2445J/2380 + 2404H passive xo help

[Juntuin]

Hi everyone,

First of all, I know this is noob question..but I hope that someone would be willing to help me with this. I don't know has anyone done this as passive and got schemas already, if not, I would need something to start work with. I have 2225H on bottom and I can drive that active through miniDSP and I would like to use that as room correction for lower frequencies.

If going with 1st order xo;

2380 and 2445J driver. Crossing somewhere between 600-800hz and maybe 8000hz. So that's single cap and single coil in series.(?) But response is rising from 900hz and falling from 5000hz, that does need some kinda attention and what kinda?

2404H, crossing from 8000hz. Only single cap in series, or something more?

Then there is level matching. Simply Lpad's to tame everything down to match 2225H levels?

Am I even close on the track here?

There is always an option to sell upper end, get better horn/driver to replace 2380/2445 and make this 2-way. Don't know is there any suitable horn/driver, since there are many octaves to cover with one horn.. I used to drive this as a 2-way but I wasn't satisfied with top end.

Thanks

http://www.jblpro.com/pub/obsolete/2404.pdf
http://www.lansingheritage.org/image...225/page02.jpg
http://www.lansingheritage.org/image...2445/page2.jpg

[Juntuin]

Hmm, funny that I haven't seen 3105 or 3106 xo's before with all this work with google. Now I found those. But I guess there are some improvements to do.. Bypass cap, where and what size? Protection cap for 2445J, I already had 47uF and I guess that'll do the trick. Any protection for 2404H? Need for zobel network?

If and when it matters, mid driver is 16 ohm and hf driver is 8ohm.

So now we got base for our xo, how to apply improvements?

My english isn't so good, so I would love to see some schemas!

[Ian Mackenzie]

http://www.jblpro.com/pages/pub/obsolete/3105-3115A.pdf

http://www.jblproservice.com/pdf/Net...%20Network.pdf

I think you are saying you want a passive crossover?

If this is the case read the above links carefully for guidelines on the 4673 system

On the schematic the low filter should be fine

On the high filter the auto transformer is no longer available so take that and the 2 39R resistors out of the circuit.

I would suggest replacing the auto transformer with a switched fixed attenuation for 12 ohms (the 2445) of 6, 8, 10 dB or simply buy an 8 ohm variable Lpad and put a 20 ohm resister in parrellel with the 2445.
The bypass horn compensation CLR is still required.

That will get you started. You really need a measurement mic and analyser.

I would keep it simple and get it going as a two way first before attempting to add the 2404

[Juntuin]

Hi Ian, and thank you for reply!

What I need is passive xo ONLY between 2445J and 2404H, I have played this system active 2-way for a long time before this attempt.

Only measuremet equipment I have are UMIK-1 and REW, I know they won't take me very far, but better than nothing?

[Robh3606]

The 2380 cannot be used in a simple 6db network. This is a CD horn that will "not work" without a compensation network that rolls off the midrange response. Take a look at the no EQ response. Did you run a CD compensation in the active set-up? Look up the SR series 4731/32 as examples of passive networks using 2380/81 and 2404

Rob

http://www.lansingheritage.org/image...2380/page4.jpg

[Ian Mackenzie]

Hi Rob

I was wondering why the need for the 2404?

The plan is not clear.

If the poster can detail specific detail of each crossover point that would make any feedback easier.

ie 500 hertz active or passive, 5000 hertz passive
CD compensation yes/no

If the horn is compensated correctly an additional HD devise should not be absolutely necessary

My impression is you are not using any compensation.

Please confirm that you have CD compensation (active EQ) on the mini Dsp.

All crossover slopes should be 12 dB or 24 dB
My suggestion is measure the horn as is and post an image.

Btw you should be able to EQ the horn flat with the mini dsp

The put in a low pass 12 slope with the mini dsp at 5000-10000 hertz

Your high pass passive filter for the 2404 can be a series capacitor and an 8 ohm
Lpad to start with

Try 1-3 uF. Look at the Jbl 8000 hertz crossovers if you need a 12 dB network

It’s a very diy space so you are going to have to work on this for a while

If you are actively crossing over the 2455 put in a 30-50 uF protection capacitor

The Jbl 5235 electronic crossover manual has specific guidelines on protection capacitors.

[more10]

The 2380 cannot be used in a simple 6db network. This is a CD horn that will "not work" without a compensation network that rolls off the midrange response. Take a look at the no EQ response. Did you run a CD compensation in the active set-up? Look up the SR series 4731/32 as examples of passive networks using 2380/81 and 2404

Rob

http://www.lansingheritage.org/image...2380/page4.jpg

https://www.jblpro.com/pub/components/2380a.pdf Looks pretty flat to me below 6 kHz.

[Ian Mackenzie]

Have another look at the unequalised response.

The EQ frequency response is flat per top attachment

In the bottom attachment l have put up a simple passive network to give an indicative “voltage” drive required to EQ the horn / compression driver @ the driver terminals.

The pad is -10 dB. The high pass filter Q is manipulated to derive the boost below 1000 hertz, the LCR bypass network crests the Hf lift to compensate the CD horn.

The values are indicative only and a working schematic may require modifications with real driver loads. But it will work.

So, if you can program your mini dsp for those curves that is a good baseline to start dialing in your system.

Get that working first and then look at the 2404.

[Juntuin]

Wow, I was not expecting this much good conversation

The 2380 cannot be used in a simple 6db network. This is a CD horn that will "not work" without a compensation network that rolls off the midrange response. Take a look at the no EQ response. Did you run a CD compensation in the active set-up? Look up the SR series 4731/32 as examples of passive networks using 2380/81 and 2404

Rob

http://www.lansingheritage.org/image...2380/page4.jpg

Hi Rob! Yes, I was using compensation for the 2445/2380, and a lot of eq otherwise too, trying to reach as close to 20khz as possible.

Hi Rob

I was wondering why the need for the 2404?

The plan is not clear.

If the poster can detail specific detail of each crossover point that would make any feedback easier.

ie 500 hertz active or passive, 5000 hertz passive
CD compensation yes/no

If the horn is compensated correctly an additional HD devise should not be absolutely necessary

My impression is you are not using any compensation.

Please confirm that you have CD compensation (active EQ) on the mini Dsp.

All crossover slopes should be 12 dB or 24 dB
My suggestion is measure the horn as is and post an image.

Btw you should be able to EQ the horn flat with the mini dsp

The put in a low pass 12 slope with the mini dsp at 5000-10000 hertz

Your high pass passive filter for the 2404 can be a series capacitor and an 8 ohm
Lpad to start with

Try 1-3 uF. Look at the Jbl 8000 hertz crossovers if you need a 12 dB network

It’s a very diy space so you are going to have to work on this for a while

If you are actively crossing over the 2455 put in a 30-50 uF protection capacitor

The Jbl 5235 electronic crossover manual has specific guidelines on protection capacitors.

Need for 2404; I don't like what 2380/2445 sounds when eq'd alot, trying to reach +16-20khz region. I have original diaphragms (ti) and would like to change them later. Sorry about my bad english, but 2445 and 2380 was eq'd quite flat and reaching +16khz freq's, but I didn't like the sound of it on higher freq's. 2404 is a nice HF driver with wide spreading horn, makes your speaker sound more "airy" on hi-fi purposes.

I already had 47uF protection cap and paralled resistor for 2445, but I don't quite know what value to use with 2404?

Targeted Xo frequencies can be found on my first post, they have been there all the time
2225H: - 600-800hz
2445J/2380: 600-800hz - 8000hz
2404H: 8000hz -

Have another look at the unequalised response.

The EQ frequency response is flat per top attachment

In the bottom attachment l have put up a simple passive network to give an indicative “voltage” drive required to EQ the horn / compression driver @ the driver terminals.

The pad is -10 dB. The high pass filter Q is manipulated to derive the boost below 1000 hertz, the LCR bypass network crests the Hf lift to compensate the CD horn.

The values are indicative only and a working schematic may require modifications with real driver loads. But it will work.

So, if you can program your mini dsp for those curves that is a good baseline to start dialing in your system.

Get that working first and then look at the 2404.

Thanks really much for the schema! I'm not expecting fully working xo at first, but I can order some components and take measurements outside with UMIK and let's take a look what value we have to change.

[Juntuin]

Here we go, here's another of them. 1/24 smoothing.

Looking this makes me think crossing at 600hz and 7khz? There is difference between these two invidual horn and driver, other one won't fall until +8khz

[ivica]

Here we go, both measure a little diffirent but here's another of them. 1/24 smoothing.

Hi Juntuin,

1.
I think that 600Hz is too low for the 2445ti&2380 combo.Such would produce quite large diphragm excursion and the sound can become hars, may be 800 to 1000Hz would be better. Do not forget that the membrane amplitude would correspons to 1/f^2, and tha 'standard sound ' level would correspons to about 1/f, so all together would produce diphragm amplitude displacement almost 1/(f^3), so the difference crossover frequency between 600Hz and 800Hz woud be (4/3)^3=64/27 ~ 2 times larger diaphragm amplitude displacement. May be THD measurements would be usefull.

2.
Using 2445Ti over about 12kHz, would emphasize diaphragm breakdown 'ringing', so using UHF driver over 10kHz would provide more 'fidelity sound', but using two drivers would 'introduce' some trouble round crossover frequency due to the comb-filter effects
that CAN NOT be EQ, due to the VHF abd UHF drivers spaced appart, and their distance is comparable with crossover wavelength (10000kHz wavelength 34mm).

Regards
Ivica

[Juntuin]

Hi Juntuin,

1.
I think that 600Hz is too low for the 2445ti&2380 combo.Such would produce quite large diphragm excursion and the sound can become hars, may be 800 to 1000Hz would be better. Do not forget that the membrane amplitude would correspons to 1/f^2, and tha 'standard sound ' level would correspons to about 1/f, so all together would produce diphragm amplitude displacement almost 1/(f^3), so the difference crossover frequency between 600Hz and 800Hz woud be (4/3)^3=64/27 ~ 2 times larger diaphragm amplitude displacement. May be THD measurements would be usefull.

2.
Using 2445Ti over about 12kHz, would emphasize diaphragm breakdown 'ringing', so using UHF driver over 10kHz would provide more 'fidelity sound', but using two drivers would 'introduce' some trouble round crossover frequency due to the comb-filter effects
that CAN NOT be EQ, due to the VHF abd UHF drivers spaced appart, and their distance is comparable with crossover wavelength (10000kHz wavelength 34mm).

Regards
Ivica

Hello Ivica!

I have tried many different crossover-points via miniDSP, for some reason I always ended up in 600-700hz range. I don't usually listen very loud, 85-90db range max.

Is there any matter that I was hoping to cross much lower than 10khz (8khz was something that I was aiming for), or is comb-effect something that will involve with this system no matter what?

This is classic "lets build something from what we have" rather than collect just the right needed parts for good quality system. The point is that it is extremely difficult to get your hands on vintage JBL parts in Finland. Heck, even in EU! For example I think that there's something like 5 pairs of 4341 in whole country

[more10]

Use the minidsp delay to handle the comb effect. If the minidsp is temporary solution you will have to deal with the combing by either accepting it or moving the 2404 backwards. Steep filters will minimize the combing if going active if analog filters are an option.

[more10]

The ti diaphragm will start to breakup at 4 kHz. Use a 2450SL diaphragm if you want to cut at 8 kHz.

[ivica]

Hello Ivica!

I have tried many different crossover-points via miniDSP, for some reason I always ended up in 600-700hz range. I don't usually listen very loud, 85-90db range max.

Is there any matter that I was hoping to cross much lower than 10khz (8khz was something that I was aiming for), or is comb-effect something that will involve with this system no matter what?

This is classic "lets build something from what we have" rather than collect just the right needed parts for good quality system. The point is that it is extremely difficult to get your hands on vintage JBL parts in Finland. Heck, even in EU! For example I think that there's something like 5 pairs of 4341 in whole country

Hi Juntin,

I think that 10kHz woud be better as comb filter effect woul be 'moved ' at upper frequency, so woul be less emphasized, may be even higher You can try.

Regards
Ivica