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Re: Headphone upgrade advice

Mon Mar 13, 2017 11:54 am

SecretSquirrel wrote:
M50x is 35 ohms
SR80e is 32 ohms
HD5xx is 50 ohms

The Grados and M50x's should be ok on a mobile phone. My M40x's work just fine on my Moto G4 and they are rated at 35 ohms. The Sennheisers are getting to the point where an amp might help.

--SS



Thanks, SecretSquirrel! I'll probably need to avoid the Sennheisers then, which is a shame but I can't get an amp (at least, not for a while).
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 12:02 pm

the '598's have a big impedance spike down low...above 80ohms. They definitely need to be amped to get the full range of happiness.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 12:48 pm

I use some Sennheisers, I am forgetting the model. Had a coworker play me some Pink Floyd from his Macbook using some Shure headphones and that was ABSOLUTELY the best audio I've ever heard from a headset, though I've never used Audio Technica. Gonna see if I can get the model of the Shures.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 1:11 pm

MileageMayVary wrote:
I use some Sennheisers, I am forgetting the model. Had a coworker play me some Pink Floyd from his Macbook using some Shure headphones and that was ABSOLUTELY the best audio I've ever heard from a headset, though I've never used Audio Technica. Gonna see if I can get the model of the Shures.


Brand only means so much- got to be specific about model, as you can't come out and say Shure > Senn > AT, for one example. As you change preferences (Open/semi-open/closed/noice cancelling/size/comfort) and traverse budget brackets, you have to be open about manufacturers to get the best (or even just adequate) solution.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 1:28 pm

turtlepwr281 wrote:
the '598's have a big impedance spike down low...above 80ohms. They definitely need to be amped to get the full range of happiness.

That isn't quite what that means. In this area of audio (as with most), sources are expected to be voltage amplifiers that care nothing for current. From the amp's side, that means the impedance can go as high as you want and it'll still be accurate, it just won't be able to put very much power in. An impedance spike like that in a headphone design causes no trouble at all for the source, it just means that less power is put in at that frequency. Sennheiser put that spike there for a reason - they wanted a bit less power to be delivered at that frequency. Take a look at the FR band and impedance curve. That impedance curve represents attenuation of over 6 dB. Try adding 6 dB to the FR band in that range. Doesn't look like such a nice FR band anymore, eh?

Honestly, I'm not convinced that this is even worth caring about as far as output volume. Maybe the Sennheisers have twice the impedance of the other two, but that means they're behind by 3 dB in output level, which isn't that much. Efficiency differences in the drivers themselves are liable to make a bigger difference than that, and I have no idea which way that comparison goes.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 1:31 pm

Airmantharp wrote:
[Brand only means so much- got to be specific about model, as you can't come out and say Shure > Senn > AT, for one example. As you change preferences (Open/semi-open/closed/noice cancelling/size/comfort) and traverse budget brackets, you have to be open about manufacturers to get the best (or even just adequate) solution.


Sennheiser HD439 is where I am coming from. Still don't know the model of the Shures.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 1:34 pm

Don't forget that low-Z cans are more current-driven than voltage-driven, thus they need beefier voice coils to absorb the current without melting. That adds weight to the moving part of the diaphragm. High-Z cans need voltage rather than current, thus the voice coils can be lighter, and the resulting moving weight is reduced. Yes, high-Z requires an amp, but all decent cans listening to lossless music should be running through an amp anyway (IMO).
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Re: Headphone upgrade advice

Mon Mar 13, 2017 1:46 pm

synthtel2 wrote:
turtlepwr281 wrote:
the '598's have a big impedance spike down low...above 80ohms. They definitely need to be amped to get the full range of happiness.

That isn't quite what that means. In this area of audio (as with most), sources are expected to be voltage amplifiers that care nothing for current. From the amp's side, that means the impedance can go as high as you want and it'll still be accurate, it just won't be able to put very much power in. An impedance spike like that in a headphone design causes no trouble at all for the source, it just means that less power is put in at that frequency. Sennheiser put that spike there for a reason - they wanted a bit less power to be delivered at that frequency. Take a look at the FR band and impedance curve. That impedance curve represents attenuation of over 6 dB. Try adding 6 dB to the FR band in that range. Doesn't look like such a nice FR band anymore, eh?

Honestly, I'm not convinced that this is even worth caring about as far as output volume. Maybe the Sennheisers have twice the impedance of the other two, but that means they're behind by 3 dB in output level, which isn't that much. Efficiency differences in the drivers themselves are liable to make a bigger difference than that, and I have no idea which way that comparison goes.


Thanks for explaining that. I appreciate it.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 2:26 pm

Captain Ned wrote:
Don't forget that low-Z cans are more current-driven than voltage-driven, thus they need beefier voice coils to absorb the current without melting. That adds weight to the moving part of the diaphragm. High-Z cans need voltage rather than current, thus the voice coils can be lighter, and the resulting moving weight is reduced. Yes, high-Z requires an amp, but all decent cans listening to lossless music should be running through an amp anyway (IMO).

Even in the low-Z case, the output voltage (not current) of the source is supposed to track the input waveform. Low-Z headphones just mean that the source has to be beefier to handle all the current being demanded. If it's insufficiently beefy, then things will become a bit more current-controlled, but that isn't a good thing.

Theoretically, impedance shouldn't have any effect on power demands. 2V/4mA and 0.5V/16mA represent the same amount of power going into the driver, and if the efficiency of the driver is the same, then the voice coil dissipation demands are the same. A lot of things change when you go from 16 ohms to 600 ohms (and efficiency and power handling aren't going to be unaffected), but they're more subtle than that, and I can think of ways for the change to affect either variable in either direction.

turtlepwr281 wrote:
Thanks for explaining that. I appreciate it.

No problem, I'm happy it was helpful.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 2:33 pm

synthtel2 wrote:
Theoretically, impedance shouldn't have any effect on power demands. 2V/4mA and 0.5V/16mA represent the same amount of power going into the driver, and if the efficiency of the driver is the same, then the voice coil dissipation demands are the same.

The higher current draw of the low-Z voice coil WILL result in more heating, hence the heavier coil.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 2:50 pm

Captain Ned wrote:
synthtel2 wrote:
Theoretically, impedance shouldn't have any effect on power demands. 2V/4mA and 0.5V/16mA represent the same amount of power going into the driver, and if the efficiency of the driver is the same, then the voice coil dissipation demands are the same.

The higher current draw of the low-Z voice coil WILL result in more heating, hence the heavier coil.

But given similar efficiency, it'll take less current to drive it to the same volume level. So unless it is also less efficient (which is certainly possible...), the heating should be about the same.

Heavier wire also *causes* lower impedance, so to say that heavier wire is used *because* of the lower impedance isn't entirely correct either.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 2:53 pm

just brew it! wrote:
But given similar efficiency, it'll take less current to drive it to the same volume level. So unless it is also less efficient (which is certainly possible...), the heating should be the same.

The heavier coil will reduce efficiency unless some other measures are taken.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 2:59 pm

Heating and output are proportional to power, not current. If you increase current while decreasing voltage (which is what's happening here), heating and output volume don't inherently change. Because of that, you don't need a heavier coil to make this work.

JBI, I think you got an effect direction swapped.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 3:05 pm

Heavier wire has less resistance, which is a major component of headphone impedance.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 3:07 pm

The number of turns can also differ, though. I'd guess it usually does.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 3:17 pm

synthtel2 wrote:
The number of turns can also differ, though. I'd guess it usually does.

If anything, wouldn't you tend to have fewer turns of the heavier stuff (to keep the coil mass reasonable)?
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Re: Headphone upgrade advice

Mon Mar 13, 2017 3:26 pm

Exactly. It doesn't take much of a wire gauge change to get a big impedance change if it's done that way, but that doesn't sound like a problem.

To get into the actually complex stuff, if you adjust impedance via wire gauge and turns such that coil mass stays constant, the high-Z coil will be able to provide more force but at a lower maximum cone velocity. This will have a lot of effects (including many I'm unclear on but would like to know more about), but I'm guessing the biggest is that Qes will fall through the floor. Low-Z that results in a heavier coil would be boosting Qts for multiple reasons, and this seems like it could get out of hand pretty quickly.

High-Z this way will tend to tie input voltage to cone velocity, where low-Z will tend to tie input voltage to cone acceleration. I'm guessing peak efficiency is right about between those two points. On the sound quality effects of this, your guess is as good as mine.

Edit, just thought of another implication. As the high-Z coil in this comparison is better at moving lots of mass around, it'll be better suited to heavier cones. This also works well with the increased electrical damping.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 3:51 pm

FYI, Massdrop had the HD650s for $199. 33% over budget, but your not going to find a better all-around crowd pleaser open high-end headphone for the money. Sold out 5000 units in about 2 hrs.

Out of curiosity what sort of internal cord break are you referring to? I haven't heard about his issue with the HD 650s. Especially since there is no internal cord in the headband (ie, each ear cup attaches to the cable). Odd that a short wire run inside a non-moving ear cup would be prone to breakage...
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 3:54 pm

Thanks, Cynan, but I'm kind of done with 600's/650's. They sound great, but the cable is simply too expensive to keep replacing. I don't know why they break internally the way they do; I don't run over them with chairs or stretch them in any way. Just normal use, they last about a year on average.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 4:02 pm

Oh, a breakage in the cable. Can't you just buy a beefier aftermarket cable if your experiences with the stock ones are so bad (and you still have the phones)? This for example..
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 4:10 pm

Whoa, at $200 I want a pair. I could mod a bit to make them durable if need be.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 4:12 pm

cynan wrote:
Oh, a breakage in the cable. Can't you just buy a beefier aftermarket cable if your experiences with the stock ones are so bad (and you still have the phones)? This for example..


These are the ones I had been getting: https://www.amazon.com/Replacement-Cabl ... ref=sr_1_1

At this point I've probably spent ~$120 on cables, which is insane because I'm hardly rough with them (barring possibly the first one). Also, the little dual-pins don't make great contact any more (probably due to replacing the cable so many times) so I'd rather not throw more money at them.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 5:55 pm

cynan wrote:
FYI, Massdrop had the HD650s for $199. 33% over budget, but your not going to find a better all-around crowd pleaser open high-end headphone for the money. Sold out 5000 units in about 2 hrs.
If we're talking Massdrop, I'd have a very hard time choosing between the HD6XX and AKG K7XX (same price). My HD600 is the better sounding model, but the K7XX is still REALLY good, and the comfort is absolutely better.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 6:04 pm

Sorry for posting a bajillion times in this thread, but I just noticed that those IF datasheets include voltage needed to reach 90 dB, which is exactly what will tell you whether an amp will be needed to get enough volume. HD598s take 90mV, M50xs take 42mV, and they don't have an SR80e datasheet but other Grados look to be somewhere in the 80-120mV range with some down to 42mV. For comparison, HD650s take 205mV.

HD598, M50x, HD650, SR60i, SR125i, SR325i, SR325e

My Grados can go really really loud, as in if I plug them into the full-power channel of my amp a normal volume is -80 dB (yes, minus eighty). I doubt volume is going to be an issue with HD598s or similar.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 6:28 pm

synthtel2 wrote:
turtlepwr281 wrote:
the '598's have a big impedance spike down low...above 80ohms. They definitely need to be amped to get the full range of happiness.

That isn't quite what that means. In this area of audio (as with most), sources are expected to be voltage amplifiers that care nothing for current. From the amp's side, that means the impedance can go as high as you want and it'll still be accurate, it just won't be able to put very much power in. An impedance spike like that in a headphone design causes no trouble at all for the source, it just means that less power is put in at that frequency. Sennheiser put that spike there for a reason - they wanted a bit less power to be delivered at that frequency. Take a look at the FR band and impedance curve. That impedance curve represents attenuation of over 6 dB. Try adding 6 dB to the FR band in that range. Doesn't look like such a nice FR band anymore, eh?

That's a typical speaker resonant curve, characteristic of driving a moving mass with an EM field. The designer can tweak it around a bit but that impedance spike is going to be down there somewhere. But I think there are two things complicating your understanding of headphone amplification:

1. In the past, when the source was usually a voltage amplifier, a large source impedance was added ahead of the 'phones (typically 120 Ohms), which helped swamp the impedance variations of the drivers.

2. Many modern heaphone amp ICs intended for portable sources use current feedback instead of voltage feedback, allowing the source to drive a more consistent power output without requiring such high swings as the impedance-loaded voltage amplifier otherwise would. Here's one example of several I turned up in a quick search.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 7:41 pm

Hm, I had no idea current feedback was a thing in this space. In that case, I've got all kinds of questions about how they (try to) keep FR bands consistent, because many of the better drivers out there are going to have that spike and probably aren't going to be happy about being driven that way. (Many drivers don't have that spike at a relevant level though, especially cheap ones.)

If I'm reading everything right, that TI amp looks like it would be basically fine driving most headphones that the average joe would be likely to own (negligible spike and moderate dependence on electrical damping), but would badly damage bass control (and/or transients everywhere) on a lot of better cans like the HD598s. If those are widespread, it does explain a lot about why the average source is so bad, and why headphone manufacturers seem a bit reluctant to rely on electrical damping.

W.r.t. [1], how long ago are we talking? That sounds like there are some interesting interactions between modern and vintage gear that I wasn't aware of. (It works fine to use a current amp if the cans are designed with that in mind.) W.r.t. [2], do you know of any modern hi-fi gear using that architecture? Now that you mention it, I do see some logic behind its use in cheap stuff, but I would still be very surprised to see it in something needing real quality.

Edit: If these are going to be driven by a source like that TI, then turtlepwr281 is entirely right and the HD598s need a real amp. If you're stuck with a source like that TI, I'd definitely lean more towards recommending the Audio-Technicas.
 
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Re: Headphone upgrade advice

Mon Mar 13, 2017 7:53 pm

synthtel2 wrote:
W.r.t. [1], how long ago are we talking? That sounds like there are some interesting interactions between modern and vintage gear that I wasn't aware of. (It works fine to use a current amp if the cans are designed with that in mind.) W.r.t. [2], do you know of any modern hi-fi gear using that architecture? Now that you mention it, I do see some logic behind its use in cheap stuff, but I would still be very surprised to see it in something needing real quality.

Where it really comes in is in the output impedance of the amplifier. Old-school tube amps had quite high output impedance (the "bad" relationship wasn't yet widely known), which allowed the varying impedance by frequency of the speaker (through back EMF) to alter the output curve of the amp to fit the curve of the speaker. Solid-state amps (except for bizzaro designs) don't have this, and modern tube amps try hard to crank down the output impedance unless they're playing to the "nostalgia" portion of the nervosa crowd. The other path has been heroic costly crossover designs that maintain a flat impedance v. frequency curve over the audible band (with some extra on the extremes, and KEF was a pioneer here) so as to allow all amps to drive them without messing with the output curve.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 8:00 pm

Yeah, I was wondering about the series resistors on the outputs too. Seems like that's gonna trash the damping factor, especially for low impedance headphones. Unless they really are doing negative feedback based on the current delivered to the load, in which case weird sh*t is gonna happen if there's a big impedance spike anywhere in the audio frequency range.
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Re: Headphone upgrade advice

Mon Mar 13, 2017 8:12 pm

In the portable world it has to be current feedback, as there's squat-all for voltage (5V max, and I don't see portables running switching power supplies to trade current for voltage for their audio outputs). When 99% of today's cans are designed on the "will it sound good on an iPhone" metric, there really isn't any other choice.

https://www.cnet.com/news/headphone-buy ... ce-models/
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Re: Headphone upgrade advice

Mon Mar 13, 2017 8:28 pm

Captain Ned wrote:
In the portable world it has to be current feedback, as there's squat-all for voltage (5V max, and I don't see portables running switching power supplies to trade current for voltage for their audio outputs). When 99% of today's cans are designed on the "will it sound good on an iPhone" metric, there really isn't any other choice.

https://www.cnet.com/news/headphone-buy ... ce-models/

That has very little to do with current vs. voltage feedback, and everything to do with the fact that portable devices simply can't provide the output voltage swing required to push adequate amounts of power into a high-impedance load. Using current feedback can't fix that, since the required voltage simply isn't available (unless there's a boost regulator, as you've already noted).
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