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.
I will continue the horn testing once weather quits threatening my home.
By the way, the 12" version of those horns seem to measure the same as mine! Thanks for sharing that scan with us!!!
Regards, Ron
JBL Pro for home use!
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 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
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.
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.
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.
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.
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
Ignorant Member
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
JBL Pro for home use!
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:
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
JBL Pro for home use!
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.
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
JBL Pro for home use!
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?
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