John Curl's Blowtorch preamplifier part III

[bimo]

I really do not care about amplifier topology. I want to design amplifier using topology that I knew. Make them as best as I can. It is about DIY audio. If you think all amplifiers sound same, it is likely you do not belong to this forum.

Several member can design CFA amplifier with very low THD, high slew rate, etc. Why the other jealous? Because they can not?

 

[dadod]

I know that, you called the first version CFA. I have seen no current mode only PA's posted here, by the strict definition. Amplifiers using open-loop current transfer into a known load are well known, please show me an audio PA made that way. Not simply something like a current mirror with gain inside a normal amplifier.

These little or no feedback circuits don't come with -120dB THD's everyone seems to love. You can't have both.

Mr. Marsh likes to read abstracts, analysis of the contents would be more revealing.

Here is simulated only, non global NFB PA using a current conveyor as the gain block and EC OPS. Never built.
GainWire-NGNFB-classB-PowerAmp
Damir

 

[dadod]

Case in point he's been carrying on for months about his design with Damir a good guy and very nice competent designs, but they are CFA's not open-loop current transfer amps with error corrected output followers.

Thanks Scott, I never received nicer compliment and yet from best professional
electronic designer I know.
Damir

 

[Tournesol]

Never built.

Too sad, Damir. Why did you abandon this project?* Power Amps without negative global feedback are not legion. It was an occasion to verify the validity of the "GNFB is bad" legend.

* (I can understand, we cannot be everywhere and building amps is more difficult with age. ;-)

 

[31697B]

Here is simulated only, non global NFB PA using a current conveyor as the gain block and EC OPS. Never built.
GainWire-NGNFB-classB-PowerAmp
Damir

Lets prototype and later build that one also. We can compare with Scotts CFB or even a CMA.


THx-RNMarsh

 

[PMA]

Why not your facility in Thailand to prototype it, if you want to make a business with it in the end?

 

[TNT]

Who do-you think you are ?

LOL!

//

 

[Max Headroom]

Why not your facility in Thailand to prototype it, if you want to make a business with it in the end?

You must be late to the party lol, that has been well suggested already.

 

[PMA]

You must be late to the party lol, that has been well suggested already.

Yes I am, my apologies then

 

[Max Headroom]

All good , RNM now in his retirement has all the facilities anyone could want to get new projects and designs up, if Mr Obstropolous were to quit his gaslighting and put his self assessed 'superior' intellect toward a new design I am sure Richard would have no trouble bringing it to testing stage, we will see what evolves.


Dan.

 

[scottjoplin]

I don't know, Joe can make a dynamic speaker perform more like an electrostatic by adding a zobel and you guys are arguing about semantics?

 

[Evenharmonics]

You mean he won't voice it?

Sure he will and so he should, why not ?.
Maybe you could specifically advise on component makes/types vs location and RNM can take a listen to that spec.

Only after applying Goop, per Dan’s spec.

Without level match or double blind.

where I do the mechanicals.
...
where I do T&M

It shows 07 05 2015 and 28 01 2017. Didn't you move since then? In such case, it should've been "where I did", no?

 

[simon7000]

Who discovered gravity?

Who invented the Wheatstone bridge?

Who invented the electric light?

 

[31697B]

Without level match or double blind.


It shows 07 05 2015 and 28 01 2017. Didn't you move since then? In such case, it should've been "where I did", no?

yep I just moved 3 months ago and all my test gear shipped by boat. I should have it soon here. Never-the-Less, i can show you where i will do all same things. Right now I am bread boarding in my office. want to see my office, too? Geez guy. I have 4 EE here plus others. One just finished a streaming DAC.
Get a clue. I got better things to do than play games with you and Scott. put up something substantial your selves.

magnetaudio - “ Streaming DAC ”By Magnet...



-RNM

 

[Max Headroom]

Who discovered gravity?
Who invented the Wheatstone bridge?
Who invented the electric light?
Am I on it ?.

 

[syn08]

Geez guy. I have 4 EE here plus others.

Like any other serious and competent DIYer . Anyways, if they can't design and prototype a high power CMA for you, you should consider firing them, they are no good.

...and what were you saying you are doing on this forum?

 

[Jakob2]

I don't believe so as almost no one drives the membrane directly. The speaker out the factory does not appear to be a particularly capacitive load when compared to other speakers unless I have missed something. So the statement that it is a 'voltage' speaker does not hold water to me.

Might be, that I'm missing something, but IMO Tournesol was starting at the actual drive mechanism and worked backwards from that.
I don't want to repeat the discussion about the benefits of current drive (in the case of speaker drivers with moving coils) but it seems that current-drive indeed is able to reduce some speaker distortions.

So, to me it is less of an argument about the amplifier, but just about the driver in the speaker.
From that point of view an electrostatic speaker (which incorporates usually an push-pull electrostatic construction) - working best , based on the theory and corrobated by measurements afair, if no charge is moved during the operation - which of course is practically impossible but approximated.

Therefore it seems to be less likely that current drive will provide any benefits.

And if you are playing word soup with understood concepts you can argue that, at the membrane you are adding then removing charge makes it a 'pure' current device. Not that I would...

Mhm.....

 

[mountainman bob]

What is the reason to have/use MQA? Why would I want reduced bits to listen to?

What is the streaming problem which MQA attempts to "solve"?

What is the issue for not streaming full 24 bits?

Seems like another BW limitation issue/work-around preventing 24 bits Maybe?

THx-RNMarsh

I have 4 EE here plus others. One just finished a streaming DAC.


magnetaudio - “ Streaming DAC ”By Magnet...

-RNM

Maybe he can answer those questions?

 

[Tournesol]

...you should consider firing them, they are no good...
...and what were you saying you are doing on this forum?

You should open yours, you will be able to distribute your good or bad points and "fire" those who displease you.
May-I propose-you a title ? "Hater's corner".
No risk of desertification.

 

[Tournesol]

Tournesol was starting at the actual drive mechanism and worked backwards from that.

I confirm.
it is difficult to get, from outside, an idea of a transducer's mechanism and its characteristics if it is mounted in a sealed multiway active enclosure ;-)