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-   -   L-Lower? (http://www.diyaudio.com/forums/pass-labs/31681-l-lower.html)

oliverh 5th April 2004 09:32 PM

L-Lower?
 
Hi all,

As Nelson Pass posted he is working on a larger JLow. He mentioned a Manger driver. This would be a great challenge because the Manger is one of the finest fullrange drivers I know. But I never could find a concept that achieves the quality of the Manger in the low end as in the mid and high range. As the Manger is a bending wave emitter (hope to find the right words as a non native speaker) I am looking forward how the Manger behaves in a backloaded horn.
Another option I would suggest is the Fostex FE 103Z. One of the finest fullrange speakers I know. For a larger horn a Lowther could be an option.
These are a few ideas to open a discussion on further JLow projects...

Oliver

jirka 21st June 2006 12:35 PM

Hallo Oliver,
from your post I understood that you have your own personal experiences with Manger transducers, Fostex FE103Z and Lowther fullrangers. Could you please explain what you have heard on identical amplifier and source? Do you think the subjectively better dynamics with Lowther driver is the natural characteristic of stronger motor or is it primarily dependent on amplifier capability?:confused:

Do you think the high magnetic flux and flow motor design is necessary for best dynamics and detail?

My personal experience is that MSW really needs very quick amplifier to sound extremely realistic, but I have also heard Lowther-like driver and tube amplification sound in a similar way.
:angel:

Nelson Pass 21st June 2006 05:57 PM

2 Attachment(s)
I had the Mangers on loan and played with them in both a
3 cf sealed box and the J-Lows. Attached is an unequalized
wideband curve from my listening position. As with other drivers,
it required a high pass filter at about 100 Hz to smooth out the
bottom, and was fairly flat to 50 Hz.

It was quite acceptable, although I make no claim that the
enclosures are optimal. I'm not working on a successor to the
J-Low, rather I followed it with the Kleinhorn and an enclosure
that resembles an upside-down BIB.

It's true that the strong motor and light mass of the Lowthers
deliver more dynamics, particularly with small amplifiers, than
the less sensitive Mangers and Jordans, but with that comes
additional colorations, and so you have to make your choice.

The Mangers are neutral compared to the Lowthers, Fostex and
similar full range drivers. It is not my experience that any of them
particularly require a fast amplifier.

Nelson Pass 21st June 2006 05:59 PM

2 Attachment(s)
Here is a curve of the same with the J-Lows and a lower
frequency sampling that shows more of the bottom end.
(ignore the curve above 1 KHz). Again, note that this is from the
listening position with all the room effect that that entails, and
that equalization has not been applied.

jirka 21st June 2006 08:15 PM

Thank you very much Mr. Pass,
I agree with you. Somewhere else in the forum I have found your note "I wonder what the manger should sound like if the sensitivity was higher". I an trying to find someone who is qualified to try redesigning the motor of my MSW for better efficiency. It should be possible to add at least 3dB without excessive cost. I hope it doesnt mean ruining the drivers. New motor must not be too large because of reflections.

I have one another question which falls within other discussion: Could you describe how big effect adds the Pioneer 100kHz supertweeter if the source is the high quality CD or SACD?

Nelson Pass 21st June 2006 08:32 PM

That very much depends on everything else. The
PRT-9 is best brought in around 10 KHz or so, and it
does sprinkle a pure top end on whatever you're using,
but it is not for every system.

jirka 23rd June 2006 12:34 PM

Frontloaded Manger
 
2 Attachment(s)
Hallo,
I have decided to introduce one of my diy projects with Manger sound transducer (MSW). The excellence of this wide-range driver as a direct radiator is well known these days. However I have not found any frontloaded loudspeaker utilizing this driver. There are just some projects of backloaded horns as Basstuba on the internet.

According to Bert Doppenberg the Manger transducer is too compliant for satisfactory frontloading. My results show very good suitability for front horns.

I have listened to Oris 150 / AER BD 3 combination several times. I also listened to Hedlund horn / MK I combination. There is no doubt these are great speakers. The contribution of front loading is absolutely clear to me. It changes the sound from dry to liquid, from sterile to colorful, from synthetic to live. But the front horn must be extremely acoustically dead. If not made properly, the sound is one of the worst you can diy.

This was my case, my friend Coffee (I owe a great deal to him) made me near tractrix front horn (something like Oris 250) but from 3 mm of laminate (fiberglass). I installed MSW into those horns and played music without any passive filter. The sound was very colored and fatiguing. The exact opposite of what the Manger sound like as a direct radiator. In addition it had decreasing response in the highs (I presumed it).

It was necessary to dampen the rear side of the horn and to reduce the horn length. I made it with small steps. Now the horns are damped by about 10 mm of bitumen-rubber material (asphaltic putty). This material will be difficult to paint, but it is acoustically dead. Horn length is reduced to about 160 mm. Horn throat diameter is 204 mm. Maximum horn diameter is 520 mm. There is no back chamber (my goal has always been to find the best dipolar application of MSW because there is nothing like ideal back chamber).

How is the sound? It has typical neutral MSW sound, but with all the advantages of front loading (more detail, more dynamics, more body, more space). Coloration is negligible. This is the pair of large Manger transducers, capable of very detailed soundstage.

Transmission range is from 40 Hz to 40 kHz and balanced output is from 200 Hz to 25 kHz.
I caught myself enjoying Faithless or Chemical Brothers without using bass drivers. Certainly for classical or rock music the bass drivers are essential.

Yes, Bert Doppenberg is right in his conclusion that smaller and shallower front horns bring less coloration and more freedom to the sound. But I think the freedom depends primarily very much on room size and listening distance. With direct radiating MSW one can register 3D sound effects in smaller room.
:D

Nelson Pass 23rd June 2006 05:52 PM

It is always a pleasure to see someone go ahead with
some experimentation. Edison said that invention is
5% inspiration and 95% perspiration.

:cool:

jirka 26th June 2006 09:10 AM

I have been doing more experimentation with those horns. It seems possible to balance bass output as properly as it will no more need any additional bass system (at least in my 55 m3 listening room). Short back chamber enables this without coloration.

It is a must to weight the MSW driver down because of its relatively low mass. I attached six strong neodymium magnets (N50) to the motor as a weighting. It does not affect sensitivity and sounds better in extreme dynamic passages. I do not know if this is firstly due to the higher mass or due to the relatively stabilized magnetic flux in air gar but it works. Later I will probably use massive iron flange instead of those magnets.

Best regards to all
;)

jirka 23rd August 2006 04:18 PM

2 Attachment(s)
I reduced the horn length to 135 mm. This sounds most open at highs (as if it was in large open baffle). The drop-like enclosure sounds more like normal box enclosure (baffle step is around 350 Hz).


I have tried also various open baffles, which are all superb with MSW (the larger the better), but the zerobox head with 3 MSW is my future favourite in every aspect (huge price) and for the low price the shallow front horn is excellent solution.


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