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Speaker amps for headphones - Page 120

post #1786 of 3116
Quote:
Originally Posted by Armaegis View Post
 

 

Also, very important to not inhale the magic smoke. That's definitely bad mojo.


I dunno, some really great musicians inhaled lots and lots of magic smoke and they ended up with pretty good mojo at least while they were alive... On the other hand, there's magic smoke, and magic smoke... I don't think smoke from fried electronics is included in the latter.

post #1787 of 3116

All that magic smoke...

 

post #1788 of 3116

Am I doing the magic smoke right? :tongue_smile:

post #1789 of 3116
Quote:
Originally Posted by robrob View Post
 

 

Single-ended refers to an amplifier topology (push-pull and differential are "double-ended") but it is commonly, but incorrectly, used to describe unbalanced cables. Balanced and unbalanced refers to circuit and component interconnects with balanced impedance. I defer to the Wizard: http://www.valvewizard.co.uk/se.html

 

Sorry Rob,

I better tell the industry that we're doing it all wrong.  :D

 

You can typically use an amplifier with a push-pull output stage (look up Class B or Class AB) in an amplifier with a single end (or unbalanced output).

 

I'm not too sure where audiophiles got it all so very wrong.

 

Pre-amp outputs a balanced signal:      +S and -S, i.e. Non-Inverting and Inverting.

Drives it down a balanced cable.  If noise is picked up then the two wires contain N+S and N-S at the receive end

Received by an amplifier with a differential input stage.

The differential input stage amplifies the difference between the two wires in the balanced cable pair, hence:  

(N+S)-(N-S) = (N-N) + ((+S) - (-S)) = 2S as noise sums to zero and is rejected and we are left with only signal.

The noise rejection ration is called CMRR:   Common Mode Rejection Ratio.

The output of a differential amplifier is typically single ended.

Noise is rejected, the job is done.

 

Chris


Edited by Chris J - 12/6/13 at 4:08am
post #1790 of 3116
Quote:
Originally Posted by brunk View Post
 

Am I doing the magic smoke right? :tongue_smile:

 

What is that???

 

:D

post #1791 of 3116
Quote:
Originally Posted by zilch0md View Post
 

 

What is that???

 

:D

 

A pot light!

 

Duh!   :evil:

post #1792 of 3116
Quote:
Originally Posted by Chris J View Post
 

 

Sorry Rob,

I better tell the industry that we're doing it all wrong.  :D

 

You can typically use an amplifier with a push-pull output stage (look up Class B or Class AB) in an amplifier with a single end (or unbalanced output).

 

I'm not too sure where audiophiles got it all so very wrong.

 

Pre-amp outputs a balanced signal:      +S and -S, i.e. Non-Inverting and Inverting.

Drives it down a balanced cable.  If noise is picked up then the two wires contain N+S and N-S at the receive end

Received by an amplifier with a differential input stage.

The differential input stage amplifies the difference between the two wires in the balanced cable pair, hence:  

(N+S)-(N-S) = (N-N) + ((+S) - (-S)) = 2S as noise sums to zero and is rejected and we are left with only signal.

The noise rejection ration is called CMRR:   Common Mode Rejection Ratio.

The output of a differential amplifier is typically single ended.

Noise is rejected, the job is done.

 

Chris

 

Maybe you should tell Texas Instruments:

"A Differential Operational Amplifier Circuit ... - Texas Instruments

Quote from the paper:
An instrumentation amplifier can be constructed from two single-ended amplifiers and a fullydifferential
amplifier as shown in Figure 2. Both polarities of the output signal are available, of
course, and there is no ground dependence.

 

Perhaps you've heard of a Single-Ended Triode amplifier?

 

The reality is the term "single-ended" is currently used by the electronics industry and audiophiles to describe circuits (amplifier and otherwise) and unbalanced circuit and component interconnects.

post #1793 of 3116
Dis hee-yuh's a puh-fek zample uh why we in Tex-us say, "Y'all doan know how tuh talk good."
post #1794 of 3116
Quote:
Originally Posted by robrob View Post

 

Maybe you should tell Texas Instruments:

"A Differential Operational Amplifier Circuit ... - Texas Instruments

Quote from the paper:
An instrumentation amplifier can be constructed from two single-ended amplifiers and a fullydifferential
amplifier as shown in Figure 2. Both polarities of the output signal are available, of
course, and there is no ground dependence.

 

Perhaps you've heard of a Single-Ended Triode amplifier?

 

The reality is the term "single-ended" is currently used by the electronics industry and audiophiles to describe circuits (amplifier and otherwise) and unbalanced circuit and component interconnects.

 




Groan.
Open question to anyone reading this:
Do audiophiles argue with lawyers about the law?
Do audiophiles argue with MDs about medicine?

Anyway.............
I think the problem is semantics.
We need to differentiate between several different things:
amplifier topologies,
cables,
inputs, &
outputs
You resolve these and everything starts to fall into line and then we agree.

By definition:
All Operational Amplifiers have differential inputs.
All Operational Amplifiers have single ended outputs.
They are just building blacks

Obviously we can design a circuit using an Operational Amplifier to output either a Non-Inverted Output or an Inverted Output.
And it can be designed to receive an unbalanced, or single ended signal OR a balanced signal.

A typical Operational Amplifier uses a push-pull output stage.
You can use two Op Amps in a bridged configuration to drive a balanced line.

A shielded cable with a twisted pair inside the shield is a balanced cable.
Obviously we can use it to make a single ended cable (for unbalanced signal transmission).
Or use it to make a balanced cable for balanced signal transmission.

The TI note probably shows 3 Op Amps in an Instrumentation Amplifier arrangement?
Can you send me a link?
I can't really comment on it if I can't see the topology.

A Single Ended Triode is called Single Ended because the amplifier topology is Single Ended.
In addition, unless it is a transformer coupled input, and depending on the transformer arramgement, it receives Single Ended (i.e unbalanced) signals.
Same with the Output stage. Obviously we can converted the output to balanced via a transformer, if we want to.

My opinion:
I think the MARKETING SCHLOCK from the audiophile amplifier companies is confusing the audiophile community at large.
post #1795 of 3116
Quote:
Originally Posted by Chris J View Post
 

 

A pot light!

 

Duh!   :evil:

Bingo! :D

post #1796 of 3116
Quote:
Originally Posted by Chris J View Post
....snip.....

My opinion:
I think the MARKETING SCHLOCK from the audiophile amplifier companies is confusing the audiophile community at large.

I agree. I still occasionally find myself confused. I guess I'm not totally reformed yet :o

post #1797 of 3116
I am most likely DET than most here. And it is the manufactories who cause this.
A bal cable was the output and input to Cary the signal further. Now it means so
Much more. And given the use of transformers and hybrid amp. Who the hell
Could make sense of this.
It is so convoluted as to just sell products with
The info that we at this time want to hear.

Only a designer might know who us what.
And I'll bet if you get a few of them in the room
There will be blood.

Al D
post #1798 of 3116

Oh and by the way. Who said "balanced" was the cat's meow anyway? Oh yeah....the audiophile companies:rolleyes:

post #1799 of 3116
Yes they did sir. But of course we all are ready for it. Lol.
post #1800 of 3116
Quote:
Originally Posted by ALRAINBOW View Post

Yes they did sir. But of course we all are ready for it. Lol.

Hehe yep :D Plus I'll add, IMO, that it's really not needed in a Head-Fi rig unless you're listening inside a server room or something lol. Your cables are so short, little power needed, that all it does for you is maybe reduce audible crosstalk and lighten your wallet by a large amount if you're not careful :tongue_smile: 

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