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)
 
Last edited:
Administrator
Joined 2007
Paid Member
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...
 
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.
 
Last edited:
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...

Hi,

Voltage noise perhaps, but not current noise and they are not cheap.

Bashing the 5532 is just tedious, what it does, it does exceptionally
well for the price and very few better all round alternatives exist.

It is course currently available and is by far the best value audio
op-amp available, and still will be for the foreseeable future.

The way they are used in this pre-amp, in pairs or quads, (the 4962
is used when a single op-amp is better), gives them low impedance
driving capabilities well beyond any reasonably priced alternative,
with 3dB for the duals and 6dB for the quads noise improvements.

Anyway, those of you that think you know better than D. Self
can of course substitute whatever op-amps you like in his design.

rgds, sreten.

This 2012 design compared to the 1996 design takes the concept
of low impedance levels throughout the pre-amp one step further,
using 1K pots rather than 10K pots with appropriate circuitry.
It will give pretty much state of the art specifications / measurements.
 
Last edited:
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?

Well, I didn't know cost was an important consideration. The price of the chips is a small fraction of the total cost of a project. The pretty box is usually far more expensive, as is the power supply.

Your hint wasn't very clear to me at all.

The NE5532 has twice the noise of say a LME49720. When you have so many chips, noise should be a primary consideration in my opinion.
 
Anyway, those of you that think you know better than D. Self
can of course substitute whatever op-amps you like in his design.

Gratuitous cynicism. People who listen to the design (after all that's the majority DIYer reason for building a preamp, to use it for audio reproduction) may not like the sound and substitute their own choice of opamp based solely on the subjective appeal. Thinking they know better than Mr. Self not required, merely a different end purpose.
 
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.

They are a little bit less than half the cost of say the LME49720. The cost of the chips is a minor cost when compared with the entire project.

Of course, when I read that this preamp has tone controls.... well, what ever. Have fun with that. I haven't had tone controls in over 20 years... what for?
 
Well, I didn't know cost was an important consideration.

Cost, in and of itself, is not the consideration. Performance (according to one's chosen metric(s)) per unit cost always is the issue in real-world engineering. This goes right back to Henry Ford, and probably even prior to him : 'An engineer is one who can do for $1 what any fool can do for $2'.

The price of the chips is a small fraction of the total cost of a project. The pretty box is usually far more expensive, as is the power supply.

The average Elektor reader can put the design in a shoebox if he/she so desires. Its not going to be an essential part of the design in a hobbyist magazine. The relative cost of the different parts is not really the issue, its a question of optimization of the whole which is engineering.

The NE5532 has twice the noise of say a LME49720. When you have so many chips, noise should be a primary consideration in my opinion.

And I'm sure it is a primary consideration in that design - which might be why Mr. Self has chosen two kinds of ICs and uses their strengths accordingly.
 
Cost, in and of itself, is not the consideration. Performance (according to one's chosen metric(s)) per unit cost always is the issue in real-world engineering. This goes right back to Henry Ford, and probably even prior to him : 'An engineer is one who can do for $1 what any fool can do for $2'.



The average Elektor reader can put the design in a shoebox if he/she so desires. Its not going to be an essential part of the design in a hobbyist magazine. The relative cost of the different parts is not really the issue, its a question of optimization of the whole which is engineering.



And I'm sure it is a primary consideration in that design - which might be why Mr. Self has chosen two kinds of ICs and uses their strengths accordingly.

Oh please. You call this real engineering? in a hobbyist magazine? give me a break. This is a joke.
 
Take your complaints up with Mr. Self then - he is a participant here from time to time. PM him and let us all know how you get on.

Oh brother, what ever. If you want tone controls and a million chips in your preamp, then please, go for it. If you think this is real engineering, please, go right ahead with your belief. I don't care about this little project, I'm not ever going to build it, and I don't care about anyone's justifications for it. You misunderstand. I don't have any complaints because I don't give a hoot about this project. Can you hear me now? I don't care about it!