Now, my own thread - Page 3  

The jack is marked 0 ohm but you are probably right, it's ~0 ohms. Could you post schematics of your voltage divider so we can have a better idea of what you're listening with?

You're really Joe Bloggs, aren't you?

Ricky's correct. I also was looking at the schematic of the Meta42 this morning and noticed the same thing. I don't have it in front of me any more, but if I recall is have something like about 40 ohms in series with the output?? I'll have to look again. In any event, as Ricky stated earlier, his voltage divider is set up to have ~11 ohms at across the headphone. That should be fairly good to tame the bump on the Senns, but the quality of the amp still may be a hindrance. Consider small signal performance, zero crossing distortion, etc. No doubt the low THD figures were achieved by lots of negative feedback which tends to hammer the phase linearity of the amp. This would not necessarrily affect the freq. response but would limit the amp's ability to portrey sounstage information. This is also one of the characteristics that separates good cable from bad, btw.

Cheers,

Yep, there's a 47 ohm resistor in series with the output. However, this is optional. You can also put the resistor inside the feedback-loop (not that I know a lot about the Meta or amps in general, it just says so at Tangents website).
Also, Ricky is not saying that HD600's do not sound better at a ~0 ohm output. Just read what he wrote and you'll see that he is making some good points (about this impedance stuff that is )

I was aware of the damping ratios...however I am saying that the Senns have little mechanical damping and rely very much on electrical damping. This is what Jan Meier has gathered from Sennheiser engineers themselves straight from the source in his visit to the factory.

Yes 300/11 = ~27....but 300/1 = 300.

Yes because the headphone has high impedance, it is easier to damp electrically, however that also means an output impedance near zero will still have that much higher damping and control. And basically it gives enough control over the diapghrams to reproduce details that IMO easily get glossed over otherwise.

Also impedance specs aside...I am basing my findings on what I hear with different headphones and different impedance outputs and I'm still saying that the Senns have a large impedance rise which makes them quite sensitive to impedance outputs. I believe Grado's are much more uniform across frequencies in terms of impedance. Both Beyer DT931 and Senns seem to respond a lot to impedance outputs...both have impedance rises. Of course the DT931 is tuned at 120 and typically sounds better at higher output impedance. It also has much more mechanical damping (I've seen the innards before).

I still wouldn't be too quick to judge the output impedances of any of those amps. I once asked thomas about the 47 ohm resisters near the output of the typical CHA47's and wheter that amounted to a higher output impedance and he basically said "no" in a more detailed answer that I wouldn't be able to recount.

I do not know for sure but I have a hunch that those SS dedicated amps such as META42's, etc, may have very low output impedances. We should get a META42 DIY buff to chime in. Creeks are some SS amps that don't have near zero output impedances, but IMO, you can also *hear* that difference when compared to other SS amps. In anycase it is something that you need to measure, or talk to the META42 buffs about.

I just have the silly notion that a speaker amp watered down to handle headphones, has more problems to deal with than a dedicated amp designed for headphones. Basically getting an amp that is designed to give 50+ watts of power for an application that only needs miliwatts (typically 1/1000th of what is needed for speakers). Often....the tolerances allowed in speaker amps are also that much higher than what is tolerable in a good dedicated headphone amp. I think a good shovel is probably a better idea to plant a small tree, than a large bulldozer modded to do the work of a shovel.

As for tube amps...I've always grossly preferred Senns being driven by the beefy overkill SS amps with output impedances as low as possible. And IMO the Senns being driven out of the "high-end" Holmes Powell was just gross. There are people that don't mind listening to their Senns from receivers with typically 220+ output impedance outputs. But IMO...they either don't care about transparency...or just haven't heard any better. Me? It wouldn't even be worth it for me to keep either Senn580/600 with a low output impedance amp that isn't good enough...much less a typical receiver jack.

ER4S have higher impedance than ER4P's...which of these headphones would prefer the lower output impedance?

Not everything is going to boil down to simple division formulas. Again even the impedance values of the Senns is not just "300" it varies across frequencies. 300 is only a simplified spec of its real-world performance.

Re: Interesting links

There are 2 topics which are alway seem to inevitably lead to unwinnable arguments: politics and religion. The topic of audio cables is like these other two in a lot of ways. Nevertheless it's good to have postings like these, as well as the others which justify the high prices of designer cables. It's important to keep the debate going, especially for people who may have heard only one side of things. Thanks for posting these links.