250ti jubilee network diagram

[dieterj]

Originally posted by CLASS A
Hi
I have the complete 250ti Jubilee network diagram and service manual. I want to share with you guys, but problem is that it was scanned to PDF files and I have since coverted it to a word doc. which I can't attached to this forum. Pls share some light to this so all 250 owners can convert their network to the charged coupled network of the jubilees.
Cheers

Thanks also, great!!!
Dieter

[Earl K]

Nice Work !

[Guido]

For the first time I had a closer look at the parts list.

Can't believe that they used ONLY NPE Caps in that network.
Even for the UHF

I think it is better to by a classic 250ti and upgrade the xover yourself to CC technology.

[4313B]

Mass produced networks made in Taiwan Guido.
At least they bypassed and biased them.

"I think it is better to by a classic 250ti and upgrade the xover yourself to CC technology."

Me too. The original 250Ti had the most expensive transducers.

[frank23]

hi,

I am always very surprised by the complexity off crossovers like these. How do they come up with such complexity? My experience is that if you use good drivers [as in certain specific areas like HF roll of and impedance rise reducing flux rings], then you can use simple crossovers and so reach the most musical sound

these 250ti crossovers must be engineered for the flattest on-axis response. But who cares? I allways say that when I turn my face away from somebody and speak to him, the person still clearly recognises it is me, though the "on axis reponse" has been greatly altered

therefore, simpler crossovers with less phaseshift, gradual response changes and less complex impedance results would be my choice

with simpler crossovers you do have to compromise on ultimate power handling, but how loud do you play anyway!

good luck upgrading....

greetings, frank

[B&KMan]

Hi
I have the complete 250ti Jubilee network diagram and service manual. I want to share with you guys, but problem is that it was scanned to PDF files and I have since coverted it to a word doc. which I can't attached to this forum. Pls share some light to this so all 250 owners can convert their network to the charged coupled network of the jubilees.
Cheers

Thanks thanks and thanks again for juicy information...

: cheers :

Jean.

n.b. thanks to Giskard to convert an post...

[4313B]

Reference the schematic in post #5.

Starting with the UHF. The series biased capacitor pair C25/C27, the parallel inductor L7, and the series biased capacitor pair C29/C31 form the high pass ~ 18 dB / octave roll off filter for the UHF transducer. The resistor R11 in series with the inductor L7 fine tunes the DCR of that inductor to 0.9 ohms. This technique is used to affect the knee of the curve. In the figure below green is with R11 in the circuit and yellow is with it removed. R12 and R13 provide ~ 2 dB of attenuation.

[4313B]

The series biased capacitor pair C13/C15 and the parallel inductor L5 form the high pass ~ 12 dB / octave roll off
while the series inductor L4 and parallel biased capacitor pair C17/C19 form the low pass ~ 12 dB / octave roll off
for the HF transducer. This bandpass circuit is attenuated ~ 7 dB by R7/R8 and R9. This L-Pad circuit also causes
the filter components to behave correctly. In the figure below, green is with the L-Pad circuit and yellow is without it.
The effects of the notch filter formed by L6, the biased capacitor pair C21/C23 and R10 can be seen in the second
graphic. Green is with and yellow is without.

[4313B]

The series biased capacitor pair C1/C3 and the parallel inductor L2 form the high pass ~ 12 dB / octave roll off
while the series inductor L1 and parallel biased capacitor pair C5/C7 form the low pass ~ 12 dB / octave roll off for
the MF transducer. This bandpass circuit is attenuated ~ 10 dB by R1/R2/R3 and R4/R5. This L-Pad circuit also
causes the filter components to behave correctly. In the figure below, green is with the L-Pad circuit and yellow is
without it. The effects of the notch filter formed by L3, the biased capacitor pair C9/C11 and R6 can be seen in the
second graphic. Green is with and yellow is without.

[4313B]

The low pass for the LF transducer is straight forward. L1 provides a 6 dB / octave roll off. The C1/R1 conjugate (Zobel) compensates for the inductive reactance and R2/R3 reduces the motional impedance of the LF transducer.

[4313B]

I suspect G.T. really does know what he's doing.

[DavidF]

hi,

I am always very surprised by the complexity off crossovers like these. How do they come up with such complexity? My experience is that if you use good drivers [as in certain specific areas like HF roll of and impedance rise reducing flux rings], then you can use simple crossovers and so reach the most musical sound...
...therefore, simpler crossovers with less phaseshift, gradual response changes and less complex impedance results would be my choice

...with simpler crossovers you do have to compromise on ultimate power handling, but how loud do you play anyway!

good luck upgrading....

greetings, frank

I understand your premise and agree that simple can equal better if this would work for me. But it would require one speaker (or one truly coincident speaker system) with no crossover at all as the paradigm and still reproduce the total audio spectrum WITH realistic dynamics. I look at the 250Ti crossover as relatively simple (charge-coupled circuits notwithstanding) for a four-way system for the exact quality-of-drivers specification you mentioned. I have seen Dynaudio kit circuits for single-pole two-way designs look absolutely intimidating. To make 250Ti adaptable to real-world amplification demands and room response demands there is a bit of additional circuitry to accommodate.

How loud? As loud as the original performance, if I can get it away with given domestic limitations.

DavidF

[Earl K]

Hmmmm,


- Great thread this is ! ( he said nodding along to his own thoughts )

- Anyone notice how 3 of these 4 components appear to be wired so that they "blow"/compress while only the 108H "sucks"/rarefies ?

- Or is this just another example of my persistent dyslexia getting the better of me ?

[Andrew Black]

I wish all good health!
I have bought{purchased} JBL 250 Ti Classic edition. But they have been altered by someone earlier. Help please! The scheme{plan} of a crossover( Network Schematics) is very necessary to Me!