MJL4281A/4302A Amplifier or MOSFET's

[zox2003]

Question:

I just received some of MJL4281 and MJL4302 samples from on semi.

In what amplifier configuration they coould be used(schematic or link)?

How many devices per channel (for 4 and 8 ohms) on +/- 42V(what power could I expect?


Quality of MJL's?

MJL's or MOSFET's?

Regards

 

[FastEddy]

http://www.onsemi.com/pub/Collateral/MJL4281A-D.PDF

NPN / PNP transistor pair for output stage solid state amp. These are not MOSFET or JFET at all, just "oridinary" silicon transistors and can be quite good in the right, "push / pull", Class A or A/B amp design. (Difficult to exactly balance in production and elimination or reduction of the 0 Volt crossing point.)

 

[zox2003]

What do you sugest (amplifier schematic)?

What is difficult about these?

 

[EchoWars]

Nothing is difficult about them...they are fine devices.

With +/-42V, you likely will have about a 80 to 95WPC amp, and you'd need only one NPN and one PNP of those devices per channel.

Amp design? Shop around.

 

[zox2003]

Am I will be able to get 150W on 4 ohms with 4 of these devices(+/-42V).

Schematic suggestion

 

[MEGA_amp]

Rod Elliott's P3A fits the bill (sort of) with your voltage and devices.

P3A

 

[XEAGLEKEEPER]

five pair will get you 500 watt with a +/- 70vdc ie.ESP P68 subwoofer amp

 

[ReidK]

Zox,

When did you order your samples? I've been waiting for two months.

Reid

 

[EchoWars]

You can always BUY them and have 'em in three or four days...

 

[XEAGLEKEEPER]

They are about 10 bucks apiece from Mouser. I got 4 pair on ebay for 5 bucks apiece.

 

[zox2003]

I ordered mine yesterday and they were shipped yesterday too.I received them today.

Zox

 

[ReidK]

Did you order from onsemi.com, or some other way?

I'm obviously not in a big hurry (I can't use them yet anyway), or I'd have bought them from Mouser or Digikey. I'm just puzzled, since the people at onsemi told me this delay was normal. Oh well, beggars can't be whiners.

Reid

 

[bigpanda]

My situation was even more wried, I received some MJL4281A but never see the MJL4302A. All I got is a order cancellation notice and I tried to reach them but never got any answer. It had been more than 3months already.

 

[AndrewT]

Hi Zox,

Am I will be able to get 150W on 4 ohms with 4 of these devices(+/-42V).

nearly.

1pair will drive 8ohm to about 75W @ 60degree phase angle.

2pair will drive 4ohm to about 140W @ 60degree phase angle.

+-42Vdc is your limiting factor for maximum peak output voltage.

These predictions were checked for continuous operation below 60degC. Music type duty at home would demand much less from the amp (Tc=60degC allows a heatsink of about 50degC which is pretty hot) will not trouble either arrangement.

You will need a stiff power supply that holds up well under load to produce these powers. I suggest 500VA and 4 by 30mF for a stereo amplifier.

 

[zox2003]

Anu amplifier schematic recommendation's with these devices?

 

[MEGA_amp]

Rod Elliotts P3A

 

[FastEddy]

You might be able to derive a decent schematic from this Wiki kit: http://www.diyaudio.com/wiki/index.php?page=Add+your+names+join+the+group+buy ... or ... http://home.ca.inter.net/~lloyd.maclean/Krell/Krell.htm

The diagram above (Rod Elliot's @ http://sound.westhost.com/p3a-f1.gif ) is great ... except that you will have to find suitable complimentary pairs for the first stage of the Darlington out put ...

....

 

[Bob03]

Try this 1

This amp is fantastic!

 

[Tim__x]

Though I'm impressed that he pulled off the CF triplet, that amp has some basic design flaws. Some which save a few cents (shared CCS reference), some which are just plain stupid (the fixed LTP collector resistor).

As I recall, we discussed this designer's work in the past and someone said he designs for "sound" (including intentional distortion), so these may not be mistakes.

I don't think I've ever seen a bias circuit quite like it.

 

[head_spaz]

Tim_X,
Who's amp are you referring to?
(Wouldn't hurt to be more specific)