The Black Hole......

[chris719]

Welp, I guess I'll work on a bunch of other things rather than the 4493 project I was hoping to start. Yowza.

If you haven’t started it, perhaps CS43198 will work instead.

 

[gpapag]

I posted a simple measurement of ESS DAC misbehavior but it require a custom fixture.

Scott it seems I 've missed this. I tried to find it, no luck.

George

 

[PMA]

George, try ASR search engine.

 

[DPH]

If you haven’t started it, perhaps CS43198 will work instead.

Chris -- I haven't and thank you! I'll have a look.

 

[PMA]

Scott it seems I 've missed this. I tried to find it, no luck.

George

ESS THD ‘Hump’ Investigation | Page 23 | Audio Science Review (ASR) Forum

 

[gpapag]

Thank you Pavel.
I spent the required time to go through all Scott's posts there.
Still no luck.

George

 

[Markw4]

IIRC, Scott's post here with the ESS graph attachment was in one of PMA's listening test threads. Also IIRC, I later reposted it in the ES9038Q2M Board thread.

 

[gpapag]

I am interested to read about the measuring method and the "custom fixture".

I posted a simple measurement of ESS DAC misbehavior but it require a custom fixture. This turns off the objectivists who want to connect everything to an AP and push a button. The measurement of these things is not difficult or esoteric but it requires work, old fashion engineering

George

 

[Nelson Pass]

Both leave me in awe and fear of the chemists who work with things that they know want to go foom with the smallest provocation.

I did once meet a chemist who was missing half a finger and asked him what had happened. He proudly told me it was lost whilst working with Oppenheimer and he'd got cocky working with the chemicals for the detonator. This was pre-web so I couldn't prove this, but made a great story.

By any chance was this chemist Clair Elmore?

 

[Markw4]

I am interested to read about the measuring method...

I'm not sure there was a measurement that produced a meaningful number (i.e. figure of merit) with respect to the graph image. It may have been more of a time-domain visualization of the distortion artifact. IMO, it does help with understanding the problem.

 

[PMA]

I am interested to read about the measuring method and the "custom fixture".



George

I see. I think it was about current balancing. Maybe Scott would correct us.

 

[Markw4]

Looks like maybe a 50Hz notch and possibly some makeup gain before going into a scope.

 

[PMA]

Talking about the plot, yes. What I meant was the reason of the ESS hump.

 

[PMA]

Here is the schematics to fix the issue

How to Fix ESS Hump on SGD1 and LA-QXD1 | Audio Science Review (ASR) Forum

 

[TNT]

Wasn't the hump level dependent?

//

 

[scott wurcer]

I am interested to read about the measuring method and the "custom fixture".

George

IME a simple notch filter. When Bruce Hofer visited my lab shortly after the first AP was released he told me that was the way they verified the AP's performance.

 

[GUNFU]

Oh yeah, there's been a new edition since 1989.
The Art of Electronics 3rd Ed. April 2015

I read this part of the book again yesterday. It is written in it, because of the layered structure, mica capacitors are inferior to film ones made of teflon and polystyrene. In fact, I think this is due to the fact that mica capacitors are additionally impregnated with technical Vaseline at the factory.

 

[billshurv]

By any chance was this chemist Clair Elmore?

It wasn't and in the thirty mumble years since my brain has lost the information. I do remember his wise advice just not his name.

 

[billshurv]

Today I am glad the children keep my disposable income under control. There is an auction running for some BBC offices being closed down and both SP10mk2 and EMT938 coming up. They will probably go for top dollar and have been worked half to death!

 

[Hans Polak]

I never heard of EMT before, but after some googling I found that in 1980 a EMT950 costed over £40,000.-
Wow, that would be over £172,800.- in todays money.

It must be an iconic piece of equipment.

Hans