Class A gainclone/chipamp idea

[mcspack]

Sorry Gentleman,

Just noticed that the Klaus circuit on page 2 is inverted. So I have to reverse the output + and -, correct?

 

[DrG]

Very clever circuit, Steven. I plan to implement it at a slightly higher current using an OPA541 and perhaps a 6SN7 super-triode feedback scheme.

Sheldon

 

[dipolar]

All solid state power amplifiers perform better into higher load impedances.

I can't think of any exception.
The national chipamps are current crippled and do not suit 4ohms loading. They require the PSU to be down graded to prevent the chipamps shutting down, or damaging themselves.

I recommend 8ohms, or 12ohms, or even higher, for the National chipamps.

Very true Indeed.

LM3886 and LM1875 sounds terrible with 4 ohms or less loudspeakers.

I wonder why LM4870 is Obsolete now,Why did they stop the production of such a fine chip?

 

[gman76]

I think you're assuming a passive crossover network is between the amp and the driver in this discussion. Driving a 5 ohm tweeter directly (bi-amp w/ active crossover) with an LM1875 is quite nice. Even relatively simple 2-way loudspeakers with 2nd or 3rd order passive crossovers create lots of havoc on the output current demand, especially in the midrange where the xo freq is. The amplifier sees a terribly complex impedance, inductive at certain freq and capacitive at freq just above. And you have multiple resonance points, each causing an ind/cap reactive load.

 

[dipolar]

I think you're assuming a passive crossover network is between the amp and the driver in this discussion. Driving a 5 ohm tweeter directly (bi-amp w/ active crossover) with an LM1875 is quite nice. Even relatively simple 2-way loudspeakers with 2nd or 3rd order passive crossovers create lots of havoc on the output current demand, especially in the midrange where the xo freq is. The amplifier sees a terribly complex impedance, inductive at certain freq and capacitive at freq just above. And you have multiple resonance points, each causing an ind/cap reactive load.

I was trying to drive 16ohms X 4 in Parallel where it sounded terrible but in Series parallel combo 16ohms||2 series16ohms||2 it sounded very nice.
Also with 4 ohms load Lm's gets hot within minutes but with 8 ohms load it remains barely warm.

 

[KlausB]

Twelve years after

.. my chipamp just needed a little bias adjustment and is still playing nicely though it does not perform equally to my SE-hybrids.