[rpgunn]

My first post gets deleted due to linking to a site that belongs to a banned member. I had no idea, not a good start getting your first post deleted !
 
I'll try again...
 
I have read that headphones shouldn't be less than eight times the output impedance of the amplifiers phone jack.
 
I have two older sansui amps (AU-4400 & AU-317) which I believe have an output impedance of around 8 ohms, its hard to actually find the specs to confirm this.  The headphones I use are Denon AH-D2000's and AH-D5000's which have 25 ohm impendance at 1 kHz.
 
Does this rule still apply with modern headphones ? Would I be better off going for high impedance headphones for use with these amps ?
 
 

 

[SanjiWatsuki]

I doubt that 8 ohm is the output impedance for the headphone jack. I bet it is referring to the speaker impedance. You can expect pretty significant bass coloration from the output impedance of vintage Sansui. I've heard that they can get to 160-200 ohm output impedance.

 

[Mad Lust Envy]

That rule is severely blown out of proportion, I'd say. I've hooked up my D7000 to a 2 ohm, 10 ohm, and 100ohm sources. they all sounded relatively the same.

My Q701 sounds amazing on both my 2 ohm and 10ohm source. It's not 1/8th either.

I really hate how people would rather listen with their eyes instead of their own ears.

 

[SanjiWatsuki]

Quote:

That rule is severely blown out of proportion, I'd say. I've hooked up my D7000 to a 2 ohm, 10 ohm, and 100ohm sources. they all sounded relatively the same.
My Q701 sounds amazing on both my 2 ohm and 10ohm source. It's not 1/8th either.
I really hate how people would rather listen with their eyes instead of their own ears.

I agree. I don't think the sources sound the same, though. Dear Lord, the Thermaltake Isurus is god awful out of any high impedance source. That's the one headphone/earphone where I've noticed a ridiculous difference between a moderate impedance source and a low impedance source.
 
The 1/8th rule was a rule of thumb for speakers. It's true for an extent. The smaller drivers in headphones, though, are less susceptible to the electrical damping effects, though. 

 

[Mad Lust Envy]

I'm not saying it's not warranted, but that people should actually test it out for themselves. It's like those who live by that rule immediately shun anything that doesn't hit that magical 1/8th number. It's stupid to me.

 

[drtturnip]

My Harmon Kardon headphone output was 470ohm impedance and it did make a difference with my hd595 and its peaked impedance at the lower end. Maybe for the better. If a headphone has a well behaved impedance curve it shouldn't make much difference. I don't think headphones care about damping factor but a wild swing in impedance at a certain frequency can cause a change in sound. This topic seems get beat to death every once in a while.

 

[rpgunn]

Thanks for the replies. I don't have many sources to compare against. Comparing the direct headphone output from an iMac (Flac->Decibel->D5000's) I had the impression I was losing a little bit pf emphasis/punch, maybe even a little distortion on the bass via the amp.
 
Of course I could be crazy and imagining all this !

 

[obobskivich]

That rule is severely blown out of proportion, I'd say. I've hooked up my D7000 to a 2 ohm, 10 ohm, and 100ohm sources. they all sounded relatively the same.
My Q701 sounds amazing on both my 2 ohm and 10ohm source. It's not 1/8th either.
I really hate how people would rather listen with their eyes instead of their own ears.

+1. It really depends on how reactive the headphone is. A lot of the most vibrant examples are from Sennheiser and Beyerdynamic, and it's usually after someone plays around with an HD 650 or DT 880 that they decide all amplifiers must sound dramatically different. But that doesn't hold true across all headphones; the Denon headphones are very stable and really do not care that much. Most newer headphones are like the Denon headphones (again, outside of some vintage stuff, and modern Sennheiser and Beyerdynamic offerings, I can't think of any other good examples). Of course there are *subtle* differences to be worried about, but it's not really that big of a deal.

It's entirely possible though that you're hearing clipping or the amplifier is otherwise current limiting, depending on how loud you want things, or what the amplifier can do. This will cause audible problems too. I'm doubtful this is the case, as the Denon headphones are very sensitive. Go with whatever headphones you like, and plug them into whatever tickles your fancy (and is compatible, of course - we can't be plugging our HD 650s into an E/90 or anything silly like that ).

The ironic bit here is actually that if you picked any of the current high Z cans (which are...Sennheiser and Beyerdynamic) you'd notice more differences between the high Z out on those receivers than you would with the Denon cans...

 

[SanjiWatsuki]

The way I see it is just that low-Z out amps are pretty damn cheap and competitive in most price brackets and I'd like to pick the colorations in my headphones myself. I'm the type of guy who would be taking the z-out, the impedance curve, calculate the dB of difference as a result of output impedance, recreate the frequency response with this altered graph, and then equalize to taste if I had to deal with a high z-out amp. Low z-out amps are so much easier to work with in that regard. 

 

[obobskivich]

The way I see it is just that low-Z out amps are pretty damn cheap and competitive in most price brackets and I'd like to pick the colorations in my headphones myself. I'm the type of guy who would be taking the z-out, the impedance curve, calculate the dB of difference as a result of output impedance, recreate the frequency response with this altered graph, and then equalize to taste if I had to deal with a high z-out amp. Low z-out amps are so much easier to work with in that regard. 

The "EQ as a cure to all ails" is also a popular glue factory around here.

 

[Chris J]

A really high quality, versatile headphone amp which works well with virtually any headphone will have a very low output impedance.

The advantages of low output impedance are the potential for lower distortion, flatter frequency response, better driver control.

Do you get this from every 'phone? It depends............on the electrical characteristics of the 'phone.