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...
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
You certainly are good-natured about my little sarcasm, which you can see I thought better of and pulled down, apparently just before your post came up. Congratulations on finishing what I'm sure was a demanding project.Originally Posted by linear
David
I also plan to work with these Usher drivers. They use the original 2235H cone BTW.
There was an interesting Project with two Ushers in a german speaker builder magazine. I'll try to find better pics but it's down right on the title here:
http://www.hobbyhifi.de/Aktuell/Aktu...e_ausgabe.html
What HF compensation do you use?
Guido,
I do not use any HF compensation, like JBL do with the DMS-1. The DE500 is somewhat of a poor man's TAD 4001. It is very flat when compared to the compression driver used in the DMS-1 (JBL 2450). So, I am driving everything flat across the audio spectrum.
It's great to know that the 15HM is "partly a JBL" (please, no flames! :-), even if it is just a 2235H cone. Is Usher just using the same cone supplier that JBL once used? I think I remember reading that it was a German company.
By the way, Guido, if you are really considering buying some 15HMs, they are now on sale for $159 at www.partsexpress.com (item: 296-630). Parts Express will ship internationally (to Germany) by UPS, and they will accept PayPal for payment. Back in 2003, I saw a German price of 350 Euro quoted in "Hobby HiFi" for the 15HM, so this might be a good deal even with the international shipping. It's almost as good a deal as the PE sale on the JBL 1500SUB sub-woofers a year or two ago, and those units sure sold out fast. Luckily, I got two of them.
Speaking of "Hobby HiFi", I would love to see some more of their 15HM article, if you have a chance.
Linear
Even if it is the same cone... Do they use a mass ring?, Since the surround is a fabric surround, even if the cone, mass ring, voice-coil, spider, and motor were the same... it would still be something other than a 2235. It may be an excellent woofer, I have no idea, but it certainly isn't a 2235.
From what I can tell, Usher is really good at making drivers that look like other people's drivers... I am not so sure they sound like other people's drivers. (I am thinking about their various tweeters and kevlar mids etc.)
Widget
Very nice looking cabinets and horn, job well done!
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
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