GregS wrote:

Eeyore wrote:
APR wrote:

What difference would you expect a different IC to make over the 4558's?

Just to put this into perspective, the 4558 is little better than the rightly
maligned (today) 741 op-amp.

4558s are most commonly found in low-rent DJ gear.

I was redoing some cheap DJ stuff. One time I put in some National
chips, one of the newer designs at the time, and I found one chip
with popcorn noise. First time I ever heard that.

I got popcorn noise from a failing TI BC184 once but that's it.

What did fox me for days was a noisy channel in a hi-fi amp that was caused by a leaky c-b ceramic
cap.

Graham

"APR" I_don't_Want_Spam@No_Spam wrote in message


I have A20's which I use in my home audio system and
cannot fault them. I have no issues with them that would
make me say the IC's should be changed.

Some people say they are too forward, some have said they
are too bright for their liking. I am quite happy with
them.

Both the A10 and the A20 were well-received on the professional market when
introduced, and still seem to be holding their value in the used equipment
market.

What difference would you expect a different IC to make
over the 4558's?

Why the NHT designers used 4558s would be an interesting question. As a
group, they were very well-informed engineers with any number of sucessful
designs for speakers and amplifiers already under their belt.

If you avoid very high and very low signal voltages, 4558s can work out just
fine. I wonder if the NHT engineers were making a statement against the sort
of bias that makes so many fly off the handle when they see 4558s in an
audio signal path.

Personally, my bespeak audio designs are mostly based on 5534s. and 5532s. I
think some LM353s snuck in a few places where impedances were high.

Arny Krueger wrote:

"APR" I_don't_Want_Spam@No_Spam wrote

I have A20's which I use in my home audio system and
cannot fault them. I have no issues with them that would
make me say the IC's should be changed.

Some people say they are too forward, some have said they
are too bright for their liking. I am quite happy with
them.

Both the A10 and the A20 were well-received on the professional market when
introduced, and still seem to be holding their value in the used equipment
market.

What difference would you expect a different IC to make
over the 4558's?

Why the NHT designers used 4558s would be an interesting question. As a
group, they were very well-informed engineers with any number of sucessful
designs for speakers and amplifiers already under their belt.

If you avoid very high and very low signal voltages, 4558s can work out just
fine. I wonder if the NHT engineers were making a statement against the sort
of bias that makes so many fly off the handle when they see 4558s in an
audio signal path.

Personally, my bespeak audio designs are mostly based on 5534s. and 5532s. I
think some LM353s snuck in a few places where impedances were high.

Never bad choices. If you have access to NJR/JRC parts many of the NJMs are very
respectable too. Notably the 4560 and 4580.

Graham