Class AB Audio Amplifiers

[TCx]

Thanks. I meant particularly the LM4702 based amps from Connexelectronic, specifically the "2x100W LM4702 MOS with Heatsink". It seems that voltages up to +-60V are safe for transistors, just wanted to know if there is any other part on the board which could limit max. usable voltage.

[Cristi]

The maximum supply voltage for the driver IC should not exceed +-70V for safe operation, since the maximum operating voltage of the IC is +-75V.

[guwakzhai]

hi there,

let say i have a LM4702 class ab amplifier base on LM4702 application notes, but with supply of +-25V, what will be the output power for it to operate in class A?

may i know how u calculate it? thx!

[Cristi]

The output power in case of class A operation is much lower, about 20-25W on 4 R and it depends on maximum bias current which the transistors accept. also, must use a large heatsink, with better than 0.25*C/W thermal resistance. i am not a fan of class A, and i have made some experiments for the sake of the art. i believe that at least similar performances as a class A amplifier can be achieved with a good performance class AB amplifier.

[magma]

sir
are these modules avavilble for shipping

Connexelectronic

Connexelectronic

Connexelectronic

if they are i would be intrested

[Cristi]

The LM4702 amplifier is available, so the speaker protection circuit, and the power supply, right now i have the one with 6x10000uF 63V, 6x10000uF 80V and 6x18000uF 71V.

[magma]

hi cristi


Connexelectronic

or
Connexelectronic

which power supply would go best with each?
63Volts is fine for me

does the mosfet require 2 independant power supplies like
this
Connexelectronic

or will the single supply 6*10000uF / 63v be fine with the mosfet and the SAP?

i wish to buy either the mosfet or SAP 4702
please advice about correct power supply

the manual here
http://www.connexelectronic.com/docu...ier_Module.pdf

recommends two power supplies for the mosfet(4*..... + 2 *....)/63v
when will these be avaible

[Cristi]

The SAP15 amplifiers does not require 4 rail power supplies, but for the MOS and BPL versions is recommended to use 4 rail supply, unless SMPS is used.
I recommend to use at least 6x10000uF at 50V for SAP15 amplifiers, and at least 2x10000uF 50V + 4x10000uF 63V for the MOS and BPL amplifier versions. In fact, beside the available capacitors combinations for the linear power supplies, almost any other combination is possible with existing and available capacitors which can fit on the board footprint. just keep in mind the minimum required capacitance and rated voltage, and if the capacity is huge (like 6x18000uF) must use a PSS on the mains side before the transformer.

For the LM4702 amplfier, any version, can also consider to use a smps, since this is a class AB amplifier and voltage regulation is not a must, the A350SMPS or A500SMPS can be used. http://connexelectronic.com/product_...85akd57lpui0c5

[magma]

Originally Posted by Cristi

The SAP15 amplifiers does not require 4 rail power supplies,

I recommend to use at least 6x10000uF at 50V for SAP15 amplifiers, and at least 2x10000uF 50V + 4x10000uF 63V for the MOS [/url]

thanks for the clarification crisiti

i would like to order either
the LM4702 SAP15 (without heat sink)module and the linear supply 6x10000uF at 50V or 63V as you have suggested

OR
the LM4702 MOSFET (without heat sink) and the 4 rail supply - 2x10000uF 50V + 4x10000uF 63V
as you have adviced


POWER SUPPLY to be the 230V version please

which combination do you have available?
please send me the links so i may order
rest we can discuss on PM if you wish

[Cristi]

I recommend LM4702 SAP15 amplifier, and power supply A350SMPS. for moderate output power levels ~ 100W this is a great combination.