[Barthandelus]

Hey gang

I'm new here at Head-fi and audio in general

I was the proud owner of Bose Triports which souneded good to me (blasphemy!) but it broke so I bit the bullet and got a AKG K701

From what I've seen, you need amps to drive these well and from what I understand is that Amps increase volume ...right?

My old triports were rated 32 ohms and my PC's on-board soundcard was more than loud enough... in fact, my volume was never more than 10% (but at max for the players like foobar and zune). The K701s are just about double that at 62 ohms. But since I have so much headroom, methinks I will be fine?

Also, I would rather spend on a new soundcard , like the X-Fi than an amp. What are your opinions?

 

[Ypoknons]

No. As you noted, there are many ways to jack up volume, and resistance does not reflect the volume you'll get from an amp. An amp's gain determines volume, which is attenuated by the volume knob (for most amps, at any rate). The job of an amplifier is to take power from some source (a battery, power outlet, hamster, whatever) and use it power your headphones and meet its current and voltage needs, so that the drivers move and produced sound. In addition, this power needs to be provided without ripples from the PSU, crosstalk between circuits, and all the considerations that a designer takes into account. From what I understand, the bloated bass from a weaker amp, such as a portable or iPod, is accounted for by the lack of voltage swing from such sources.

A better soundcard, or digital to analog converter in general, will only improve the decoding of digital information into analogue. It will not power headphones better. Providing your headphones with a better analogue signal does not mean the headphone will be sufficiently powered. For the K701, I would recommend a good desktop amp first, and then maybe a source improvement.

 

[Barthandelus]

Thanks for the explanation. I get the part about how an amp acts like a surge protector, providing clean noise-free power to the headphones.
But I would like some numbers

For example, my zune 30 is 0.9 watt, not sure about the x-fi but probably much higher since its PCI-E (> 3 volts). What kind of power do I need for the K701?

 

[Ypoknons]

That's beyond me. Fallen Angel calculated a 8V voltage swing for the HD600 here to start you off. Most of the 'big amps' should be able to do at least 300mW into 300ohms (the Zune's numbers depend on the impedance too), many of them far more, but then again power is divided into voltage and current, some headphones need a lot of voltage others need current...

There's not going to be numbers that determine how any given circuit design sounds though. The graphs the designers use might help, but really, that's in their language XD

 

[furyagain]

if you just want to buy sound card ,
get a sound card with built in headphone amp

like the auzentech forte 7.1 / Bravura 7.1
or asus ASUS Xonar Essence STX ( it is more expensive)

 

[m1abrams]

Quote:

Originally Posted by Barthandelus /img/forum/go_quote.gif Thanks for the explanation. I get the part about how an amp acts like a surge protector, providing clean noise-free power to the headphones. But I would like some numbers For example, my zune 30 is 0.9 watt, not sure about the x-fi but probably much higher since its PCI-E (> 3 volts). What kind of power do I need for the K701?

That number is meaningless and pointless to help you decide which would be best for your headphones.

 

[Ra97oR]

The Essence drives the K701 pretty ok. If you don't have a good source for an amp, Essence is a good choice to start with.

 

[Barthandelus]

^^^ then can you explain what number is?

the auzentech cards look like a good deal. ~100 for a soundcard and an amp !!

 

[m1abrams]

Quote:

Originally Posted by Barthandelus /img/forum/go_quote.gif ^^^ then can you explain what number is? the auzentech cards look like a good deal. ~100 for a soundcard and an amp !!

No single number will give you any idea about an amps ability to drive a headphone.

You need to know how an amp responds over a number of factors.
Output impedance, transient response, freq response, thd+n, etc.

 

[5aces]

Looking at that Bravura 7.1 card here:

Auzen X-Fi Bravura 7.1 review

Amazing features for $129 retail.

16/24-bit / up to 192.0khz Headphone playback (24/96 with xp drivers,I see)

10Hz to 94kHz, +/-3dB @ 192kHz(Headphone)

Headphone load impedance 16ohm ~ 600ohm

Headphone Output : 1/4”

Hell,I'm still rockin' my old X-Fi Platinum with the I/O front drive bay,never a problem.
Even installed the optional Dolby Digital Live and DTS connect to run the 5.1 signal on a single cable to an HT receiver.

 

[DTrain]

Do you play games? If so, I would get an Azun Forte. If not I'd get an Asus ST/STX. I've used the headphone amp of both of these cards on my k701s, and the sound was pretty good on both. You'd probably want to get a dedicated amp eventually though.

Another route you could take, albeit a more expensive one most likely, would be to buy the cheapest X-Fi card you could find (or use just the mobo's onboard sound or a USB port if you don't game), and connect to a DAC and an amp or a DAC/amp combo (either USB or SPDIF).

 

[Ypoknons]

The thing is, every headphone output has some kind of headphone amp behind it, usually cheap opamps. iPods, laptops, DACs with HP, sound cards, motherboards whatever. No amp, no sound. So just because it's marketed as a headphone amp in it doesn't mean it'll automatically be as good as one of the dedicated headphone amps, you should rate it case by case...

 

[5aces]

I have not shopped sound cards in a long time and the Bravura review shows me how the engineers are progressing forward with PC sound,since the last time I bothered to look.

Quote:

We can use generic headphones on almost any soundcard but to use many of the higher end offerings from companies such as Sennheiser, Grado and Beyer Dynamic, your source needs to have a little more power than just simple line level output. Headphone Output, AK4396 - The Digital to Analog converter used for the headphone output is the AK4396. This DAC is an advanced multi bit Delta Sigma Architecture unit and has a Signal to Noise Ratio and Dynamic Range of 120dB. This units features oversampling of 128X and an 8X 24bit digital filter and offer a low THD-N value of 100dB. LME49720 (Headphone output) - This opamp has becoming very popular among the DIY crowds and audio designers. According to National Semiconductor this chip is a model variation to the famed LM4562. Some people suggest they can hear differences between the two, suggesting the LME49720 is a higher quality chip and other suggest they are the same. In either case they are far from a generic opamp and they sound quite good. These opamps are all in sockets and ultimately they can be changed by the end user to further tune the sound or improve sound quality using higher grade models.

The review website even shows you what parts to upgrade for more performance.

I was impressed that this inexpensive card could hold it's own for gaming,even though it is considered a music/movie soundcard,producing mostly excellent results on the sound graphs,even concerning the headphones.

Another new feature is:
Quote:

Ground Source Switch This feature has not been seen on any consumer cards up until this point so we figured it was worth noting. This switch changes the grounding source between the chassis or the signal. We have all heard about audio products with hum and other noise issue that can usually be attributed to ground loops. This switch would effectively kill any such issue if your hardware configuration has such a problem.

Often a ground loop isolator was required at additional expense to eliminate the issue when connecting your PC soundcard to an external amplifier.
Hats off to the designers for that feature alone!

 

[Barthandelus]

^^^ Yeah I've noticed static when i turn up my volume really loud on my on-board sound cards with the bose. I'm guessing the ground loop isolator is a feature aimed to reduce static?

I game, mostly console though. It would be nice to have a soundcard to process audio (instead of the CPU) but I doubt that I will notice the improvement in the PCs performance

 

[5aces]

Yes,the static from a ground loop can be a distraction and a built in isolator switch could be a useful feature on a soundcard.
Safer than removing the grounding pin on your equipment!
On closer inspection,the AuzenTech Bravura perhaps uses lower quality DAC's than both the Forte and the Prelude?
It uses the software-based X-Fi.The thing going for it is all channel user replaceable opamps.
The best cards seem to be the Prelude for multichannel and the Essence ST/STX or the Forte for headphones.

I have one of these from Xitel(@ $35!-but handy for in the field laptop/headphone/PA use):

Here is all the spam:
Quote:

Xitel GLI1-S1 Ground Loop Isolator Home Stereo Ever wondered why sometimes your stereo speakers start to hum when you plug certain components in? The most likely cause of humming in audio equipment is due to a ground loop in your home or apartment mains power wiring. A ground loop occurs through differences in resistance in the electrical system. When you connect your computer to your stereo, a path is provided for electricity to flow from one wall socket to another as the electrical system tries to balance itself. This causes your speakers to hum. How does a ground loop isolator work? Xitel’s ground loop isolator has been fully designed, built and tested to exacting standards for high fidelity audio applications. It works by breaking the earth between your computer or audio components and stereo so there’s no path for current from an electrical imbalance to flow. This prevents your speakers from humming! It’s a simple and effective way of eliminating ground loop issues without having to resort to an electrician. How do I install the ground loop isolator? Turn the power of your computer or audio component and home stereo system off. Plug the cable end of the ground loop isolator marked stereo directly into your stereo RCA input. Plug the RCA cable running from your computer or audio component into the RCA connectors on the ground loop isolator marked input. That’s all there is to it! No more ground loop hum!