PDA

View Full Version : 1400 Array Question - Calling all Crossover "Gurus" !



Audionutz
10-19-2010, 09:48 PM
In my 1400 Arrays, I'd like to find out if it's possible to increase the SPL, or volume, of the Horn and Tweeter only, by 3db.

I believe this could be done WITHOUT changing the crossover points, by changing one or more resistors in the crossover ?

I've attached a schematic of the crossover below, if anyone can assist ?

Thanks in advance.

'Nutz

Woofer
10-19-2010, 11:26 PM
Well, if you're "bi-wiring" as the x-over suggests, why don't you just turn the 'bass' amp down by 3dB?
(... or is it bi-amping still but without an Active x-over???)

Audionutz
10-20-2010, 12:34 AM
Well, if you're "bi-wiring" as the x-over suggests, why don't you just turn the 'bass' amp down by 3dB?
(... or is it bi-amping still but without an Active x-over???)

Its bi-amping or bi-wiring but still goes through both passive crossovers.

Woofer
10-20-2010, 01:23 AM
Its bi-amping or bi-wiring but still goes through both passive crossovers.

Well there ya go then.
Turn the bass amp down.....
Problem solved :applaud:

.... on the other hand, are you sure you have the 1400's the right way round?

It's just that you're the only person in the whole world that's asked about that 3dB mod which makes me think also that you might only have one ear, and nobody's told you yet.

Just funnin' ya, 'nutz! ;)

Audionutz
10-20-2010, 03:04 AM
Well there ya go then.
Turn the bass amp down.....
Problem solved :applaud:

.... on the other hand, are you sure you have the 1400's the right way round?

It's just that you're the only person in the whole world that's asked about that 3dB mod which makes me think also that you might only have one ear, and nobody's told you yet.

Just funnin' ya, 'nutz! ;)


Have a look around - you'll see a coupla similar comments from other listeners ........:D

But I'll try turning them upside down anyway .....:crying:

Woofer
10-20-2010, 03:12 AM
Have you still got that valve thing driving your top end?
If so, maybe put brighter valves in it.

Audionutz
10-20-2010, 03:37 AM
Have you still got that valve thing driving your top end?
If so, maybe put brighter valves in it.

Man , you're just brimming over with useful advice tonight, 'ain't ya ! :applaud:

Woofer
10-20-2010, 03:39 AM
... did you try it? Did it work? :confused:

Robh3606
10-20-2010, 03:40 AM
I believe this could be done WITHOUT changing the crossover points, by changing one or more resistors in the crossover ?


Sure but you would need to open up the crossovers and change the pads on the 435AL and 045Ti. Use the amps volume controls if they have them.

Rob:)

Woofer
10-20-2010, 03:44 AM
Sure but you would need to open up the crossovers and change the pads on the 435AL and 045Ti. Use the amps volume controls if they have them.

Rob:)

Yeh, what he said. (Hi Rob :wave: )
.... but much easier just rolling a few tubes. :)

Audionutz
10-20-2010, 03:57 AM
Sure but you would need to open up the crossovers and change the pads on the 435AL and 045Ti. Use the amps volume controls if they have them.

Rob:)


I did consider that, but a post from the designer, with a schematic of the crossover, suggested a mod had to be done to allow correct bi-amping voltages ?

Cheers

'Nutz

Audionutz
10-20-2010, 04:06 AM
This one here ...

http://www.audioheritage.org/vbulletin/showthread.php?23763-Bi-amping-the-JBL-Model-1400-Array

Woofer
10-20-2010, 04:24 AM
If that's the case, then you're just gonna have to give bi-amping the 'flick' (for now).
Try it and have a listen, to see if that solves your problem.
If it does, your only alternative for now is to just be happy with it, or use a bigger amp until you decide to mod your x-overs.
.... but, I'd leave that to much much later.
As much as you've played with the 1400's, you, and they, are still settling in I reckon.

Audionutz
10-20-2010, 04:34 AM
If that's the case, then you're just gonna have to give bi-amping the 'flick' (for now).
Try it and have a listen, to see if that solves your problem.
If it does, your only alternative for now is to just be happy with it, or use a bigger amp until you decide to mod your x-overs.
.... but, I'd leave that to much much later.
As much as you've played with the 1400's, you, and they, are still settling in I reckon.

They have a Krell KSA 150 on 'em now - should be more than enough power. But yes, its early days yet .....

Cheers

'Nutz

Woofer
10-20-2010, 04:47 AM
Maybe it's because your speakers are so good, that they might be revealing problems further up the chain?

Audionutz
10-20-2010, 04:54 AM
Maybe it's because your speakers are so good, that they might be revealing problems further up the chain?


Nope, its not that. I've experimented with different sources, preamps, cables etc. It's definitely a characteristic of the speakers. I'm not the only one to hear it, or the only owner/listener to comment on it remember.

My theory is that the Horn/Tweeter is padded down that far, the the bass driver is coming up into the mid-bass area. That's whats giving the impression of "softness" in the bass.

Its not subtle either, it's there. Acceptable for Home Theater duties maybe, but not for a Hi-End two channel sound.

That's why I want to get to the bottom of it. They are such an awesome speaker in almost every other regard. That's what makes this so noticeable I guess !

Woofer
10-20-2010, 05:10 AM
Yes, I understand exactly what your saying.
It's always been easy for me having grown up with PA's and working Studios with their assorted Monitors whereas whatever problem we had, we'd just chuck another piece of electronics at it to fix it. eg GEQ's or Parametrics etc.
In your case, where you're doing the exact opposite, ie, you're trying to get it right by not using eq's etc makes it just that bit tuffer to resolve, without pulling your boxes to bits. :(

4313B
10-20-2010, 06:57 AM
Nope, its not that. I've experimented with different sources, preamps, cables etc. It's definitely a characteristic of the speakers. I'm not the only one to hear it, or the only owner/listener to comment on it remember.

My theory is that the Horn/Tweeter is padded down that far, the the bass driver is coming up into the mid-bass area. That's whats giving the impression of "softness" in the bass.

Its not subtle either, it's there. Acceptable for Home Theater duties maybe, but not for a Hi-End two channel sound.

That's why I want to get to the bottom of it. They are such an awesome speaker in almost every other regard. That's what makes this so noticeable I guess !Mr. Widget seems to like his 1400 Arrays well enough.

From what I've read so far your pair appear to have weird resonances and soft bass. You did just give up 7 dB of efficiency and a bit of bottom end by going to the single LE14H from the 2202H's and dual 2235H's...

You could just sell the 1400 Arrays and buy a pair of SAM1HF's to put over your 2202H's and dual 2235H's :D Getting a really nice voltage drive on the 2202H could be just as tough as truly bi-amping the 1400 Arrays as per Greg's post though. Greg provided the correct active crossover values to get the voltage drive on the LE14H correct when going active. The only way it could be easier is if you had someone else build that circuit for you instead of doing it yourself. In that case, have someone like Marchand build one for you.

Woofer
10-20-2010, 07:11 AM
You could just sell the 1400 Arrays and buy a pair of SAM1HF's to put over your 2202H's and dual 2235H's

What an awesome solution..... :eek:

http://www.audioheritage.org/vbulletin/showthread.php?22543-sam1hf-sam2lf&p=227636

Woofer
10-21-2010, 02:05 AM
The one thing that bothers me most about the connectors on the back of the 1400, is, WHY?

If you have to modify the boxes crossovers yourself to make them suitable for bi-amping, then what's the purpose of splitting the connectors like they are?

It would seem logical, that if a box came so equipped, then one would automatically assume these boxes are then bi-amp-able, Yes? No?
To have to find that invaluable piece of info, by Greg Timbers as pointed out by 'nutz at http://www.audioheritage.org/vbulletin/showthread.php?23763-Bi-amping-the-JBL-Model-1400-Array, would normally never be seen by your average run of the mill 1400 user, surely?

Audionutz
10-21-2010, 03:36 AM
The one thing that bothers me most about the connectors on the back of the 1400, is, WHY?

If you have to modify the boxes crossovers yourself to make them suitable for bi-amping, then what's the purpose of splitting the connectors like they are?

It would seem logical, that if a box came so equipped, then one would automatically assume these boxes are then bi-amp-able, Yes? No?
To have to find that invaluable piece of info, by Greg Timbers as pointed out by 'nutz at http://www.audioheritage.org/vbulletin/showthread.php?23763-Bi-amping-the-JBL-Model-1400-Array, would normally never be seen by your average run of the mill 1400 user, surely?

I think (but stand ready to be corrected) that the bi-amping solution/mods kindly listed by Greg Timbers are for use with an active crossover running two amps ? Otherwise, passive bi-amping via the existing twin sets of terminals is easily done without mods.

Anyway, some successes in the last couple of days in my hunt to tame the elusive bass of my 1400's.

I'll have more to report once I'm certain I've got it right this time ;)

Cheers

'Nutz

Robh3606
10-21-2010, 03:52 AM
If you have to modify the boxes crossovers yourself to make them suitable for bi-amping, then what's the purpose of splitting the connectors like they are?


To Biwire, they are not biampable out of the box anymore than the L250Ti Jubilee is.


It would seem logical, that if a box came so equipped, then one would automatically assume these boxes are then bi-amp-able, Yes? No?


Absolutely No, there has to be some kind of Biamp switch there. When ever you biamp there are part deletions and there can be changed part values in the left over poles to compensate for the removed parts to keep the original voltage drives. To properly active biamp you always need an active crossover and changes to the passive netwrorks. Usually the bass driver crossover is simply eliminated but the high pass on mid needs selective part deletions depending on driver type and network topology.

Rob:)

Woofer
10-21-2010, 06:10 AM
I thought the straps between the terminals were the "switch".
I understand what you're saying Rob:), (... and thanx 'nutz for what you said too), but what I'm having difficulties with is why do these drivers need any sort of compensation at all, if these drivers are deemed to be flat to start with.
I'm sort of stuck with old school drivers and amps and still using active x-o's. With PA's etc, we had switches, but nothing to add any sort of compensation for either running bi-amped or passive. The passive x-overs were still in situ either way, and amps used, didn't see this as a problem. More importantly, the audio did not suffer, and my boxes and systems (and my ears) were good enough to tell if there were any discrepancies. Obviously the differences between a PA, and home set-up are vast, but my home system is quite capable of doing either job. I s'pose to my ageing ears it's good enough. (Thank God I'm not an Audiophile like 'nutz is, and possibly yourself too Rob:).)
All this new stuff just blows my mind. It's just all too difficult to comprehend at times.
..... and, eg when people start adding Charge Coupled Devices into the discussion (not that they have.... yet), I'm lost.
What happened to the single capacitor between the tweeter and woofer? That's what I'd like to know.
.... oh, and the old crystal set radio!
All these new exotic material-ed drivers coming out lately, seem to need an awful lot of added compensation to get the job done for my liking.
I s'pose the proof is in the hearing, but jeez, it's getting complicated AND dear! I certainly envy you guys that can follow (and afford) it.

I'm dreading the day when speakers go Digital. Does that mean they'll only be either On or Off?

Robh3606
10-21-2010, 07:49 AM
I thought the straps between the terminals were the "switch".


Those a just shorting straps if you don't biwire.


but what I'm having difficulties with is why do these drivers need any sort of compensation at all, if these drivers are deemed to be flat to start with.


Well think about it for a minute. When you use an active crossover in PA work with a CD horn many active crossovers have a canned CD Compensation curve built in as an example. The Horn in the Arrays is a CD Biradial so there is CD compensation built into the passive networks. It's exactly the same thing. With passive PA boxes they keep the passive CD compensation in the circuit and only switch out the poles for the crossover at say 1K like the 4430/4435. When you get a chance look at the schematics for these 2 systems and you can see what gets dropped out by the Biamp Switch.


and, eg when people start adding Charge Coupled Devices into the discussion (not that they have.... yet), I'm lost.


Don't be none of this is rocket science. When you charge couple you have funtionally the same capacitance value as if you used a single capacitor. If you look at JBL's simplified schematics for a CC system you will just see a single capacitor there. As far as the Crossover is concerned it functions as just a single capacitor. If you look at a CC schematic all you have to do the convert it to a simplified version is to take the summed value of the capacitor pair and divide by 4. So if you had 2 10uf it would be equivilent to a single 5uf capacitor. Nothing to it once you understand what's happening to the values. When you covert to CC you double the number of capaitors and double the value of each one so with a 5uf you end up with 2 10uf in series.


All these new exotic material-ed drivers coming out lately, seem to need an awful lot of added compensation to get the job done for my liking.


An example would be the 2435/435Be not as simple to do the EQ certainly not as simple as say a 2426 with a 2344. It's bit harder to work things out but I think the results are worth the effort.

Rob:)

Woofer
10-21-2010, 08:10 AM
Rob:),

You have a terrific way of explaining things. I got all of that. My gratitude knows no bounds. ;)
I'm actually left without questions for a change. :o:
I'll give it some more thought after I've compared the schematics as you suggest.
.... but for now, it's just gone 2.00am and I'm off to bed. :wave:

Audionutz
10-21-2010, 07:00 PM
OK, here's the story so far .....

Got my 1400's about 6 weeks ago now. Immediately found they needed far more power than suggested. Otherwise the bass was deep, but flabby and quite loose. Tried a variety of amps, both valve and solid state to no avail.

Then I addressed the room (20' x 20' with 20' high pitched roof). Tried about 20 different positions without any major improvement. Next tried stuffing the bass ports with Dacron of varying density. Slight improvement, but loss of impact and dynamics. Still too much bass information in the midrange area.

Had a big re-think at this point. Reconfigured the room to a Diagonal setup. Much better imaging, less boom in the bass and better separation, but still that impression of bass clouding in the mids, no matter what I did.

Went to bi-amp about a week ago. (not active but passive without any speaker/crossover mods) Very powerful solid state amp on the bass. An Odyssey Khartargo on the mid highs. This is a 130 wpc solid state amp with good impedance drive, but has a 10k input impedance. The bass amp is slightly less sensitive on inputs. This was the trick. it reduced the bass output by about 3db I reckon.

Immediately better all around and really starting to sound special.

Then after listening for a few days, I tried some more very small movements on the speakers. Namely, tilting fore and aft to varying degrees. Tilting them back produced the desired result. Highs were immediately smoother and more defined. Bass was where it should be and not intruding into the mids as much.

I also found lifting the speakers by about 5 inches, just using blocks of wood for now, was an improvement. It tightened the bass quite a lot.

Now, I am by no means an expert and can't offer much technical reasoning as to why all this worked. I'm just very persistent in trying to get the sound I want.

So please, don't take this as "Gospel" at all. It's just one mans' experience with these speakers, in one particular room with one set of ears !

I still believe this model has been "voiced" slightly toward Home Theater use, as opposed to 2 channel. But, they obviously do 2 channel pretty well too.

And lastly, a heartfelt thanks to those who contributed throughout this thread and by email. I'm a far more educated listener thanks to your input :applaud:

Cheers

'Nutz

Woofer
10-21-2010, 07:17 PM
OK, here's the story so far .....

.... Tilting them back produced the desired result. Highs were immediately smoother and more defined. Bass was where it should be and not intruding into the mids as much.

.... I also found lifting the speakers by about 5 inches, just using blocks of wood for now, was an improvement. It tightened the bass quite a lot.
'Nutz

ROTFL :p

4313B
10-21-2010, 07:40 PM
How high up off the floor is the centerline of that horn now?

Audionutz
10-21-2010, 07:44 PM
How high up off the floor is the centerline of that horn now?


About 45'' ?

Woofer
10-21-2010, 08:19 PM
About 45'' ?

That's pretty well spot on ear level, give or take.....
Shame you can't take 'em up a tad higher and tilt them forward a tad safely, and without too much hassle.
Does lots for eliminating standing waves and the like.
... and when you lie back and rest your head on the back of your 'comfy chair', then the planets all come into alignment..... :blink:

Audionutz
10-21-2010, 08:39 PM
That's pretty well spot on ear level, give or take.....
Shame you can't take 'em up a tad higher and tilt them forward a tad safely, and without too much hassle.
Does lots for eliminating standing waves and the like.
... and when you lie back and rest your head on the back of your 'comfy chair', then the planets all come into alignment..... :blink:

About 6'' above with my seat ...I'm 6'6'' remember :)

Woofer
10-21-2010, 08:44 PM
About 6'' above with my seat ...I'm 6'6'' remember :)

6' 6". Is that standing or sitting?

Audionutz
10-21-2010, 10:48 PM
6' 6". Is that standing or sitting?

Im not one to boast ....;)

Woofer
10-22-2010, 05:12 AM
Im not one to boast ....;)

Lying down, huh? :thmbsup: