as a loading chamber playing for the outside world.
The whole room becomes part of the horn!;)
When I walk from my living room through the dinning room at the far end on the dinning room the bass is just something to feel, coming from my JBL loaded "K" horns. With corner horn speakers the longer the walls are from the corner the better the bass. The effect of the room loading of the horn is something to feel.:)

[scott fitlin]

Hey Scott! Yeah, nothing like giving a woofer a real load to work against rather than having it flail about. Horn loading is a beautiful thing. I get quite a few folks through here, glad to hear the talk is not all bad.BAD TALK? No, what this guy had to say was that looks are deceiving, and that your horn system made instruments and vocals sound UTTERLY real, which is something the vintage horn stuff was known for. He was also taken by the magnet wire, and your tube amps, and HOW YOU CAN GET SO MUCH OUT OF SO LITTLE!

I must admit, I love the way your horns look, I lust for them! And the one thing I REALLY want to hear, is YOUR midrange! From everything I have read that you post, I get the impression that part of your philosophy is IF THE MIDRANGE AIN'T RIGHT NOTHING ELSE WILL BE, EITHER!

The vocals and instruments sounded UTTERLY real! That's the tell, for that to happen, you have that special midrange.

My dad has a huge home in Austin, and while I was visiting dad asks me what kind of speakers do I think he would like, so we go online, looking for your stuff, I show him pics, I tell him THIS IS THE DEAL! Here comes my mom, takes one look at the horns, and starts doing the "SCOTTAREYOUOUTOFYOURFUCKINGMIND" dance! Dad was intrigued by the field coil operation, and being that our bumper cars motors are field coil DC motors we have MORE than a hint of understanding about the principles of operation. Dad says he vaguely remembers big speakers with all kinds of wires, I mean he was born in 1937, so even when he reached ten or twelve years old, there was stuff like that still in use! Then, we look at pictures of the old RCA stuff, and he says YEAH, THAT I DO REMEMBER! There was alot of Altec stuff, and also RCA, and you know, I was never into audio like you, but, I remember RCA!

He was reading though, had his attention!

[originaltubino]

Here's more Jensen info/data I found useful while researching:
http://aafradio.org/audio/Jensen_G-610_triaxial.html


Nice link! I have a pair of these beasts in my basement, and it is quite amazing what they can do with JBL LE15B drivers (and with Tannoy dual concentrics, and with Altec 515E's ...) Even with crazy-loud and crazy-low bass making objects dance off the shelves, the cones will have extremely low excursion -- so they sound remarkably clean over the rest of the frequency range. I also have Tannoy GRF-R's, which are a considerably smaller version of the giant Jensens (30 cu ft: 5' tall x 3' wide x 2' deep). With a crossover at 800hz and the HF done with a 2" compression driver on Yuichi horns (which I got from Woody on this forum!), it's a truly remarkable two-way.

A friend of mine was inspired by my pair to build his own, and I recently heard the TAD 1601a in there. Impressive.

[scott fitlin]

You must have a really sweet sound. I like the bottom end from these kinds of cabinets, punchy.

You liked the TAD in that kind cab? I think the TAD 15,s make outstanding low end, and have a very clean sound. I use the 1603,s in Altec VOTT horns, and am thinking of upgrading to the 1601B, it is JUST hideously expensive.

I dig those 15,s too!

[Dingusboy]

You must have a really sweet sound. I like the bottom end from these kinds of cabinets, punchy.

You liked the TAD in that kind cab? I think the TAD 15,s make outstanding low end, and have a very clean sound. I use the 1603,s in Altec VOTT horns, and am thinking of upgrading to the 1601B, it is JUST hideously expensive.

I dig those 15,s too!
I'm the friend with the 1601, it didn't load the horn to quite the extent the LE15B did but it DID load it enough to offer some punch. We only recently dropped them in there and it was impressive with some room for improvement in some areas but a very clean yet punchy presentation.

[scott fitlin]

For me, the TAD 1603 deals with the extreme amounts of low end in todays digital music. I found the 1603,s tightened up the bass for me as well as offering prodigious low frequency. It is a flatter response than my old Altecs, and not as midrangey as the altecs were, but for todays music, that turned out to be good.

I also find my speakers, as always has been the case, are amp sensitive. And Crown is what I prefer on them, and they sing.

They do work thats for sure.

[spkrman57]

Steve,

I think I was getting ready to make a mistake in using a driver in my horns that have a Fs of 40hz (JBL 2225).

Now after reading your post over and over again enough times for my feeble brain to understand what you are trying to say, I'm going to use my JBL D131(reconed w/2202 conekits). They have a Fs of 70hz without being broke-in!

I ordered the cork gaskets for them from edgewound(Thanks Ken!) and after my windows get installed(next week or so), I'll get new baffleboards cut and install the D131/2202 drivers and get them broke in and see how they sound.

If the horn has a theoretical horn flare frequency of 43hz and I have a driver with 70hz, how low will the horn reproduce the bottom LF response?

Thanks, Ron




Some designers yield to the temptation of placing the driver resonance down around the flare cutoff frequency. This will produce more output down low, but at the cost of some boom. I have always had better results using exponential horns of low cutoff frequency and placing the driver resonance somewhere up higher in the passband where it is swamped by the horn load.

[Steve Schell]

Spkrman57, my way of doing things is definitely the path less traveled, and YMMV. One can surely obtained the widest bandwidth in a given volume using a driver whose resonance is down around the flare frequency. I am primarily after clarity and transparency to the source, and suppressing resonances is the way to go IMO. It is hard for a driver to slavishly follow the signal if it is trying to go nuts at its resonant frequency at the same time. If you try it both ways you might at first be seduced by the extension of the low Fs driver, but eventually come to prefer the clean sound of the high Fs driver. With a finite horn (all of them) the response achieved never quite makes it to the flare frequency, though I would expect you'll get good response to 50Hz. or so.

Re: Bruce's Seismic, he does employ several dB of EQ boost on the low end to flatten response to 20Hz. Not my way of doing things, though its hard to argue with the big grins on the faces of those leaving his demo rooms at shows.

[spkrman57]

Thank you Steve for once again educating us!

I will also explore the issues that occur using the "sidewall" position that Jensen indicated is possible in the technical note No. 3.

I'm guessing that the horn will lose some LF response without the full corner-loading. But I will be interested in trying it out anyways when the time comes. I have to do these projects in my bedrooms as they are the only rooms with usable corners right now!

As soon as windows get replaced the project will continue along!:bouncy:

Thanks, Ron

[Dingusboy]

Spkrman57, my way of doing things is definitely the path less traveled, and YMMV. One can surely obtained the widest bandwidth in a given volume using a driver whose resonance is down around the flare frequency. I am primarily after clarity and transparency to the source, and suppressing resonances is the way to go IMO. It is hard for a driver to slavishly follow the signal if it is trying to go nuts at its resonant frequency at the same time. If you try it both ways you might at first be seduced by the extension of the low Fs driver, but eventually come to prefer the clean sound of the high Fs driver. With a finite horn (all of them) the response achieved never quite makes it to the flare frequency, though I would expect you'll get good response to 50Hz. or so.


Hi Steve,

I too appreciate your explanation to Ron. He has taught me what little I know. It's nice to be able to follow along at home.

I have a pair of the Build In '52 Imperials that I had been loading with low FS drivers. Your explanation might be spot on - I was seduced (sometimes still am) but have also enjoyed the clarity of a relatively higher FS driver in the same box.

The build in's are supposed to load to roughly 45hz, can you recommend a minimum Fs for a driver to work well in this cabinet?

[Beowulf57]

Having both a D131 (fs=75Hz) and a D130 (fs=40Hz) in the Jensen back-loading folded corner horns, I can confirm from actual listening experience that the lower fs provides more bass power down low at the expense of a bit more "boom" whereas the higher fs doesn't go as low, but has a bit less "boom." I suppose that having both playing simultaneously in the same room provides a bit of the worst and a bit of the best of both worlds.:D The cutoff for my cabinets is ~43Hz, so I would imagine similar results in your '52 Imperials.

[Beowulf57]

Yo Ron...have you tried to "break" in those new windows with those folded corner horns yet? :D

[spkrman57]

Yo Ron...have you tried to "break" in those new windows with those folded corner horns yet? :D


I'm waiting for the cork gaskets to arrive next week for my D131/2202 JBL drivers.

I'm talking to my contractor and getting new gutters in a few weeks to be sure that I'm totally broke her in the near future!!!

I'm guessing that in apporx 3 - 4 weeks I'll be caught up enough to get the horns up and running. I'm going to use a tubed electronic crossover and using 800hz as a starting point.

More to follow later, have to get back to painting and more home repairs. Here's pics of me painting and the new look on the front of the house w/new windows, new trim and a (new to me) metal front door.

Ron

[Beowulf57]

Fantastic Ron! Nice cabinet, a real corker of a paint job and now that you have the leaks fixed, you should get much better bass response. ;)

[Wilberforce]

Found it for $50 bucks on Craiglist, and posted the question "What would YOU do with this cabinet?" on diyaudio.com. Two weeks later, and 11 pages in, I'm listening to it now with a JBL 2220A 15" woofer, a QSC 10" x 14" Waveguide horn with a Selenium driver and an Econowave crossover. It sounds wonderful, and I haven't even moved it into the corner yet--it's smack in the middle of the living room and filling it with more big clean sound than I ever expected.

My original idea was a 50's vintage mono mid-fi system, powered by a Heathkit A7. But this thing is definitely not mid-fi, it's fi is very hi. I'm thinking of taking it to a cabinet maker to have it replicated for stereo.

The discussion can be found here: http://www.diyaudio.com/forums/multi-way/169755-what-would-you-do-cabinet.html

This thread was referenced today in that thread. This is my first post here, but I have been scavenging info at this site for a long time. I'm old school, JBL and Altec are audio comfort food to me.

These cabs are awesome. It's amusing that Jensen's name for it was a "compact back loading folded horn." OK, compared to the refrigerator in their tech bulletin no. 1 maybe, but it's a big, beefy cabinet, and sounds just like it should, and I haven't even put it in the corner yet.

[spkrman57]

I read your thread on diyaudio and hope to have my horns up and running in the fall.\

Too many other projects to do first.

Regards, Ron

[Beowulf57]

Great to read of your DIY journey with this design. Having two of these babies, I hope you'll go for broke and get a good cabinet maker to build you another. Or...might you try it yourself?

The horizontal shelf bracing reduces cabinet wall resonances, but never having heard this design without it, I can't comment on the improvement. The horn walls are large and if you play some bass heavy music and place your palm on the outside of the wall, I'm sure you'll feel some vibration. Hook up a signal generator to your amp and sweep the low end and you can identify the cabinet wall resonant frequencies with the "palm test."

On the other hand...if you love the sound, just sit back and enjoy!

[Earl K]

An update to an ancient thread .

Wilberforce eventually had constructed this pair of wonderful cabinets.

77822

:)

[spkrman57]

I've been busy with several friends with medical issues. But I'm looking at trying JBL 2206/2447 on 2332 horn using modified 4pi x-over(Wayne Parham pi forum).

I'm still trying to get my house cleaned from hoarding too much audio gear and drivers.

Ill be driving my spkrs with 6CA7/EL34 single ended for 9 PC.

Ill. Post results in future.....

Regards, Ron

[Mikesignal]

Reviving it again....I just bought this corner cabinet which I believe is a Brociner. It has a JBL n1200 crossover (old style) with a Tannoy direct radiator 12", a JBL d131, and a JBL 175.

81732
81733
81734

[MikeS]

Revived once again.

[MikeS]

I'll try to type up a post here soon...

[MikeS]

I acquired these through a friend whose into horns and collects Altec.

They are made entirely of solid 3/4" Mahogany. Actual 3/4" material.

So the supposed story is a guy in town back in the mid-late 50's, bought a 15" Tannoy Silver and had a local furniture maker build a Jensen BLH for the Tannoy.
(from what I can guess they used the Jensen plans)
Then stereo became popular. So the guy had another cabinet made, but couldn't afford another 15" Tannoy Silver.
So he bought an Altec 15" duplex of some model, can't recall the model the friend mentioned.

The old glue was failed or failing, and it took some time to repair some seams and seal things up. The task at hand is mostly finish work...
Once the repairs were done, I was a bit impressed at the bass presence. It's rolling off rather fast at 50Hz, but what they do above that is rather nice.

I'm using a Crites CW1526/K33 woofer, with Faital Pro LTH142 horn, with the HF140 driver. A passive 2nd order network using an autoformer, with cut-off at 500Hz.

Mike Stehr