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-   -   New Doug Self pre-amp design... (http://www.diyaudio.com/forums/solid-state/209004-new-doug-self-pre-amp-design.html)

nickds1 17th March 2012 11:25 AM

New Doug Self pre-amp design...
 
Just a heads-up...

This month's (UK) Elektor (April 2012, dropped on the mat this morning...) has a long article by Doug Self with, what he says is, his first published new pre-amp design since 1996. Side notes on Peter Baxandall, references to "Baxandall and Self on Audio Power" - all sorts of stuff. Pt. 1 is about design methodology and his pet subjects of sources of noise & distortion - does include the schematic though.

Kind of fun... (if you are a Self-devotee)

Specifications
Test conditions: supply voltage 17.6 V; all measurements symmetrical; tone control defeat disabled.
Test equipment: Audio Precision Two Cascade Plus 2722 Dual Domain (@Elektor Labs)
THD+N (200 mV in, 1 V out) 0.0015% (1 kHz, B = 22 Hz – 22 kHz)
0.0028% (20 kHz, B = 22 Hz – 80 kHz)
THD+N (2 V in, 1 V out) 0.0003% (1 kHz, B = 22 Hz – 22 kHz)
0.0009% (20 kHz, B = 22 Hz – 80 kHz)
S/N (200 mV in) 96 dB (B = 22 Hz – 22 kHz)
98.7 dBA
Bandwidth 0.2 Hz – 300 kHz
Max. output voltage (200 mV in) 1.3 V
Balance +3.6 dB to –6.3 dB
Tone control 8 dB (100 Hz)
8.5 dB (10 kHz)
Crosstalk R to L –98 dB (1 kHz)
–74 dB (20 kHz)
L to R –102 dB (1 kHz)
–80 dB (20 kHz)

Mooly 17th March 2012 12:34 PM

Can we ask what the main active devices are... I'm guessing maybe LM4562's

currentflow 17th March 2012 12:55 PM

According to Elektor's web page, the following ICs are used:

IC1,IC3,IC5-IC10,IC12,IC14-IC18 = NE5532, e.g. ON Semiconductor type NE5532ANG

IC2,IC4,IC11,IC13 = LM4562, e.g. National Semiconductor type LM4562NA/NOPB

dirkwright 17th March 2012 01:02 PM

Quote:

Originally Posted by currentflow (Post 2949600)
According to Elektor's web page, the following ICs are used:

IC1,IC3,IC5-IC10,IC12,IC14-IC18 = NE5532, e.g. ON Semiconductor type NE5532ANG

IC2,IC4,IC11,IC13 = LM4562, e.g. National Semiconductor type LM4562NA/NOPB

Oh, you're kidding... There are better chips than these out there. What ever:sleep:

TheShaman 17th March 2012 01:05 PM

Quote:

Originally Posted by dirkwright (Post 2949603)
Oh, you're kidding... There are better chips than these out there. What ever:sleep:

I'm sure Douglas Self is aware of the alternatives (and "aware" is an understatement in this context). :rolleyes:

abraxalito 17th March 2012 01:07 PM

If the primary metric is THD+N (and I believe we can safely assume that it is, with this design) then those devices are pretty much on the sweet spot.

dirkwright 17th March 2012 01:09 PM

Quote:

Originally Posted by abraxalito (Post 2949607)
If the primary metric is THD+N (and I believe we can safely assume that it is, with this design) then those devices are pretty much on the sweet spot.

There are many chips that have lower noise than the ones he has chosen.

Maybe he expects hobbyists to go ripping into old consoles and sound equipment to get at the NE5532 chips...

abraxalito 17th March 2012 01:10 PM

Yes but not at the prices of NE5532 - which was what I was hinting at in speaking of the 'sweet spot'. Unless you can enlighten us?

Mooly 17th March 2012 01:13 PM

Quote:

Originally Posted by currentflow (Post 2949600)
According to Elektor's web page, the following ICs are used:

IC1,IC3,IC5-IC10,IC12,IC14-IC18 = NE5532, e.g. ON Semiconductor type NE5532ANG

IC2,IC4,IC11,IC13 = LM4562, e.g. National Semiconductor type LM4562NA/NOPB

Thanks :)

I've great respect for Doug's offerings but I do feel he overlooks or rather dismisses listening tests as part of the design procedure. I'm not surprised to see the 5532 tbh

Interesting...

brianco 17th March 2012 01:20 PM

Quote:

Originally Posted by dirkwright (Post 2949609)
There are many chips that have lower noise than the ones he has chosen.

Maybe he expects hobbyists to go ripping into old consoles and sound equipment to get at the NE5532 chips...

You seem to forget that the end purpose is to play music etc....not to drive test instrumentation.;)

They are available in bulk or singly virtually everywhere for very low cost.....except, I expect, at audio component 'boutiques' which delight in making far larger profits per $ than do the big players such as digikey etc.


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