[Skylab]

It amazes me how many times the topic of how easy or hard something is to drive gets confused.

What determines how easy or hard a headphone is to drive is NOT impedance. It's sensitivity. sensitivity, as measured in dB per watt or milliwatt, is how loud a headphone will play given a certain output power.

Where impedance comes into play is how many watts a given amp can produce into the load presented by the headphone. That will depend on the topology of the amp.

 

[grokit]

Quote:

I recently asked Jason of Schiit a similar question (whether the Valhalla would be best matched with 32, 250, or 600 ohm headphones).  Here is his reply:
 
"The short answer is "the lower the impedance, the harder the headphone is to drive."
That's why 25-ohm Denons and 16-ohm orthodynamics have such a hard time with most amplifiers. The Valhalla will have an easy job with 250-600 ohm headphones, and can drive them to very high overall levels. When you start getting down to 32 ohms (like with Grados, for example), you're reaching the limits of its capability, and it may not play loudly enough for you.
The perception that higher-impedance headphones are harder to drive comes from using them with devices like iPods, which can only manage 1 or 2 volts of output. They simply don't have the voltage to run high-impedance phones. Valhalla will do 30V, so that's not a problem."

Quote:

I wonder why the 770/880/990 people keep saying that that the 600 ohm versions are the hardest to drive, compared to the 32 and 250 ohm versions.

Quote:

It amazes me how many times the topic of how easy or hard something is to drive gets confused.

What determines how easy or hard a headphone is to drive is NOT impedance. It's sensitivity. sensitivity, as measured in dB per watt or milliwatt, is how loud a headphone will play given a certain output power.

Where impedance comes into play is how many watts a given amp can produce into the load presented by the headphone. That will depend on the topology of the amp.

 


Well with the Beyers they all have the same sensitivity (96db), but Beyer themselves says the 32 ohm is the easiest to drive while Jason at Schiit asserts the opposite so perhaps you can see why the subject can be confusing. Since the sensitivity rating on the three different ohm versions is the same, what makes the 600 ohm version the hardest to drive and the 32 ohm the easiest?

 

[Skylab]

That's the point - one cannot say whether the 600 ohm or 32 ohm versions are harder to drive in absolute terms. One can only say whether they will be easier or harder for any given amplifier to drive.

 

[Thecoolguy]

Quote:

It amazes me how many times the topic of how easy or hard something is to drive gets confused.

What determines how easy or hard a headphone is to drive is NOT impedance. It's sensitivity. sensitivity, as measured in dB per watt or milliwatt, is how loud a headphone will play given a certain output power.

Where impedance comes into play is how many watts a given amp can produce into the load presented by the headphone. That will depend on the topology of the amp.

Thanks for clearing that up, Skylab. Will the Valhalla be able to drive the HF-2s very well though?
 

 

[grokit]

Quote:

That's the point - one cannot say whether the 600 phi pr 32 ohm versions are harder to drive in absolute terms. One can only say whether they will be easier or harder for any given amplifier to drive.

 
So it depends on the output impedance of the amp, but that can be a hard spec to find when many amps spec sheets will say something like "ohm rating: 8 - 600" rather than giving the nominal output impedance rating. Some amps have high and low impedance switch or jacks to choose with, but that still doesn't tell you which it will perform best with.
 
And Beyer says that the 32 ohm version of the 880 for example can be driven from an unamped iPod, but evidently the Valhalla is a bad match 

 

[Skylab]

Thanks for clearing that up, Skylab. Will the Valhalla be able to drive the HF-2s very well though?
 

On paper it doesn't seem like an ideal match-up, but I cannot really say, having not tried it.

 

[Thecoolguy]

Thanks for all the replies! I might just get the asguard since its supposed to better with Grados, and if I dont like the asguard, I can always send it back within the 15 day period to get my money back and get the Valhalla, or maybe the Gilmore Lite, since its supposed to have great synergy with the HF-2s

 

[Asr]

Quote:

Well with the Beyers they all have the same sensitivity (96db), but Beyer themselves says the 32 ohm is the easiest to drive while Jason at Schiit asserts the opposite so perhaps you can see why the subject can be confusing. Since the sensitivity rating on the three different ohm versions is the same, what makes the 600 ohm version the hardest to drive and the 32 ohm the easiest?

A 600 Ohm headphone is not necessarily any "harder to drive" than a 32 Ohm headphone. The 600 Ohm headphone simply requires more voltage to be properly driven, while the 32 Ohm headphone requires more current. There's a prevalent misconception that low-impedance headphones in general are "easy to drive" - it depends on the headphone. Audio-Technica and Grado headphones, for example, are commonly spec'd at 32 Ohms (or thereabouts) and tend to be easy to drive and are also relatively efficient. Then there are other cases like the AKG K701 rated at 62 Ohms but it's actually quite inefficient.

 

[grokit]

Does current = gain, that might explain why an unamplified iPod for instance can drive certain low-impedance headphones decently, while an amp like the Valhalla pumps out more voltage? Sorry to be a PITA but while I am familiar with most of the concepts you guys are mentioning, my overall understanding of headphone/amplifier compatibilities is not second nature yet. From what I can gather I am not alone in this regard.

 

[Aynjell]

Quote:

Does current = gain, that might explain why an unamplified iPod for instance can drive certain low-impedance headphones decently, while an amp like the Valhalla pumps out more voltage? Sorry to be a PITA but while I am familiar with most of the concepts you guys are mentioning, my overall understanding of headphone/amplifier compatibilities is not second nature yet. From what I can gather I am not alone in this regard.

What I'm reading suggests that this is a hard question to answer. Per wikipedia, gain can mean voltage or current.
 
Funny thing, I can't drive my "HD600's" (truly HD580 modded to HD600 specs) from my I+ satisfactorily. My bithead off of usb can't do it either. But, daisy chaining them works well. O.o
 
The HD800 sounded wonderful straight off the I+. It wasn't as good as the ultra desktop I had on hand at the time, but it was actually acceptable. Well... if you consider 1500$ headphones on a 110$ amp acceptable.
 

 
Quote:

It amazes me how many times the topic of how easy or hard something is to drive gets confused.

What determines how easy or hard a headphone is to drive is NOT impedance. It's sensitivity. sensitivity, as measured in dB per watt or milliwatt, is how loud a headphone will play given a certain output power.

Where impedance comes into play is how many watts a given amp can produce into the load presented by the headphone. That will depend on the topology of the amp.

 
Also referencing this post, it seems to confirmed what I learned. An HD800 is 5db more sensitive than the HD600, and has the same impedance. 5db is a notice-able volume improvement. I personally remember actually enjoying the HD800 on my I+, but my HD600 lack body and warmth. It lacks everything but the ... final part of a note I guess. I don't know how to describe it, but every note was weak and uninspiring. This part I personally am confused about. I think I'd understand a lot more if somebody could explain why this is.

 

[Asr]

Quote:

Does current = gain, that might explain why an unamplified iPod for instance can drive certain low-impedance headphones decently, while an amp like the Valhalla pumps out more voltage? Sorry to be a PITA but while I am familiar with most of the concepts you guys are mentioning, my overall understanding of headphone/amplifier compatibilities is not second nature yet. From what I can gather I am not alone in this regard.

Current is not gain. To put gain into plain English, it's the amount by which volume is multiplied in a discrete interval when you adjust the volume knob. An amp with low gain on low-impedance, efficient headphones allows for gradual volume fine-tuning; conversely high gain on high-impedance, inefficient headphones allows for sufficient volume headroom on the knob (as opposed to it "running out of headroom"), provided that the amp has enough voltage output to drive the headphones without distortion, of course.
 
Also the idea that "an unamplified iPod for instance can drive certain low-impedance headphones decently" is not entirely accurate. To some people, certain low-impedance efficient headphones might sound good out of a DAP, but that doesn't mean the DAP is sufficiently powering the headphones. Just because perceived volume might be adequate and scale appropriately with the device's volume settings doesn't mean a random low-impedance efficient headphone will be properly driven - for example the Audio-Technica AD2000, which highly benefits from an amp that can supply enough current for it, and in almost every instance it tends to not sound as good as it's capable of when paired with non-optimal amps.

 

[Myrrhman]

Quote:

Thanks for all the replies! I might just get the asguard since its supposed to better with Grados, and if I dont like the asguard, I can always send it back within the 15 day period to get my money back and get the Valhalla, or maybe the Gilmore Lite, since its supposed to have great synergy with the HF-2s

Valhalla #130 here.
 
I've owned a Grado 325i / Gilmore Lite combo for a while, so I'm familiar with the sonic characteristics of the pairing. To me, it seems that the Valhalla provides an extra depth to music ... in comparison to the G-Lite, harmonics seem less one-dimensional. 
 
I find that the G-Lite provides a comfortable listening level at 9 o'clock whereas the Valhalla's volume knob needs to be at 10 o'clock to deliver the same level. Apart from that difference, subjectively the Valhalla seems to drive the 325i's adequately.
 
Given the similarity between the 325i and HF-2 specs, I would suggest the Valhalla would be capable of driving the HF-2 too.

 

[RedBull]

To me 32 ohm phones are easier to sound loud from DAP, but does not necesarily sound good.  Sometimes it's just plain LOUD but no definition.

 

[Jason Stoddard]

Hey all, sorry to jump into this so late.
 
Perhaps I can shed some light on the "hard to drive/not hard to drive" subject with some general rules of thumb.
 
1. For low impedance headphones (32-50 ohms), you need high current capability, and voltage output doesn't matter as much.*
 
2. For high impedance headphones (300-600 ohms), you need high voltage capability, and current output doesn't matter as much.
 
This is why low-impedance headphones can typically be driven to reasonable volumes by a sound card or iPod source--they may only put out a couple of volts, but they can source enough current for low impedance loads. This is also why high-impedance headphones seem harder to drive with a sound card or iPod--they don't put out enough voltage.
 
As for our products, Valhalla can put out more voltage into high-impedance loads than Asgard, and Asgard can put out more current into low-impedance loads than Valhalla. 
 
*Except in the case of orthodynamics, which typically need both high current and high voltage--which is why we wouldn't recommend them with Valhalla.
 
To go beyond this, I need to start getting into equations. 
 

 

[grokit]

That's a great explanation Jason, thanks for that!