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Multi-Way Conventional loudspeakers with crossovers

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Old 2nd November 2012, 10:46 PM   #11
Zoran is offline Zoran  Serbia
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Join Date: Jan 2004
Location: Belgrade
Not to forget to inspect the crossover in this cabs.
I found WE elements of about 5mH and 8uF
12db/oct JUST THE same for booth units.
BUT that is mistake and that means, because of the app same Z of the units,
that they start to cut on the same F. If that so, then they are forming a peek on F
with some bandwidth.
This is not propper and starting F's should be little remote from meeting F
Exact value shpuld be calculated based on -point of meeting, Z, order and type of crossover for each unit.
Sorry for long post
cheers
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Old 27th April 2013, 09:58 PM   #12
AndyEMT is offline AndyEMT  United Kingdom
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Hi Zoran

What did you use for a phase plug when you used the 2390's as compression drivers?

Regards A
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Old 29th August 2013, 08:13 AM   #13
Zoran is offline Zoran  Serbia
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I didnt use anu plug or so.
Iremoved original triangular cuved plate that covering membrane surface
.
I made a new lenses from wood and hyperbolic shape
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Old 29th August 2013, 08:48 AM   #14
Zoran is offline Zoran  Serbia
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Join Date: Jan 2004
Location: Belgrade
there is some topic on local site if You dont mind the language
Westrex 2080E zvucnici u novim kutijicama - Zvucnici - diyAudio.rs
merenja nekih horni i drivera - Zvucnici - diyAudio.rs
.
i have some more pics but cant find them now...
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Old 30th August 2013, 08:16 PM   #15
AndyEMT is offline AndyEMT  United Kingdom
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Hi Zoran

The triangular plate over the diaphragm with the layers of polythene "leaves" serves an important function in that it privides some back pressure to prevent damage to the diaphragm.

The 2390 driver was built without a phase plug and the throat is stuffed with foam. Using it as a dipole will mean that output from the throat will not be phase corrected although foam will probably dampen the output sufficiently as not to be too noticable.

Below is some information I received from an ex Westrex field engineer regarging the 2626A speakers


"Westrex Book Radiator
I was a field engineer at Westrex, my patch was NW London. I left to set up my own company and Westrex were my main Distributor, so I was often in and out of the Works at Coles Green Road. The following paragraph is not for the squeemish.

Most UK cinemas using Westrex sound and projection equipment were on a lease plus service contract, the gear was owned by Westrex. During late 60's cinemas were fast being converted to multiples, bingo halls or bowling etc, so masses of equipment was being removed. Having no storage space they put large skips behind the works. These were daily filled with 2040 40 watt tube amps (best ever), 2080 bass drivers and 2090 drivers and horns, and sold as scrap. Bass bins were broken up on site. Crying is allowed.

One day when visiting I saw lying by the skip a 2090C driver complete with Book Radiator. I grabbed it and remarked to the warehouse manager (Mr Bill Diamond) 'pity there is not a pair'. 'Wait',we are having a clear-out' he said and went inside and returned with another, which was obviously a prototype, having a rough looking makeshift bracket for mounting but otherwise identical.

I beleive these speakers as shown here were intended to superceed the original Acoustilens model, I cannot be certain but few if any were sold, in which case they are extremely rare. The only ones I knew of were owned by a very few of my fellow engineers. The guys that had them were the cream of the West End sound men, like Gorden Isaacs and Billy Bell. I heard them on a system consisting of a pair of 2040's, a Decca FFSS cartridge and tone arm. I never heard before or since such gorgeous quality from vinyl. But I must say the best systems I ever heard were the circa 1954 4 track mag Cinemascope movies with 3 Westrex bins with cellular horns. Its all gone backwards since. It is no surprise to me that efficient speakers sound far better, its the tight control by the huge magnets and small accurate gap, and stiff ouput of the transfomer coupling, damps overshoot and flapping around.

Back to the Book Radiator; I do still own the original prototype. At one time I pondered copying the perforated sheild and the Book 'pages' and offering them as conversion kit for 2090A. Too old to bother now. I am not familiar with the type number 2390, my memory is fading but as I recall the original horn driver was 2090A (24 ohms) and 2090C (15 ohms and no phase plug) but I could be wrong.

As you may know, if you put LF power to an unmounted bass driver, no loading to control it, it will likely bust the spider and surround. An HF pressure driver with no horn will do the same, fly to bits. Thats why they are tightly bolted up with a gasket. Failure of these drivers is often result of blown seal. If HF diaphragm was left bare with no horn load it would only be able to work at low level without damage. The name Book Radiator is the clue; you cannot slam shut a book however hard you push, you are working to push out the air. Thats what the leaves are for, to load the thing so it has some work to do. The perfotated shield holds the leaves in place and restricts overshoot.

This may be likely reason crossover frequency of these units was raised to 1000hz (Acoustilens was 675 i think, cinema horns were 500).
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Old 30th August 2013, 08:35 PM   #16
AndyEMT is offline AndyEMT  United Kingdom
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Join Date: Oct 2005
Changing the subject slightly

here are some pics of cabinets under construction for my BTH K10A 18" dual concentrics.

It's beyond me to attempt anything like this but Steve who has designed and is building the for me has amazing skills.

Click the image to open in full size.

Click the image to open in full size.
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Old 15th September 2013, 02:57 PM   #17
Zoran is offline Zoran  Serbia
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Join Date: Jan 2004
Location: Belgrade
Hi AndyEMT
thanks for the great text from former eng in WE
really nice thanks
I have also a pair of mono-blocks some WE germanium amps of about 25W per ch
removed input section, only left output section with just 4 same Ge transistor by Mullard
and input-phase split transformer. extremely big power transformers, and I was surprised, but they hod offset zero very very nice.
I just listened a bit them with a pair of old alnico lowthers and was beautiful...
Now I am planning to skip original ugly chasses and too big also, and perform a very simple, Ge WE amp. try to search on this forum i posted original SCH of the amp
but I cant remember where it was?.
.
Anyway I simply cant stand the very high db preasures from the WE 2390A
and I am using 4 units, so that is because I release a preassure
.
cheers
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Old 15th September 2013, 03:09 PM   #18
Zoran is offline Zoran  Serbia
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Join Date: Jan 2004
Location: Belgrade
Oh and my WE 2390A units are loaded
from the front with a "Lenses", I put more leaves of lenses and made a hyperbolic shape
of the cutted space. Was simple triangle before and lenses was from metal...
and from the other side, where was the stuffed closed compression chamber,
I removed the old spunge from the stuffing, and leave open the duct.
In the duct I was mount a Karlson coupler or horn.
So I left with lenses on one, and Karlson horn on the other side of the each driver.
So I have some thtoat loading and on each side...
.
Still is very hard to stand the preassure, and with a new 24db/oct xover,
I have to put some T attenuation net...
.
I am using now the old 2 pieces of Quad II tube amps
with a sufficient power for the WE units...
.
Probably I will mount a step down transformer and combine it with a C to acomplish some Xover and attenuation.
cheers
sorry for long txt...
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