Suggest improvement for this design

[Leolabs]

Hi all.Need any improvement on this design???

[djk]

If you want to do sometihing like that I would change a few things.

I would probably run an OPA604 off a ±24V regulated supply.

[lineup]

Originally posted by Leolabs
Hi all.Need any improvement on this design???

I think that circuit will work good, Leolabs.

What we don't know is BIAS in output transistors.
Could be anything from 80mA - 2000mA.

NE5534 will work good at +-19 Volt (absolute max = +-20).
NE5534, I guess, at +-15V would have an max output swing of like +-11-12 Volt peak.
(The datasheet will tell if this is correct.)


This should give max power for this circuit:
8 Ohm: 7.5-9 W RMS
4 Ohm: 15-18 W RMS


=================================

your circuit is an excellent and simple way to build
a REAL HiFi amplifier with moderate output power

I have built a similar long ago, using NE5534 + Bipolar in Class A
with 2x12 Volt Transformer.
It has got a very good sound.


lineup

[AndrewT]

Hi,
the limiting voltage from the output is set by the voltage from the opamp.

This in turn is {Vzener-VopampLoss}.
For +-15Vrails, your Vout will be <10Vrms

Run the opamp as high as the datasheet will allow less a margin for reliability. (?+-20.5Vdc!)

The FETs shown are obsolete.
Try 2sk1058/j162 1057/161 1056/160 or
Exicon ec10n16/p16 ec10n20/p20 or
Renasis equivalents.

Why fit the compensation cap 5 to 8?
You are not running unity gain.

[Ultima Thule]

Leo,

perhaps some capacitor over each resistor R7 and R8, or else they are part of the gate resistor.

Cheers Michael

[Leolabs]

Many many thanks guys!I m not concern much about output power/efficiency,but stability and sound quality.

Regarding the Cc issue,can it be omitted???

And the LATFETs,I do have them.

[Ultima Thule]

Cc?

You mean my suggestion?

100 Ohm gate resistance is better than 570 Ohm, actually MUCH better!
Use at least 1 uF plastics over each R, by frequency they come into play very well as FET's input are capacitive.
You also save some job for the feedback component, eg. your op-amp which should be hopefully equal with better sound, perhaps..

Cheers Michael

[Leolabs]

Originally posted by Ultima Thule
Cc?

You mean my suggestion?

100 Ohm gate resistance is better than 570 Ohm, actually MUCH better!
Use at least 1 uF plastics over each R, by frequency they come into play very well as FET's input are capacitive.
You also save some job for the feedback component, eg. your op-amp which should be hopefully equal with better sound, perhaps..

Cheers Michael

Got it!

Also the compensation cap,can it be omitted too???

[Ultima Thule]

Just to be polite and replying to your post, I don't know!
You mean that small 22 pF for the op-amp, I have not seen the datasheet, but I would be carefull and read what it says if there is such an option for an op-amp.

Cheers Michael

[DCPreamp]

Actually, the NE5534 has an absolute max supply voltage of +/-22V and will run happily at +/-20V. So, you can up the zeners to 20V parts, up the supply rails a little, and gain some output swing.