View Full Version : JBK Ti10K need Crossover layouts
Jan De Smet
02-01-2004, 02:52 PM
Hi can anyone help me to the original Xover layout of the JBL Ti10k speakers (made in Denmark - high-end range).
I want to tri-amp these speakers and need the filter layouts to work on them.
Thanks for any help,
02-01-2004, 03:57 PM
Jan De Smet
02-01-2004, 10:17 PM
Thanks a lot for your fast reply and help! Super!!!
Helps me a lot!
Jan De Smet
02-04-2004, 12:55 AM
I've looked at the schematic and technical sheet next to it. I'm puzzled since the crossover frequencies on the data sheet differ from what the Speaker manual and brochure mention!
The data sheet says: 200Hz-1.2kHz-3.5kHz.
The brochure says: 250 Hz -1kHz-4kHz.
Of course this is quite a difference if you want to multi-amp.
The only difference I think I'm seeing in the filter itself between the real filter and the schematic is the absence of a 1µF cap parallel to the 120µF cap at the entrance of the Mid-bass section. (although I cannot read the inductor values from the real filter of course).
Is there any way to check or calculate the crossover freq. without having to do that through measurement equipment (freq. generator and scope) which I don't have?
02-04-2004, 06:48 AM
I notice the discrepancies as well. I would need the DCR values of all the chokes in the passive filter and the electrical equivalents of the drivers to calculate anything to great accuracy.
Another solution would be to run a voltage drive on the system using the driver loads.
If you want an easy solution you will simply need to get a continuously variable active filter and start dialing in frequencies until it all comes together. At a glance it looks like it might be a difficult system to tri-amp while maintaining the original design parameters.
Jan De Smet
02-04-2004, 10:41 AM
Actually I was planning to actively tri-amp with the Behringer DCA2496 which is a digital system where up till 3 channel stereo active filtering can be done Both input & output gains of each channel can be set. It allows a wide range of filter configurations and slopes. There is a very active thread on this machine on DIYAudio.
Why do you think it might be difficult to tri-amp my speakers?
Would finally the best option to find the Xover frequencies not be to test with sound generator and scope? This seems still easier to me then desolder all inductors and then have them measured...
Would be very grateful for your advice :D
02-04-2004, 11:45 AM
You can use the sound generator and scope.
I stated that it might be difficult to tri-amp the system while maintaining the original design parameters, not that tri-amping was necessarily difficult.
Here are the voltage drives using dummy loads and zero DCR for all the inductors. Yellow is 4 ohms and green is 8 ohms.
The midrange bandpass drive appears it might have a bit of tweeking going on but it's difficult to tell without knowing the DCR values of the chokes.
02-04-2004, 12:05 PM
Here's the voltage drive using driver DCR dummy loads and 0.5 ohms as the DCR for all the inductors. Again, it appears the 180mm midrange driver might require a bit of tweeking.
Jan De Smet
02-05-2004, 11:26 PM
Hey are those your measurements on a Ti10K filter or do they come from data?
Could you comment in laymens words on waht should be done about the midrange in a active setup?
On this graphs it does look loke 200Hz-1200Hz-350kHz.
I seems that the Behringer does allow a lot of tuning so I might be able to 'tweek' the midrange' a bit.
I also guess that going active with 48db slopes will avoid a lot of the passive Xover flaws?
02-06-2004, 05:30 AM
"Hey are those your measurements on a Ti10K filter or do they come from data?"
They come from plugging the schematic into spice and applying dummy loads. For actual design work one would use electrical models of each transducer for the loads. One would also know the DCR values of all the components.
In this case I just used dummy loads as is standard operating procedure for coming up with a voltage drive of a network for service purposes.
"Could you comment in laymens words on waht should be done about the midrange in a active setup?"
No. I personally would run a voltage drive on the network with the actual drivers as loads to see if that "shelf" really existed.
"On this graphs it does look loke 200Hz-1200Hz-350kHz."
You would probably do pretty good going with those frequencies. That's where I would start.
"I seems that the Behringer does allow a lot of tuning so I might be able to 'tweek' the midrange' a bit."
"I also guess that going active with 48db slopes will avoid a lot of the passive Xover flaws?"
Going with steeper slopes kills transient response. It also has some benefits. Can't have something for nothing. Try it, you might be able to live with the decrease in transient response just fine. Ignorance is bliss, unless it's really bad, you would possibly need a direct A/B to tell the difference.
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