[deviusdragger]

So your comparing your old receivers to the new ones? 

 

[obobskivich]

I'm pretty sure I qualified that I was not understanding what you said - that doesn't excuse being rude; just being honest. Again, no need to be rude. 
 
Regarding a switch - some receivers have a switch which defeats the speaker/pre-amp outputs, without putting the receiver into stand-by. Usually it's labeled "Speaker On/Off" or may simply be an A+B switch (on many stereo receivers). This is different than auto-sense jacks which defeat the outputs when a connection is made, and receivers/devices that drive headphones and speakers in parallel and more or less "don't care." 
 
Regarding the resistance question: yes, generally a speaker amplifier will have a small network that allows the amplifier to couple to headphones without damaging the headphones (you can actually build these yourself, if you really dislike the internal one, or have an amplifier that's very basic, it's just a couple of resistors: http://sound.westhost.com/project100.htm). That does impact FR, as noted earlier; it reduces the level (which usually isn't a problem with larger amplifiers, they may actually expend more power driving some cans than speakers, but they usually have enough juice to deal with this (in other words, you've usually got 100W or so sitting behind those resistors, and you only need a few mW of that - Elliot has a table that explains this)), and may cause some slight FR deviation. This is (mostly) unrelated to damping (which is a wonderful marketing creation that gets at "how well the cone is controlled by the amplifier" - unless the DF on the amplifier is stupidly low (like 10 or less, which is something you'll work to find) the overall system DF will average out about the same across amplifiers). This also assumes that high DF values are always "best sounding" (which is not the case either).
 
See here:
http://www.butleraudio.com/damping1.php
And here:
http://gilmore2.chem.northwestern.edu/faqs.htm#amp
And here:
http://www.roger-russell.com/wire/wire.htm#resistancehigh (notice that it's not uniform attenuation, but does actually result in some FR deviation - if memory serves the JND for these variations is 2 dB). 
 
Regarding what the various Sennheiser HD 595, it depends on what the amplifier does with the load. The thing is, that impedance swing never goes away - it's always there, as a part of the device's performance. As long as the amplifier doesn't choke into whatever the load is, you should be more or less fine. It's going to sound like an HD 595 from anything you plug it into. You aren't going to magically change that. Also, I'm pretty sure Sennheiser targets the 120 ohm output with the Premium line (the 5x5 and 5x8); they're generally regarded as very easy to drive and run from most devices. Aside from some of the planars (which are dreadfully inefficient), and the 600 ohm Beyerdynamic models (and the AKG K1000, but that's very specific), most headphones can drive from most headphone jacks. That's basically my point. FR variation can (And probably does) happen, but it's not like you (usually) have a reference; it's uniformly "non-standard" (the deviated FR doesn't entropically change, it deviates by X and X stays constant) - which is why I'm saying it's not the end of the world. If you've got some sort of ABX comparator feeding something like a T1 (which has huge impedance swings) and tested it between multiple amplifiers with dramatically different output characteristics, you *might* be able to pick out some differences, but I'm guessing they'd be very slight (this assumes they could all drive the T1 without clipping). Hence my general advice: get an amplifier that provides suitable power for whatever the nominal impedance/sensitivity demands are, and forget it. 
 
"Suitable amplification" does not mean "esoteric" or "dreadfully expensive" amplification.
 
Oh, and don't trust your ears - they lie.
 
Finally, with newer receivers and other devices, it's not uncommon to see an opamp driving the headphone output (it's certainly more efficient!). I think this is probably more common for processors and devices that use switching amplifiers, but given that headphone jacks on most devices are taken for granted, I doubt there's a definitive listing anywhere.
 
I probably had a bit more fun reading about this than is normal, but I found some more references you might be interested in:
http://www.epanorama.net/circuits/headphone_attenuator.html
Which reminded me of this:
http://www.afrotechmods.com/reallycheap/soundcard/sennheiser.htm
 
So again, minor FR deviation (which will be consistent-in-context), but not a whole lot else "wrong." Especially if the device can provide enough power. I assume most big receivers and amplifiers have no problem here (again, aside from wasting lots of power). 

 
Quote:

The last post makes absolutely no sense - "impedance resonance"???

I thought that was rude so whatever.​

 ​

some have a switch that gets you half-way​

 ​

What does this mean?​

 
The headphone output of every amp I have owned ( all vintage ) use a large resistor in series with the headphone jack. Not a big problem with with high impedance headphones but makes a difference when impedance jumps from 50 to 250 ohms on a low impedance headphone.
 

 

 

[yakapo]

 
Bad news regarding using the headphone jack on the Pio VSX 1120.  If you are listening to something encoded in dolby digital, it doesn't send the lfe channel to the headphones (I tried stereo and simulated surround).  I listened to a DVD audio demo disk that has a little test mode and there was no sound during the lfe test.  When I used my Turtle beach dss, the lfe was loud and clear.  Also the pioneer simulated surround for the headphones is worthless compared to the turtle beach audio processor.   
 
---
 
Best stuff I've listened to so far on the HD 518's - zorro soundtrack cd.  I would never have imagined that I would pick an instrumental movie soundtrack...  but then again, I never really heard it before.  Btw, my front tower speakers aren't exactly cheap.      

 

[obobskivich]

The Dolby decoder is designed to discard the LFE track during stereo playback apart from bass management (which no receiver that I'm aware of will do into headphones). This is the same behavior you can expect from a DVD player's analog stereo outputs. A Dolby 2.0 track won't do this (it lacks an LFE track to discard), so really only Dolby Digital Surround and Dolby EX are the "problem children" here (and I wouldn't really consider it a problem, but that's me - it's less than optimal, but it doesn't defeat any functionality). Certainly if you have a 2.0 soundtrack available, or a processor that does some bass management, I'd pick that. 
 
The Turtle Beach is giving you a more "ideal" scenario, by managing the signal. If you used the pre-outs of the Pioneer to feed the headphones (via amplifier or not, basically take that signal) and configured it for stereo only and set those channels to "Large" it should send FR + LFE when running ST downmix. Should.
 
Quote:

 
Bad news regarding using the headphone jack on the Pio VSX 1120.  If you are listening to something encoded in dolby digital, it doesn't send the lfe channel to the headphones (I tried stereo and simulated surround).

 

 

[PurpleAngel]

I've been reading up on the Pioneer VSX-1120, as far as I can tell the headphone only outputs a 2.0 channel with no real surround sound effects like you would find with Dolby Virtual Headphone or Yamaha's Silent Cinema.
Or have I missed something?

 

[deviusdragger]

I think they just add the headphone jack as a convenience for people who need to use headphones. If you see my sig, i have my receiver running a polk audio front stage. I have no complaints as far as the sound i get from it and my speakers. So like i said, i dont think they throw too much money and technology into the headphone output as a dedicated headphone amp would. Even though i think they should for the price they want for these dang receivers now a days!

 

[PurpleAngel]

Quote:

I think they just add the headphone jack as a convenience for people who need to use headphones. If you see my sig, i have my receiver running a polk audio front stage. I have no complaints as far as the sound i get from it and my speakers. So like i said, i dont think they throw too much money and technology into the headphone output as a dedicated headphone amp would. Even though i think they should for the price they want for these dang receivers now a days!

Could be that Pioneer built this with a good DAC and amps in mind over headphone features that most customers do not think about.
 
 
 

 

[Magick Man]

I'm having a blast driving my headphones with my recently excavated McIntosh MA6100 (circa 1976), my Q701s in particular have an amazing synergy with it. It smooths off a little of their high-end peaks and makes them more lush, while they impart more detail and a wider soundstage, the sound they make together is more than the sum of their parts.

 

[KG Jag]

Quote:

I'm having a blast driving my headphones with my recently excavated McIntosh MA6100 (circa 1976), my Q701s in particular have an amazing synergy with it. It smooths off a little of their high-end peaks and makes them more lush, while they impart more detail and a wider soundstage, the sound they make together is more than the sum of their parts.

That takes me way back.  In the early and mid 70's a McIntosh was the unobtainable dream equipment of many a music loving college student.

 

[stv014]

Regarding output impedance and damping, I did a level matched blind test of the signal recorded from a high impedance headphone output that caused a 0.5 dB bass boost against the original sound, and heard the difference in all the attempts. Although it was not a major difference, and did not necessarily sound bad. On the other hand, I tried to simulate the effect of driving an HD598 with a 100 Ohm source (slightly less than +6 dB at 90 Hz) with a parametric equalizer, and it was clearly audible, and made the bass boomy with a "one note" character on fast bass notes. Of course, I can easily imagine people actually liking the effect, but it is definitely not insignificant. I doubt these headphones were designed for high output impedance, since they have a well balanced (maybe not enough for some) bass response without it. Also, high output impedance can increase bass distortion. With the combination of a 250 Ohm headphone and 100 Ohm output, I measured about one tenth of the headphone's distortion on the output; that is not a major difference, and is likely not audible, although I guess it would be worse with the HD598. Overall, with the majority of full size headphones, high output impedance does not have a large effect, but why have it if it is avoidable ?
 

 

[obobskivich]

I agree with this. My contention is basically that there's no point fussing over it either way, because it *does not* have a large effect. If you want things to sound differently, use a proper tone control or get a different headphone, but don't fuss about with a dozen different amplifiers or whatever else; get one that works and be through with it. I'm also curious about "level matched blind test of the recording of..." - you mean you recorded the output of A and B and listened to both? Or you tested two different amplifiers with the same recording? (And if this question makes no sense to you, it's probably far too late at night and your post probably makes sense to the non sleep deprived). 
 
Quote:

Overall, with the majority of full size headphones, high output impedance does not have a large effect, but why have it if it is avoidable ?  

 

 

[stv014]

Quote:

you mean you recorded the output of A and B and listened to both?

Yes, I meant (and did mention) the recording method, since it is much easier to implement accurately. Of course, it assumes that with the same actual signal (measured as voltage as a function of time) on the headphone it sounds the same no matter what the source is. But I think it should reproduce the frequency response effect well enough.
 

 

[drtturnip]

I use a Harman/kardon hk505 most of the time. I changed the headphone resistors to a 150ohm series and 10ohm to ground. This helped deal with the 595 impedance hump but still has a slight bass bump compared to my op-amp based headphone amp.  

 

[Chris J]

Quote:

 

With some headphones the resonance of the driver creates a large peak in impedance which causes a change in output when driven by a high impedance amp. Less voltage drop across the headphone output resistor at higher impedance = more volume plus poor damping. Duh.

Some of us know what you meant!
LOL!

 
 

 

[yakapo]

I received the Q701's and tried them out today.  They were used so - no burn in necessary.  They definitely sound better than the HD 518's...  once again I'm not qualified to give a detailed review but after doing an A B test, I'd say that the 518's sound a little more muffled and mushy (if those are actual terms).  However, my only qualm is that the soundstage isn't as big as I expected on the Q701's.  I guess I expected a whole lot more "WOW factor".  I'll continue listening to them and either sell them or invest in a headphone amp to see what they can do.  I can easily increase the bass with a number of options on the Pioneer 1120.  
 
Regarding the bumps in the headband...  I  wrapped a washrag around the center of the headband - problem solved.  (at least a temp. solution)   
 
I'm sure this has been discussed a dozen times but just in case someone has an opinion - please suggest an amp under $150 that will help widen the soundstage and warm up the headphones.  I listen to mostly rock and jazz.  I primarily bought these for listening to jazz trios and quartets - piano, upright bass, drums.   
 
btw if anyone can recommend some piano led jazz with lots of walking bass lines I'd appreciate it.