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fast_mick
12-28-2012, 06:29 AM
I have 2 x PS1400 and PT800 combinations.

i have noticed in some of the threads the amp in the PS1400 is generally considered a weak link. One of my amps has failed. I have pulled it out and had a look but i could'nt see anything obvious and i am not an electronic whiz also I am not in USA so my choices are more limited.

I am thinking it may be possible to use the crossovers in the amp by changing some wiring and use it passively. The crossover for the PT800 is separate i think i could even move this to the PT800. I have read you cant power the PT800's directly as they are prone to damage with signals below 80hz.

But before i try this has anybody else tried to passively run the PS1400's?

I have had these since about 2005 and they have been really good but i think the PS1400 is a bit wimpy where as the PT800 is fantastic. I was thinking using a power amp on the PS1400 might improve them a bit.

thanks
FM

MikeBrewster77
12-28-2012, 08:03 AM
I've not, but here's what I think I do know:
- the high pass to the PT800 is passive @ 130hz
- I believe the low pass is part of the PD1400 amp circuitry, so you would need to use some form of external crossover / bass management to achieve that if you bypass the amp
- The PT800 can be run with a (sane) signal below 80hz; box design,etc achieves a pretty steep roll off below that. I'm not recommending this per se, but it can be done
- While you may consider the PS1400 'wimpy' its best to think of the stack as a single full range speaker. Better amplification might net you better control, maybe some tightening or additional subtle impact, but if it's balanced properly, I don't think you're going to hear a huge change

rdgrimes
12-28-2012, 02:21 PM
The 130Hz HP filter on the PT800 output is passive and completely separate from the sub's amp. Pull the amp and you'll see it mounted up behind on the back baffle.

The sub amp employs a switchable active filter that's either in or out depending on the "normal or separate" switch. That LP filter is at 130Hz also.

This configuration gives the stack a "bi-amp" function, and in order to duplicate that you'd need to actually bi-amp the PT800 and sub stack using a 130Hz LP filter on the sub.

pathfindermwd
12-28-2012, 03:21 PM
I am thinking it may be possible to use the crossovers in the amp by changing some wiring and use it passively.

The XO for the amp is electronic. As I understand it, this is a line (low) voltage XO, it probably can't be used with speaker level power.



The crossover for the PT800 is separate i think i could even move this to the PT800. I have read you cant power the PT800's directly as they are prone to damage with signals below 80hz.

It is separate, located in the PS1400 cab. You can power it without an external XO, but for some reason, JBL is not recommending it. The bigger issue is integrating the 14" with the PT800. An AVR that has active filters is one way. A multi-amp setup with electronic XO is another. The PT800's are NOT prone to damage, even under full signal! Where did you hear that?


But before i try this has anybody else tried to passively run the PS1400's?

I'm sure someone has. One highly regarded forum member has recommended it, specifically.


I have had these since about 2005 and they have been really good but i think the PS1400 is a bit wimpy where as the PT800 is fantastic. I was thinking using a power amp on the PS1400 might improve them a bit.

The main problem is not the amp (IMO), but the volume of the cabinet is not ideal. This (and all other issues/ideas) has been discussed in length on the Performance Series Thread:

http://www.audioheritage.org/vbulletin/showthread.php?3272-JBL-Performance-Series

Don C
12-28-2012, 03:58 PM
I am running mine without the internal amplifiers. One of my amps failed, like yours. I pulled both of them out and blocked the holes with pieces of wood. I'm using an external active crossover and separate amplifiers for the woofer and the PT800. There is no internal passive crossover for the woofer to PT800, there is only a high pass filter for the PT800 and I've removed that. The extra amplifier and crossover were expensive, and the changes make the system pretty much impossible to ever resell. It sounds just the same as it did with all of the factory electronics installed, fantastic.

pathfindermwd
12-28-2012, 04:21 PM
It sounds just the same as it did with all of the factory electronics installed, fantastic.

Good to know!:)

Thanks Don!

fast_mick
12-30-2012, 11:14 PM
Thanks all,

I had a look on the weekend at the amp as said above the crossover for LE14H is integrated into the active circuit and cant be used.

The options are:

a)
Build a box on the back of the PS-1400 cabinet and put a plate amp in it. This would have the advantage of allowing me to increase the PS1400 cabinet size with additional volume. Disadvantage is I have to find a suitable plate amp.

b)
Go with Don C's solution I have a suitable amp (a Perreuax PMF2150) just need a suitable crossover. When i had my 4425's i had a Ashley XR1001 it was good but Don you may have a suggestion?

Thanks
Michael

Don C
12-31-2012, 02:02 PM
I'm using the JBL Synthesis SPP-AC1 crossovers. I think that these are re-badged Rane FAC-28 units. It's hard to say, documentation is hard to come by. Neither JBL nor Rane will provide any support. Like a lot of Pro type gear, they have balanced (XLR) inputs and outputs. Upgrading the rest of my system to use this style of interconnect was where the major expense was. The result is good though, the system is nice and quiet. To my perception, the crossovers are perfect, adding nothing, taking away nothing, they just do their job. I like the stepped frequency controls, you never have any doubt which frequency is selected.

pathfindermwd
12-31-2012, 05:22 PM
a)
Build a box on the back of the PS-1400 cabinet and put a plate amp in it. This would have the advantage of allowing me to increase the PS1400 cabinet size with additional volume. Disadvantage is I have to find a suitable plate amp.


Taking into account Don's experience that the speaker sounds the same with the added components and expense, I would choose option #1. Gaining more volume by extending the back of the cabinet seems the simplest way. But as Don points out, it may hurt the resale value.

Could you build new 1400 cabinets with more volume and add new plate amps to them? This way you could store the original cabs, and figure out what to do if you ever wanted to sell.

More volume will get you better bass over more power. My 240ti's do better in the bass department with no bi-amping or built in amps. How are your construction skills?:D

pathfindermwd
12-31-2012, 05:49 PM
Check out how this member decided to increase cabinet volume for his LE14H3's. Judging by the picture's, I think he is very close to ideal, about 3.5 cubic feet. I would get the Woofer as high as possible up off the floor and notch an area and put a sloping transition to the setback PT800.

http://www.audioheritage.org/vbulletin/showthread.php?33821-Early-Christmas-present-comes-to-light

Don C
12-31-2012, 08:19 PM
If you look in the performance series thread, post #1400, you can see a simulation of the increased volume in the cabinet from removing the amplifier. It's not a big difference.
http://www.audioheritage.org/vbulletin/showthread.php?3272-JBL-Performance-Series/page35

pathfindermwd
12-31-2012, 10:07 PM
If you look in the performance series thread, post #1400, you can see a simulation of the increased volume in the cabinet from removing the amplifier. It's not a big difference.
http://www.audioheritage.org/vbulletin/showthread.php?3272-JBL-Performance-Series/page35

You've done the math and it's hard to argue with that.... but my real world speakers don't lie, and neither do the 240ti/250ti's I have heard, with no mods, bi-amps or plate amps. One friend bought a PS1400 for bass reinforcements for his 250ti's, it sits unused unable to make a positive contribution.

Anyway, the OP already thinks they are lacking. The amps are already 400 watts, do they need 1000 to be more effective????

There's no way around the physics, they need bigger enclosures to go BOOM! The question at that point is, can you integrate them nicely?

4313B
01-01-2013, 02:57 AM
The PS1400 volume/tuning is somewhere between a Lancer 55 and a 240Ti.

The Citation 7.4 was very similar to the 240Ti.

The 240Ti and 250Ti used the same ducted port. The 240Ti was roughly 3.5 cu ft and the 250Ti was roughly 4.0 cu ft.

The best subs using the LE14H are arguably 4.0 cu ft tuned to 28 Hz, the 250Ti volume/tuning. No real shock there.

Although the LE14H was spec'd for volumes up to 5.0 cu ft it was supplanted by the 2235H in that large of a volume. The 2235H simply worked better in that larger volume.