[Catharsis]

Quote:

That would be part of it.  I've read from few different people who professionally design high end speakers that past a damping factor of 20 or so, the difference can sometimes be measurable, but is generally not audible.  I have no idea how much of this applies to to headphones though.  Since the diaphragms have far less mass, electrical damping may not be quite as important so the threshold of audibility for it may be lower than with loudspeakers, but I don't really know.

 
Headphone drivers are resistance controlled as opposed to mass controlled, and the relatively flat impedance curves of most headphones (every headphone I've ever seen) means that "damping factor" which is a non-sensical, non-quantitative measurement, has far less bearing on headphones.  Generally speaking, if the Zout of the source is less than the impedance load of the headphone, you'll hear very little difference in sound.  To put it into perspective a damping factor of 5 produces insignificant changes in FQ response with the DT880.  A damping factor of 5 with speakers however (which have a more varied impedance curve) will have far more FQ response fluctuations. 
 
I believe the desired term is "impedance bridging", as opposed to "impedance matching", which is reserved for the telecommunications industry. Until somebody (anybody please) can support the hypothesis that the higher impedance beyers measure better than the lower impedance beyers with any physical evidence, I stand by my position that there is no correlation between impedance and sound quality as far as audibility is concerned. 
 
Hundreds of posts on the subject, and all there is is anecdotal evidence (which sucks as far as evidence is concerned).

 

[Tiramisu515]

Gee, thanks for the explanation Uncle Erik...
 
that is really useful for my knowledge.
 
 
Quote:

Tiramisu515, output power has very, very little to do with circuit topology. OTLs and transformer-coupled amps have varying output power depending on the circuit, power supply and tubes used. You could build an OTL with 150mW of power and a transformer-coupled amp with 1.5W of power. The transformer-coupled amp would be ten times more powerful. Output power depends on the design, so there's no way to generalize.

As to the original question, damping factor is important. The higher it is, the better control an amp has over a driver. If the amp's output impedance is 10 Ohms and you use a 600 Ohm headphone, you have a factor of 60:1, or really good control. But if you use an amp with high output impedance (like a lot of OTL amps) around 200-300 Ohms, you'll have a lower damping factor. I think this is a big reason why the 600 Ohm cans sound good - they allow most amps great control.

The opposite is true, as well. If you use 32 Ohm headphones with an amp that has a 200 Ohm output impedance, the damping factor disappears and you get bad performance.

Also, one of the big benefits of running transformer-coupled amps is that transformers really push the output impedance down. You generally get a higher damping factor with them. The drawback is that cheap output transformers don't sound good and the good ones make amps significantly more expensive.

 

[ImitationOfLife]

Quote:

However, not any tube amp. A OTL tube amp would provide more power to drive the 600 ohm phones compared to one that is transformer coupled.   

I dunno, I think my DT770/600 sounds excellent out of my Woo Audio 6.

 

[Katun]

I have been wanting to try a Beyerdynamic headphone for the longest time, and I definitely want to get one, but I don't have an amp.
 
The 32ohm might be "decent" straight out of my iAudio 7, but maybe I should just keep away all together for now. But they look so comfy!

 

[Tiramisu515]

I meant easiler to drive the 600 with a OTL. Your Woo Audio, I am very sure is an excellent sounding amp that I too would love to own some day.

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Quote:

I dunno, I think my DT770/600 sounds excellent out of my Woo Audio 6.

 

[jr41]

This is an awesome thread, lots of useful information here (particularly the posts by Uncle Erik and Catharsis) for those trying to understand different amp designs and related specs. etc.
 
Cheers!

 

[brod]

Until somebody (anybody please) can support the hypothesis that the higher impedance beyers measure better than the lower impedance beyers with any physical evidence, I stand by my position that there is no correlation between impedance and sound quality as far as audibility is concerned. 

In the absence of hard evidence I tend to believe the manufacturer's info.

http://europe.beyerdynamic.com/service/faqs/headphones.html

The transducers of the 80 ohms versions are stronger and more powerful, a bit more mid accentuated and therefore this version is ideal for powerful reproducing of low-frequency material f.e. coming from a bass guitar. The 250 ohms version sounds more smooth and voluminous and can be used for mixing situation within the studio to analyse the whole mix.

Higher impedance = better sound = higher power requirements.

 

[Kevin Brown]

^^^
 
I'm glad I don't believe everything a manufacturer tells me !!
 
Every heard of "marketing" ?
 

 

 

[brod]

I don't see how Beyerdynamic would benefit by misleading people on this topic. Given that their info matches the subjective experiences posted here it does appear to be accurate.

[SIZE=10pt]- 250Ohm[/SIZE]
This Ohm version is good improvement over the 32Ohm version.

[SIZE=10pt]- 600Ohm

This is the best model of this headphone available.

I think what catches many people out is the fact that higher impedance headphones require more power to sound good. If someone uses a low power amp to compare a 32Ω headphone to a 600Ω model they are going to think that the 600Ω version is worse when in fact it's just not getting enough power to reach its potential.

 

[Kevin Brown]

OK, I looked back and I haven't posted my comparison in this thread, but I have in others.
 
I did buy and own at the same time DT880/250's and DT880/600's.  I had enough power to drive the 600 ohm model too. 

 
I liked the 250 ohm model because I felt they had a mellower, softer, warmer top end response.  I liked the 600 ohm model because I thought the bass was tighter and more impactful.  In the end I kept the 250 ohm model because they were less fatiguing and harsh for long term listening.
 
So in the end, it's not necessarily the case that the higher impedance model is the one you're going to prefer.
 

 

[maverickronin]

Quote:

I think what catches many people out is the fact that higher impedance headphones require more power to sound good. If someone uses a low power amp to compare a 32Ω headphone to a 600Ω model they are going to think that the 600Ω version is worse when in fact it's just not getting enough power to reach its potential.

They actually all need about the same amount of power.  Beyer rates them all at the same 96/dB mW and the 32, 250, and 600 were all measured to similar amounts of power to reach 90dB.  The higher impedance models need more voltage and the lower impedance models need more current but power is voltage x current so they end up drawing similar amounts since their efficiencies are similar.
 
You still might want to go with the lower impedance models if you won't use them with an amp with much voltage swing.  On the 600s measured above, 5VRMS will give you 110dB peaks along with 114 for the 250s and 122dB with the 32s but it would be slightly over the 250's max power and 7x the 32's max power.

 

[brod]

Yeah, I meant more voltage.