Dx-1

[pasadena]

Originally posted by Giskard
The HF12-16466 card could be done two ways.

I personally would try the simple way first using the best capacitor I could find and see how it sounded.

Giskard,

If the cards were left for XPL-200 listening, what mods would you perform to maxmise performance using the best parts available?

What would you recommend modiyfing the rest of the DX-1, if any were to be done? With unit being a decade old technology wise, I'm sure there will be a few things you can to the DX-1 in gerneral to tweak some serious performance out of it?

Look forward to some interesting comments!!!

Cheers
Mark

[Ian Mackenzie]

With great care you could use better quality filter capacitors, but the snap is they would need to fit the boards.

The main limitation is the unit is not balanced and unless you were careful, the otherwise lower dstortion would be masked by hum and noise.

As one JBL designer told me............" the bottom line is that an electronic crossover on this system probably will sound better than the internal passive, but it is a bunch of extra parts and trouble."

Experience proves this to be the case unless carefully engineered such as in a pro monitor application

My advice is invest in a better amp and upgrade the filter caps in the existing internal network.

Ian

[pasadena]

Originally posted by Ian Mackenzie
My advice is invest in a better amp and upgrade the filter caps in the existing internal network.

Ian

Ian,

What would be required to make the unit balanced?

I have been thinking about adding XLR inputs to the DX-1 but have yet to investigate whether or not this is worth pursuing.

You could probably upgrade the power supply and a number of other mods but everything still has to work harmoniously once modded.

Cheers
Pasadena

[4313B]

Originally posted by Ian Mackenzie
As one JBL designer told me............" the bottom line is that an electronic crossover on this system probably will sound better than the internal passive, but it is a bunch of extra parts and trouble."

Yeah but building one's own amplifier is a bunch of extra parts and trouble too. In fact, this whole DIY Audio thing is a bunch of extra parts and trouble.

I'd be inclined to try normal and bi-amped in any case and see which one is preferred.

Originally posted by Ian Mackenzie
My advice is invest in a better amp and upgrade the filter caps in the existing internal network.

I'd definitely support those ideas. The existing internal network could probably use a complete rework. Be forewarned - either route will require extra parts and trouble though...

[Earl K]

Hi Giskard

- Fine work on helping our new friend in Hong Kong.

And again, a big ThankYou to bbno4 for the very fine & informative pictures of your XPL-200 cards .

Pasadena; since you actually own some DX-1 units , I'd buildup the necessary cards and do as Giskard mentioned , see if you prefer the biamping option. That's likely the least hassle at this point. If this biamping option doesn't do it for you then selling the unit(s) with some working cards will be a lot easier. Rebuilding an existing network to ones taste is always a great endeavour and of course pursuing the best "the sounding amp you've ever heard" is a very worthy goal (for all of us).

Giskard; did JBL ever workup a DX-1 card for the S5800 ? I'm wondering how it might differ from the S5500 info that you posted.

regards <> Earl K

[4313B]

It took three covert ops teams, two dozen smoke grenades, and twenty-four hot ham and cheese sandwiches to get the S5500 data...

I'll try to aquire the S5800 and/or S9800 data sometime in the future.

[Earl K]

It took three covert ops teams, two dozen smoke grenades, and twenty-four hot ham and cheese sandwiches to get the S5500 data...

Wow,,,, sounds like I missed an excellent Simpsons episode.

I'll try to aquire the S5800 and/or S9800 data sometime in the future.

Thanks - it's all very helpful info .

<> Earl K

[pasadena]

Originally posted by Giskard
It took three covert ops teams, two dozen smoke grenades, and twenty-four hot ham and cheese sandwiches to get the S5500 data...

I'll try to aquire the S5800 and/or S9800 data sometime in the future.

Giskard,

I've just been speaking to someone who has a pair of DX-1's and he said that he ran them in full balanced mode as a pair and he also went on to say that the DX-1's were single ended? What would he mean by single-ended?

I thought that a unit could not be run in balanced mode unless they had balanced XLR inputs? As you may already be aware, the DX-1 have only RCA input/outputs!!!!

Care to shed some light on this?

Cheers
Pasadena

[boputnam]

I'd be inclined to think he ran pin1 to chassis ground, pin2 to (+) and pin3 to (-), for each. Or maybe I'm lost.

Pasadena - can you ask him what he actually did?

[pasadena]

Originally posted by boputnam


I'd be inclined to think he ran pin1 to chassis ground, pin2 to (+) and pin3 to (-), for each. Or maybe I'm lost.

Pasadena - can you ask him what he actually did?

Boputnam,

He quotes saying "The DX-1 is single ended meaning RCA hook-up only (one positive and one negative signal). For balanced mode operation, one DX-1 takes the negative signal thru the RCS positve and the other DX-1 the positive signal thru the positive RCA plug and then there is a common ground. Believe me it works great."

Now, shouldn't it be "negative signal thru the RCS NEGATIVE (instead of RCS positive)" I thought....I got him to check this out exactly how his set it all up so I will post more info once I get something.

So, there's no XLR cables involved in this process (I would think) and all done with RCA's.

In any case, my initial intention with my two DX-1's was two use one DX-1 per side and hook-up(for the moment) one two-channel amp per side in a non-true bi-amped state and later on, source another two amps to have a true bi-amped setup.

Cheers
Pasadena

[boputnam]

Wow... Goofy.

It appears, the Giskard was cyber-intuitive on this. Figures. Too bad his post is gone... Giskard has seen it all.

That XLR-to-RCA wiring is not truly balanced. All the User is doing is making an adaptor...

[bbno4]

Hi
If I can't find the cards for K2-S5500, is M552 good for my spearkers?

[Earl K]

Hi bbno4

If I were you, I'd try as hard as I could to get the proper S5500 cards for the DX-1 .

The reason; only the DX-1 cards will have the "proper" assymetrical crossover slopes. They also provide some EQing for your S5500 speakers as well as maintaining the proper "phase" between the woofers and horn . Giskard pointed out that the cards for the S5500 have a 18 db/octave slope for the low pass while having only a 6 db/octave slope for the high pass. Those slopes are there to mimic some of the passive design "wizardry" that is present in the passive crossover. These 2 cards ( hi & lowpass ) aren't working ( or turning over ) at exactly the same crossover point. As I mentioned, the DX-1 is doing more than just crossing over signal to low and hi at a single fixed point - it also is setup to maintain proper phase relationships for the special MTM design.

To duplicate the features built into the DX-1s' custom S5500 cards - you'd need to buy a crossover that has large amounts of variation for each pass-band section. The M552 that you mentioned just doesn't qualify because it can't provide these necessary functions.

- I'm still mystified how you "cooked" 4 woofers before you first actually biamped. You said you put the switch into "biamp" mode and that was all. What happened to your amplifier ?

- Here's a picture from the S5500 Operators Manual showing the proper method for a "biamp" hookup . Do you have this manual ?

regards <> Earl K

[grumpy]

If XLR pin 1 was used as ground and went to the
RCA ground of two RCA connectors, then
pin 2(+) went to the center pin of one of the RCA
connectors and pin 3(-) went to the center pin of
the other RCA connector, then you have your
adapter to use 2 single ended processors
(crossovers in this case) to continue the
"balanced" signal. The signals running through
each crossover are out of phase with respect to
each other, including the hi/lowpass outputs.

(this is all mono... one could do a single channel 'balanced' with a dual channel processor).

One would have to form two more such adapters
for each crossover output to drive the two
(presumably) balanced input amplifiers, each
amplifier being driven from 1/2 of each crossover.

lots of adapters...balance would depend on both
circuit gain and frequency matching. Does seem
like a lot of work and $$$, but it would indeed be
balanced. Would be fun to try if one had all this
equipment laying around...

-grumpy

[bbno4]

Hi Earl K

Thanks for your information. I had the manual of K2. Before I use K2, I had a pair of L250 TiQ Ltd, I use two Macintosh Amp to drive them in BI-Wire Mode. After I had the pair of K2, the staff of Hong Kong JBL agent told me that if I using two Amp, I should set it on Bi-Amp Mode (even I don't have DX-1). So all the woofers burned within a minute
Maybe my amps with protection, so they are safed.