[tfarney]

When they are there, they confuse me. In the world of amps that are measured in watts (rms) into ohms and speakers that are measured by load (ohms) and sensitivity (which will give you a pretty good indication of the overall power requirements of the thing), I can sit here on the internet, where most hifi shopping must be done in a retail world gone wile with HT, and get a pretty good idea of what speakers might be a decent match to what amps. I'm not talking about synergy here - warm speakers/cold amp, that sort of thing - I'm talking about a basic match that says that amp will be strong enough to drive that load with sufficient headroom.

But here in the HP world, where ohms range from near zero to 600 or more, amps are measured in milliwatts and those milliwatts are rarely related to a load (which makes them useless to me), and where sensitivity ratings almost never exist...what am I missing? How does one navigate this world? Can someone show me the map?

Tim

 

[tfarney]

Anybody got a clue?

Tim

 

[Jaska]

Headphone amp specs are generally quite insufficient as disclosed by the manufacturers. Some very expensive boutique amps are sold with almost no specifications provided.

With headphones, at least there are the Impedance Measurement graphs you can build on HeadRoom's site, but unfortunately these seem to be broken since some time ago. The rated impedance of headphones in itself says almost nothing meaningful, but when the impedance is measured properly over the whole frequency range, then at least some ballpark/educated guesses can be made about driving them sufficiently with this amp or that one--provided the amp manufacturer will demystify the technical performance and behavior of the amp by providing adequate information about the product.

 

[tfarney]

Quote:

Originally Posted by Jaska /img/forum/go_quote.gif Headphone amp specs are generally quite insufficient as disclosed by the manufacturers. Some very expensive boutique amps are sold with almost no specifications provided. With headphones, at least there are the Impedance Measurement graphs you can build on HeadRoom's site, but unfortunately these seem to be broken since some time ago. The rated impedance of headphones in itself says almost nothing meaningful, but when the impedance is measured properly over the whole frequency range, then at least some ballpark/educated guesses can be made about driving them sufficiently with this amp or that one--provided the amp manufacturer will demystify the technical performance and behavior of the amp by providing adequate information about the product.

Yeah, I really don't get it. Some amp manufacturers don't even list power output. Some that do don't relate it to anything. A Gilmore lite puts out 1 watt. 1 watt into what? A meaningless spec without a load specification. Then there are the phones. AKG rates the K701's sensitivity and 105 db. A speaker with a 105 db peak, much less average sensitivity, and reasonably even resistance, could fill a small living room with sound on a couple of watts of SET. Just about any headphone amp, portable or otherwise should be able to run them like hi test runs a Ferrarri. But evidently not...

Tim

 

[Asr]

Quote:

Originally Posted by tfarney /img/forum/go_quote.gif Yeah, I really don't get it. Some amp manufacturers don't even list power output. Some that do don't relate it to anything. A Gilmore lite puts out 1 watt. 1 watt into what? A meaningless spec without a load specification. Then there are the phones. AKG rates the K701's sensitivity and 105 db. A speaker with a 105 db peak, much less average sensitivity, and reasonably even resistance, could fill a small living room with sound on a couple of watts of SET. Just about any headphone amp, portable or otherwise should be able to run them like hi test runs a Ferrarri. But evidently not... Tim

1W into 32 Ohms of course. Did you forget the Gilmore Lite is a Dynalo, which is essentially open-source?

HeadWize - Project: A Pure Class A Dynamic Headphone Amplifier by Kevin Gilmore

Generally you need to compare voltage & amperes on an amp to see how much it pushes at 32 Ohms and 300 Ohms. Some amp vendors publish this info. HeadAmp doesn't really need to since the Dynalo is very well-published.

Output power at 32 Ohms and 300 Ohms gives you a basic idea on whether an amp is geared more towards low- or high-impedance headphones. Some amps, like the Dynalo, are essentially great for both due to high-current and high-voltage output compared to most other amps.

 

[tfarney]

Quote:

1W into 32 Ohms of course. Did you forget the Gilmore Lite is a Dynalo, which is essentially open-source?

No, I didn't forget. I never knew.

Tim

 

[Jaska]

Quote:

Originally Posted by Asr /img/forum/go_quote.gif Some amps, like the Dynalo, are essentially great for both due to high-current and high-voltage output compared to most other amps.

This is primarily why I bought the Gilmore Lite. Although there are many reviews and a lot of published commentary on this amp, I found a lot of your (Asr) input on this amp extraordinarily useful.

 

[Asr]

Thanks, I do what I can.

 

[tomb]

Actually, I'm wondering why the OP thinks it's so easy to match speakers with an amp. Granted, there's a bit more info out there than for headphones, but speakers are also notorious for less-than-real impedance ratings. Many are lower than they claim, the impedance varies over the frequency spectrum, and then there's damping factor. Some like a lot, others don't. Many amps don't quote it. Yet, it can make or break the speaker-amp matchup.

Agreed that headphones and headphone amps are worse - that's why you see many of the threads that start with "Will this headphone match up with this amp?" Still, there are some reasonable generalities one can conclude about two types of headphones: low impedance headphones that are not very efficient and high impedance headphones that may not be very efficient. In the first case, you need an amp that can deliver lots of current, in the second, lots of voltage. The ability of amp to deliver instantaneous current, or slew wide voltage swings is pretty much the quality of control that the amp can deliver with those disparate-type phones.

Again generally speaking, portable amps can do neither as well as a desktop amp. However, most likely they have an easier time with voltage instead of current. That's another sweeping generalization, but P = I^2 * R. That means high current results in high heat. It's also wasteful. Both facts lean toward heavy heat sinks and relatively limitless line power, not batteries and light-weight portability. Of course, there are portable amps that can deliver large bursts of current, while voltage swings will never have as much potential as with a desktop amp.

 

[tfarney]

Quote:

Actually, I'm wondering why the OP thinks it's so easy to match speakers with an amp.

Well I wouldn't go so far as to say it's easy, but it is certainly easier. There is more information out there, and while there are some speaker systems that are notoriously uneven and hard to drive, there are a lot of really good-sounding speakers available that are relatively easy to drive, and very predictable based on commonly-published amp and speaker specifications. If this, or anything like it, is the case in the headphone world, I've really got the wrong impression, and I need a headphone/English dictionary.

Tim

 

[tomb]

Quote:

Originally Posted by tfarney /img/forum/go_quote.gif Well I wouldn't go so far as to say it's easy, but it is certainly easier. There is more information out there, and while there are some speaker systems that are notoriously uneven and hard to drive, there are a lot of really good-sounding speakers available that are relatively easy to drive, and very predictable based on commonly-published amp and speaker specifications. If this, or anything like it, is the case in the headphone world, I've really got the wrong impression, and I need a headphone/English dictionary. Tim

This link may help. It puts a lot of info into one place:
Understanding Headphone Power Requirements

There's a particular link at the bottom of that article for a "Table of Headphone Specifications" that lists most of the info you seek. As we've discussed, getting that same info for the amps may be a bit more difficult.

 

[tfarney]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif This link may help. It puts a lot of info into one place: Understanding Headphone Power Requirements There's a particular link at the bottom of that article for a "Table of Headphone Specifications" that lists most of the info you seek. As we've discussed, getting that same info for the amps may be a bit more difficult.

Thanks Tomb, I really appreciate that.

Tim