Discrete opamps.

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It does look professionally done (spice macro-model included), datasheet looks like it was done by TI/BB.
They are advertised as Translinear Current Mode Amplifier. Some of the characteristics are quite impressive.

Haven't seen any full data sheets, but there are partial spec sheets on some if you have a look.
Cheers George

professionally done by... some of the ...what characteristics?
Honestly...i think people must start reading some real books on op-amps!
Let's just debunk this new myth:
4.5 nv today is just a shame.Nothing on current noise as they needed to run the input transistor at large currents.

On the other hand i bet they measured its noise with a ne5532/34 based sound card or analyzer as they couldn't get lower than the ne532/34 noise itself.
270db open loop gain to get just 0.0001thd in closed loop...I can understand thus the source of its big but not huge slew rate...
What phase inversion in common bjt op-amps?
18v max supply with discrete transistors? WTF!!!


Well let me quote Jodie Foster on Contact(i never read the book, the movie was awesome enough) : If it's only us then the Universe is an awful waste of space.
 
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professionally done by... some of the ...what characteristics?
Honestly...i think people must start reading some real books on op-amps!
Let's just debunk this new myth:
4.5 nv today is just a shame.Nothing on current noise as they needed to run the input transistor at large currents.

On the other hand i bet they measured its noise with a ne5532/34 based sound card or analyzer as they couldn't get lower than the ne532/34 noise itself.
270db open loop gain to get just 0.0001thd in closed loop...I can understand thus the source of its big but not huge slew rate...
What phase inversion in common bjt op-amps?
18v max supply with discrete transistors? WTF!!!

dreamth

Your previous forum name wasn't "Jocko Homo" by any chance was it??

Cheers George
 
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Unfortunately not!He's probably making big money by just being a "proffessional outcast" ! I thought of trying his i/v discrete circuit then i found much better ways combining real IC op-amps and transistors.
Looking at his former account it looks like he's from the USA...The only other country i ever lived in apart from mine was the UK...and i've heard that the Americans need a VISA to get to Romania :)
 
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Hi Scott,

Yes, these sounds impressive to me. I've only seen few bjt op amps with less than 50pa Ib. And the 260dB Aol? Never heard. Perhaps they are exaggerating. I don't know. You're an expert. Would love to hear your opinion about it.

Poting

I meant BJT not FET, 40pA is not possible so it must be a confusion. All the illustrations are CAD drawings so who knows?
 
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FYI, Douk Audio also sells chassis with huge heatsinks, suitable for class A amplifiers, on eBay. I bought one and built a First Watt M2x in it. Good mid-grade quality and corresponding mid-tier prices. Here's the one I bought, the JX085 (link)

What the photo in the eBay listing does NOT show, is that the front panel is engraved with the words "PASS ALEPH AMP CLASS A". I consider this a little misleading; the photos in the listing are carefully arranged so the engraving is out of frame. The one head-on picture is lighted so no shadows fall in the engraving and you can't see it or read it.

Those are the kind of folks you're dealing with when you buy from Douk Audio.

(It turns out I don't actually care very much whether the case is or is not engraved; this has no effect upon the sound of the amp :) . But I do think it's not a completely honest way to advertise goods for sale).
 
I can't find any information on this SX-22B except for this Ebay listing which gives Audience as the source???

SX22B Discrete Dual Op Amp HiFi Preamp Board Integrated Module Replace 4558d for sale online

Where is the SPICE model?

I do find this opamp, which has much reduced specs:

Dual Discrete Op Amp HiFi Audio Preamp Operational Amplifier OPAMP replace ad827

The whole frequency band is very average with accurate and soft high frequency, full mid-frequency, flexible and strong low frequency. The sound is near to gallbladder machine and LP records.
 
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