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Balanced amp for HD 650's at 500~800$ - Page 2

post #16 of 23
3/26/11 at 2:13pm

 

Quote:
Originally Posted by BlackbeardBen View Post

That's only twice the voltage swing of the exact same amplifier running in single-ended mode.  In effect - if your amplifier is truly "balanced" - it is working exactly like a pair of bridged stereo amplifiers in the same case.  Like the Adcom GFA-1, for example.

 

Actually, no. Not like a pair of bridged stereo amps, which would yield two monoblocks. A true balanced amp will be like having the left and right channel (of a single-ended version of the same amp) driving the + and - phases of one channel, and the left and right channel of a second amp doing the same with +/- in the other channel. In other words, like two stereo amps running alongside each other on one chassis. 

 

A single-ended amplifier with a better, more powerful output stage can potentially outperform a balanced amplifier in all aspects - it really just comes down to the particular output stage design and devices. Yes, of course.

 

Current is a similar story.  It's going to be the same with the same voltage swing, of course assuming you're not clipping.

 

That said, I do like the PB1 with my HD 600.  My Asgard never gets used anymore, although that is much a function of the lack of portability.

 

Your PB1 must be doing something right. smile.gif



 

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Gear mentioned in this thread:

Sennheiser HD 650 Headphones
post #17 of 23
3/27/11 at 4:35am
Quote:
Originally Posted by jeffreyfranz View Post

 

Actually, no. Not like a pair of bridged stereo amps, which would yield two monoblocks. A true balanced amp will be like having the left and right channel (of a single-ended version of the same amp) driving the + and - phases of one channel, and the left and right channel of a second amp doing the same with +/- in the other channel. In other words, like two stereo amps running alongside each other on one chassis.


 

I guess you don't understand that that is exactly what bridging a stereo amp does - it makes the second channel's output the inverse of the main channel, by feeding the single input to both channels and reversing the polarity of the second one - precisely what a "balanced" headphone amp does.

 

Lookie here:

 

Bridge_amp.GIF

 

So no, you do not in any way end up with a pair of normal monoblocks if you bridge a pair of stereo amplifiers.  Normal monoblocks have a common ground, bridged amps do not, obviously.  To use your own words, in a bridged amp it's like there are two stereo amps running alongside (but in reverse polarity of) each other!  Amazing!

 

The Adcom GFA-1 is an example of a stereo amplifier that does this internally, so in headphone-world terms it would be a "balanced" amplifier...


Edited by BlackbeardBen - 3/27/11 at 4:44am
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post #18 of 23
3/28/11 at 1:24am
Thread Starter 
Very interesting, I must confess. But isn't this slightly off-topic, and is the information posted the last few post easily found using google and the forum's search function? wink.gif
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post #19 of 23
3/28/11 at 2:06am
Quote:
Originally Posted by Tilpo View Post

Very interesting, I must confess. But isn't this slightly off-topic, and is the information posted the last few post easily found using google and the forum's search function? wink.gif


Yes, although I have to admit that now I sort of want to finally get the second Adcom GFA-555 I've been after and try the pair of them bridged (i.e balanced) into headphones...  That would cost on the order of $600 or so total, if you didn't already have one to start with...

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post #20 of 23
3/28/11 at 4:43am
Thread Starter 
The GFA 555? Isn't that a power amplifier?
Why not get a bridged pre-amp?
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post #21 of 23
3/28/11 at 7:18am
Quote:
Originally Posted by Tilpo View Post

The GFA 555? Isn't that a power amplifier?
Why not get a bridged pre-amp?


Yes, it is a power amp.  A bridged pre-amp?  No such thing...  Unless you mean a balanced pre-amp.  Not much use for one in home audio.

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post #22 of 23
3/28/11 at 11:26pm
Thread Starter 
And here was me thinking bridging was just a way to make it balanced...
I think I have some extensive research on the technical side of balanced amplifiers waiting for me.

Anyway, how do you call it then when you turn two pre-amps into one big balanced pre-amp? Or is that not possible?
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post #23 of 23
3/29/11 at 4:41am
Quote:
Originally Posted by Tilpo View Post

And here was me thinking bridging was just a way to make it balanced...
I think I have some extensive research on the technical side of balanced amplifiers waiting for me.

Anyway, how do you call it then when you turn two pre-amps into one big balanced pre-amp? Or is that not possible?


You don't do that.  You could, if you were building your own - but it's not like a power amplifier where you can flip a switch to put it into bridged mode.  You'd need two outputs for each channel, to start with...

 

There are converters that will take an unbalanced signal and balance it (called a balun), but there's no point for home audio unless you have a power amplifier with balanced input and are having ground loop issues with just an unconverting adapter.

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Gear mentioned in this thread:

Sennheiser HD 650 Headphones
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