Is there some technical reason that Sennheiser couldn't make normal impedance versions of their HD 600, 650, 700 or 800 model headphones?  I understand that there are historical and market reasons that they don't, but could they do it, if they wanted to.  I guess the sound wouldn't need to be identical, but the point would be to get darn close.
 
I ask as a happy 598 listener who thinks it might be nice to upgrade cans someday without having to upgrade my whole system.
 
Thanks.

charlesc said:

  Is there some technical reason that Sennheiser couldn't make normal impedance versions of their HD 600, 650, 700 or 800 model headphones?  I understand that there are historical and market reasons that they don't, but could they do it, if they wanted to.  I guess the sound wouldn't need to be identical, but the point would be to get darn close.
 
I ask as a happy 598 listener who thinks it might be nice to upgrade cans someday without having to upgrade my whole system.
 
Thanks.

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Bwahahahahaaaaahahaha
He said "normal impedance" like there is some defacto standard. 
Bwahahahaahhhhhahahaha 
 
When one looks at headphones that actually work well and sound nice "normal impedance" for high quality headphones means 300-600ohms. 
A few companies have made some low impedance headphones that do work well, but they are the exception. 
 
There is no real reason that the headphones need to be high impedance. Its just that this is what the designers are more comfortable building. 
 
When you consider the difficulties of working in both the electrical and mechanical fields that headphone designers face, it is quite impressive that they can get anything done at all. 
 
Let them do what they want, there job is hard enough without our meddling. 

nikongod said:

 
Let them do what they want, there job is hard enough without our meddling. 

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OK, so what I meant by normal impedance is something in the 25 to 50 ohm range.  I'd be surprised if many people defined "normal" differently but, hey, I'm not a Headphoneus Supremus.
 
So what I've gleaned from your response is that most designers of "high quality" headphones aim for higher impedance but that is more a choice than a necessity, technically speaking anyway.  I get that most people in the market for high end headphones are likely to be using powerful headphone amps so going with 300 to 600 ohms makes some sense.
 
But, I'll repeat myself here, it sounds like there is no technical reason that a top of the line dynamic driver headphone must be high impedance.
 
BTW, I posted this in Sound Science because I wanted to address this theoretically.  I have not interest in meddling.

charlesc said:

 
But, I'll repeat myself here, it sounds like there is no technical reason that a top of the line dynamic driver headphone must be high impedance.
 

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No, There is no reason that a good headphone can not be made in any range of impedances. 
 
Except that the guy doing the work doesn't want to do it that way, and he is high enough on the food chain that he calls the shots. 
 
Considering how hard op amps fail at driving low impedance loads, are high impedance headphones really at any disadvantage?

If you want lower impedance you need the voice coil to have fewer turns (less length on it) or be thicker (maybe means they can't pack it as tight as they want or perhaps the extra weight makes some difference) or something or other I'm forgetting. Hopefully you get some better responses than mine. That said, whatever Beyerdynamic did on their DT 770/880/990 line doesn't seem to affect all that much with the different impedance versions.
 
Sennheiser's also seemed to have said that they design their headphones aren't having high damping factor from the source, so making a higher headphone impedance would help ensure that. They need it, too, considering how pronounced the midbass resonant hump in impedance is on many of their models.
 
 
Practically speaking, Sennheiser's headphones aren't even that low sensitivity so say the HD 700 should be no more than 5 dB quieter than HD 598 out of any source as per InnerFidelity measurements (HD 800 no more than 9 dB). That's not some huge difference.

nikongod said:

 
Considering how hard op amps fail at driving low impedance loads, are high impedance headphones really at any disadvantage?

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The only disadvantage I can think of would be if you (meaning 'I') wanted to get new headphones without getting a new amp.  But, I don't want to set the tail to wagging the dog. 

mikeaj said:

  If you want lower impedance you need the voice coil to have fewer turns (less length on it) or be thicker (maybe means they can't pack it as tight as they want or perhaps the extra weight makes some difference) or something or other I'm forgetting. Hopefully you get some better responses than mine. That said, whatever Beyerdynamic did on their DT 770/880/990 line doesn't seem to affect all that much with the different impedance versions.
 
Sennheiser's also seemed to have said that they design their headphones aren't having high damping factor from the source, so making a higher headphone impedance would help ensure that. They need it, too, considering how pronounced the midbass resonant hump in impedance is on many of their models.
 
 
Practically speaking, Sennheiser's headphones aren't even that low sensitivity so say the HD 700 should be no more than 5 dB quieter than HD 598 out of any source as per InnerFidelity measurements (HD 800 no more than 9 dB). That's not some huge difference.

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Thanks. That's interesting about the sensitivity.  So much to learn.

charlesc said:

 
Thanks. That's interesting about the sensitivity.  So much to learn.

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Yea it is
 

mikeaj said:

  If you want lower impedance you need the voice coil to have fewer turns (less length on it) or be thicker (maybe means they can't pack it as tight as they want or perhaps the extra weight makes some difference) or something or other I'm forgetting. Hopefully you get some better responses than mine. That said, whatever Beyerdynamic did on their DT 770/880/990 line doesn't seem to affect all that much with the different impedance versions.
 
Sennheiser's also seemed to have said that they design their headphones aren't having high damping factor from the source, so making a higher headphone impedance would help ensure that. They need it, too, considering how pronounced the midbass resonant hump in impedance is on many of their models.
 
 
Practically speaking, Sennheiser's headphones aren't even that low sensitivity so say the HD 700 should be no more than 5 dB quieter than HD 598 out of any source as per InnerFidelity measurements (HD 800 no more than 9 dB). That's not some huge difference.

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ZOMG I missed you PRINNY DOOD, sorry but he makes a good point. Ditch Sennhesier adn switch to Beyerdyanmic :3, we've got wonderful headphones in 32 ohms ;3 [no just kidding... but beyerdyanmic ftw] 
 
also, truth b told the new AKG K812 is 32 or so ohms is it not? So You may enjoying upgrading to something like a Beyer Dynamic T90 [250 ohms] [Or the Dt 880 32 ohm]  than an KAG K812.
Still, there are a LOT of very high end Amps that push out a TON of power, I think it's the common practice of pairing high end headphones with these uber powerful Amps that has lead to the higher ohms
 
also i read some where to that 600 ohms used to be an industry standard within the Audio Recording and manufacturing industry, so guys in recording studios could get all there gear from seperates OEMs and not have to worry about impedance mis matching, I could be wrong but
 
the Dt 880 32 ohm and AKG K 812 seem like upgrade to your current headphone, that offer low impedances 

charlesc said:

   
The only disadvantage I can think of would be if you (meaning 'I') wanted to get new headphones without getting a new amp.  But, I don't want to set the tail to wagging the dog. 

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I would just get new headphones. Get a new amp if you think you need to once you have the headphones sorted out. 
 
For as much time as the measurements first crowd spends arguing over whether an amp can drive a headphone to 120db or not. Or whether it has 0.001 or 0.0001%THD nobody considers the FACT that the difference between 2 "good" (whatever you want good to mean) is an order of magnitude larger. 
 
If you think you would like how the HD600 or 650 or 800 or DT880 or whatever would sound, buy it. Worry about the amp later. 
 
Please, make no mistake - there are still differences in amps and sometimes they are even audible! But if you have the wrong headphones, it doesn't matter. 

Why are you convinced that you would need a new amp for high impedance headphones? Impedance alone doesn't tell you how hard a headphone is to drive. You must also consider the headphone's sensitivity. Sensitivity tells you more than impedance, really.

For example, according to Innerfidelity the HD-650 has a sensitivity of 90 dB / 0.2 Vrms. Your Microstreamer can do 1.4 V, so you should be able to get past 90 dB pretty easily. Each +6 dB doubles the voltage, so we have ~96 dB at 0.4Vrms, ~102 dB at 0.8 Vrms, and then your amp will run out of steam before ~108 dB at 1.6Vrms.

Admittedly this is an over-simplification since the HE-650 has a big impedance peak and changing phase angle, I don't know if that 1.4 V spec for the HRT is referring to peak or RMS voltage, and it depends on how much dynamic range your music has, but you'd be surprised at how much amp requirements are overstated on this forum. High impedance headphones don't necessarily need a huge monster amp. Comfortably loud for most people with healthy ears is somewhere around 80 dB. HD-650 would only need 0.1 Vrms for ~84 dB and 0.05 Vrms for ~78 dB. That's not hard to drive at all.

Please note that these are only rough armchair approximations, but hopefully you get the idea.

charlesc said:

  I understand that there are historical and market reasons that they don't, but could they do it, if they wanted to.

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Yes, they could.