Nigel
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Post by Nigel on Mar 19, 2009 21:23:00 GMT
Has anyone tried this? Is it as wonderful as everyone says? Have you got to use XLR plugs? Is there anyway standard amps could be modded to offer this facility? Basically I need an idiots guide
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Post by Deleted on Mar 19, 2009 21:27:58 GMT
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Nigel
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Post by Nigel on Mar 20, 2009 1:22:47 GMT
Thanks Alex. Interesting reading.
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Post by PinkFloyd on Mar 20, 2009 1:38:46 GMT
Has anyone tried this? Is it as wonderful as everyone says? Have you got to use XLR plugs? Is there anyway standard amps could be modded to offer this facility? Basically I need an idiots guide You want an idiots guide? OK...... grab two headphone amps, balance them in your hands..... plug in two pairs of headphones.... grow a second head, balance it on your shoulder.... put the headphones on both your heads....... Now stand on one leg and clap your hands in the air to signal to others you are about to go into "balanced mode"..... OK, now's the hard part.... spread your legs as far apart as you can without going into a full body split, raise both arms in the air and shout "Yakimba yakimba waloo waloo rama rama".... clench your buttocks, take a deep breath and, again, shout out "yakimba yakimba waloo waloo rama rama"........ Do a full slazenger flip followed by a triple salko and when you're uprighting yourself do a standard Cheshire flop with your pelvis in a trapezoidal position..... you are now fully balanced. Well..... you did ask for an idiots guide didn't you ;D
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Nigel
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Post by Nigel on Mar 20, 2009 10:18:08 GMT
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Post by Deleted on Mar 20, 2009 10:41:53 GMT
Nigel Did you get to read the attached part ? Alex EliasGwinn View Member Profile Apr 17 2007, 18:11 Post #24 Group: Members Posts: 10 Joined: 17-April 07 Member No.: 42613 QUOTE (Zane @ Apr 15 2007, 12:35) Perhaps this link may shed some light on your arguments... www.6moons.com/audioreviews/balance...phones/one.htmlHello! My name is Elias Gwinn, I'm an engineer at Benchmark Media Systems. We've been getting a lot of questions lately about balanced headphones. We are interested in the debate, but I can't say we agree with any technical explanations about the benefits of the set up. So far, there are 4 major points mentioned so far (that I have heard, at least): 1. Unshared common conductor reduces crosstalk 2. Two amps (per channel) increases slew-rate 3. Two amps provide better damping 4. Balanced cabling provides better common-mode rejection If I may, I'd like to add my thoughts on these points: 1. Most headphones (at least those of decent quality) do not share a common conductor through the length of the cable (as opposed to what was said in 6 Moons). Most headphones have a separate wire from each negative terminal that remain isolated through the length of the cable. In other words, most headphone cables are effectively balanced inherently. If they were sharing a common through the length of the cable, the impedance of the cable may cause some of the signal to show up on opposing channels. However, they are not connected until the plug, and therefore have a minimal impedance to ground. 2. Any headphone amp that is struggling with slew-rate is a poorly designed headphone amplifier. The HPA2 headphone amplifier on the DAC1 has a bandwidth of 55 kHz, and it doesn't even approach any slew-rate limitations even at those high frequencies. 3. Two amps provide WORSE damping. This is why power amplifiers run better in normal mode vs. bridged mode. A balanced (dual-active) headphone amplifier is exactly analogous to a bridged amplifier driving one speaker. The only advantage is increased power, but it comes at an expense of increased distortion, decreased damping, and altered frequency response. This is common knowledge for bridged amplifiers. 4. Headphones don't need any help with common-mode rejection because they inherently will not respond to common mode signal. If, for example, you apply a signal to both terminals of a speaker, it will not move at all. A speaker only responds to differential voltages. 5. There is another cost incurred by dual-active headphone amps that is not addressed. Headphone amps should have as low of a source impedance as possible. If you are using two amps to drive a channel, you are doubling the source impedance. This will cause the headphones to suffer in frequency response, distortion, and ringing. Please continue the great discussions. It is important to resolve these debates so that product manufactures can respond to provide the best audio solutions possible. Thanks! Elias Gwinn -------------------- Elias Gwinn Engineer Benchmark Media www.BenchmarkMedia.com
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robertkd
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Post by robertkd on Mar 20, 2009 11:24:18 GMT
So let me see if I've got this right, Sure if our head phones used a common return wire for left and right transducers there sure would be some artifact generated, that would either cause a kinda cross modulation,... mmm some might. Well most head phones have separate -/+ feeds all the way back to the plug so this would limit any effect to the resistance of the plug assembly and the return wire from the socket back to the common point on the amplifier PCB, in a good system likely not much resistance. Ok next for a fully balanced system we would essentially double the component count for each channel giving more noise and more inherent distortion which of course means the circuitry gets more expensive. the other method involves a some method of generating a 180 degree or mirrored copy of the unbalanced signal so we can now drive our headphones in yah! differential or as you like to refer to it "balanced" signal source. Now the trap here is how we develop the differential signal and the fact the we also now have to have twice as many components in the circuit. So the trade off's and the pay off's of a practical system means that it may look good on paper but what of the real world. My next observation how much of the "improvement" results from the use of heavier (larger cross section) interconnects and reduced capacitance, as well as from what I see separate left and right cabling from source to transducer(s) let me see for a given instance sample of signal say -.25V and +.25V on a differential system yields a total difference voltage of 0.5V and for a single ended system (unbalanced) you have 0V and 0.5V for a total of oh um 0.5V, so as far as the transducer is concerned we have the same diaphragm displacement. So for the same diaphragm displacement in a balanced system we added more components, introduced more noise and distortion sources as well as other artifacts such as group delay and differential phase shift to achieve a better sound. I don't discount that a "balanced" system can't sound bloody good but I do wonder if better gains could be made by simply using a single ended (unbalanced) system and more attention to keeping the return paths as separate as possible. some musings Robert
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robertkd
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Post by robertkd on Mar 20, 2009 12:00:35 GMT
seems more like a promotional article to convince you to buy expensive cable upgrades, and then gear upgrades ;D Robert
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Nigel
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Post by Nigel on Mar 20, 2009 16:54:59 GMT
Yes I read that post Alex.
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Spirit
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Post by Spirit on Mar 22, 2009 3:39:59 GMT
Ah Miguel. You crack me up
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robertkd
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Post by robertkd on Mar 22, 2009 9:46:06 GMT
oh what it's not referring to a balanced mix of classical, rock, jazz and alternative &etc um I see
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Post by wink on Mar 23, 2009 12:49:45 GMT
Can we please restore some balance to this whole argument..?? Where's Merton when we need him...
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robertkd
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Post by robertkd on Mar 23, 2009 13:18:52 GMT
Can we please restore some balance to this whole argument..?? Where's Merton when we need him... well that's difficult it's pretty much a single ended world
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rickcr42
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Post by rickcr42 on Apr 25, 2009 16:47:11 GMT
Hello!
My name is Elias Gwinn, I'm an engineer at Benchmark Media Systems.
We've been getting a lot of questions lately about balanced headphones. We are interested in the debate, but I can't say we agree with any technical explanations about the benefits of the set up.
So far, there are 4 major points mentioned so far (that I have heard, at least):
1. Unshared common conductor reduces crosstalk
Seems to me MORE crosstalk would be a desired feature in a system that effectively blocks the interaural crosstalk between channels because of the presence of a big ass mass of bone and meat (the human head) between the two channels.You also end up with many of the same problems as a typical balanced bridge power amp where anything hooked up to the outputs that has a common ground connection (speaker switchers for instance) will pretty much destroy the amp
2. Two amps (per channel) increases slew-rate
unless the amp is a piss poor design the slewing would already be more than adequate for audio signals so more of an ad copy "selling point" than anything worth the added cost considering the value ratio
3. Two amps provide better damping
Than what ? A single ended version of the same design ? If so then yes but so would a DIFFERENT amp if that is a particular design goal intended to match up with a very specific headphone model.Increased damping may be a non factor with some amp/cans pairing or it may be very important with others depending on the impedance and power into load matchups
4. Balanced cabling provides better common-mode rejection
Maybe useful in a mobile studio setting or in a studio with high levels of interference where very long lines may deem a balanced system the only workable method but in a typical domestic system way overkill in my own experience thus not worth the added circuit complexity (active balancing) or cost (passive transformer balancing).
my personal opinion is headphone amp technology is pretty much stagnated there being nothing truly NEW or revolutionary going on in the amp design field so engineers/designers are looking for ways to do things that are different just to stand out from same old with balanced bridged headphone amps just one of the "twists" on the same old it being no more than twin copies of the same amp,one that BTW depends on total amp pair matching to be a plus rather than a detriment.
Does a balanced amp sound different ?
You betcha.As does a push-pull amp when compared to a single ended amp (cancellation of even order harmonics) or even an SEPP version of of the very same single ended amp the basic harmonic nature of the end product having been changed even though the amp is recognizable for what it is when looking at the schema so it comes down to taste more than need or put another way-
Is the cost effectiveness of a balanced amp in a domestic setting where RFI and/or other forms of interference can be easily contained by basic circuit design technique or the need for MORE power and/or HIGHER damping (pretty much the same end result of a design meant to be more mini power-amp than overbuilt line stage which is what most "headphone" amps really are) worth the effort when it can be matched or bettered most times by using a REAL amp in the 1-5 watt range and a simple resistor attenuator network on the amps output ?
My personal opinion is no but others of of the inverse opinion as the presence and sales of balanced amps proves.Personal taste aside i think one should assses needs THEN read the ad copy/white papers rather than the other way around which more often than not convinces one of need before they even know they need a thing
Rick out
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rickcr42
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Post by rickcr42 on Apr 25, 2009 16:51:04 GMT
BTW-a simple test for those with access to identical amps would be to use a bridging transformer ,one for each stereo channel,feeding the left and right inputs of the FORMER stereo amp with one becoming the left balanced amp and the other the right balanced amp taking the headphone feed from the two "HOTS" (one positive hot,one negative hot) for each earpiece. Sounds harder than it is to actually DO and in fact can be done quicker than I can type the description
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