Tuning / Tweaking Dynavox TC-20

Here some pictures modding Phono Preamplifier

Dynavox TC20.

In this forum there is a modding of a similar but different version:

https://www.analog-forum.de/wbboard...gegen-ear-834-clone-oder-david-gegen-goliath/

In my Preamp is a NE5532 op amp instead of the 4558.

As this component is good enough my mods only concern putting to the electrolytics foil capacitors in parallel.

One cap is across the rails of the op.

I think I will buy another preamp of this type to make a listening comparison.

And later putting an LM4562 in it. The 4562 is an op which I liked a lot in an old Nad CD player and made it sound very good.

If I would like to transform the NE5532 to class A.
From which leg(s) of the op to which leg I would have to wire a resistor of what value? 10k?

I did not change the wall wart of 12v.

Would a power supply of 15volts instead of 12 volts bring more dynamic sound or dynamic headroom? The caps are all rated 25volts.

The max power supply for the NE5532 would be 18volts? Or can it stand even more?
 

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Ah, in the other Dynavox TC-20 was an MC1458 which was changed to opa2134. I added here the schematics so you can see what was changed in order to make it more linear.

On my board of the Dynavox is written 4558 to be put in but there is a good NE5532 in it. Not worth changing it. Already very good specs.
 

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Yes you are right.

I invest here a lot of my time:
https://www.diyaudio.com/community/threads/how-to-make-a-loudspeaker-sandwich-cone.402917/

What I found out is that amplifiers can make loudspeaker sound better with current drive:
here my latest post in a thread started by me:
https://www.diyaudio.com/community/...fication-to-current-drive.389985/post-7450952

Of what concerns biasing into class a of op amps I would like to know how to do it. At the moment I have STK4132 amplifiers which I modify to current drive ("CFA amplifier") and in it is a 4558 op amp. As I do not want to change it I would like to know how to do some tweak on in in order to listen to it.

Already the power supply of op amps can make a big difference to the sound - like the quality of coupling capacitors in signal chains.
 
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