Handmade, part M9500, part Zingali, and part D2.
Handmade, part M9500, part Zingali, and part D2.
Well, they certainly look cool. You've done a nice bit of cabinet work there. Tell us more. Did you turn the horns? I'm guessing JBL 2225 woofers and a 2" exit driver, 2440 or the like. Looks like you've used the staggered tunings. Tell us about the crossover, and if you have process photos it would be cool to see those as well. Thanks for bringing this on the forums.
David
Impressive looking.
Yes, some photos of the construction would be interesting and informative.
Out.
Thanks for your interest.
First the bad news. I don’t have any pics of the construction phase (which took about a year). As well, there is no “physical” JBL content in these speakers, but there is a lot of JBL “intellectual” content.
The cabs are constructed from 1” thick MDF and were covered with red oak veneer. The top box is 5 cu ft (25”x25”x19”) and the bottom is10 cu ft (43”x25”x19”). Like the JBL M9500, they are tuned to 35 Hz and 28Hz respectively. They are necessarily bigger in volume than the ‘9500s (2.8 cu ft & 4.1 cu ft), due to the non-JBL drivers (sorry!) used, but as a result, the response curve matches that of the 9500 almost perfectly.
I turned the horns and the ports myself, out of poplar wood, on a $200 lathe! The round horn is exponential taper and as close a copy to the Zingali units as I could manage on my crude equipment.
The bass drivers are Usher 15HM (which are used in the Usher D2 speaker) and the compression drivers are B&C DE500 1” units (used by Zingali). (The Usher D2 has two identical 10 cu ft cabs, each tuned to about 28 Hz. So, my “stagger tuned” design is pure M9500.)
The system is bi-amped, with the 15HMs (in parallel) and the DE500 driven directly, just like the JBL DMS-1. I designed and built a custom active analog crossover unit (similar to the JBL DX-1) that uses high-speed buffers (no opamps!) and has the filter components on small daughter boards. I am presently using a 4th order Linkwitz-Riley alignment crossing over at 800 Hz. I also have 4th and 3rd order Bessel daughter boards built, but I have not tried them yet. No delay was required, as the horns and woofers measured in phase at 800 Hz. This surprised me somewhat, due to the fact that the DE500 voice coil is about 6” behind that of the 15HM. However, this is also the geometry of the DMS-1, and JBL spec a zero delay for that cab, so I guess all is well.
How do they sound? Well, I guess the fact that my wife is actually happy to have these hybrid monsters in our living room speaks for itself!
Linear
absolutely stunning...
Very nice looking cabinets and horn, job well done!Originally Posted by linear
I think your placement of the ports on the top and bottom of the cabinets is an improvement over the Usher D2 design, which has the drivers on the top and bottom, and the ports inboard, close to the horn. I believe your configuration will provide better MTM imaging, and the staggered distance of the driver centres from floor and ceiling will act to distribute modal response in the listening room, compared to a D2. (Nice to see a cabinet with edge bevels large enough to be acoustically useful)
I also heartily approve of the use of the axially symmetric horn, which appears to be well integrated into the front baffle. These type of round (simple) horns should generate less "horn honk" compared to bi-radial, or standard square mouth old-school horns. (modern finite-element designed waveguides excepted)
The horn you turned appears to be blocked up from planks of Poplar, with the plank at the mouth consisting of a single, full width, 15" plank! (you must have had trouble sourcing that). You also describe the horn contour as exponential, yet the wooden section appears to be too flat faced to be pure exponential, however photo's tend to distort depth perception so I might be mistaken.
Could you post a diagram of the exact contour, I'm curious.
I also note a short black tunnel running from the compression driver to the wooden section. This might form the exponential throat.
The B&C has a recommended crossover of 1.5 kHz (2nd order), and you are crossing over about 1 octave below that, with 4th order, so you might want to be cautious with the volume control. Adding that extra octave of bandwidth on the low side results in somewhere between 3-6db more power dissipation in the voice coil (based on typical music spectral density). The 4th order will have better attenuation below 400 Hz, but it's the extra midrange energy above 800Hz that may potentially cause damage in your alignment.
I would also like to see your measured response curves (on and off axis), as you mentioned that you have not used any response tailoring. The exponential horn contour has strong directivity narrowing with increasing frequency, which will compensate for the mass breakpoint induced HF response roll off of the compression driver. (thus flattening the response)
I suspect you will enjoy these speakers well into the future,
Jack
This is available through the usher website so I think there are no copyright issues.
Some data 15HM (2235)
Gap depth 8mm (7,14)
Winding depth 19mm (19)
BL 16,1 (20,8) !!!! There is a new Usher with stronger magnet released
MM 92 (150)
Vas 463l (525)
This is certainly no 2235 which I never said. The newer model with the stronger magnet looks very much like a 2234 but I don't have a scan at hand.
If we don't discuss JBL, it's difficulty to get them in Germany,
I'm inclined to mention European manufacturers like
18Sound, B&C, BMS, Beyma, Ciare, Craaft, Oberton and others.
They are worth a look.
But I really want to add, not every car is like Mercedes or BMW.
____________
Peter
Jack,
First let me say that your own project, detailed elsewhere on this forum, is very very impressive, with incredible detail and measurements. Any member who hasn't checked it out, should do so! Unfortunately, I won't be able to meet that standard of documentation.
The Usher D2 cabs can be turned either way (there are 3 separate sections to the speaker). The US rep for Usher says that the "photo shoot" for their brochure was set up wrong! (JBL would NEVER make a mistake like that, right?) I've attached a photo of a D2 that is set up "correctly".
Now, regarding my own project:
The front piece of poplar was two 10" boards glued edge-to-edge. The wood part of the horn is 15.5" dia at the mouth and 6" deep. It has a 2" throat. I use a 3" deep, cast black anodized adapter (JBL designed, I think), to attach the B&C DE500, which is a 1" unit. All of this is exponential taper with a total depth of 9" (from 1" throat to 15.5" mouth). Check out the photos that show all this.
B&C spec the DE500 on their ME45 horn, which has a 1" throat with a 11"x4.5" mouth, and 4.9" depth. This cuts off at about 1 kHz, acording to their spec sheet. The set-up I have described above cuts off at a significantly low frequency, due to the large depth and mouth. My calculations and "crude" measurements indicate a number between 600 and 700 Hz. So, I think I'm OK with a 800 Hz crossover, and that is what Zingali use in their loudspeakers.
One major reason that you don't see any "shallow" round horns, like the above design, in commercial production, is the Guiseppe Zingali holds a US patent 6079514 (and other worldwide patents) on any "round horn in which the mouth diameter is larger than the depth". You can check this out my going to www.pat2pdf.org and entering the above number. (It's a free service to download any US patent!)
Linear
WOW !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
which amp do you prefer ?
One of the main reasons for undertaking this speaker project was that the wood turning and cabinet building tasks were a pleasant diversion from my 36 year electronics engineering career as a linear analog circiut designer. I have specialized in zero global feedback/local feedback configurations, in an attempt to make solid state circuits sound more like tubes.
Therefore, almost all of my electronics is custom built. This includes my active crossover (previously described), and my power amps, which are a local feedback, fully complementary bipolar design. They can output 300 watts into 4 ohms (the two 15HM LF drivers), or 150 watts into 8 ohms (the DE 500 HF transducer). Since the speaker system is very efficient (98 dB), this equipment will produce an SPL level of almost 120 dB in my living room. (This is more than adequate, according to my wife!)
My system presently uses a Wadia 861 CD player (www.wadia.com) driving my custom crossover and power amps. There is no preamp or other equalization used. (I also have a Revox reel to reel and a Thorens turntable with Stax cartridge, now seldom used.)
Although I did not build the 861, I did design and patent the analog circuitry of this player, and licensed it to Wadia. They call it their "swift current" block. If anyone's interested they can check this out by entering my patent 4983930 into www.pat2pdf.org or by seeking out my AES paper on this topic.
Linear
i guess in combination with such startling and revolutionary design breakthroughs such as using not simply wood, but knot-free, wood for a horn, a us patent was inevitable
you have to wonder who they have working at the patent office.
Guiseppe's patent may be trivial, but a least the concept works and it protects his business interests. If you want to see the "outer limits" of what can be patented, look at 6025810 in www.pat2pdf.org. The inventor simply claims that he is "sending the signal faster than light" due to the fact that his design "pokes a small hole into another dimension". (This is NOT a joke! Check it out.)i guess in combination with such startling and revolutionary design breakthroughs such as using not simply wood, but knot-free, wood for a horn, a us patent was inevitable
you have to wonder who they have working at the patent office.
Linear
OK, I'm guilty of plagarism, but I only steal the best ideas!
Who knows, maybe there will be an "Usher Heritage Form" 20 years from now, but somehow I doubt it! However, Usher does offer a pretty good driver for the price (In stock for $218 at Parts Express), and they even publish distortion curves for that unit.
The 1400nd and 1500al are beautiful speakers, but even if I could afford the cost, availability is somewhat problematic (to put it mildly). If anyone wants to donate some JBL drivers to the cause ("Project May" for Linear :-), I will be more than happy to do a retrofit!
Linear
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