Crown ITech Schematics !!(?)

[TOINO]

Hi guys. Found this one on JBL site. It seems the Crown ITech...
I have opened one some time ago and locks like the some topology ;-)
Anyway has very good info about the SMPS, gate driver and class BD modulation.
…but the gate drivers are a little bit slow….?

http://www.jblproservice.com/pdf/Ver...Schematics.pdf

[fredos]

That's the Vertex integrated power amp...1700W Ch/4 ohms, unreliable....Sorry!

Fredos

www.d-amp.com

[TOINO]

That's the Vertex integrated power amp...1700W Ch/4 ohms, unreliable....Sorry!

Fredos
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Why???

Ok! Let’s learn some thing!!

Have posted this link because it has many info about circuits discussed in other threads of this forum.
Don’t forget that the project is signed by Crown, one of the most competent Amplifier producers around.

Could we seriously analyze this thing and learn some thing with it?....


We could start by first page:
The gate drivers with their level shift circuit. It seems very complicated; 5 transistors for level shifting and next you have a relatively slow propagation Gate Driver (120nS).

Any comments ??

[fredos]

Sorry to hurt you, just to say that I have repair of lot of these amp in the last fews week, they dont like cold air (-30 celcius) and sometime burn for nothing. So it was the base of the I-tech, you could learn a lot with this schematics, but that's all! Dont try to built something like this, you will spend a lot of time to make this to work! To many stock for nothing!

That's my opinion...sorry if I hurt you!

Fredos

www.d-amp.com

[TOINO]

Thanks for your advice fredos.
My intention was just to discuss the circuits and not to build the thing…

They are some strange things (for me) inside, like the way they generate the triangle wave.
They use an discreet-opamp as an integrator for that. I could identify the function of each circuit, but everything is very complicated, with lots of components.

Anyway, apparently nobody is interested on this discussion maybe because the circuit is to complicated

I have found another very interessant link for a student project based on One Cycle Control.
Eventually will post the link one of these days…

[classd4sure]

Don't like the cold? Are they too reliant on certain electrolytics?

I find the wave generator interesting as well, would take some simulation on my part to appreciate it fully.

What makes you say the drivers are slow? Seems to be about what's required to get good control over the waveform when using a driver IC, funny isn't it? Though it could be improved on still, curious to see there isn't even any anti-parallel diodes across the turn on resistors for instance. I'd imagine this would be a very fickle circuit, and am not surprised at all by what Fredo's said.

Anything else about it you'd like to discuss more in depth?

Look forward to seeing that single cycle control link posted.

Cheers

[TOINO]

I have found the some discreet integrator on other place of the some website:
http://www.jblproservice.com/pdf/EVO...%20Diagram.pdf

This implementation from C-Audio has fewer components.
I have made a quick simulation with it and the result is a perfect triangle wave.
Much better then the one I have simulated with LM318 just for check.

In other place:
http://www.jblproservice.com/pdf/JRX...MAIN%20AMP.pdf
It seems that the IR2111 is not enough for drive the mosfets. They have Q22 and Q23 as emitter-follower and Q16/Q18 for quick turn-off. Apparently IR2111 is just for level-shift…

I am surprised with this first contact with “pro” switch amplifiers.

Will show the OCC amplifier in another thread with Patent links.

[classd4sure]

You should some schematics from JBL that are floating around here, sssssssshocking!! They had to discontinue the line and offer customers rebates on their next purchase, after at least four failed revisions. Fun stuff this class d.

Try to have a look at amps that you know work good and see how they did it. Like UCD for instance.