BI-amping JBL JRX125's

[marsonpee]

Having a pair of JBL JRX125's, I want to know if it would be at all possible to be able to re-wire the speakers to be able to operate them BI-amped. My plan would be to detatch the lower woofer and connect this straight to pins 2-/2+ on the speakon input, the other woofer and the compression driver would stay connected to the existing x-over.

I did have a think and was wondering if the x-over network is set at 4 ohms or something, or is the 4 ohms only made by the 2 drivers coupled? Any help would be greatly appreciated.

[dan slv-tech]

hiya,

 

from what you have written, I dont really see any benifit in what you propose to do- can you provide more info?

 

dan

[Rob_Beech]

I dont know the cabinet personally, but generally speaking I dont think you will benefit from doing this.

I'll assume you are going to use an active crossover to filter the correct frequency band for the LF/MF driver in the cabinet, why dont you do the same for the HF?

 

If your plan is to run the LF/MF full range and then just have the HF running HF then I would advise against it. You will no doubt run into many phase issues and there is IMO no benefit to doing this.

 

As Dan mentions we need to know a little more information, we can have a few guesses but its much easier to give you information when we know exactly what you are doing. A few pointers therefore :

 

*Amplifier make, model, outputs, For each of the components.

*Crossovers in use.

*the rest of the system (what is it used for etc).

*anything else we might need to know.

 

 

Rob

[TonyMitchell]

the JRX is a very basic entry level JBL 2-way cabinet, they do a fair enough job for what they are/cost, but I'm with the others in failing to see the point in biamping the drivers. You won't improve what you get out of this box by doing so.

[marsonpee]

Basically the cab would be supplied by 2 amplifiers run on an active x-over, one amplifier would power the bottom driver for bass only, the other would power the tweeter driver + upper (mid) driver with high and mid frequencies through the internal passive x-over. The amplifiers I have are Crown XLS 802's, having one spare which I rarely used, its a thought that came to my mind about bi-amping. If its not gonna benefit then no probs, better to find out on here before.

[Rob_Beech]

Hello again, having looked up the specs I now understand what you are on about.

 

this is certainly possible and in actual fact you may see some benefits from this (then again they may only be small and outweigh the hassle of doing it, you'll still require an active crossover). for the benefit of archiving and anyone that doesn't know :

 

the cabinet is a 2x15 and compression driver unit of 500watts rms. the unit is configured for the lower driver to handle low frequencies only. the centre driver handles low and mid. and the compression driver the HF. Unless there are 2 crossovers in the cabinet allowing you to use the Low Pass one only for the lower driver you will need an active crossover. Then simply use the low outs to drive the low amp the high outs to drive the rest.

 

be advised that the original combination from what I can make out uses BOTH 15 inch drivers for LF. you may lose some LF from the system if you alter this. however, this may be gained again by use of a more efficient crossover (ie and active one) and a separate amplifier channel for the LF driver.

 

 

Looking at the work involved, I'd say its not worth it unless you are unhappy with the sound. Whilst the cost would be small (active crossover and some 4 core cable and a few connectors) you have to look at whether (as you already have the amp) the extra money may be better spent elsewhere, I can only assume you are wanting a better LF response, would a pair of subs give you this (the answer is yes).

Few things to think about there.

 

Rob

[Bad_Rock]

Will be hard to find a benefit from bi amping this budget jbl's. They already sound very flat with lot's of mids instead of lows ( even when they are 15"'s and Jbl's ). I got 2 of them and trust me it would be useless.

[paulears]

I concur with the others that there seems very little possibility of improving their sound. Bi or even sillier, tri-amping is at best going to give just tonal change, and on these the HF isn't very smooth to start with, and the bass a bit wooley at best. Wouldn't the OP be better off spending the amp/x-over money on better source speakers, rather than try to improve a basic level product?

[Bobbsy]

Agreed, paulears. Pretty much anything CAN be done, given enough time effort and money. However, I'm highly sceptical that the results would in any way be commensurate with the effort involved. Put your money in a high interest account and begin to save up for better speakers to start with.

 

One other thought I just had...I'm pretty sure that when you eventually do upgrade, standard speakers will be easier to sell than ones that have been heavily modified by the user.

 

Bob

[marsonpee]

Thanks for the help guys. What I didn't mention before was that I already had an active x-over so it was just a case of 4-core cable. From what you have all said, I think ill give it a miss because the sound is adequate from them for my purposes. (Although it is always nice to have a little extra bass sometimes) Again, many thanks.

[Rob_Beech]

As I mentioned, you may actually lose bass. You may then gain it back by the increased efficiency of not using a passve crossover for the low driver. However, this is only recovering that lost from using the 1 driver.

 

its not possible to tell exactly what results you would have but thinking about it, its unlikely you'll see an increase in bass response with regard to volume.

 

Rob

[Greenhousemoto]

(My first post) I completely understand the desire to bi-amp one of the 15's that handles the low frequencies for JRX 125'S.

 

I run subs crossed at 150hz and everything above goes to 2 pairs of JRX 125'S. When I listen to the LF driver there is no response.

 

I have been thinking about running amplified sub signal to those 4 LF drivers. They produce no sound now. I predict no problems with separating these LF drivers from the JRX crossovers and powering separately. I have a good sized place and 4 additional 15's helping the low end makes sense. Additionally, I upgraded the horns in the Jrx's. I use a graphic equalizer to help all sound better. I agree there are better speaker solutions but I'm making lemonade.

[Simon Lewis]

Welcome to the Blue Room - and thanks for your comments on this post...!

 

You might notice, however, that the discussion was last added to in January 2007.... I suspect the OP has got things sorted by now! :-)

[Greenhousemoto]

I look forward to any updates on this subject.