Can a single ended amp be truly balanced?

Uhm... what?

Well, aren't you answering your own question?

Quote:

Originally Posted by DavidMahler 

An amp which is single ended design but has balanced ins and outs, can it be balanced for real?

Are you thinking of (for example) the DNA sonnett or ZDT which has balanced outs even thought it is a single-ended amp?

The output is balanced (in that the hot and ground are both driven in opposite directions) due to the way the output transformer is wired. You lose the common mode noise cancellation properties of being balanced all the way through but this should only really make a difference for (really) long cable runs.

You should read this: http://www.eddiecurrent.com/uploads/Balancewhitepaper1.doc

Basically this is what I said above and answers your question.

Quote:

Originally Posted by DavidMahler 

No I mean like the Balancing Act and Pinnacle.....they are single ended design and use transformers

The same as what I said above applies. 

Quote:

Originally Posted by DavidMahler 

An amp which is single ended design but has balanced ins and outs, can it be balanced for real?

I think you're confusing balanced with differential.

Quote:

Originally Posted by DavidMahler 
An amp which is single ended design but has balanced ins and outs, can it be balanced for real?

An amp with XLR balanced input and output is a balanced amp, period. You're making things way too complicated. Another way a balanced amp can be made is either through phase inversion (not ideal) or an output transformer (more ideal). (XLR input is just one way to do it, it can also be done via solely RCA input.)

You're also mixing up your terms and it seems you don't know half of what you're referrng to, so maybe you should read this: http://www.headphone.com/learning-center/balanced-drive-article-series.php

but "explanations" like the link above may not reduce confusion - not that I'm going to clear things up in a single post

the main 1st point is to understand that the term "Balanced" has different meanings/usages to different audiences - and even in one domain may be "overloaded" and its meaning change with context

professional audio often uses balanced signaling differential transmitter/receivers and balanced impedance transmitter/receivers/cabling - Bill Whitlock has pointed out the distinction between differential signaling and the role of balanced impedance interfaces for common mode interference rejection

some high end consumer audio components have adopted the pro "Balanced" signal interface for the source (most often DAC) analog out to the amplifier input

"Balanced" headphone drive is more often about opposing polarity signals to each driver and is less often clear about the balanced impedance (which is arguably inconsequential in headphone drive) - in loudspeakers amps that drive opposing polarity to the loudspeaker terminals are call "Bridged Amps"

Locally we also use "balanced headphones" (or balanced headphone cabling) to distinguish between the standard TRS and any of the several cable connectors that give separate connections to each of the 2 headphone driver's 4 wires - however nothing says that just because you have 4 wires available that you have to apply "balanced" opposing polarity drive signals - but most here would consider it cheating to call a amp "Balanced" that wasn't Bridged (or use balanced output xfmr) even if you could only plug in "Balanced (cable/connector) headphones

it is not uncommon for headphone amplifiers that are advertised a Balanced in, Balanced Output to be built of 2 single ended amps for each channel and they do not have common mode rejecting "true differential" inputs and absolutely require opposed polarity "balanced" input signals and use the source shield gnd as signal ground

The better question than "can it be balanced" is "does it matter".

Why does it matter if something that a majority of people who hear it agree sounds good is made balanced or single ended?

A large bunch of people agree that the amp sounds good. The few that dont consistently say "I dont like it myself, but can see where others would". Its a very nice amp: even people who dont like it like it! Thats the mark of a winner in my book.

After that whether the designer goes to the trouble of making it look balanced or not is simply a matter of knowing your target market's biases and prejudices and improving your odds that they actually take the time to listen to your amplifier. Or if they cant find yours and the other thing they are interested in to compare for themselves that they buy your amp over an amp that "isnt balanced" sound-unheard.

This thread has left me feeling somewhat confused, more so than when I first got here... so I decided to investigate for myself. Can a single ended amp be truly balanced? First lets decide what is "truly" balanced vs. just balanced. I think to truly balance something it should ideally involve a seal; balancing on top of a large ball, and in turn balancing the object on it's nose. Having a large ball, but no time to head down to the bay to enlist the help of a seal, (or sea lion as the case may be) I decided to use myself as the 'balancer'. And yes, after some initial failures I was eventually able to balance the amp on my nose on a large red ball. You will have to decide yourself whether this constitutes "truly" balanced or not... although considering the damage incurred to my amp during the course of these tests I hope you will find these findings at least satisfactory if not fully conclusive.

Quote:

Originally Posted by runswithaliens 

This thread has left me feeling somewhat confused, more so than when I first got here... so I decided to investigate for myself. Can a single ended amp be truly balanced? First lets decide what is "truly" balanced vs. just balanced. I think to truly balance something it should ideally involve a seal; balancing on top of a large ball, and in turn balancing the object on it's nose. Having a large ball, but no time to head down to the bay to enlist the help of a seal, (or sea lion as the case may be) I decided to use myself as the 'balancer'. And yes, after some initial failures I was eventually able to balance the amp on my nose on a large red ball. You will have to decide yourself whether this constitutes "truly" balanced or not... although considering the damage incurred to my amp during the course of these tests I hope you will find these findings at least satisfactory if not fully conclusive.

 

I bet your amp sounds better now that its been balanced. I will try your methods and report back.

After reading the APEX Pinnacle review in TAS and also after reading Jason Stoddard's (Schiit) comments regarding balanced amplifiers, it seems unclear on what constitutes a real balanced amplifier.

First, given Jason's comments from the 6moons review on the Lyr: http://www.6moons.com/audioreviews/schiit/10.html
"... Just a few questions to ask are, is balanced gear simply converting the inputs to single-ended? Or is it creating the differential signal with a separate gain stage after the main one? There are a bunch of ways to do it wrong. Real balanced gear is differential all the way through without splitters and summers and other band aids. This means among other things a more complex gain stage, 4-gang pots and 4-pole input selectors. It's worth it though not just for the elimination of ground current effects but for common-mode noise cancellation - very very nice for headphones."

Next, here's some interesting Pete Millett quotes from TAS APEX Pinnacle magazine review (Issue 214):

""The amp is a two-stage, single-ended amp, with transformer-coupled balanced or unbalanced inputs and outputs"

"The input (balanced or unbalanced) is ... fed through a Lundahl input transformer that drives an unbalanced (DACT) stepped attenuator."

And a very interesting quote --

" He says 'the market for this type of equipment demands balanced headphone outputs.  Personally I am unconvinced that they're better.  In any case, I wanted a single-ended amp.  I'm not a big fan of the sound of fully balanced headphone amps.  Hence the transformers.' "

There are other quotes of interest, please see the article for yourself.

* However this is all academic as someone already previously posted, what's most important is how it sounds ... and the consensus seems to be it's an amazing headphone amplifier.