Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › Cheap balanced amp?
New Posts  All Forums:Forum Nav:

Cheap balanced amp? - Page 3

post #31 of 62
Quote:
Originally Posted by gradofan1 View Post

Thanks for all the info guys! Unfortunately I understand only about 30% of it >_<<br />
I'm considering the Schiit Mjolnir, which has a dual 3pin XLR AND a 4-pin XLR, which is what I'm looking for; however, it's only slightly out of budget and doesn't have the 1/4" jack I'm looking for.

Ideally I would spend up to $1000 IF it has all the outputs and inputs I'm looking for (Dual 3XLR + Single 4XLR + 1/4"). I've yet to find any amp that does that. 


I know this is a noob question (I'm planning to move 1/2 my headphones to balanced cables), but how does a dual 3-pin XLR input work? How do I connect that to my computer? Do I have to use a DAC with dual 3-pin XLR, or can I just use the chip on my Mac Pro Desktop (which has a good DAC chip in it anyways)?    

I'm afraid we high jacked your thread...........redface.gif

The one flaw with the Mighty Mo (if you want to call it a flaw) is that it only drives balanced headphones, hence, no 1/4" 'phone jack for "normal" 'phones!

Just about any computer that I can think of (not that I've seen every computer in the world! biggrin.gif) does not have a DAC that outputs a balanced signal.
Typically you will need a headphone amp with at least one set of plain old RCA input jacks for plain old Single ended (I.e. "Normal") output DACs.

To answer your question, the dual 3 pin XLR input is a balanced input, you would only use that with balanced source, for example, a balanced output DAC.

Bryston makes a headphone amp with these inputs:
RCA single ended (SE)
1/8" phone jack single ended (same as an iPhone headphone jack)
XLR balanced

And these headphone outputs:
1/4" headphone jack
4 pin XLR headphone jacks
3 pin XLR headphone jacks

The bad news is a new one is $1400 USD.

Not too sure how much a used one is.
They have a 20 year warranty.
Edited by Chris J - 2/14/14 at 10:49am
post #32 of 62
The Audio-GD NFB-6 headphone amp has almost all the features you want except it does NOT have a pair of 3 pin XLR headphone jacks.
$400 USD.
post #33 of 62
Quote:
Originally Posted by robrob View Post

Many modern high-end amplifiers that use balanced push-pull amplification use single-ended output (speaker negative terminals are grounded) for safety and liability reasons. If you look at the amp's schematic you'll see the ground symbol attached to the negative speaker terminal.

Why would there be safety and liability issues with a balanced ( bridged) output power amp?
Just because the amp has a balanced output does not mean that the outputs are not referenced to ground or common or a signal common.
post #34 of 62
Quote:
Originally Posted by Chris J View Post


Why would there be safety and liability issues with a balanced ( bridged) output power amp?
Just because the amp has a balanced output does not mean that the outputs are not referenced to ground or common or a signal common.

 

In the example below you have a long cable (speaker cable) running out of a metal box with 120 or 240 volts inside (the amplifier). If the speaker cable becomes electrified due to a loose wire or amplifier damage with no ground the speaker cable stays live and could cause electrocution.

 

Single-Ended_Amp.jpg

The speaker wire is essentially a loop with a coil on each end (output transformer's secondary coil and the speaker's voice coil).

 

 

You wouldn't have the electrocution threat with a single-ended output amp like this:

Push-Pull_Amp.jpg 


Edited by robrob - 2/14/14 at 12:28pm
post #35 of 62
Quote:
Originally Posted by robrob View Post

In the example below you have a long cable (speaker cable) running out of a metal box with 120 or 240 volts inside (the amplifier). If the speaker cable becomes electrified due to a loose wire or amplifier damage with no ground the speaker cable stays live and could cause electrocution.

Single-Ended_Amp.jpg
The speaker wire is essentially a loop with a coil on each end (output transformer's secondary coil and the speaker's voice coil).

That output transformer secondary is technically neither balanced or single ended.
It's just floating.
The primary side may be tied to approx. 500 Vdc.
I'm 99% sure you would not get that past either UL or CSA or CE.
The secondary would have to be grounded as the primary voltage is above the limits set by those safety authorities.
I'll have to look this up when I get a moment, but I think CE's limit is 50 Volts, CSA's limit may be either 50 or 250.

If the secondary side had a centre tap then you could ground the centre tap and say the output is balanced.
Edited by Chris J - 2/14/14 at 4:10pm
post #36 of 62
Quote:
Originally Posted by robrob View Post



You wouldn't have the electrocution threat with a single-ended output amp like this:
Push-Pull_Amp.jpg 

We'll agree that this is a single ended output as one end of the output transformer secondary is grounded.
The safety agencies should be OK with this configuration (I.e. Grounded secondary) as the primary side is tied to 420 Vdc.
Edited by Chris J - 2/14/14 at 4:05pm
post #37 of 62
Little Dot has at least 3 amps that might fit the bill. The MKV is a solid state dual mono amp that is inexpensive. The MKVI is a dual mono tube design that is about $750 and has 4pin XLR and 1/4 TRS. The MKVIIIse is similar to the MKVI but lower power and more finesse. It is slightly more but IIRC has both 4pin and 1/4 TRS.

www.littledot.net

I think there is a MKVII but can't recall if it is balanced or not. (on my phone or I'd look these suggestions up better)
post #38 of 62
Quote:
Originally Posted by Chris J View Post

If the secondary side had a centre tap then you could ground the centre tap and say the output is balanced.

 

I thought as long as the pair of transmission lines had equal impedance they were balanced and would benefit from common mode noise rejection. I don't see how the addition of a grounded center tap to the output secondary would make a difference.

post #39 of 62
Quote:
Originally Posted by Chris J View Post

I have a lot of respect for Ray Samuels work.

I suspect much of what you are hearing is due to the superior design and execution of the Ray Samuels design.
I have some FiiO gear, it is good, but I got what I paid for.

Again I have to disagree I have had the opportunity to listen and demo the RSA Shadow and while the sound is great the reason I opted for balanced was for the sonic improvements I mentioned.
post #40 of 62
Quote:
Originally Posted by spook76 View Post


Again I have to disagree I have had the opportunity to listen and demo the RSA Shadow and while the sound is great the reason I opted for balanced was for the sonic improvements I mentioned.


You're making blanket statements though that balanced > single ended.  Even in your comparison of lightning to shadow is that of a newer more expensive model vs an older less expensive one.  It's a little ridiculous of me to go with the opposite and say that single ended > balanced because i prefer my super 7 to my mojo. (Yes the super 7 has a balanced headphone jack and can output a balanced signal.  It's still a single ended design though)

 

It's one thing to say that you prefer this balanced amp to this single ended amp, but it's another thing altogether to say that balanced is better than single ended because you preferred the lightning to the shadow, o2, or fiio amp. 

post #41 of 62
Quote:
Originally Posted by spook76 View Post

Again I have to disagree I have had the opportunity to listen and demo the RSA Shadow and while the sound is great the reason I opted for balanced was for the sonic improvements I mentioned.

Let's just that's my opinion.
If you don't agree, OK.

Looking this another way, I would think that a Single Ended output Ray Samuels head amp would sound better than any FiiO.
To be honest, I've never heard a Ray Samuels amp, but the build quality is very impressive.
post #42 of 62
Quote:
Originally Posted by thinkingoffish View Post

Yes the super 7 has a balanced headphone jack and can output a balanced signal.  It's still a single ended design though

Kinda weird statement there.........confused_face_2.gif

What are you getting at.
It only accepts SE inputs?
post #43 of 62
Quote:
Originally Posted by thinkingoffish View Post


You're making blanket statements though that balanced > single ended.  Even in your comparison of lightning to shadow is that of a newer more expensive model vs an older less expensive one.  It's a little ridiculous of me to go with the opposite and say that single ended > balanced because i prefer my super 7 to my mojo. (Yes the super 7 has a balanced headphone jack and can output a balanced signal.  It's still a single ended design though)

It's one thing to say that you prefer this balanced amp to this single ended amp, but it's another thing altogether to say that balanced is better than single ended because you preferred the lightning to the shadow, o2, or fiio amp. 

No I did not just compare the RSA lightning to the Shadow I also compared it to the RSA Protector which is now a four year old model. The easiest way to answer this for me was when I compare the single output from the Protector to the balanced output. I much prefer the balanced output for the reasons I stated.
post #44 of 62
Quote:
Originally Posted by Chris J View Post

Let's just that's my opinion.
If you don't agree, OK.

Looking this another way, I would think that a Single Ended output Ray Samuels head amp would sound better than any FiiO.
To be honest, I've never heard a Ray Samuels amp, but the build quality is very impressive.

Chris,

I cannot recommend RSA amps highly enough. Balanced or single ended, in my opinion Ray Samuels makes the best portable amps on the market. The build quality is like a tank and there is absolutely no background noise or hiss just black hole quiet.
post #45 of 62
Quote:
Originally Posted by robrob View Post

I thought as long as the pair of transmission lines had equal impedance they were balanced and would benefit from common mode noise rejection. I don't see how the addition of a grounded center tap to the output secondary would make a difference.

Problem is in actual practice you don't really know if the output is balanced if it's floating like that.

There may be more stray capacitance at one end of the transformer than at the other end.
The stray capacitance may be inherent to how the transformer is wound.
Or it may be in the case.
Or the wiring from transformer to the binding posts.
So the transformer is not really balanced with respect to ground.
I'm sure you could find some other non-symmetries.

To enforce balance, wind the transformer with a centre tap on the secondary and ground the centre tap.
If anybody reading this takes exception to the term ground, then OK, let's call it signal common.

It's probably not too far a stretch to assume the loudspeaker cable is a balanced transmission line.
Let's assume it's a twisted pair.
So the cable is OK.
It will pick up common mode noise.

So let's take a look at the loudspeaker.
There's normally a crossover with some components on the hot side and some components hot to common.
So the loudspeaker system is probably not symmetrical with respect to ground.
The loudspeaker designer probably gave no thought to trying to create a balanced load.
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Headphone Amps (full-size)
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › Cheap balanced amp?