Dang these Jordans!

[planet10]

I'm not sure how a MLTL would compare with a BR operating purely as a bass enclosure.

I'd expect an ML-TL to work better...

My designed is a triangulated tapered transmission line i did up for woody.

dave

 

[planet10]

Planet 10, any chance for those dimensions?

Here it is.

dave

 

[Colin]

Hi Dave

As you've more experience with TLs, would you mind expanding on your comment? In what sense would the TL be superior to the BR? More power handling or reach lower into the bass? Or is it the quality of the bass?

I'm particularly interested as in this case the driver would be rolled off above 100Hz, so I'd have thought box effects would have be minimised. And from one of JVA's previous posts, it looks as though the reflex will reach 20Hz.

Colin

 

[planet10]

As you've more experience with TLs, would you mind expanding on your comment? In what sense would the TL be superior to the BR? More power handling or reach lower into the bass? Or is it the quality of the bass?

Just a couple quick comments...

A TL has much more design range than a BR... it can go all the way from looking much like a BR (ie ML-TL, similar group delay and impedance humps) to almost horn-like (TQWT) to aperiodic that looks quite similar to a sealed box but with a much less pronounced peak (heavily stuffed line).

Comparing a BR to an ML-TL we have 2 related features that give an ML-TL an edge. 1/ instead of 3 cabinet resonances that can be problematic, by changing the aspect ratio of the box we push 2 of the very high up where they can be inconsequential, and the 3rd we turn into a very strong resonance. this is then used to augment the bass, and geometry tricks & stuffing are used to ensure that little of the higher harmonics get out the port.

In any TL, we also have the "suck-the-backwave-down-the-pipe" effect, whereby less energy is passed back thru the cone reducing time smear.

If your goal is 100 Hz, with active XO to a woofer, then a heavily tapered aperiodic TL makes a lot of sense... and as short as that is can be fairly small (make it straight or fold it once, but point it back)

dave

 

[Dave Jones]

If your goal is 100 Hz, with active XO to a woofer, then a heavily tapered aperiodic TL makes a lot of sense... dave

Reminder: This thread was originally about a Jordan JX92S system with a sub. The mains are in .3ft^3 sealed boxes. I'm crossing over to the sub at 96Hz. I can't imagine the system could sound much better. The last, best improvement was putting the active highpass filter on the mains.

 

[audiobomber]

The mains are in .3ft^3 sealed boxes. I'm crossing over to the sub at 96Hz. I can't imagine the system could sound much better. The last, best improvement was putting the active highpass filter on the mains.

Hi Dave. What is the system resonant frequency? I imagine around 70 Hz? Is there any (theoritical?) problem crossing over that close to resonance?

 

[soongsc]

Reminder: This thread was originally about a Jordan JX92S system with a sub. The mains are in .3ft^3 sealed boxes. I'm crossing over to the sub at 96Hz. I can't imagine the system could sound much better. The last, best improvement was putting the active highpass filter on the mains.

.3ft^3 seems real small for the JX92s, I though the minimum of 3 liters was recommended. Didn't know the JX92s could have good sound with this small volume.

 

[GM]

Greets!

0.3ft^3 = ~8.49505L so is considerably larger than the 3L minimum.

GM

 

[soongsc]

Greets!

0.3ft^3 = ~8.49505L so is considerably larger than the 3L minimum.

GM

Oh! I was thinking (0.3ft)^3 instead, sorry for the confusion.

 

[Dave Jones]

Hi Dave. What is the system resonant frequency? I imagine around 70 Hz?

It's 76.5 Hz.

Is there any (theoritical?) problem crossing over that close to resonance?

Dang, I don't know. I ain't no theorist. The group delay is pretty flat. (Qtc is something like .67.) Plus, both the high and low filters in the crossover are effectively very steep. The mains have 12dB/oct from the sealed box and 24dB/oct from the Richter Scale. The sub has 12dB/oct from the plate amp and 24dB/oct from the Richter Scale.

 

[audiobomber]

It's 76.5 Hz.



Dang, I don't know. I ain't no theorist. The group delay is pretty flat. (Qtc is something like .67.) Plus, both the high and low filters in the crossover are effectively very steep. The mains have 12dB/oct from the sealed box and 24dB/oct from the Richter Scale. The sub has 12dB/oct from the plate amp and 24dB/oct from the Richter Scale.

I wonder if it would improve it you rolled off the Jordans @ 12 dB electrically (for 24 dB acoustic slope) and then match it to a 24 dB slope on the subwoofer for a classic LR4? Phase performance should be better?

 

[soongsc]

I wonder if it would improve it you rolled off the Jordans @ 12 dB electrically (for 24 dB acoustic slope) and then match it to a 24 dB slope on the subwoofer for a classic LR4? Phase performance should be better?

The phase diagram of the JX92s is really funny, you probably want to look at it closer at the web site.

 

[miriam]

My Jordan JX92 s

Hello everyone !

I bought a pair of JX92 TML on ebay! 500 EUROs is not too much I think
I started to build them, material was already purchased when I found this ebay announcement. Well, maybe I will build another pair later...

The housing is made of 15mm OSB + 18mm beech , so it's 33mm!!
It's made by a professional craftsman, I won't be able to do things like this in my small workshop.

I have added a impedance correction circuitry (5R6 + 6,8uH) in parallel to the speaker. An optional BSC circuitry can be connected in series to the whole system (2R7 + 0.68mH + 22uF). This is also the suggestion on the german Jordan dealers' homepage (hifisound). Well, the BSC is not really needed...

So, the sound is amazing, but you know this....
Now my TDL SMCs are for sale!


Greetz

Markus (alias Miriam)

 

[sardonx]

JVA, is that the LCY ribbon supertweeter on top of the Jordan?

It looks like it but but the front opening seems smaller than the LCY. That's interesting..

 

[JVA]

Sardonx


I used a Fostex FT17H, on top. I placed the tweeter in a 4 inch black P.V.C. pipe ,about 5 inchs long including the end cap.
Inside is stuffed with pollyfill,plus a Cap and Lpad ,with the Lpad control and binding posts coming out the back.

Joe

 

[RAndyB]

Heav'nly harmony, said St.Cecilia

My pair of JX92s arrived at lunch time. By tea time one was mounted in a 4ft.square baffle and connected to the system. After tea for me, and a recharge for the drill, the second one was connected (suprising foresight to have bought a sheet of chipboard along with the MDF for the proper cabinets).
These are producing a more convincing sound than the 3 way Peerless units that expired last year. I have already relaxed more than ever before whilst listening to favourite pieces, apparently they get better with time.
So much more detail: flute and oboe immediately differentiated; the tenors have started singing at last; the stringy thingies are only normally screechy.
Why did I wait so long?

 

[soongsc]

Envy you guys! I can't get to that project yet. But I'm starting to do some modeling on spare time.