Jordan/Acoustic Energy Hybrid

[soongsc]

Soongsc
You have nothing to loose by taking one driver, (the worst damaged) apart. At least you will know how its put together, and with luck you should be able to fix. These drivers are very prone to coil rubbing because the tags fastening the suspension wires to the housing tend to shift.

Re adding a tweeter, in the original J-W info and cabinet designs, , the Jodrell and Jupiter designs used an MTM arrangement (16 ohm JWs in parl) with an 8 ohm "HF" unit (unspecified), fed by a 2mfd cap and 50 ohm series pot. The GT was similar, using one 8 ohm J-W. The recommended postioning of the cabinets is hard against the wall. The curve of the unit alone seems to droop above 10K, unlike the modern ones which rise. That was typical in those days to reduce the effects of clicks,pops and noise.

I'm also thinking about using some silicon rubber or somthing as a mold to reshape the cones, which should be an interesting experience.

I think the MTM is a perfect idea, that's. I also have a good tweeter that goes to 40K.

 

[rjb]

send me an email and I will send original designs and info

 

[keladrin]

Thanks for all the interesting comments

Well I did do a few tests on my system yesterday:

First I disabled the AE tweeter by removing the binding post bridge - the result was definately much less 'sparkle' even after turning the treble up

Then I passed the signal into the AE tweeters only and was amazed at how little sound came out - just a kind of tinkling that was of no appreciable volume compared with the original signal - so what is happening?

I then did some tests with a frequency generator and discovered that there was a major difference to the sound of the treble (at 5K) of the AE unit, compared with the JX92 - the AE unit provided a more dispersed sound that was noticeably piercingly loud when facing the speaker from a distance. The Jordan only reached this volume when one ear is placed directly facing the front of the speaker - so the sound goes directly down the ear canal. Perhaps relections from the room reinforce the AE volume making it sound so loud? In the normal listening position the AE unit seemed louder, whereas the Jordan seemed slightly louder with an ear directly in line with the speaker - but then the other channel is nearly lost.

The two units seem to complement one another, one providing spaciality and the other volume and stability.

Regarding the comment that reproducing frequencies about the limit of hearing improves the sound - I can't see this, unless you count intermodulation distortion (beat frequencies) or the fact that a driver capable of high frequencies is also very fast and dynamic at lower ones.

Possible a few items here for further discussion.

 

[rjb]

soongsc

you have mail

 

[soongsc]

Thanks rjb,

The FR plots certainly look different from my test runs, but this could be due to the material change after all these years.

 

[keladrin]

Sounds like a good idea. I'm really interested in looking for different models that I currently don't have, and fix the ones I do. The various designs really provide lots of inspiration, especially when they are based on broad considerations. Most other designers really seldom take the time for overall understanding of sound reproduction which really involves electromechanical, material, structural, aerodynamics, and acoustic waves as well.

It's amazing how confusing the hi-fi reviews are regarding speaker quality - they are extremely subjective with few impirical measurements - just impressive-sounding descriptions of how their favourite tracks sound when played (I feel they are simply using the tests to enjoy themselves!). I suppose this is designed to sell more magazines and feed the Hi-fi hype.

They seldom mention double-blind tests or under what conditions they are tested - sound levels, other hardware, room, listeners, and provide no comparison data regarding resolution, distortion etc. The long articles on the differences between the performance of speaker cable, stands, and amplifiers is farcical. I believed that such considerations (especially biwiring) to be mostly a waste of time and expense. I remember the reviews of the Jordan Watts when it was around (somebody made the finished speaker) and it was mostly overlooked or underrated at the time, simply because it did not have stereotypical disco boom/rasp.

It is designers like Jordan who really dictate the quality of the listening experience and the speaker is by far the most important consideration in a modern hi-fi system.

 

[soongsc]

One of the things I've found during recent testing is that the Jordan drivers always have very short decay time making them sound very clean and precise. Many other drivers that I've measured have long decay time which really messes up the sound image and sound quality. Other things that I have found relates with the design and manufacturing techinques that is not appropriate to reveal, but really helps the Jordans reveal lots more detail than other drivers of similar category. Recently I pulled out 3 aluminum cone 6" drivers to test, and the decay properties of the Jordan JX125 was the best. I really hope Ted gets these perfected so that it works great in almost all 2 way systems.

I also understand that lots of magzines have to live off of advertisements, which really makes it difficult for them to say bad words about any particular product. If there were a magazine that did not rely on adds to survive, maybe the reports would be more objective. I personally only look at some CD reviews nowadays because it really makes no sense reading different ways of praising a product unless one just wants to improve writing skills.

 

[Triumph]

Keladrin

What you have got to loose. Just a few penny’s for a cap each.

I have experimented for months combining different tweeters BSC's and XO’s with the JX92S and I find a first order XO only on the tweeter with a high cut-off point gives the best results. But I am not only searching for the best sound but also on the best stage experience. To get this phase problems must be minimalist. So do not listen only for its sound but also to directness, stage etc! I think it is a magic experience to be able to pinpoint the sound exact and that sounds come from places you never expect. Try a CD from Madonna with Q-sound effects, if your system is built properly the sound also comes from far outside your speakers and even next to you and not only between the speakers.

The way you presently built this is a bit against classical built of XO’s. The drivers are in action simultaneously in a too wide frequency range. It is too extreme. Colin loves the pure JX92S without anything. Like I, you love to add a tweeter, but I only do it on the last half octave. I think I am in between the both of you.

If you decide to try, first calculate the cap! There are many online calculators to find on the web. And there are loads of information to find for designing XO’s. If you are satisfied buy the best cap available. Congratulations you now built a excellent XO for nothing compared with complex ready made XO’s from cheap parts!

About no desire of adding high frequencies above the normal hearing range. You gave the answer yourself. The tweeter almost give no sound but it adds a lot combining with the Jordan. That is what (can) happen if you add a (super) tweeter with a range far above normal hearing. A piano, violin etc. also produces that ultra high frequencies. There is also a lot too find about research that has been done on the human ear. A person who can not hear anything above 8K can still notice if frequencies above 8K are on/off because it does something with the sound of the lower frequencies.

I am can not reply for the coming month(s). So I wish you all a Happy New Year.