Jordan JX92S Center Channel

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I'm building a Jordan JX92S based home theater system.

The main speakers will be the Jordan design Transmission lines. The surround will be based on Dr Griffin's minimonitors (the earlier ones withouth the tweeter).

I have not, however, settled on a center channel design. The only requirement I have is that I don´t want it to be deeper than the mains (and the plasma tv) so 15 cm is the max depth. This shouldn't be a problem with the Jordans. It should also fit below the tv so approx 75/80cm height is the max.

I can use as many as three drivers and they can be individually amplified as I'm building a multichannel amp.

The options are:

1. A single JX92S.
2. A single JX92S and a G2Si ribbon tweeter. Probably crossed over at 3k (based on Dr Griffin's new minimonitor design) with line level xo's. This would provide me with better horizontal dispersion.
3. Two JX92S drivers and a GS2i (also crossing at 3K -line level- and triamping). This idea attracts me because I think I could use the additional SPL (since the amplifiers will be somewhere around 30 watts per channel). I've read that the usual way of placing this kind of center channels (horizontally) is not good for dispersion but I could set the "array" vertically.

I will appreciate any ideas,

xavier
 
Xavier,

You asked about the following for a center channel application:

1. "A single JX92S."

Very good choice for a center and could be used vertically or horizontally for a lower profile.

2. "A single JX92S and a G2Si ribbon tweeter. Probably crossed over at 3k (based on Dr Griffin's new minimonitor design) with line level xo's. This would provide me with better horizontal dispersion."

I have done this before with good results. If you use the enclosure in the horizontal position, just clock the ribbon tweeter 90 degrees so that the ribbon is vertical.

If you are using a home theater subwoofer, I would use the new JX92S/ribbon minimonitor design for the left and right speakers and then use the JX92S alone in the surrounds as you suggested in your post. Just set-up the HT so that all minimonitors are 'small' and thus route all low bass to the sub. You'll not get serious bass from the Jordan TL configuration any way for a HT configuration.

3. "Two JX92S drivers and a GS2i (also crossing at 3K -line level- and triamping). This idea attracts me because I think I could use the additional SPL (since the amplifiers will be somewhere around 30 watts per channel). I've read that the usual way of placing this kind of center channels (horizontally) is not good for dispersion but I could set the "array" vertically."

A MTM configuration like you suggest is not recommended with this choice of drivers. With a MTM you would need to crossover lower in frequency--say 2000 Hz which is much too low for the G2si.

Finally, the Aurum Cantus G2si (and all their other ribbons) are well shielded so that operation near a CRT or plasma TV is not an issue as suggested by EC8010.

Jim
 
FWIW, I recently experimented with GM's MLTL as speakers for a projector/home cinema arrangement, either side of the screen and toed in the recommended amount (ie crossing well in front of the listening position). I didn't feel any need for a centre channel as the dialogue etc imaged very well. However, I appreciate HT set up is rather different from music-only.

Colin
 
Colin said:
FWIW, I recently experimented with GM's MLTL as speakers for a projector/home cinema arrangement, either side of the screen and toed in the recommended amount (ie crossing well in front of the listening position). I didn't feel any need for a centre channel as the dialogue etc imaged very well. However, I appreciate HT set up is rather different from music-only.

Colin


HT setups are just because the decoding of proccessed sound requires a center channel.
 
Colin said:
FWIW, I recently experimented with GM's MLTL as speakers for a projector/home cinema arrangement, either side of the screen and toed in the recommended amount (ie crossing well in front of the listening position). I didn't feel any need for a centre channel as the dialogue etc imaged very well. However, I appreciate HT set up is rather different from music-only.Colin

I assume you did not feel the need for the ribbon either. what about using MLTL for left and right and a really small sealed box for the rears. how small a box can the JX92 live with. 4-5L?
 
Hi Navin

It was a very brief experiment - I happened to have my hands on a data projector for a talk I was giving and couldn't resist trying it out ... I'm not really a fan of HT surround.

I run the JX92s without any ribbon HF - running in GM's taller MLTL, they sound fine and I wouldn't want to risk upsetting the holographic imaging. But I do use them with the recommended toe-in.

According to the Jordan site, the smallest enclosure suitable for the driver is 3L.

Colin
 
You definately don't need (or want) a center channel - so long as all your listeners are centered between the L & R speakers. For me, that is almost never the case, I don't usually watch movies by myself. I built a center channel using one CSS WR125 (which is probably similar in output capablity to the JX92), and find that it is sounds great! Dialogue in particular is crystal clear, even when soft or whispered, I don't know if this is because there's no crossover, but it is certainly the best dialogue reproduction I've heard.

I cross over at 100hz and have no problems with reaching volumes at which my sub starts bottoming, so long as I cross them center over at 100hz in my receiver. Then again my room is fairly small, in a large room I would probably want to cross it over higher. As for the HF dispersion, I wouldnt worry about it too much, unless the money for the ribbon+xo is burning a hole in your pocket.
 
morbo said:
You definately don't need (or want) a center channel - so long as all your listeners are centered between the L & R speakers....
I cross over at 100hz and have no problems with reaching volumes at which my sub starts bottoming, ...As for the HF dispersion, I wouldnt worry about it too much, unless the money for the ribbon+xo is burning a hole in your pocket.

1. if you dont use center then what does one do with the center channel output from the decoder. do you direct it to other channels if so how?

2. 2 reasonsI dont like the ribbon. (a) you need an XO - I would not mind a simple 6db XO and let the fullrange run wide open but anything more it a headache to design right (b) cost

only i wonder if the JX92 HF dispersion will suit HT.

3. Given the price of the FR125 would you say that one could use the FR125 in a 1.5 way v/s a JX92 as a fullrange. It would cost the same.
 
navin - in answer to your questions

1. the surround decoder sends the center channel info to the L & R speakers creating a 'phantom' center. The sound is centered between them, just like in a stereo recording when a singer is dead center in the soundstage. Only works when sitting near the sweet spot though, otherwise the image pulls to one side or other

3. I'm sure you could do a 1.5way. Personally, I don't find the need, output is fine, and in my experience there is little need for BSC as the WR in a ported box has a bit of an upwards tilt in the midbass-bass area (model it to see what I mean) and if mounted flush with the TV screen its effective baffle becomes very large anyway.
 
Xavier

This week I listened to the Bower & Wilkins demo DVD “A Sound Experience”. Which you can get free if you listen to the new 800 series from B&W at your local dealer.

The DVD opens with a live concert from Peter Gabriel in Milano. On my Jordan JX92s center I can clearly hear the difference between the two microphones he use, one bad headset and one slightly better handheld microphone (they are probably from good quality but there is too much atmospheric interference). But his voice is coming right out of my center, it is like Peter’s throat is my Jordan. It’s like I am sitting in Milano myself!

Another piece on the same DVD is a song from Sarah K. Two Spanish guitars and female vocals. Strange mixed, the guitars are coming from the centerspeaker, the voice is coming from the front speakers.
On my Jordan you can exactly locate the guitars, in the middle of the center. The sound is crystal-clear with a nice deep bass. The vocals tough are coming from the middle but are not exact to locate, it’s an area from 30cm were Sarah K throat is somewhere. Sounds more diffuse comparing with the guitars.

My frontspeakers are much better than my center Jordan. As front I use the Italian Diapason which is a two way system, a wideband driver with a tweeter connected without any crossover and with the conemiddle only 10cm from each other. So from listening distance it is almost a point source. But the Jordan has something unique to offer as a center. It is a fullrange driver, it is a point source and can imitate the human voice and the reception of a microphone like no other system can.

The point source effect is what I like about using a full range driver like the JX92s as a center. But honestly the sound of the JX92s has also some bad sides.
-the high isn’t of the best quality
-the low isn’t of the best quality
-there is a lack of dynamics (it just isn’t fast enough).

So therefore here my comment on the suggested designs using the JX92s:

1 using a single Jordan, its ok. But then you have live with the limitations of the Jordan, which are the quality of the high and low region.

2 using the Jordan as a two way system with GS2i and a xo at 3K. I think this will make a fine monitor but even as a monitor it will not be my choice. Cutting of the high end from the Jordan seems a good idea but then I would use a wide band driver instead. This can deliver a much better quality of bass with more dynamics in the middle. As a center it is almost like a normal two-way system without using the advantages of a single full range driver as a point source.

3 using two Jordans and a GS2i in a ‘D Appolito configuration. Seems also a good idea. But a d’Appolito imitates a point source, a full range driver is a point source.
A d’Appolito always sounds a bit more diffuse. And I listened to many d’Appolito centers. My experience a d’Appolito vertical gives a better sound (less diffuse) than a d’Appolito horizontal but the source is further from your screen, and most of the times it does not fit in the interior design and in our image how a center must look like.

My recommendation
Use the full range of the JX92s. Place it as close as possible underneath your screen. Use a BSC to flavor the sound to your taste. And put a cherry on top with a tweeter, only to give something extra on the high end.
Please consider the design I described on this forum at http://www.diyaudio.com/forums/showthread/t-58565.html
I use a mini magnetostat, the Italian EB Cantare Super Slim supertweeter, which can deliver a fast high from 7k to 40k with a total flat curve. It is so small that it is possible to place it only 7cm from the conemiddle off the Jordan. The supertweeter is connected only with a 3,3µF cap. So no cutting off sound from the Jordan.

What you get is almost the full advantage of the full range driver, it gets a little more diffuse but it almost stays a point source. You can not compare it with a standard ‘d Appolito!
It is very important to place the tweeter as close as possible. I glued it on the edge of the Jordan. The tweeter is only 9mm thick and 33mm round. Only then no fase problems occur.

What I promise you is that you’ll be surprised about the realistic sound. Not only for voice but also for solo instruments like sax and guitar. It stays less suitable for piano because of the quality of the bass. Do not be afraid it will give you too much high or that it will be too sharp. Especially for S, F and T sounds it will not be more than without the supertweeter. Sharp S sounds are mostly because of bad recordings.
Adding a supertweeter will give you a much better quality of high, better understanding of vocals and even a more dynamic mid and bass.

The BSC I used is on the forum also but is now improved with help from my friend and forummember Soonqsc. You have to design one yourself for your own taste also depending on the type of housing. I also experimented with different caps for the tweeter but the 3,3 did it for me. It kicks in at about 14K so it will join the Jordan with the last half octave. It goes to 40K but that is total overshoot because there is no signal above 22K on DTS audio.

Do not understand me wrong I do not think a ‘d Appolito is a bad design. It is excellent if you need more volume because of your room size or if you like a better quality of sound because you like instruments like piano or alt sax.
I am just very enthusiast about this new possibility, so far I know this has never been done before with a JX92s. So consider it also because of the simplicity to build and cost.
But please do not cut off the Jordan it is a wonderful full range, what a waste!

I think I have got the most of the Jordan, it won’t go better. For me this is it! This is perfection.
 
for $150 per speaker the choices are:

JX92 ($140) no tweeter

FR125 ($75) with the EB Cantare ($60)

WR125 ($50) mated to GS2Si ($90)

i'd prefer to use as few XO components as possible and preferably run the fullrange direct with no XO. this eliminate the WR125.

mating the EB Cantare to the JX92 will run up cost to $200 per side. For this one could mate the FR125 with the GS2Si?
 
Suggest you try the JX92 on its own first and avoid all the x/over mucking about.

I run a pair of MLTLs using this driver and feel no need for an additional tweeter. In fact, I'd be loath to add one for fear of messing up the imaging. In comparison with a JX53/JX125 system, the 53's superior treble response shows up as a bit more air and a slightly more relaxed sound to the HF, but it is slight. (Proviso - at least it is with my hearing, which tails off above 15k, penalties of being over 40, etc)

If the 92 is facing direct towards you, you may need to roll off the HF slightly, as they are designed to be used off-axis. The easiest way to do this, of course, is turn them off-axis by having them face up or down.

BTW, back in the early 70s Ted Jordan designed a centre speaker system using two drivers and two reflectors which would be ideal for HT and requires only two audio channels. It was intended to achieve the sort of 'fixed' imaging that his linear array went on to achieve. Not much use if you are running a full 5-way set up, though.

Colin
 
colin, thanks i suffer from the same hearing deficiancies being on the same side of 40 as you are :)

the JX53/125 combo or Fostex FF85k/Seas CA21REX combos were my initial choice but
a) the JX125 is not being produced anymore
b) I heard the 103 and found the sound a bit papery and feared the 85 would be similar.
c) my wife nixed the idea of floor standing boxes esp. 5 of them.

Since I have time before i need to buy my drivers I am waiting for a verdict on this forum between the FR125 and JX92. The FR125 is about 50% of the cost of the JX92 and if it turns out to be just as good.....

I remember the 50mm module the Ted Jordan was using (2 per channel). It was not very sensitive though.
 
The FR125 seems to be getting some good reports but I doubt they'll be interchangeable with the JX92. The sensitivity seems to be somewhat less and the HF doesn't have the lift required for the 92's extreme toe-in. However it might be what's needed for centre channel use.

The JX53/125 is about 2-3dB less sensitive than the 92, so I used the amp's balance control to level them up and tested them on a mono signal. (How to spot someone who builds loudspeakers - he's made a mono CD of all his favourite tracks.)

Colin
 
I would take caution in taking any manufacture publihsed data for granted unless you have a second independantly tested results such that conditions can be duplicated. If you have comparible data from independent tests, then you can assume the data is at least close to what you expect.

Listening preference is personal, so you really need to know what kind of music other people base there comments on.
 
There are so much wonderful things to choose from.

-the FR is an upgraded WR, you have to use the WR with a tweeter. For the FR they claimed it is not necessary.
-compared with the JX92s the FR goes to 65Hz the Jordan to 45Hz

I still would recommend the Jordan you have more bass. But the price of the FR is very attractive.
Wait and save some until you can afford the Jordans you have more bas and…..

I think a supertweeter is a wonderful asset to a fullrange driver. It gives sparkle and dynamics. So later on you can upgrade with a supertweeter. You will have fun for many years.
Ordering in outside Europe can be a problem try: http://www.lautsprechershop.de/hifi/index.htm I hope they deliver world wide.

I promise you will have the same experience I am having this week. Finally I have a DVD with an excellent quality (Peter Gabriel is highly recommended by others but I think there is too much disturbance from his microphone). I listened to a jazzy DVD from a female vocal singer “Trijntje Oosterhuis, a thousand days” it has a DTS 5.1 track and is recorded in a smaller setting.
What I am now experiencing is the feeling that the microphone is straight plugged in to my Jordan. The membrane of the Jordan is almost her vocal chord. I have never experienced this before and I have listened to many centerspeakers.

This effect is totally because it is a point source, and second because of the quality of the speaker.

Unfortunate it is impossible to listen to my configuration trough the internet. But others have. And I let them listen with or without supertweeter and BSC because I have made two switches in the circuit. Everyone agrees the tweeter adds sparkle and dynamics in it. The credit is not mine, the design is from a German magazine. I only did it with a JX92s.

About the high frequencies are out of range for the (damage) human ear. The strange thing is that even people who can not hear above 5k can clearly notice when you shut off a tweeter in loudspeaker even with a XO from 10K. A supertweeter adds, fore everyone! Its adds quality of sound.

So the choice is yours. I only can share my experience and I have never done this on the internet and I probably never will, I dislike a bit PC use. But this is one worth it to share.

Regards
 

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As for the data taken on the FR125S.
Not a manufactures data at all far from it.
Testes were take by Dan Wiggins of Adire on a standard IEC baffle.
AS well these were not proto types they were some picked out of the batch before the shipment was sent via water and these came by AIR.

So I hope this helps out with a little unrest about the data that is provided.

I would be the same way if I did not know first hand for sure the data is correct.


Al
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