[rsaavedra]

Quote:

Originally Posted by heretical /img/forum/go_quote.gif I would add that I remember Rodolfo i.e. Rudi (Rudistor) saying that the K701 specifically has significant intermodulation products in the treble compared to other high end headphones like the HD650.

There you go. I wasn´t even aware Rodolfo had said that, but there you go anyway.

 

[granodemostasa]

I hate to say this, but can it be the amp? have you tried taking the same set up to another amp or another source and seeing what happens? (btw, silver cabled balanced HD650 from the GS-X= beautiful treble)

 

[Roam]

Quote:

Originally Posted by Azure /img/forum/go_quote.gif PiccoloNamek - I've been curious about that. So, would it be psychoacoustics that would cause somebody to claim that a headphone sounds "faster"? Are there any measurements that could account for this perception of various speed among headphones? Or is the case that there are measurements that prove that electrostats are faster than the HD650, but the difference in speed is so small that it should not be audible (I recall some discussion about this in the STAX thread awhile back; Carl was talking about measuring "slew rate" or something)?

In headphones, the measurements which would best correlate to "speed" are low intermodulation distortion and fast settling time along with freedom from driver and housing resonances. To measure these you'd need an impulse response plot, a waterfall plot, and an IM distortion graph.

Electrostatics by virtue of their low mass diaphragms have a much faster settling time, along with lower energy storage and thus reduced resonances. This can be seen in the impulse response & waterfall plots where the drivers quickly decay to zero, usually several times faster than dynamics. This is also why open headphones are a lot easier to design than closed ones; closed headphones by their nature store a lot more energy which will lead to all sorts of resonance problems. Absorbing and dissipating the energy so it doesn't muck up the sound is not an easy task.

 

[PiccoloNamek]

Quote:

Electrostatics by virtue of their low mass diaphragms have a much faster settling time, along with lower energy storage and thus reduced resonances. This can be seen in the impulse response & waterfall plots where the drivers quickly decay to zero, usually several times faster than dynamics.

I thought as much, although I'm not sure how this translates into "real world" differences. I'm sure that my ER4s, having an incredibly small and virtually massless diaphragm, attack and decay more quickly than my HD650s, but I'd be hard pressed to actually tell the difference when sitting down and listening to music.

 

[MaloS]

Quote:

Originally Posted by PiccoloNamek /img/forum/go_quote.gif No, it really doesn't. Not that it really matters. Even if the electrostatic headphone is faster, it is not anything significant. We're talking perhaps only a few microseconds worth of difference at most in impulse response speed.

Then why does a balanced hd650/hd600 system still come out with having poorer instrument separation than a Stax system? That further goes on to exact statement you went with to counter my suggestion about diffuse EQ - yes it is going for similar sound to that of a diffuse field, with sound coming from all sides...but that exactly causes smearing in detail and layers, that also happens during live performances. It can be preferred, or it can be disliked, but either way that does not defeat that argument that a diffuse-field EQed headphone will have a sense of smeared detail. Not that there is anything wrong with that per say, its just a different presentation.

Next - on the case of THD vs Intermodulation Distortion - THD cannot possibly produce what VinylRipper is presenting, play back 66.6 hz and get a sudden spike at 2500 hz? Personally I am not sure if that can even sound pleasant, since those 2 frequencies would not be in the same harmonic set for a musical instrument. (There is a fairly simple way to derive the set of harmonics that make up notes based on any reference pitch).

 

[MaloS]

Quote:

Originally Posted by PiccoloNamek /img/forum/go_quote.gif I thought as much, although I'm not sure how this translates into "real world" differences. I'm sure that my ER4s, having an incredibly small and virtually massless diaphragm, attack and decay more quickly than my HD650s, but I'd be hard pressed to actually tell the difference when sitting down and listening to music.

Surprizing, because when I put up AKG K340 vs HD650, I could easily tell which was faster.

 

[PiccoloNamek]

Quote:

Then why does a balanced hd650/hd600 system still come out with having poorer instrument separation than a Stax system?

I wouldn't know. I've never compared the two directly. For all I know I might not feel that way if I had the chance to hear them side by side.

And personally, I thought the K340 sounded horrible, (there were actually two pairs there, both sounded awful) but that's just me.

Quote:

but that exactly causes smearing in detail and layers

Just because the frequency response is equal to what would be experienced in a diffuse field doesn't mean the actual sound will be "diffuse", you know. The ER4s are diffuse-field equalized, (referenced to a flat diffuse field) and I don't think anyone would ever say that they are smeared. (They say a lot of things, but never that!)

Quote:

Next - on the case of THD vs Intermodulation Distortion - THD cannot possibly produce what VinylRipper is presenting, play back 66.6 hz and get a sudden spike at 2500 hz?

Of course not. What is happening is that the bass spike is affecting the treble spike. (Which was already there. Perhaps if he labeled his screenshots more clearly this would be more obvious).

 

[rsaavedra]

Quote:

Originally Posted by heretical /img/forum/go_quote.gif That's because he said it in another forum (in Italian). But anyway, his was a competent statement for sure (and laboratory measured).

Is it possible to provide a link to that post of his? I can understand some Italian when reading it, but in general, would be much better to not leave the reference you mention just as hearsay.

 

[TheVinylRipper]

Quote:

Originally Posted by Roam /img/forum/go_quote.gif Congratulations, you've proven that intermodulation distortion exists. IM distortion exists in all audio gear.

I should have realized what it was myself, now I feel like a dumboy..

In this case though, isn't the intermodulation distortion largely happening in the driver?

 

[Daroid]

Proper IMD tests for headphones, i'll promise you, regardless of costs are not a pretty sight. The same goes for speakers.
I still think that IMD and THD measuremenst should never be made on anything but amplifiers, and not the transducers themselves. This is due to:

As a speaker designer; the THD and IMD won't tell you exactly what the culprit is when a transducer is tested - is it the amp? microphone? room? speakers? slight off axis measurement?

Measuring in a closed system with no transducers tells you exactly what is wrong and what part of the circuit might be the culprit. At least, one would have an idea, if it was designed from scratch, and know the datasheets for any non-linear devices.

Apart from that, i think another problem might be a dampening issue.
Unfortunately the impedance curve of the HD6X0/HD580 is anything but 300 Ohms at the audible frequency range.
Sennheiser have not stated anywhere what dampening factor would be ideal - i.e. stated the desired output impedance from the amp. Really unfortunate.
All headphones are voiced with different output impedances.

I think i have found that the HD650 is best suited with a <5 Ohm output impedance in order to have a good bass and treble response.
On the other hand the HD25-1 truely sucks with <5 Ohm. At 50-75 Ohm output impedance, the bass is not overpowering, no boominess is present, and does actually sound very refined and detailed.

That explains why i still use the output of my RME with the HD25-1 directly.

 

[AS1]

Quote:

Originally Posted by heretical /img/forum/go_quote.gif Btw, personally I don't hear any smearing, just a quite welcome refinement (of course not all need refinement, or rather, not all need a certain degree of it). The HD595 had a sharper sound, but ultimately was less pleasing.

x2
A HD595 sounds smeared to me compared to a HD650. The HD650 is much more precise. It would say its definition around the edges is particularly good. Far from smeared...
I can hardly imagine a K701 would do it much better. I'm not talking about v*** here. That something entirely different...

 

[TheVinylRipper]

Quote:

Originally Posted by Daroid /img/forum/go_quote.gif Proper IMD tests for headphones, i'll promise you, regardless of costs are not a pretty sight. The same goes for speakers. I still think that IMD and THD measuremenst should never be made on anything but amplifiers, and not the transducers themselves. This is due to: As a speaker designer; the THD and IMD won't tell you exactly what the culprit is when a transducer is tested - is it the amp? microphone? room? speakers? slight off axis measurement? Measuring in a closed system with no transducers tells you exactly what is wrong and what part of the circuit might be the culprit. At least, one would have an idea, if it was designed from scratch, and know the datasheets for any non-linear devices. Apart from that, i think another problem might be a dampening issue. Unfortunately the impedance curve of the HD6X0/HD580 is anything but 300 Ohms at the audible frequency range. Sennheiser have not stated anywhere what dampening factor would be ideal - i.e. stated the desired output impedance from the amp. Really unfortunate. All headphones are voiced with different output impedances. I think i have found that the HD650 is best suited with a <5 Ohm output impedance in order to have a good bass and treble response. On the other hand the HD25-1 truely sucks with <5 Ohm. At 50-75 Ohm output impedance, the bass is not overpowering, no boominess is present, and does actually sound very refined and detailed. That explains why i still use the output of my RME with the HD25-1 directly.

Serious question..

How hard would it be to design an amp with variable output impedance?

With a full duplex, thee or more input sound card and the right software I don't see why it couldn't be done digitally.

Put a digital feedback loop around a voltage to current converter and use that to control the voltage or current across the driver.

 

[Daroid]

I'm not sure, it would also be nice to have different impedances at varying frequencies too. My take on why it isn't seen is that manufacturers think "the higher dampening factor the better", and thus keeps the output impedance near 0 Ohms - that is certainly the case with speakers amps.

Manufacturers can cut costs this way, and always do.

I don't know anything about about digital feedback circuits, only all the analog stuff - but i'll hopefully learn alot about digital feedback theory (next semester), but the rest of it should be relatively easy.

 

[Roam]

Quote:

Originally Posted by TheVinylRipper /img/forum/go_quote.gif I should have realized what it was myself, now I feel like a dumboy.. In this case though, isn't the intermodulation distortion largely happening in the driver?

Impossible to determine without measuring your signal reproduction chain one piece at a time.

Quote:

Serious question.. How hard would it be to design an amp with variable output impedance? With a full duplex, thee or more input sound card and the right software I don't see why it couldn't be done digitally. Put a digital feedback loop around a voltage to current converter and use that to control the voltage or current across the driver.

Easy to design, though designing it well is another story. Here's a hint. Think tube amplifiers, and the multiple output taps for 4, 8, and 16 Ohm speakers.

 

[Gurra1980]

I hear the "smear" on the 650, but don't really now what causes it. I think they are designed to sound that way, to me it is a part of the smooth sound they have and it gives them character, unfortunately I don't want that much character in my headphones so they had to go.

As we all percieve sounds different it might just be that some of us picks it up more than it was ment, therefor it is not so pleasant for us, I don't think amps and such will take it away.