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do my hd650's need an amp - Page 3

post #31 of 41
But regardless, he should at least have a cheap amp/external sound card. ?Integrated laptop audio is generally low quality, and won't let the HD-650 perform up to its full potential.
post #32 of 41
Originally Posted by mechtech View Post
But regardless, he should at least have a cheap amp/external sound card. ?Integrated laptop audio is generally low quality, and won't let the HD-650 perform up to its full potential.
I say without a ~$3500 DAC and a ~$4000 balanced amp + $400 cable the HD 650 won't show its true potential.
post #33 of 41
Originally Posted by JaZZ View Post
I say without a ~$3500 DAC and a ~$4000 balanced amp + $400 cable the HD 650 won't show its true potential.
And they say headphones is a cheaper alternative for speakers. For that £5700 you could build a supererb Hi-Fi.
post #34 of 41
what if it is running from a computer (through sound card) ?
post #35 of 41
Originally Posted by xcluded View Post
what if it is running from a computer (through sound card) ?
Still would need one to maximize their potential
post #36 of 41
As has been said, yes, you need a better DAC before you talk about headphone amplifiers. That being said, an audibly perfect DAC need not be very expensive. I would suggest, for a lapop, an emu 0404 USB. Since this is the sound section, and you want a scientific explanation, here are the RMAA tests for the emu 0404 USB:

RightMark Audio Analyzer test : E-MU 0404 USB loopback unbal 16b 44k

All of those measurements are well, well beyond the threshold of audibility. If you're looking for a different card, make sure that they match these specs and you'll be fine:

Frequency response +/- 0.3db
Noise level < -80 db
Dynamic range < -80 db
THD < 0.05%
THD + Noise < -80 db
IMD + Noise < 0.05%
Stereo crosstalk < -20 db
IMD at 10 kHz < 0.05%

Now, these figures are good general guidelines for getting perfectly transparent sound coming out of your entire system, so it's a good idea to keep the values low on your source so your amplifier won't create additional distortion which additively will put you past the thresholds. That being said, the Emu 0404 is WELL below those points.

The Emu 0404 is pretty expensive for what it does (the PCI version is about half the price and the same performance - I verified this with testing that you can see here: RightMark Audio Analyzer test : [MME] E-DSP Wave [EC00]), so you may want to look for other soundcards within your price range. That said, since you plopped down the cash for the 650's, you may as well spend the extra money on a good USB DAC that measures well, because the 0404 has a lot of other advantages to it as well.

If you're looking cheaper, there's a USB DAC called the Alien DAC that you can get for much cheaper, around 30 dollars in parts if you build it yourself, and I'd assume under 100 dollars if you got someone to build it for you. You can see the measurements here:

RightMark Audio Analyzer test: Alien DAC 16b 44.1k USB power

It's not a stellar DAC, but it's pretty good, especially if you can find it at that 30 dollar price range - it'll be more than enough to get you started.

A lot of people on the forum will overestimate the importance of the source - while it is extremely important to get a transparent one, I find a lot of people overspend on sources - it doesn't take much to get an audibly perfect DAC.

Onto amps: this post is very informative and lets you understand, from a scientific standpoint, what a headphone amp's function is:

Is a headphone amp needed? - Hydrogenaudio Forums

Notice how, when sufficient voltage is given, the clipping stops (as you can see from the scope readings). The headphones used there are beyerdynamic DT880's, and they're pretty inefficient, hard to drive phones. Even with worst-case scenario, heavily dynamic music driven at loud levels, only 3.90 VRMS is needed, but the rail voltages still need to be at around 16 volts. High impedance phones like the 650's need a lot of voltage swing, but not a lot of current output - you can see that through Ohm's law. So long as you have an amplifier with sufficient voltage, a low enough THD, and a flat frequency response (99% of properly designed amps), you'll also have an audibly perfect headphone amplifier - one that won't color the sound at all, and simply eliminate clipping/distortion.

Take a look here: Headphone Amps and Distribution | Sweetwater.com

Go through them, look at the spec sheets, and find one that's reasonably priced with enough rail voltage (you can't tell rail voltage just by looking at input voltage which will be what's listed, but it's a good rough guide that ~16V input voltage should be enough). One benefit of getting the emu 0404 as above would be that you can run 1/4" TRS cables from the headphone amp to the DAC, which in theory can reduce the noise of the cables, but in practice they're great cables because they're nearly impossible to break or destroy.

Good luck with your setup.
post #37 of 41
Without a doubt, go for the amp. I tried both amped and unamped 650's and the difference was night and day off the same source.
post #38 of 41
Thread Starter 
I am still using the HD650's from my Laptop Headphone out, and also occasionaly with a Sansa Fuze, both using FLAC media, and they still sound great to me.

Thank you so much for all the feedback;

The explanations about an AMP possibly being required to providing a high enough voltage to power the headphones correctly.

The explanations about the benefit of a USB audio DAC to provide a cleaner source.

So I appreciate, that I might not be getting to hear the true sound that was intented in the recording.

For the moment, I want to concentrate on if the headphones are getting enough voltage to drive them correctly.

Is there an easy way for me to measure this? Can I just use a multimeter?
post #39 of 41
You don't need to measure anything, your laptop won't be able to drive 650's, in fact I wouldn't even use PX100 due to crap sound quality and background noise from laptop onboard.

Buy a USB DAC/headphone amp.
post #40 of 41
Dude dont do this injustice to these headphones ! I bought them and used them with my integrated audio of my PC for a good 2 months. I liked the sound that they gave me and was happy that I chose to disbelieve all the people who begged me not to go for the HD650 since I did not have an amp.

Then one day someone was selling a Hotaudio DAC for cheap. I bought it just for kicks thinking I may get a slightly better sound. I was wrong !

The sound became MUCH better ! The bass extended much more, the treble suddenly came alive and the mids also improved somewhat. Later on I forced my dad to give me his amp to listen to and WOW ! The sound had improved further ! The soundstage just expanded and I could now hear finer details that was missing earlier.

The downside was that all my 128 kbps tracks that sounded great earlier were now sounding not so great. So I had to upgrade all my tracks to a higher bit rate but its all worth it when I listen with the HD650.

Get a good DAC first and then only if you feel the sound has improved, get a good amp.

I do not have any scientific proofs to sway your decision but I was in your shoes as I also used the HD650 with onboard sound and let me tell you a DAC + good AMP will make a LOT of difference to your sound.
post #41 of 41

300 Ohm hd6x0 need more V

Originally Posted by jcx View Post
I really don't think the Gilmore Lite should be the 1st suggestion for someone to appreciate the full capabilities of the HD600/650 - it simply doesn't have the V swing capablility to drive the higher Z headphones to their full potential

HeadAmp specs their Gilmore Lite output swing at 15 Vpp => 5.3 Vrms

looking at the circuit I think this could really be the clipping limit - the Lite circuit is very wasteful of supply V

the HD650 specs work out to ~100 dB/V

5.3 Vrms gives ~ +14 dB power re 1 Vrms

this gives ~ 114 dB SPL at HeadAmp's output V swing spec

Probably good enough for most listening, but “rocking out” at live event levels could still clip

look up Dynamic Headroom, peak SPL of well recorded music before naively pointing out that even 100 dB is "too loud" - only as a average listening level
HeadWize - Article: Preventing Hearing Damage When Listening With Headphones (A HeadWize Headphone Guide)
Silk: CuteStudio Ltd. Audio, electronics, graphics and embedded software

see the original Headwize article for Gilmore's own suggestion to raise the supply V - the Gilmore Class A was intended as a 32 Ohm headphone amp – perhaps Justin could mod one for higher V
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