JBL M9500X Crossovers - Need Help!

[Andersen]

My speakers include LF: 515B (16ohms), HF: 288B (16ohms) + Horn: 311-60. I am using one 2A3 amp, one 300B amp and JBL M9500X crossovers for this system and looking for technical information or manual of this crossover. Can you please send me this if you have. In fact, my problem is that there are 2 options in the crossover: one is bi-wired (normal) and the another is bi-amp. Currently, I use the bi-wired (normal) option with the 2 amps but I don't like the sound. I prefer the bi-amp option's sound but when I connect the HF line out from the crossover to 515B speakers I still hear LF sound, then I worry that my 288B drivers would be damaged if I use the bi-amp option as LF (I don't know if the LF is lower than 500hz or not) goes through 288B drivers. So, should I worry about this issue? Please advise. Thanks a lot.

[Robh3606]

Not sure I understand you correctly but what active crossover are you using??

Rob

[Earl K]

Currently, I use the bi-wired (normal) option with the 2 amps but I don't like the sound.

- I'm not surprised you don't like the sound .
- The values chosen for each passive component ( in the N9500 ) work only as designed for a very specific set of drivers , none of which you own .
- The most significant difference being they ; ( your drivers ) have very different working impedances, resulting in dramatic filtering variations ( from the original design ) .

My speakers include LF: 515B (16ohms), HF: 288B (16ohms) + Horn: 311-60.

- The Low Frequency portion of the M9500 network is designed to work into @ a nominal 4 ohm load. Your LF load is 16 ohms if you are using just a single 515b .

I am using one 2A3 amp, one 300B amp and JBL M9500X crossovers for this system and looking for technical information or manual of this crossover. Can you please send me this if you have.

- Having the schematic ( or owners manual ) for the network won't help you.
- You can't just alter one components' value here ( or there ) and fix the situation .
- To run your setup in a passive ( or biwire ) mode, you'll need to buildup a completely new custom network .

In fact, my problem is that there are 2 options in the crossover: one is bi-wired (normal) and the another is bi-amp.

- Your systems' problem isn't deciding between these 2 options / you need to find a third option that actually works . Neither option from the N9500 will give you good sound .

I prefer the bi-amp option's sound but when I connect the HF line out from the crossover to 515B speakers I still hear LF sound,

- I hope you're aware that when "biamping" , one needs an electronic crossover in the signal chain before the two amplifiers used to drive the woofers & horn-drivers . If you have omitted the electronic crossover in the sigal chain / then / you will be sending full-range signal into the horns ( and the woofers ) eventually destroying the diaphragms of the 288(s).

,,,then I worry that my 288B drivers would be damaged if I use the bi-amp option as LF (I don't know if the LF is lower than 500hz or not) goes through 288B drivers. So, should I worry about this issue?

- Yes you should worry. It appears to me that when you use the biamp switch ( which bypasses the 2 main LC filters ) on the N9500 you are sending full range signal into the horns ( assuming there is no electronic crossover before the amplifier ) / this will eventually destroy your diaphragms .
- Also, without an inline electronic crossover before the amps / the 515b is getting fullrange signal. This won't destroy the woofer doing this , it's just that you aren't crossing out the high frequencies that are meant for reproduction by only the horn-driver .

Please advise. Thanks a lot.

- Sell the N9500 networks / then buy some inexpensive stereo 2-way electronic crossover ( like an Ashly 1001 ). Then you can implement, actual "biamping" .
- You can place a sales advertisement here in the Lansing Marketplace forum.
- I suspect there are some around here who may be interested in them ( since they own some of the necessary parts for a M9500 ) .
- "Buying & Selling" into Vietnam may have a bunch of trade ( embargo ) issues that I'm not aware of .

[Andersen]

Hi Earl K,
Thanks a lot for your kind detailed and very helpful advice.
Previously, I only used one amp, the 2A3 to drive the whole system with the same crossovers at normal/bi-wired option, and I was fine with this. However, I should solve the current problem now.
As you mentioned, in order to bi-amp, I need an active crossover in the signal chain before the 2 amps and then I don’t need the M9500X crossovers anymore, right?
If so, I would prefer to diy one simple active crossover, I think I need an 3-way one: below 700/800Hz for 515B, from 700/800Hz to 6.5kHz for 288B and above 6.5kHz for tweeter JBL2405 or 175DLH. Do you have any appropriate schematics for my case? Please also advise if my suggestion for cut-off lines is appropriate.
Thank you a lot, indeed.
Andersen

[Earl K]

As you mentioned, in order to bi-amp, I need an active crossover in the signal chain before the 2 amps and then I don’t need the M9500X crossovers anymore, right?

- Yes that's correct.

If so, I would prefer to diy one simple active crossover, I think I need an 3-way one: below 700/800Hz for 515B, from 700/800Hz to 6.5kHz for 288B and above 6.5kHz for tweeter JBL2405 or 175DLH.
Please also advise if my suggestion for cut-off lines is appropriate.

- Yes, 700 or 800 hz is a reasonable crossover point for most 15 inch speakers including your 515b(s) . The 311-60 horns will properly load the Altec 288 drivers to that frequency ( & even lower ) .

- I would take the 288(s) up to 9 or 10K . So I would crossin whatever tweeters you get, around that point

,,, I would prefer to diy one simple active crossover, I think I need an 3-way one. Do you have any appropriate schematics for my case?

Sorry, but no, I don't have any stereo, three-way crossover schematics . I hope you realize you are going to need another amplifier when you go stereo , 3-way active ( I also, don't have any amplifier schematics ) .

You should consider registering at diyAudio . They have some on-going threads about DIY crossovers ( & amps ) which have also included "Group Buys" for some ( or most ) of the necessary parts .

Thank you a lot, indeed.

Your welcome ! <. Earl K

[Andersen]

Thanks a lot, Earl K.
I’ve just got a pair of JBL2405 tweeters. Is it ok if I connect my 300B amp to these tweeters with a 1uf capacitor (each channel) in series?
Andersen.

[Earl K]

I’ve just got a pair of JBL2405 tweeters. Is it ok if I connect my 300B amp to these tweeters with a 1uf capacitor (each channel) in series?

- You can do that if you wish . You'll need to balance the tweeter to the other components using your amplifiers' volume knob .

- JBL typically used a 3 element design for a sharper 18 db per octave slope. Since your 1 uF cap would be incorporated within the standard JBL 3-pole circuit / you can easily start with the single 1 uF cap and then add the other parts later ( if you need to ) .

- A single inline cap on an @ 10 ohm tweeter gives a 3 db down point in the neighbourhood of @ 16K .

- See the following impedance plot ( courtesy of Mr. Widget ) for 4, JBL 2405s & 077(s) that were labelled as either 8 or 16 ohm impedance . This is where the 10 ohm figure is derived from ( it's my "eyeball" average of a typical curve ) .



- Here is the FR curve showing the polar response of a 2405/077 .



These images are included in a "Widget" thread that includes measurements for various JBL Ring Radiators .

[Andersen]

- You can do that if you wish . You'll need to balance the tweeter to the other components using your amplifiers' volume knob .

- JBL typically used a 3 element design for a sharper 18 db per octave slope. Since your 1 uF cap would be incorporated within the standard JBL 3-pole circuit / you can easily start with the single 1 uF cap and then add the other parts later ( if you need to ) .

Thanks, Earl K.

Can you please upload the standard JBL 3-pole circuit here for my reference?

I'm going to build a 3-way passive crossover as the attached schematics but don't know how to calculate the values of C1, C2, C3, L1, L2, L3. So, can you please help me with this and in your opinion, is this schematics ok for my system?

Thanks
Andersen

[Earl K]

Hi Andersen,

Can you please upload the standard JBL 3-pole circuit here for my reference?

- Sure, I'll do that today at some point .

So, can you please help me with this and in your opinion, is this schematics ok for my system?

- In my opinion, you don't want to use that type of network .
- The schematic that you posted shows only 6 db per octave filtering on both, the woofers' lowpass and on the horn circuits' hipass. You ought to go with 12 db per octave filtering at these points .

- I'll look around this weekend to find, and then post schematics for Altecs' standard networks / for use with your parts .

[Andersen]

Hi Andersen,
- Sure, I'll do that today at some point .
- In my opinion, you don't want to you that type of network .
- The schematic that you posted shows only 6 db per octave filtering on both the woofers' lowpass and on the horn circuits' hipass. You ought to go with 12 db per octave filtering at these points .
- I'll look around this weekend to find, and then post schematics for Altecs' standard networks / for use with your parts .

Thanks a lot, Earl K. It's really great for me.

[Earl K]

Hi Andersen,

As promised ;

- Here's a hipass for use with a 2405/077 tweeter . This comes from the N3133 network. It's a 18 db per octave hipass set to filter, somewhere around 8500 hz .

[Andersen]

Hi Andersen,
As promised ;
- Here's a hipass for use with a 2405/077 tweeter . This comes from the N3133 network. It's a 18 db per octave hipass set to filter, somewhere around 8500 hz .

It's wonderful!
I'd like to confirm the values of the parts as below:
C1 = 1uf
C2 = 1.5uf
L1 = 0.16, I'm not sure, is it mH or uH?
R1 = 20ohms/10W, are 12W Miller resistors ok?
The difficult part is the L.PAD 8ohms. As the resistance of 2405 is 16 ohms, should I use L.PAD 8 or 16 ohms and how many watts is enough?
So, after building this hipass, I can connect directly from my amp to this and then to the tweeters, right?
Well, as you mentioned previously, my JBL M9500X crossovers are designed for 4-ohm drivers, is there any way to modify them to suit my drivers? As I remember, last time when I opened them up, their insides look very cool and I don't really want to get rid of them or sell them.

Thanks a lot and have a great weekend.
Andersen

[Earl K]

I'd like to confirm the values of the parts as below:

Okay

C1 = 1uf
C2 = 1.5uf
L1 = 0.16, I'm not sure, is it mH or uH?
R1 = 20ohms/10W, are 12W Miller resistors ok?

yes, C1 = 1uf, C2 = 1.5uf, L1 = 0.16 mH , R1 = 20 ohms ( 5W , 10W or more / whatever you can obtain )

The difficult part is the L.PAD 8ohms. Can you please advise me where I can buy this stuff.

Try Parts Express 8 ohm Lpad
- Look around their site to get an idea of what parts are worth .
- They might ship to Vietnam ( but I don't know ). These parts are typically made in Taiwan / therefore I think you need to find a mail-order supply house based out of Taiwan or even Japan and then buy from them .

So, after building this hipass, I can connect directly from my amp to this and then to the tweeters, right?

- Yes .

Well, as you mentioned previously, my JBL M9500X crossovers are designed for 4-ohm drivers, is there any way to modify them to suit my drivers? As I remember, last time when I opened them up, their insides look very cool and I don't really want to get rid of them or sell them.

- I understand your wish to modify what you have, but the last time I checked the M9500X schematic there just wasn't much that could be salvaged from these crossovers and subsequently used with your Altec stuff . I'll take another look .

- What is the DCR for each of your 4 Altec components ?
( DCR = dc resistance measured with an ohm meter )

Thanks a lot and have a great weekend.

You're welcome .

[Andersen]

Okay
yes, C1 = 1uf, C2 = 1.5uf, L1 = 0.16 mH , R1 = 20 ohms ( 5W , 10W or more / whatever you can obtain )
Try Parts Express 8 ohm Lpad
- Look around their site to get an idea of what parts are worth .
- They might ship to Vietnam ( but I don't know ). These parts are typically made in Taiwan / therefore I think you need to find a mail-order supply house based out of Taiwan or even Japan and then buy from them .
- Yes .
- I understand your wish to modify what you have, but the last time I checked the M9500X schematic there just wasn't much that could be salvaged from these crossovers and subsequently used with your Altec stuff . I'll take another look .

Can you please also upload the M9500X schematic? Thanks.

- What is the DCR for each of your 4 Altec components ?
( DCR = dc resistance measured with an ohm meter )

If I use an ohm meter to measure the drivers by connecting the test leads of the meter to the binding pots of the drivers I get the below:

2405: 6.5ohms
288B-16: 13ohms
515B-16: 13ohms

Thanks and regards
Andersen

[Earl K]

Can you please also upload the M9500X schematic? Thanks.

Okay,, here's a link to its' image .

This release is courtesy of Giskard .