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In Reply to: RE: Crossover point for Altec 816/JBL E140 & EV DH1012/HR9040 posted by Synthsayer on January 07, 2010 at 21:55:08
I'm glad that you have your woofer problem sorted out. I have to wonder about using the Klipsch crossover though. Does it have compensation for the CD horn?
When I ran an active system with 288H's mounted to HR9040's, I settled @ 500 Hz, 12dB/octave.
Follow Ups:
I am attenuating the horn with a good quality 50W L-Pad for the time being if thats what you mean. When I was running the system with an active 24db crossover I would run the EV's crossed over around 400-500Hz like you said. EV Tech Support told me the EV's could safely be crossed over as low as 350Hz. The 800Hz is really just a starting point in the process of tweeking the system to where I like it.
The crossover is not made by Klipsh per se, but is a design by ALK Engineering http://www.alkeng.com/klipsch. Al Klappenberger allows the download of some of the crossover designs that he sells as upgrades for the K-Horn, La Scala and others. His designs looked sound and I thought it would give me a good idea of where to start. Plus, through communicating via email with Mr. Klappenberger, he was kind enough to offer me some help with tailoring the crossover to my system.
I went with the 800Hz crossover point as somewhat of a compromise between the low frequency limits of the EVs and where the Voice of the Theater systems, which I like, are crossoed over. Plus, I wanted to keep in line with the general concept of crossing tweeters/mids over at 1 to 1.5 times the Fs of the driver.
Another reason I chose the current crossover frequency was to keep the inductor values lower and hopefully eliminate some of the problems associated with larger inductor values; higher DC resistance, hysteresis, bulkiness. It was really just a starting point in this stage of the project experiment. I have the components to build a crossover at 450Hz if I decide to do that. Actually, I expect I may change the crossover point to a 450Hz 12db L/R configuration just to try and keep the octave spread on the band pass as wide as possible. Plus, I would just like to see how it sounds. Right now I am going to enjoy listening to the system as it is for a few days before making any further changes.
Thanks for the suggestions.
Have a nice day
I am attenuating the horn with a good quality 50W L-Pad for the time being if thats what you mean.No, this isn't what I mean. The eq I was talking about is necessary because of the way a CD horn/driver combo like the EV will start to roll-off above 3-5kHz because there isn't any "horn eq" built into the design. This can be compensated passively, but I'm not sure if any of the Klipsch type crossovers are designed to do this. If you can eq the horn, I think you will find that you don't need a separate tweeter and won't have to deal with the consequent integration problems. I think you might have better luck with something like Jean Hiraga's VOTT crossover design.
Edits: 01/08/10
"If you can eq the horn, I think you will find that you don't need a separate tweeter "
The DH1012A starts to roll-off at 2.5Khz at 6dB/oct to about 6Khz, then at 12dB/oct to about 12Khz. Therefore, about 8dB of boost is required to 6.3Khz, and an additional 12dB from 6Khz to 12Khz, or a total of 20dB of boost.
The E140 in the 816 will be about 106dB, the HR9040 with 1012A about 112dB. Therefore a passive crossover may be made to pad and EQ the HF flat to 6Khz or so, and cross the tweeter over in that region.
With an electronic crossover and a complex pad/filter with about 25dB insertion loss, it is possible to EQ this horn/driver combo to about 12.8Khz.
This seems rather pointless.
If a two-way is wanted the Altec 288G (or newer) will produce much better results, or an EV DH1A with the adaptor removed.
I can give some tips about passive EQ/pads if need be.
A few years ago I needed to purchase a new replacement diaphram for one of the EV DH1012 Drivers. According to EV Support a new DH1A diaphram would considerably improve the high frequency response of the DH1012/HR9040 combination.
I was unaware that the new diaphram is Titanium and the old/original one was Aluminum/Berrylium(?)
I purchased new matching diaphrams and have a question about horn high frequency response:
Is a horn system's high frequency response the sole function of the driver or can the horn lense limit/improve the high frequency response?
I thought that better high end response along with improved dispersion were the reason for CD Horns. No?
Thanks for the help in advance.
"Ad Astra Per Alia Porci", - To the stars on the wings of a pig: John Steinbeck
Whatever you could suggest as a passive EQ/Pad would be greatly appreciated. I used Jeff Bagby's Passive Crossover designer to start with a contour filter. What it came up with that looked 'okay' was 8uf in parallel with 20 ohm resistor.
I haven't had enough time to fully evaluate it yet.
I would use a reverse L-pad for attenuation.
Adjust the series R for the attenuation required on the lower end, and the parallel input R for proper loading at the crossover point.
The series R should be bypassed by a cap in series with an inductor, try about 6µF and 120µH. This should make the horn/driver combo flat to about 6.3Khz, and roll off above there.
DJK:Thanks for the help with the Passive EQ circuit.
I just happened to have a couple of Perfect Lay 1.2 mH coils and old 6uf MIT MultiCaps. I used a 20 ohm 1% 10W resistor in parralel with the L and C as you suggested. The 20 ohm might be a bit much but I will listen to it a few days before making any further changes.
The difference is astonishing. I can finally really hear the cymbals and high-hats in both music and film scores.
Last night I watched Alfred Hitchcock's, "North by Northwest" and even though it's a ver old film, the orchestral pieces sounded better than I have heard.
On Genesis, "The Lamb Lies Down on Broadway", which I have listened to for 30 years, they sounded better than I have ever heard.
I previously tried 8uf in parallel with 20 ohm without an inductor, just the simplest R-C Contour Circuit and that was okay. But, adding the inductor to create the RLC Notch Filter made all the difference.
The response is very smooth and the sound seems to be much more transparent. The speakers almost seem to disappear. But the transistion between the bass cabinet and mid horn is much, much better. The mid horn has lost all of its 'honk' :-)
Thank for your invaluable help. I greatly appreciate it.
Have a great day.
Sincerely,
Synthsayer
Edits: 01/10/10
I had no idea the 1012A rolled off so much. My only experience with the HR9040A was with the 288H which didn't need such dramatic compensation. If the OP sticks with the 1012A, then he probably will be better off building a 3-way.
I have looked and looked for Jean Hiraga's EQ crossover but cannot find a site w a schematic or good description. The one I did find had an invalid URL.
Do you have a link to a schematic you could post, please?
Thanks
Thank you.
I take it you mean something like an R-C Contour filter that would cut some amount of db between 2-5k?
I have heard of something like that. I can't remember what cap and resistor values were mentioned but I have a calculator that gives a graphical depiction of the driver, circuit, and combined response. It is built into the Jeff Bagby Passive Crossover Designer for Excel.
I will look at the design you mentioned and give it a try.
Thank you very, very much.
I'll let you know how it works out.
Have a great day.
Synthsayer
...because I don't think I have explained the CD eq issue very well. Below is a link to a Peavey article which does a pretty good job of explaining the special needs of CD horns like the HR9040.
I wanted to thank you for posting the link below that displays a graph of the frequency response of CD horns.
This is a great illustration and helped me to calculate the needed Passive EQ filter with the help of DJK.
I also used the Jeff Bagby Excel program (version 2.0) which shows a great graph of notch filter response compared to original driver response.
After adding the parallel EQ circuit of 8uf, 1.2mH, and 20 ohms, the system has an all together new sound. I kept the current 3-way configuration. I will do some measurements over the next week to double check what I think I am hearing but the big hump which starts at 800Hz, where the mid band pass crossover section begins, going to around 10kHz seems to have been greatly reduced. I like the sound of the system much better now.
Thanks for your invaluable advice.
Have a great week.
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