[gp23]

Hi. I am a long-time headphone user, but a newcomer to the world of decent ones. I recently bought a pair of HD600s after reading so many good things about them. My previous pair were HD215s, which were reasonable, if slightly light in the bass. My amp is a 1999 Sony CMT-SD1 - an integrated CD player, tuner and amp, not ideal but it's all I currently have available. It sounded OK with the 215s and I figured it would sound at least as 'OK' with the 600s (i.e. good enough until I upgraded). On first listen, however, I was shocked at just how much more bass there was with the 600s. Too much, in fact. Whereas the 215s had a slight lack of bass, it was still in proportion. The 600s just sound bloated and woolly, with what seems like a boost in the 100hz area. Not only this, but the mid-frequencies seemed distant and there appeared to be a slight roll-off in the treble, although I initially put this down to being used to the 215s. The general sound is not very impressive.
 
So I did some reading about things like output impedance (all new things to me!) and although I am still uncertain about what it all really means, I get the impression that what I am experiencing may be due to an impedance mismatch between my amp (I cannot find reference to the output impedance of the headphone jack on the Sony, but I assume it is probably on the high side) and the headphones. I tried the HD600s directly out of my iPod Shuffle and was surprised at how much more balanced everything sounded. The bass boom was gone, and it generally sounded better to me. Looking around for other things to plug into, I dug out my old Soundcraft Spirit Folio mixer. This also displayed the boominess, although to a lesser extent than the Sony. Again, I have no output impedance rating for the mixer.
 
So, I can only conclude that I either need a new amp, or different headphones. If the former, I don't want to spend more than £150 (perhaps second-hand). I get the impression that another integrated amp (even if vastly better than the Sony) may result in a similar sounding output with these headphones, but I may be wrong (there surely must be people successfully using HD600s with an integrated amp). So I'm now looking at headphone amps and I gather that as low an output impedance as possible is considered a good thing with the HD600s.
 
I'd love to hear opinions about whether what I'm experiencing is due to impedance or something else entirely. I can't bring myself to believe that the HD600s are really supposed to sound like this.

 

[Head Injury]

It sounds like it could be an output impedance issue to me, too. 90-110Hz is exactly where you'll get the biggest boost. The output impedance would have to be very high though, as the HD600 has 300 ohm impedance. You'd have to expect at least 40 ohm output impedance or more to hear a difference. The Shuffle would have lower output impedance than that.
 
You want lower than 40 ohm output impedance, but the lower it is the better it will match all other headphones as well. 2 ohms and below is best, anything under that doesn't really make a difference. 

 

[gp23]

Thanks. I appreciate your input.
 
It would be nice to know what the output impedance of my Sony's headphone socket is, and other gear for that matter, but it seems that this rating is rarely disclosed in the manufacturer's associated literature.
 
I'm considering the Fiio E9, at least as an initial step as it is reasonably priced and should at least prove (if the iPod didn't already) that the problem is impedance related. Not keen on the mini-jack input though. Any other suggestions welcome.
 
BTW, my source is Winamp out of an M-Audio 1010LT.

 

[Wapiti]

Quote:

 
It would be nice to know what the output impedance of my Sony's headphone socket is, and other gear for that matter, but it seems that this rating is rarely disclosed in the manufacturer's associated literature.

Soundcraft recommends a 200 ohm or greater headphone for use with the Spirit Folio headphone out, but I don't know the impedance of the output.  As its "outputs" are listed to exhibit 75 ohms, my guess is that the headphone out is on the high side.
 

 

[RexAeterna]

you usually fellow the 1/8 rule when it concerns dampen factor and so forth. 1/8 of 300ohms is about 37.5 so the output impedance needs to be at least 38-40ohms(rounded off). too low of dampen factor can be a bad thing in some cases cause too low of an output impedance can cause what is known as ''over-dampening''. which can cause bass and treble extension to roll-off much sooner then the driver were design to do.

 

[Head Injury]

Quote:

you usually fellow the 1/8 rule when it concerns dampen factor and so forth. 1/8 of 300ohms is about 37.5 so the output impedance needs to be at least 38-40ohms(rounded off). too low of dampen factor can be a bad thing in some cases cause too low of an output impedance can cause what is known as ''over-dampening''. which can cause bass and treble extension to roll-off much sooner then the driver were design to do.

I wasn't aware you could have an output impedance that is too low. Benchmark must not be aware of it either, because they claim 0.01 ohm output impedance on their amp. Do you have a source for that?

 

[RexAeterna]

I wasn't aware you could have an output impedance that is too low. Benchmark must not be aware of it either, because they claim 0.01 ohm output impedance on their amp. Do you have a source for that?

well it's in some cases but not always exact. here's couple very quick explanation over critical dampen compared to over dampen.

http://physics.ucsc.edu/~josh/6A/book/harmonic/node20.html

http://en.wikipedia.org/wiki/Damping


close to zero impedance is great for speakers but not headphone but then again is the benchmark amp a push-pull discrete design? if it's like a speaker power amplifier which are normally all discrete push-pull design the power transformer inside will take care of all the impedance spikes and dips so dampen factor will mean very little in most cases. in the end though it might not really matter to the individual on how they perceive sound. i was just telling op what i know and answering his question about impedance.

 

[Wapiti]

Excellent.
 
It will be fun to learn of your experience.

 

[elixile]

Have you considered lets say, oh I don't know. listening to the HD600 without your amp and finding out?

 

[ohaider]

I own a pair of HD600s - the bass is very controlled and "full". Additionally, the mids sound forward -- nowhere near recessed for me, except for maybe a few of my tracks.
 
I think it is whatever you're driving them out of causing the issue. I'm using an ASUS Essence ST.

 

[gp23]

OK, the E9 arrived this morning and I've had over three hours with it. Wow. To use the cliché - the difference really is 'night and day'! The sound is balanced and the bass controlled with that awful 100hz hump gone. Not only that, but the whole effect is massively more involving. I hadn't realised just how scooped the HD600 sounded on the Sony compared to the E9. Another thing that has surprised me about these 'phones is how smooth the top-end is. I haven't experienced all that many headphones, but this combination is undoubtedly the best I've heard.

The E9 is very impressive, especially considering its price. The Sony will be retired now. I thought I could hear a very subtle difference between the low and high gain settings with some tracks, but I couldn't decide which was preferable. High currently seems to hit the sweet spot slightly better for me. I haven't tried the HD215 with the E9 yet, but don't expect very much. It will probably sound as shrill as they did through the iPod.

So, I think I can safely say that output impedance does have a significantly audible effect upon the HD600. At least this is my experience. I would be surprised if there people out there satisfied with the sound of the 600s via the high-impedance headphone jacks of most integrated amps. I'm sure there are, but to me it was like listening to a different (and vastly inferior) pair of headphones.

 

[Head Injury]

If you're getting good volume with it (not turning the knob past half), use low gain. It likely has less distortion.
 
Always use the 1/4 inch jack with all headphones, the 1/8 inch one has high(er) output impedance.
 
Congratulations on your purchase, now you can stop buying stuff 

 

[gp23]

Cheers!
 
I haven't used the 3.5mm jack yet. It might be an interesting experiment to see how it affects the sound. If I can be bothered!
 
I've switched back to low gain. I don't think there is anything in it really. Dial is at about 10:30 and plenty of volume.

 

[Wapiti]

Excellent result!