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Woofer for hybrid Janszen 750Hz cross-over
Woofer for hybrid Janszen 750Hz cross-over
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Old 29th September 2006, 08:36 AM   #1
AR_sound is offline AR_sound  Israel
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Join Date: Jun 2004
Location: Modiin
Default Woofer for hybrid Janszen 750Hz cross-over

I have an old Janszen Z2CF hybrid Electrostatic, It have wonderful Electrostatic element flat down to 750Hz (two per speaker), and a 10" woofer in 90! li closed enclosure,

Problem is that the cross-over frequency is 800Hz and the 10" cone brake-up starts low, there is 9db peak at 1050Hz.

so I'm for better 10" that will sound good up to 1.2Khz and will blend nicely with the fast electrostatic element– is there such woofer or I must put some 6.5" or 8" into the existing enclosure?.

The original woofer (unknown brand) is paper cone and rubber surrounding, 2" coil, Q=1.1 in the box.
I guess Paper cone is fast and can match the fast electrostat at x-over point, But since I'm using active cross over now- 24db/oct and using notch filter to treat the cone brake-up above cross-over frequncey, Can it will be good choice to try an aluminum cone woofer for example seas H1209? (I'm not sure if this driver is OK to a 90li closed box).

Is it possible that non-paper 10" woofer cone can sound good at say 1 k-2 kHz?

What is the best woofer that can go up to 800Hz cross point and can deal such big (90li) cloesd box?

Any advice will be welcome.

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Old 8th November 2009, 04:06 PM   #2
DavidJanszen is offline DavidJanszen  United States
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Join Date: Oct 2005
Originally Posted by AR_sound View Post
I have an old Janszen Z2CF hybrid Electrostati . . . i
Hi, Avi.

I'd go onto the Parts Express and Madisound sites, or wherever, and look at the response curves for a variety of woofers. I think 10" metal cones will tend to ring and break up more dramatically where you do not want them to, and going with something stiffer, with a carbon or Kevlar fiber cone, or going the other way and staying with a paper or paper/carbon cone would be best if you stay with a 10" size. On the other hand, if there is room in the baffle area, you might consider replacing the baffle and using a pair of 7" or 8" woofers, which will generally start breaking up at higher frequencies, and where a metal cone might be among the best choices.

Once you have narrowed down your woofer selections, get one of the free box design software programs and use it to evaluate the in-box response based on the dimensions of the box. AVI Speaker Designer is a good one and will work in console mode under any PC OS.

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Old 18th November 2009, 04:44 PM   #3
AR_sound is offline AR_sound  Israel
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Join Date: Jun 2004
Location: Modiin
Hi David,

Thank you very much for your advice

I have replaced the Z-2 CF Loudspeakers woofer two years ago with hard paper cone 25W/8565-01 Scan-Speak. After long measurements and modifications to the baffle; heavy bracing, damping polymer, and reducing baffle size to 75li to achieve Qtc of 0.6- the low Qtc made the bass response very agile to match as possible to the Electrostatic fast nature.

Actually apart from the original electrostatic elements, all the parts of the loudspeaker been replaced (X-over, new EHT switchmode supply, cables, new Grill....
All of this was a looong journey but the final results are very good.

To my surprise the original Janszen electrostatic elements are sounding very good even today (after about 25 years). there is seems to be a little dip in measurements (5-7db) in the 8KHz or so, I wonder if this was there when the element was new or if this is an ageing sign for some drop in sensitivity?

I find it great that Janszen speakers lovers have now a place to
seek for help and from what I have read in your web-site the new Janszen seem to be a very interesting loudspeaker.

BTW I have in hand a pair of new (packed 20 years ago) electrostatic elements bought from "Multicore Bolders N.Y or Team Central Inc in Minneapolis". I wonder if these are original Janszen or the Z-2 CF loudspeakers are only "Janszen type" as you mention in your web site regarding these later 80' models?

Anyway it was great to get an advice directly from you so thanks a lot.

Kind Regards,

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Old 19th November 2009, 08:13 PM   #4
tiefbassuebertr is online now tiefbassuebertr  Germany
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Join Date: Jul 2005
Location: D-55629 Schwarzerden
The most important character of the Thiele-Small parameters was the very low loss in the surround (clothes material instead rubber) and in the spider, low weight of diaphragm (cone) and very high compliance (high value of Vas).
At this image is such a woofer
A similare transducer was the legendary SP-12C from Electro Voice,

Currently transducers with similar TSP you will find from TAD, Fostex and Supravox
Pioneer Pro AV TAD - Prof. Speakers
Fostex Speaker Components - Home
Welcome to SUPRAVOX
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Old 30th November 2010, 04:59 AM   #5
Thomas James is offline Thomas James  United States
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Join Date: Nov 2010
Location: Aspen Colorado
Default Janzen Z2 CF

Hi Avi, I used to work at the Janzen factory back in the 70s. The original woofers were from Sony and were the first drivers with carbon fiber and paper cones. I have a pair of Z2 CFs that I found without the woofers. If you still have the original woofers, I see it has been some time since you removed them, I would like to buy them. If you no longer have them could you give me some more detail on your upgrade?

Thanks, TJ Dorr
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Old 30th November 2010, 11:09 PM   #6
bentoronto is offline bentoronto  Canada
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Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
Woofer for hybrid Janszen 750Hz cross-over
Ah, memories from long ago. Great speakers and as good as it gets, short of full-range ESLs!

Can't say as I ever found a "special sound" or anything else was needed to match a cone to an ESL tweeter, other than all the other things that go into cobbling a speaker together. And with those tweeters, a lot of shortcomings in the woofers can be overlooked.

Seems to me, as I say every few days, the best strategy today is to go to the second-hand store (I wonder if the Salvation Army has stores in Israel?) and buy some old amps. Then get a Behringer CX3400 electronic crossover for the seasonal holiday of your choice. You can make that extremely flexible crossover do ANYTHING you want including 24dB/octave slopes, like at Alice's Restaurant.
HiFi aspirations since 1957. Currently working on motional feedback again... the final frontier in audio

Last edited by bentoronto; 30th November 2010 at 11:39 PM.
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Old 1st December 2010, 03:29 AM   #7
Thomas James is offline Thomas James  United States
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Join Date: Nov 2010
Location: Aspen Colorado
Default Janszen Z2 CF woofer replacement

I was looking at Peerless SLS 830669 12" coated paper woofer as a temporary solution because it would basically bolt in without cabinet modification. It is recommended for a 3 cubic foot IB cabinet and the existing cabinet is 3.2 CF. I think the 12" woofer will be a little beamy but the speaker is cheap. The original woofer was a driver made by Sony and had a carbon fiber & wood pulp cone. the problem is the original woofer had a very large cast aluminum frame so the cut out is 10.5 inches and so I need a modern 12" to fit the existing cut out. In the future I may fill in the existing cut out and use something like a SEAS Exel W26FX-001 with an electronic x-over and bi-amped. I can fill in the existing cut out then re-veneer the entire cabinet. I used to be a cabinet maker at the Soundmates factory and actually built this pair of Z2 CFs.

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