Sennheiser HD 598 Impressions Thread
Feb 4, 2014 at 9:42 AM Post #3,316 of 7,535
   
 
The HD598's impedance is 50 Ohms. Using the 1/8th rule for damping the output impedance of the should be less than 50/8 or less than 6.25 Ohms. I prefer 1/10th which would be 5 Ohms.
The phones output is too high and would cause a poorly controlled bass boost due to poor damping and the HD598's impedance curve. You could instead put the cans on the speaker taps, however, if you do this directly you can play far too loud for your ears and possibly burn out the 598's if you turn up the volume too high. The way to deal with this is to attach your cans to the speaker taps by way of an L-PAD which would lower the power delivered to the 598's as well keep the impedance to the cans low, like 5 Ohms or less and drop the power. You can find out about what an L-PAD is by asking Google. Basically it's two resistors per channel. You can also buy variable stereo L-PADs.

 
I am kind of worried now.  I have been using my Grado SR-60i (32 Ohms) with my NAD amp.  If it's output is too high for 50 Ohms HD 598, then I must be killing my SR-60s. The weird thing is, I don't hear anything unusual with the sound.....maybe it's there but I am just not listening for it? 
 
Feb 4, 2014 at 11:18 AM Post #3,317 of 7,535
   
I am kind of worried now.  I have been using my Grado SR-60i (32 Ohms) with my NAD amp.  If it's output is too high for 50 Ohms HD 598, then I must be killing my SR-60s. The weird thing is, I don't hear anything unusual with the sound.....maybe it's there but I am just not listening for it? 

The danger is if you turn the volume up too high that you might hurt your ears or damage your phones. This is more of a danger when directly using speaker taps. Some phones like the HE-6 are not sensitive and need gobs of power, not many are that power hungry.
 
Feb 4, 2014 at 11:20 AM Post #3,318 of 7,535
  I would say to give it a try! I use mine with a speaker amp aswell, and they pair very well. Everything sounds much better with the amp than on PC alone or portable sources (mp3 player, mobile phone, tablet etc.)
 
The biggest difference is the bass, that has a lot more presence with the amp. Without it it's kind of light, no wonder people say the cans are bass light, but that's not true, it matters on what you're using them, regardless of what it says on the box (optimised for ipod).

That depends on what you are plugging into. Perhaps you were using the tone controls or loudness contour switch on your amp or just playing louder on the amp.
 
Feb 4, 2014 at 11:34 AM Post #3,319 of 7,535
Actually i don't like tone corrections, hence i never use them, either software or on the amp itself. Everything is on flat (zero). 
So why it does sounds better with more "muscle"? I'm afraid i don't have a technical explanation, on the amp manual it doesn't say a word on the specs of the amplifier headphone's output.
 
The sound fullness doesn't changes even if i press the Direct button to bypass the amp own equalizer. 
 
I've tried the Loudness button before, but it makes no good to the cans, the bass is superbloated (about +10db) and everything sounds too muddy to be bearable. Definitely a no-no for me. 
 
Feb 4, 2014 at 11:34 AM Post #3,320 of 7,535
  The danger is if you turn the volume up too high that you might hurt your ears or damage your phones. This is more of a danger when directly using speaker taps. Some phones like the HE-6 are not sensitive and need gobs of power, not many are that power hungry.


So I would have no problems using the HD598 with my NAD C320BEE if I listen at a reasonable volume and not turn it up too high....even if my NAD output is too much?  In theory, I am guessing, is that my NAD will be able to use higher Ohm headphones with it but the SR-60i and 598 should work with it too without the danger of "breaking them" unless I turn up the volume too high and I start hearing distortions.
 
Feb 4, 2014 at 11:40 AM Post #3,321 of 7,535
 
So I would have no problems using the HD598 with my NAD C320BEE if I listen at a reasonable volume and not turn it up too high....even if my NAD output is too much?  In theory, I am guessing, is that my NAD will be able to use higher Ohm headphones with it but the SR-60i and 598 should work with it too without the danger of "breaking them" unless I turn up the volume too high and I start hearing distortions.

Actually you can turn up the volume more for most higher impedance cans as they require a higher voltage. If you are careful you should be OK, just don't make any mistakes when on the speaker taps. You could look into stereo L-PADs.
 
Feb 4, 2014 at 2:13 PM Post #3,322 of 7,535
 
   
I am kind of worried now.  I have been using my Grado SR-60i (32 Ohms) with my NAD amp.  If it's output is too high for 50 Ohms HD 598, then I must be killing my SR-60s. The weird thing is, I don't hear anything unusual with the sound.....maybe it's there but I am just not listening for it? 

The danger is if you turn the volume up too high that you might hurt your ears or damage your phones. This is more of a danger when directly using speaker taps. Some phones like the HE-6 are not sensitive and need gobs of power, not many are that power hungry.


I would trust the NAD manual for the C320-BEE: "A 1/4” stereo jack socket is supplied for headphone listening and will work with conventional headphones of any impedance" (my emphasis). I suspect that the circuitry behind the socket is more sophisticated than the single impedance reading indicates.  I have been using my NAD 3130 with many different kids of headphones (including my HD598) with very good results.  The manual for that older amplifier has similar language to the one I have just quoted.  The 3130 has a "low level" button (which reduces sound level by approximately 20db) that I always use when listening to headphones.  Also, I used the speaker taps for my Stax Electrets (now, sadly retired).  The NAD 3130 manual explicitly adds to the language quoted above that the adapter unit that comes with electrostatic (and, I add, electret) headphones "must be connected directly yo the speaker terminals on the rear panel."
 
Feb 4, 2014 at 4:18 PM Post #3,323 of 7,535
 
So I would have no problems using the HD598 with my NAD C320BEE if I listen at a reasonable volume and not turn it up too high....even if my NAD output is too much?  In theory, I am guessing, is that my NAD will be able to use higher Ohm headphones with it but the SR-60i and 598 should work with it too without the danger of "breaking them" unless I turn up the volume too high and I start hearing distortions.

 
 
  Actually you can turn up the volume more for most higher impedance cans as they require a higher voltage. If you are careful you should be OK, just don't make any mistakes when on the speaker taps. You could look into stereo L-PADs.

 
 
 
I would trust the NAD manual for the C320-BEE: "A 1/4” stereo jack socket is supplied for headphone listening and will work with conventional headphones of any impedance" (my emphasis). I suspect that the circuitry behind the socket is more sophisticated than the single impedance reading indicates.  I have been using my NAD 3130 with many different kids of headphones (including my HD598) with very good results.  The manual for that older amplifier has similar language to the one I have just quoted.  The 3130 has a "low level" button (which reduces sound level by approximately 20db) that I always use when listening to headphones.  Also, I used the speaker taps for my Stax Electrets (now, sadly retired).  The NAD 3130 manual explicitly adds to the language quoted above that the adapter unit that comes with electrostatic (and, I add, electret) headphones "must be connected directly yo the speaker terminals on the rear panel."

Sorry but I just looked up the headphone output impedance from the C 320BEE manual and it is 220 Ohms. Not good at all, especially bad in combination with the HD598's impedance curve.
 
Feb 4, 2014 at 4:22 PM Post #3,324 of 7,535
 
 
So I would have no problems using the HD598 with my NAD C320BEE if I listen at a reasonable volume and not turn it up too high....even if my NAD output is too much?  In theory, I am guessing, is that my NAD will be able to use higher Ohm headphones with it but the SR-60i and 598 should work with it too without the danger of "breaking them" unless I turn up the volume too high and I start hearing distortions.

 
 
  Actually you can turn up the volume more for most higher impedance cans as they require a higher voltage. If you are careful you should be OK, just don't make any mistakes when on the speaker taps. You could look into stereo L-PADs.

 
 
 
I would trust the NAD manual for the C320-BEE: "A 1/4” stereo jack socket is supplied for headphone listening and will work with conventional headphones of any impedance" (my emphasis). I suspect that the circuitry behind the socket is more sophisticated than the single impedance reading indicates.  I have been using my NAD 3130 with many different kids of headphones (including my HD598) with very good results.  The manual for that older amplifier has similar language to the one I have just quoted.  The 3130 has a "low level" button (which reduces sound level by approximately 20db) that I always use when listening to headphones.  Also, I used the speaker taps for my Stax Electrets (now, sadly retired).  The NAD 3130 manual explicitly adds to the language quoted above that the adapter unit that comes with electrostatic (and, I add, electret) headphones "must be connected directly yo the speaker terminals on the rear panel."

Sorry but I just looked up the headphone output impedance from the C 320BEE manual and it is 220 Ohms. Not good at all, especially bad in combination with the HD598's impedance curve.


I saw that too.  I just do not think that the published impedance number matters in this case.
 
Feb 4, 2014 at 4:24 PM Post #3,325 of 7,535
   
 
 
 
Sorry but I just looked up the headphone output impedance from the C 320BEE manual and it is 220 Ohms. Not good at all, especially bad in combination with the HD598's impedance curve.

 
Urgh.....so I am now on the fence.  I am not even sure not that I should be using my SR-60s with the amp now.  That's weird that an entry-level amp would not even let us use $100 to $300 headphones (with low to medium impedance). 
 
Feb 4, 2014 at 4:51 PM Post #3,326 of 7,535
 
I saw that too.  I just do not think that the published impedance number matters in this case.

 
There are several factors regarding amplifier output impedance and headphone impedance that affect headphone frequency response.
 
One that has been mentioned is voltage dividing and the impedance curve of the headphone. Headphones like the HD 598 (and pretty much all the other Sennheisers) have wild impedance swings and therefore frequency response is greatly affected by a high amplifier output impedance. A near-zero output impedance mitigates this issue, as does a headphone with a flat impedance across the audible frequency band.
 
Another factor already mentioned is "damping factor." This is the "1/8th rule" that dictates that for the driver to be sufficiently damped by the amplifier, the output impedance of the amp needs to be 1/8th (some say 1/10th) or less than the headphone impedance. This issue can be mitigated by headphones with high levels of driver damping built in. Heavy magnets and rigid drivers used in headphones like the Denon AH-D series and Beyer Tesla series do not rely on amplifier damping and so are less affected by low damping factors.
 
This is why some headphones seem to be unaffected by amplifiers in spite of their output impedance. Its also why some headphones are often described as "don't scale up" and others are "very amp picky."
 
Feb 4, 2014 at 5:00 PM Post #3,327 of 7,535
   
Urgh.....so I am now on the fence.  I am not even sure not that I should be using my SR-60s with the amp now.  That's weird that an entry-level amp would not even let us use $100 to $300 headphones (with low to medium impedance). 

 
If your SR-60 sounds good plugged into the headphone jack of your amp, then there is no problem.
 
StanD's comment about risk to your headphones pertains to the speaker taps. This means that you have a cable with four wires on one end and a headphone plug on the other. You are literally hooking your headphones up to the speaker terminals on the rear of the amp. This means that you can go from zero volume to earsplitting volume with one detent on your volume knob. You will never want to do this with a pair of Grado's.
 
The 220 ohm comment StanD made above applies to the headphone jack on the front of your amp. There is little risk of damaging your headphones this way. The only issue is that with a low damping factor (220/32), the bass may sound muddy or looser than normal. Some people really like this sound so its not a "problem" per se.
 
Feb 4, 2014 at 5:12 PM Post #3,328 of 7,535
   
Urgh.....so I am now on the fence.  I am not even sure not that I should be using my SR-60s with the amp now.  That's weird that an entry-level amp would not even let us use $100 to $300 headphones (with low to medium impedance). 

Most receivers and non-headphone-amps follow the same cheap mistake of putting a series resistor inline with the cans. You can always go for L-PADs and hang that off the speaker terminals. Envision one headphone cup for the below speaker.
http://www.electronics-tutorials.ws/attenuators/L-pad-attenuator.html
Stereo L-PAD, on Amazon, can't vouch for the quality: http://www.amazon.com/L-Pad-15W-Stereo-Rated-Shaft/dp/B0002KR1E6/ref=sr_1_1?ie=UTF8&qid=1391551750&sr=8-1&keywords=Stereo+L-PAD

 
Feb 4, 2014 at 5:17 PM Post #3,329 of 7,535
   
If your SR-60 sounds good plugged into the headphone jack of your amp, then there is no problem.
 
StanD's comment about risk to your headphones pertains to the speaker taps. This means that you have a cable with four wires on one end and a headphone plug on the other. You are literally hooking your headphones up to the speaker terminals on the rear of the amp. This means that you can go from zero volume to earsplitting volume with one detent on your volume knob. You will never want to do this with a pair of Grado's.
 
The 220 ohm comment StanD made above applies to the headphone jack on the front of your amp. There is little risk of damaging your headphones this way. The only issue is that with a low damping factor (220/32), the bass may sound muddy or looser than normal. Some people really like this sound so its not a "problem" per se.

I'm not a fan of loose bass. That's why I got an HE-500 and an HD600 in my collection. I like being able to discern the pitch of each note and have a snappy sounding bass. Without proper damping the cone/diaphragm will keep moving due to inertia when it should reverse direction. IMO that can't be good, at least not for me.
 
Feb 4, 2014 at 7:14 PM Post #3,330 of 7,535
  I'm not a fan of loose bass. That's why I got an HE-500 and an HD600 in my collection. I like being able to discern the pitch of each note and have a snappy sounding bass. Without proper damping the cone/diaphragm will keep moving due to inertia when it should reverse direction. IMO that can't be good, at least not for me.

 
I feel the same way. Proper damping is key to tight controlled and articulate bass. Its why I love the HD 800.
 
The point I was making is simply that amplifier output impedance isn't the only way to control driver excursion. With some headphones, the impedance damping factor is irrelevant.
 

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