JBL M9500X Crossovers - Need Help!

[Andersen]

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

This release is courtesy of Giskard .

It seems that you forgot adding the link.

[4313B]

If you right-click on the red x and select Properties you can then highlight and copy the Address link into a new browser window.
In any case here is the link:

M9500 Schematic

[Andersen]

If you right-click on the red x and select Properties you can then highlight and copy the Address link into a new browser window.
In any case here is the link:

M9500 Schematic

Thanks, Giskard. But following the link, I got this message. Please help.
Andersen

[4313B]

.

[Andersen]

Thanks a lot, Giskard.
BTW, can you please explain further why it needs 18V battery, I think, two of 9V batteries.
Andersen

[Earl K]

Hi Andersen,

BTW, can you please explain further why it needs 18V battery, I think, two of 9V batteries.

- The dc voltage from the battery provides a dc bias to the twinned ( inline ) capacitors.

- Click on the following link to go to the Bypassing & Biasing Thread. At the bottom of the page there are links into an article on the S-5500 system that talks about the audible benefits of dc biasing capacitors .

- 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 .

- I had another look at this JBL network and I can't see any reasonable way to make it work with the Altec components which you have.
- As I advised earlier , sell it and then buy a more suitable network . I notice that right now on eBay there's a pair of ancient N500-F networks that happen in be in Vietnam . Given the history of these parts in your country / look around for another pair of those networks..

- Also, I looked around to see if I had any Altec network schematics that would be suitable for use with your old Altec parts / sadly / I can't find anything .
- If you want to build up a network from stock plans then I'd suggest that you register at the Altec Users' Board. Once there , ask if someone has schematics for a stock network suitable for your components .

- Here's is a graphic that shows the individual AC impedances for a cache of old Altec 515b woofers . This was done by "oldblindjim" .
- When I see impedance curves this dramatic, I think "Zobel" / impedance equalizer on the woofer, used as impedance correction . I can't see how a standard LC network would work properly without such a network.
- Therefore, ask the guys at the Altec forum if they know of a Zobel that's designed to work specifically with these old 515b woofers .

[Andersen]

Hi Andersen,
- The dc voltage from the battery provides a dc bias to the twinned ( inline ) capacitors.
- Click on the following link to go to the Bypassing & Biasing Thread. At the bottom of the page there are links into an article on the S-5500 system that talks about the audible benefits of dc biasing capacitors .
- I had another look at this JBL network and I can't see any reasonable way to make it work with the Altec components which you have.
- As I advised earlier , sell it and then buy a more suitable network . I notice that right now on eBay there's a pair of ancient N500-F networks that happen in be in Vietnam . Given the history of these parts in your country / look around for another pair of those networks..
- Also, I looked around to see if I had any Altec network schematics that would be suitable for use with your old Altec parts / sadly / I can't find anything .
- If you want to build up a network from stock plans then I'd suggest that you register at the Altec Users' Board. Once there , ask if someone has schematics for a stock network suitable for your components .
- Here's is a graphic that shows the individual AC impedances for a cache of old Altec 515b woofers . This was done by "oldblindjim" .
- When I see impedance curves this dramatic, I think "Zobel" / impedance equalizer on the woofer, used as impedance correction . I can't see how a standard LC network would work properly without such a network.
- Therefore, ask the guys at the Altec forum if they know of a Zobel that's designed to work specifically with these old 515b woofers .

Thanks, Earl.
I'm going to build the hi-pass for the tweeters following your schematics.
Before using JBL M9500X, I tried N500-F networks but didn't like N500-F. The sound was loud and harsh. Last week, I found this schematics designed for Altec A5 (HF - 288 and LF - 515) by Jean Hiraga. What is your opinion on that schematics? Can I use 2 different crossovers i.e. your hi-pass one and the Hiraga's at the same time? If it's ok, I will build these 2, then consider to sell JBL M9500X.

[Andersen]

- Click on the following link to go to the Bypassing & Biasing Thread. At the bottom of the page there are links into an article on the S-5500 system that talks about the audible benefits of dc biasing capacitors .

BTW, I cannot open the link for Bypassing & Biasing Thread. Please help me through.
Thanks.
Andersen

[10 Watt Street]

Try this one:
http://audioheritage.csdco.com/vbull...ead.php?t=3555

[Andersen]

Try this one:
http://audioheritage.csdco.com/vbull...ead.php?t=3555

Thanks a lot. I got it.

[Earl K]

BTW, I cannot open the link for Bypassing & Biasing Thread.

Okay, sorry,,,( I'm working here with 1950s' eyesight ) / I've fixed the link .

I'm going to build the hi-pass for the tweeters following your schematics.
Before using JBL M9500X, I tried N500-F networks but didn't like N500-F. The sound was loud and harsh.

- In case you don't know / Altec 288 diaphragms wear out after a certain amount of use.
- It is more likely that the sound was "loud & harsh" because those old 288b diaphragms are worn out and need replacing .
- One can purchase , authentic & new 288 diaphragms' from Great Plains Audio. ( Don't ask me about cheaper imitations / / because I don't know )
- Using the "Hiraga" circuit is not going to fix a pair of "bad" sounding diaphragms . ( 6 mH coils are pretty expensive to just purchase and then hope for the best .)
- Measure the frequency response curve of your existing diaphragms and post the results here in this thread .

- If you don't have any software/hardware to measure the horn-drivers' response / then / download a free version of TrueRTA from here !
- You'll need to use a microphone with a reasonably wideband to make this testing worthwhile / though even a Shure 57 or 58 for this type of rough FR test is good enough .
- The free ( octave wide ) spectrum analyzer software will allow you to determine the relative health of those 288 diaphragms.
- Measure the frequency response, on axis to the horn, with a bit of pink noise running through the horndriver ( not loud / just above the level of normal conversation ). Measure about 1 meter away from the horn mouth.

- The response of a new diaphragm on a large radial horn ( such as you have ) should look something like this ( ignore everything over 15K ) ;


- A diaphragm that is unlistenable ( without using a tweeter & crossing the woofer in at 1000 hz ) will look this ( ignore everything over 15K ) ;


- In the last picture, Hi-end and Low-end ( for this driver ) is drastically rolled off. I would conclude that it wouldn't sound very nice at all with a 500 hz crossover point and no tweeter .

- To review; Get the RTA software, hookup a test microphone , shoot some response shots with it ( using TrueRTA ), capture the screen-shots from these TrueRTA plots and then post those image files here . Then we'll talk about what your next step should be .
- IMPORTANT : When measuring the raw response of a compression driver / use a large value series capacitor as protection against feeding too much low frequency information into the driver . A 25uF cap will offer some protection against LF content when used with a 16 ohm diaphragm .

( There's no point buying or building new crossovers with the assumption that they can "fix" the poor sound of wornout diaphragms / if that is the main problem with your system ).

[speakerdave]

Hi, Anderson,

It looks like Earl has gotten you on the right track, so the rest of us are just standing by and eavesdropping.

I'm mildly fascinated by your having a pair of the N9500's. I really shouldn't think of buying them because I plan to use a line level low pass for my woofers, and I'm not using the JBL treble driver and horn, but I would be interested in seeing some detailed photographs of their innards. I'm especially interested in seeing what type of resistors are used for the pair of 82 ohm resisters across the woofers (that is, if they are in the can).

If you have the opportunity to take some digital photos of the components of those crossovers and post them on the forums here, I would appreciate it.

I'm sure you're right--they are very cool to have, and massively quality-built. However, Earl speaks the truth, they really are not adaptable for your current project, and to modify them would probably erase most of their value.

Thanks,

David

[Andersen]

- In case you don't know / Altec 288 diaphragms wear out after a certain amount of use.
( There's no point buying or building new crossovers with the assumption that they can "fix" the poor sound of wornout diaphragms / if that is the main problem with your system ).

Again, thanks a lot for your detailed advice, Earl. I indeed appreciate your support.
I don't think that I got a serious problem with the Altec 288 diaphragms. My system is currently working well after several times of my balancing the volume controls between the two amps, one driving 288s and another driving 515s. However, since I knew that the JBL M9500X crossovers were designed for 4-ohm speakers not 16-ohm speakers, I hoped to find out another way either building a new crossover network or modifying the M9500X for 16-ohm speakers which could improve, if any, the sound.
I bought my speaker system from a guy who at that time, already built up and sold several Altec A5s (Altec 515B-16, Altec 288B/C/G-16+Horn 311-60/311-90, and JBL 077/2405) and A7s (Altec 416-8, Altec 806-8A+Horn 511) using this M9500X and from what I know, there have not been any complaints from the users of these system. I'm not sure if he did any modification to the M9500Xs as last time when I opened them up, I did not take any photo nor had its schematics in hand to compare. So, I will check with him this matter, and at this point of time, I will first build the hi-pass for the tweeters.
BTW, what is your opinion on Hiraga's circuit if my 288 diaphragms are still in good condition?


To David: Regarding the 82 ohm resistors, I cannot remember its type but I was recommended to use either MILLS resistors or DUELAND resistors for crossovers. I will take photos and post them up next time I open them up.

[hmolwitz]

http://audioheritage.csdco.com/vbull...ead.php?t=3555

[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 .

Finally, I've completed the hipass project for my 2405 tweeters. It's really great.