Analogue Engineers in the house?

[The_Audio_Lord]

Hello my dear audio friends,
Just came to this forum in order to got in contact with fellows engineers who work on the field and chat about anything on a designs matter.
I work in the pro audio industry doing design of analogue equipment for world class studios.


Remember, feedback is a weaknesses

 

[sarumbear]

Hello my dear audio friends,
Just came to this forum in order to got in contact with fellows engineers who work on the field and chat about anything on a designs matter.
I work in the pro audio industry doing design of analogue equipment for world class studios.


Remember, feedback is a weaknesses

it has been a while I worked on pro audio gear but I can categorically tell you that I don’t believe feedback to be a weakness. Like everything else it can be used wrong, but without feedback you can’t process audio signal and stay within universally acceptable distortion levels.

 

[sergeauckland]

I hope your last sentence wasn't a troll, just to get us going, as until I retired, my whole career was based on analogue pro-audio gear, mostly for broadcast. I too echo Sarumbear's comment that feedback is a Good Thing. It linearises the transfer function, flattens frequency response, reduces output impedance, increases input impedance, and without it, audio would be in a far worse position.

Of course, like any technique, it has to be used appropriately, and one only has to look at vintage valve amplifiers to see how feedback was used, mostly correctly, within limitations of phase shift, and how modern valve amplifiers without feedback (mostly SETs), are terrible amplifiers. Stability criteria have been understood for a very long time, and as long as those are followed correctly, feedback is universally a Good Thing.

Anyway, welcome to ASR, and I look forward to your reponse.

S.

 

[sarumbear]

Stability criteria have been understood for a very long time, and as long as those are followed correctly, feedback is universally a Good Thing.

Ditto

 

[Speedskater]

There are other forums that focus on circuit design:

Pro Audio Design Forum - Pro Audio Design Forum

GroupDIY Audio Forum

GroupDIY - Do it yourself (DIY) audio & electronics forum. Electronic forums for audio design & audio schematics.

groupdiy.com

 

[Timcognito]

Gearspace.com - Gearspace.com - The No. 1 Website for Pro Audio

Forum for professional and amateur recording engineers to share techniques and advice.

gearspace.com

 

[Speedskater]

"Gearspace" seems to have a lot more semi-pro users than design engineers. And the design engineers spend most of their time helping newbies.

 

[The_Audio_Lord]

Hello guys.
The feedback thing is a troll... Just to spice it a little bit.
Nice to see you guys around.
I do work mainly designing dynamics, eq and pre amp for pro audio and recordimg industry, where feedback is a must.
But I can name a lot of golden gear used on industry that do not have feedback. But this is another theme.
Any one active in the industry around here?

 

[Barter]

Is this maybe ripe for seeding the new Pro Audio section?

 

[sarumbear]

But I can name a lot of golden gear used on industry that do not have feedback.

I like to know a few examples.

Meanwhile, I assume by feedback you mean overall, output to input feedback. Otherwise, I can’t imagine a linear circuit without any feedback.

 

[DVDdoug]

I have an electronics degree but I don't work in audio.

But I can name a lot of golden gear used on industry that do not have feedback. But this is another theme.

As you probably know, negative feedback (corrective feedback) tends to improve EVERYTHIONG. Anybody with an engineering degree should know this but not all equipment is designed by degreed engineers or under the supervision of a degreed engineer.

You can make a good amplifier without global feedback but higher open-loop gain with feedback usually makes it better, and gain is cheap these days... It's not like the tube days where an additional gain-stage added cost.

Most of the "anti feedback" golden ear characters "don't believe in" measurements or blind listening tests. And, they describe sound using meaningless terminology like, "This amplifier is more detailed". or an unlimited number of meaningless-flowery words. Then when they fail a blind listening test they start making excuses about why blind listening is invalid...

The "audiophile community" is dominated by nonsense,

There is a fair amount of nonsense in the pro audio world too but at-least in the pro world you don't find much interest in expensive-exotic cables and that kind of thing. And not understanding the underling science or engineering doesn't mean you can't record, mix or master, or produce, a good recording!

 

[The_Audio_Lord]

I like to know a few examples.

Meanwhile, I assume by feedback you mean overall, output to input feedback. Otherwise, I can’t imagine a linear circuit without any feedba

I like to know a few examples.

Meanwhile, I assume by feedback you mean overall, output to input feedback. Otherwise, I can’t imagine a linear circuit without any feedback.

The famous Fairchild 660 and 670 has an open loop gain circuitry.

 

[sarumbear]

The famous Fairchild 660 and 670 has an open loop gain circuitry.

How can it be open loop if it’s a compressor? Not to mention that there’s only one reason to use a unit designed in the 50s: distortion!

 

[wwenze]

Probably using the curving transfer function as a limiter?

I suck @ tube circuits but looks pretty open loop to me

 

[sarumbear]

Probably using the curving transfer function as a limiter?

I suck @ tube circuits but looks pretty open loop to me

Do you think that diagram reflects this device with multiple controls?

 

[MakeMineVinyl]

The Collins U26-1 limiter uses a somewhat similar circuit as the Fairchild, and like the Fairchild, uses the 6386 variable Mu triode as the gain control element. The limiter is transformer coupled throughout and there is no global feedback.

 

[Zaireeka]

Probably using the curving transfer function as a limiter?

I suck @ tube circuits but looks pretty open loop to me

The connection between the output transformer and the cathodes of V6 look like a feedback line to me.

 

[sarumbear]

The connection between the output transformer and the cathodes of V6 look like a feedback line to me.

It sure is. However, as I said above, are we sure that’s the correct unit?

 

[Zaireeka]

Only a part of it obviously.

 

[sarumbear]

Only a part of it obviously.

Even if the earlier was part of a larger circuit, the two circuits are different.