New LME Design -bridged / balanced inputs

[AudioGrade]

Hi,

I want to design a 150W amp with the LME 49830 / IRFP240 for an active speaker (SMD).

But Ive a problem to find an nice symmetrical design for such an amp for a bridged applikation which should be controlled by a balanced input.

Does anyone use the LME in inverted mode?
Ok, I could use the standard-application for each side, but I think it must be possible to use a symetrical design for a perfect performance?!

Does any user has done this before or any experience with such a design?

Thanks and regards,

Wolfram

[qsa]

You should use Quasi symetrical design for mosfet amplifier with LME..., performance and sound will be excellent compare to than IRFP9240 / IRFP240.

IRFP9240 / IRFP240 looks symmetrical but they are not symmetrical. If you want symmetrical design you should use IRFP310 for IRFP240.

I had build many years before symmetrical mosfet amplifier with IRFP9240 / IRFP240 devices, performance in sound was worse...


Check schematic from Quasi member for Quasi symetrical mosfet design

Next time i will designing Quasi symmetrical mosfet design with LME

[ostripper]

IRFP310 ?? google says it is discontinued.

[Nelson Pass]

Originally posted by qsa
I had build many years before symmetrical mosfet amplifier with IRFP9240 / IRFP240 devices, performance in sound was worse...

The IR version of the P channel parts have a known flaw in which
the transconductance "shelves" to a lower figure in the mid-band.

This makes them even less of a match for the N channel parts, and
you want to consider that when designing with them.

[AudioGrade]

Hi,

thanks for the answers. The module should be a part of a new acitve speaker electronics as shown:



In this picture is only one LME placed, so Ive to update it soon.

Here is my sheet for the first, with no values and a bit drawn "quick and dirty":



Here is the seen the beginning of the pcb-placement for this sheet:



So it will be a very tiny amplifier module, I hope

Because the SK1530/SJ201 are very difficult to buy here in Germany I want to use the IRFPs.

@Nelson:

Im having no much experience in matching FETs. Do you advice the SK1530 or to match the IRFPs?

Thanks and regards

Wolfram

[AudioGrade]

Ups, just seen that the embedded screens arent really good read ..

Here are the attached ones...

Regards,

Wolfram