[ludvigrollover]

Well, Fulla is specced at 40 mW at 300 Ohms so I think this is in the ballpark of what you can do with just USB power, without battery. Using Fulla as example because Schiit is a rare company that actually publishes wattages to different loads.
 
According to numbers I pulled from Teh Internets (caveat emptor), 17 mW is enough to give you 110dB on HD650. Should be loud enough.

 

[Rem0o]

  Well, Fulla is specced at 40 mW at 300 Ohms so I think this is in the ballpark of what you can do with just USB power, without battery. Using Fulla as example because Schiit is a rare company that actually publishes wattages to different loads.
 
According to numbers I pulled from Teh Internets (caveat emptor), 17 mW is enough to give you 110dB on HD650. Should be loud enough.

According to my ears, Fulla can get the HD650 to mad loud levels.

 

[Solrighal]

   
Thanks for the explanation. I'm curious to see how this is going to play out. Did they really think that the public can't perform basic algebra?

 
Basic? The last time I saw formulae like that it was on Sheldon Coopers Blackboard

 

[jimmers]

   
Basic? The last time I saw formulae like that it was on Sheldon Coopers Blackboard

P= VI, V = RI is Sheldon territory

 

[Solrighal]

P= VI, V = RI is Sheldon territory :rolleyes:

I'm just going to have to take your word for that.

 

[DavidA]

Hope that's all the physics/math lessons for the day, I want to kick back and listen to some music with no homework to worry about

 

[mysticstryk]

A schiit stack is a great option for around 300.00

I can also vouch for the schiit stack. Can even be had for $200. I went for the $300 uber versions though as I needed the extra connection options.

 

[colinallcarz]

Didn't see a tattoo anywhere....

 

[DDDamian]

  Hope that's all the physics/math lessons for the day, I want to kick back and listen to some music with no homework to worry about

Lol - amen to that. And be careful of the math which uses DC simplifications like that - there's a lot more to the math than those simple calcs when dealing with audio.
 
When's your trip?

 

[DDDamian]

Something for EQ/crossfeed tweakers: Resonance correction and crossfeed VST

 

[castleofargh]

Quote:

 

  Hope that's all the physics/math lessons for the day, I want to kick back and listen to some music with no homework to worry about

Lol - amen to that. And be careful of the math which uses DC simplifications like that - there's a lot more to the math than those simple calcs when dealing with audio.
 
When's your trip?

please feel free to point where I'm wrong or how the proper way to do it gives a difference that invalidates my results. I'm always willing to learn.

 

[DDDamian]

  Quote:
please feel free to point where I'm wrong or how the proper way to do it gives a difference that invalidates my results. I'm always willing to learn.

Those equations translate DC power using impedance (the AC equivalent of resistance in a steady-state). I.E. a fixed signal through a fixed pseudo-resistance, As soon as either of those change, meaning a signal, all kinds of dynamics come into play. There's interaction. Phasing. Control. And peak demand vs supply. By the basic math you're using you're saying a cellphone will drive an HD-650 (for example) to very loud levels. It will. And sound terrible.
 
Again, by those calcs there should be no difference between a 12V battery and a top amp driving a musical signal. See the difference?

 

[castleofargh]

 

  Quote:
please feel free to point where I'm wrong or how the proper way to do it gives a difference that invalidates my results. I'm always willing to learn.

Those equations translate DC power using impedance (the AC equivalent of resistance in a steady-state). I.E. a fixed signal through a fixed pseudo-resistance, As soon as either of those change, meaning a signal, all kinds of dynamics come into play. There's interaction. Phasing. Control. And peak demand vs supply. By the basic math you're using you're saying a cellphone will drive an HD-650 (for example) to very loud levels. It will. And sound terrible.
 
Again, by those calcs there should be no difference between a 12V battery and a top amp driving a musical signal. See the difference?

that's why RMS values exist...  you get an estimate that works just fine compared to measurements. at least electrical engineers seem very fine with it.
now driving power is just one part of getting the sound right, just like those specs are usually limited to 1khz, so maybe you're just reading too much in my posts IMO. when I say a source will drive the hd650 to a given loudness, I'm saying only that. and only based on the specs I'm provided with. I don't know if the source's impedance goes berserk at some other frequencies or if there will be distortions, crosstalk, etc. but we can at least try to check that we won't add distortions or clipping because of a lack of voltage/current. and there is a way to do that that isn't buying a 5W amp to drive a hd650 because "better safe than sorry". and I'm really not doing anymore than that.
 
 
 
Quote:

  Something for EQ/crossfeed tweakers: Resonance correction and crossfeed VST

just read through the page, it's a cool toy TBH but it needs personnal work with test tone in the ears(there are nicer ways to spend an evening), I'm not sure many people here would be willing to go through it to do it right triple check go at it again the next day to see if moving the headphone affected something...
I've been doing this with Joebloggs combo in his tuto on EQ, using sinegen, virtual audio cable, vsthost, and whatever parametric EQ I used at the time(always looking for a better/ more convenient one ^_^). at the time with VAC costing 39$ I would have probably gone with that all in one solution for 60$ .
 
 
the crossfeed part now is but another crossfeed and you can have several for free as vst for foobar.

 

[mikoss]

The equations work on paper. For calculating power with amps, they also do a fine job to determine dB output...

However, as you alluded to DDDamian, I mentioned that electricians use P = I x E x power factor, because the load may not be purely resistive, and the frequency of the source may be changing.

Since an audio signal is not pure DC, it's most definitely a changing signal while we are listening to music, so the result may be a bit different than the paper formula.

Personally, I think it works just fine in conjunction with "known" impressions. Eg. The 300 ohm 650's enjoy voltage swing, whereas lower Z planars have a need for current. Both still produce power the same way, but if the amp is for example an OTL tube amp, it's much better suited for high Z headphones, despite someone calculating that it "should" be loud enough. IMO, the lower Z can will achieve volume, but really doesn't sound good at all.

Not disagreeing with anyone, just a caution that I think people who have gone from an O2 to other amplifiers can understand.

 

[DDDamian]

 Originally Posted by castleofargh /img/forum/go_quote.gif
that's why RMS values exist...  you get an estimate that works just fine compared to measurements. at least electrical engineers seem very fine with it.
now driving power is just one part of getting the sound right, just like those specs are usually limited to 1khz, so maybe you're just reading too much in my posts IMO. when I say a source will drive the hd650 to a given loudness, I'm saying only that. and only based on the specs I'm provided with. I don't know if the source's impedance goes berserk at some other frequencies or if there will be distortions, crosstalk, etc. but we can at least try to check that we won't add distortions or clipping because of a lack of voltage/current. and there is a way to do that that isn't buying a 5W amp to drive a hd650 because "better safe than sorry". and I'm really not doing anymore than that.

 
That's what electrical engineers use to for steady-state AC circuits you mean. And that's fine for light bulbs or an AC motor (although not a servo or inverter-driven one with varying loads and accelerations). Using it to basically tear apart some amp like you did a few posts ago is imo a dis-service to them. Again, by your math of several pages ago a cellphone is capable of driving the 650. I don't think many here are rushing to sell their amps. That and you completely miss the much more important impulse or peak power. There's a very old stereo adage: not all watts are created equal.
 
Quote:

 
just read through the page, it's a cool toy TBH but it needs personnal work with test tone in the ears(there are nicer ways to spend an evening), I'm not sure many people here would be willing to go through it to do it right triple check go at it again the next day to see if moving the headphone affected something...
I've been doing this with Joebloggs combo in his tuto on EQ, using sinegen, virtual audio cable, vsthost, and whatever parametric EQ I used at the time(always looking for a better/ more convenient one ^_^). at the time with VAC costing 39$ I would have probably gone with that all in one solution for 60$ .
 
 
the crossfeed part now is but another crossfeed and you can have several for free as vst for foobar.

 
Yes, as noted, it's for tweakers. Listen to a sweep, reduce the peaks. You should see the lengths HD-800 or HE-400 owners will go through to relieve resonances lol. I haven't tried it, but I thought it would be a useful link for, as I said, tweakers. And yes, a have a couple crossfeeds for Foobar, you don't even need the VST wrapper.