[sacd lover]

Quote:

Originally Posted by tot /img/forum/go_quote.gif What is the rationale for different headphones benefiting or not of balanced drive? As far as I know the headphone itself does not care which way it is driven.

Some headphones have flaws that balanced drive seems to mitigate .... case in point the Senn 650.

I have both a Singlepower Squarewave XL and the standard Square Wave single ended version. The only balanced headphone cables I have fit the Senn 580/600/650. Therefore, my balanced headphone sample is quite small. However, so far, the 650 improves the most. The 650's excess bass and closed in treble are noticeably improved. But, overall the 600 sounds the best to me with the SW XL despite the fact the improvement isnt as drastic.

As for balanced operation .... I have no doubt I prefer balanced to single ended operation with the Square Wave amps. I cant believe how similar the SW XL amp sounds to my MPX3's. This amp uses only discrete MOSFET devices throughout instead of the typical cheap op amps most designers use these days. So, the sound difference may be more discernable with the improved resolution and lack of harshness the MOSFET's deliver in the SW XL. The result is smooth, warm but uncolored sound that also reminds me of the MPX3 as well as the Class A Nelson Pass designs with a little added body. If any SS amp could intice me away from tubes the SW XL is the amp.

But, I have a balanced PPX3 SLAM arriving at the end of the week. We will see if balancing tubes will deliver the same degree of improvement. If so, the sound is going to be amazing.

 

[euclid]

the impedance of the headphone determines how much distortion is introduced by balanced drive.

 

[vcoheda]

Quote:

Originally Posted by euclid /img/forum/go_quote.gif the impedance of the headphone determines how much distortion is introduced by balanced drive.

what does this mean.

 

[euclid]

Quote:

Originally Posted by vcoheda /img/forum/go_quote.gif what does this mean.

the benefit of balanced operation is susposed to be that by driving both the + and - signals any common interference(noise) is canceled out and only the source signal remains. this makes sense when talking about sending signals from sources to preamps to amps, especially over long distances.

but when talking about driving headphones balanced remember that any noise that is present before the headphone amp will be amped just as the genuine source signal would... so the only noise capable of being rejected is the noise that is introduced in the actual headphone cable after the amp stage. however, any noise that enters the headphone cable is going to enter the + and - lead equally and does not affect the movement of the driver which is based on voltage differetial between the two leads. so because of this principle single ended operation already funtions as common-mode interference rejection, its already balanced.

the sound differences we are hearing in balanced headphone operation are coming from damping factor changes based on load impedance/source impedance. we want low output impedance from the amp going to a higher load impedance(the headphone), but we are effectively halving the headphones load impedance when driving a single driver from two seperate amps(balanced), this lowering of damping factor affects the resonation properties of the driver and ultimately introduces distortion which affects the frequency response. completely opposite of ideal but sound change is sound change and any change can be perceived as beneficial.

 

[tot]

Quote:

Originally Posted by euclid /img/forum/go_quote.gif the sound differences we are hearing in balanced headphone operation are coming from damping factor changes based on load impedance/source impedance. we want low output impedance from the amp going to a higher load impedance(the headphone), but we are effectively halving the headphones load impedance when driving a single driver from two seperate amps(balanced), this lowering of damping factor affects the resonation properties of the driver and ultimately introduces distortion which affects the frequency response. completely opposite of ideal but sound change is sound change and any change can be perceived as beneficial.

That explains why same amplifier in balanced drive would sound the different (better or worse) from single ended mode. But it does not explain why balanced drive itself would be better (apart from noise rejection.)

You could have another amp with can do the same in single ended mode. Is it just that it is easier to build a better amplifier by duplicating existing and using balanced operation than designing a better single ended one?

(Well, you could take that better single ended one and use it in balanced mode...)

 

[Veniogenesis]

Quote:

Originally Posted by euclid /img/forum/go_quote.gif but when talking about driving headphones balanced remember that any noise that is present before the headphone amp will be amped just as the genuine source signal would... so the only noise capable of being rejected is the noise that is introduced in the actual headphone cable after the amp stage. however, any noise that enters the headphone cable is going to enter the + and - lead equally and does not affect the movement of the driver which is based on voltage differetial between the two leads. so because of this principle single ended operation already funtions as common-mode interference rejection, its already balanced.

Yes, it's not a mistake that engineers (Lavry and Benchmark come to mind in the community) are often baffled by balanced headphones.
Quote:

Originally Posted by tot /img/forum/go_quote.gif You could have another amp with can do the same in single ended mode. Is it just that it is easier to build a better amplifier by duplicating existing and using balanced operation than designing a better single ended one?

You would be surprised by the measured impedances of many tube headphone amps (RSA often comes to the minds of some).

 

[vcoheda]

are you saying that balanced operation in terms of sound is a distorted version of SE.

 

[J-Pak]

Yeah I'm not buying balanced drive is the end all for dynamic headphones either. I would rather have a balls to the wall push pull tube amp

To these ears opamp designs don't sound bad (I'm temporarily using a well regarded opamp SS amp), I'd just want a design that is more high end and doesn't introduce its own limitations on the amp.

 

[Veniogenesis]

Quote:

Originally Posted by J-Pak /img/forum/go_quote.gif Yeah I'm not buying balanced drive is the end all for dynamic headphones either. I would rather have a balls to the wall push pull tube amp

You should get SET monoblocks for your cans.

 

[J-Pak]

Quote:

Originally Posted by Veniogenesis /img/forum/go_quote.gif You should get SET monoblocks for your cans.

Yeah if my speakers end up using SET amps, the monoblocks for the K1000 will be pretty nice (probably the most ridiculous K1000 amp on this forum, except for Roam's amp).

But if I go with less efficient speakers I definitely won't get something so extravagant.

 

[Veniogenesis]

Quote:

Originally Posted by J-Pak /img/forum/go_quote.gif Yeah if my speakers end up using SET amps, the monoblocks for the K1000 will be pretty nice (probably the most ridiculous K1000 amp on this forum, except for Roam's amp). But if I go with less efficient speakers I definitely won't get something so extravagant.

Dew eet. Get some horns. And then you'll want the most outrageous SET amp out there, mwahaha.

 

[tot]

Quote:

Originally Posted by Veniogenesis /img/forum/go_quote.gif You would be surprised by the measured impedances of many tube headphone amps (RSA often comes to mind).

I think it is the case even with tube power amps, and reason why they often are a bit soft on the bass side.

Resistance of stock headphone cables does not help either, Proline 750's straight stock one has R of 1.5Ω.

 

[sacd lover]

I had asked Mikhail at Singlepower about this some time ago and he is not as concerned with the noise rejection offered by balanced designs as he is with the slew rate and power output. His power supplies already offer extremely low noise. Balanced drive gives you double the slew rate and double to quadruple the power.

Slew Rate ..... in electronics, the slew rate represents the maximum rate of change of signal at any point in a circuit. Limitations in slew rate capability can give rise to non linear effects in electronic amplifiers.

Instantaneous electrical power .... the instantaneous electrical power P delivered to a component is given by

where

P(t) is the instantaneous power, measured in watts (joules per second)
V(t) is the potential difference (or voltage drop) across the component, measured in volts
I(t) is the current flowing through it, measured in amperes

 

[sinsiang]

While slew rate is a certain spec or benchmark alot of people use to determine the quality of the amps, it's not always the case.
The limitation in slew ratemight cause distortion but too much slew rate seems artificial or pushed. In the end it the correct balance of everything when designing an amp. What the amp designer wants (tone and speed, etc..) are what determines the outcome.
Power is not everything either, if that was the case, then all amps would be solid state. As a qoute from Nelson Pass, "It's all in the FIRST WATT".
Also Noise rejection is very important, wheather it is tube or ss. If noise is not important, no need for good interconnects, no need for braiding, twisting and such. Noise is noise you cannot just not worry. I have seen many ****** amp designs all because of poor psrr. Also I have seen some amps that have poor grounding and some that don't even have a ground plane!!!

siang

 

[sacd lover]

Quote:

Originally Posted by sinsiang /img/forum/go_quote.gif While slew rate is a certain spec or benchmark alot of people use to determine the quality of the amps, it's not always the case. The limitation in slew ratemight cause distortion but too much slew rate seems artificial or pushed. In the end it the correct balance of everything when designing an amp. What the amp designer wants (tone and speed, etc..) are what determines the outcome. Power is not everything either, if that was the case, then all amps would be solid state. As a qoute from Nelson Pass, "It's all in the FIRST WATT". Also Noise rejection is very important, wheather it is tube or ss. If noise is not important, no need for good interconnects, no need for braiding, twisting and such. Noise is noise you cannot just not worry. I have seen many ****** amp designs all because of poor psrr. Also I have seen some amps that have poor grounding and some that don't even have a ground plane!!! siang

To much slew rate sounds artificial or pushed? Have you ever heard an amp with to much slew rate? If so, which one?

Power is important! Listen to a tube amp using low output tubes OTL, say a 6DJ8 or 6SN7GT. The difference once you add tubes like a 5687/ 6BX7GT or EL84 is night and day. The first watt is certainly important but so are the remaining watts for controlled and extended bass response and lifelike dynamics.

The noise comment should have read he is not as concerned with noise rejection as with slew rate and power output in a balanced amp. I will correct that. If you have ever heard a SP amp they are dead quiet. His basic design philosophy revolves around a stiff regulated power supply that is a brick wall to noise. Noise is already a non-issue in his designs because they are designed for extremely low noise from the outset.