[tintin47]

Quote:

Originally Posted by gbx2006 /img/forum/go_quote.gif I just purchased a pair of k701 headphones, and while I absolutely love the sound of them, they distort as soon as I turn the volume up to a normal listening level. I thought perhaps it was just a problem with this pair of headphones, but now I see after the purchase that this is a problem with quite a few people on this forum. Has anyone had a chance to compare HD650's to K701's and did you notice that the HD650's had any distortion like the K701's do? Also, I am running a PS Audio DLIII DAC connected to a RSA Raptor. I have tried 3 other pairs of headphones that I own, (DX1000, Edition 9, D5000) and there is no distortion that I can detect at a normal listening volume level with any of these headphones, so I do not believe it could be coming from my source or amp. Thanks to anyone who can help.

If your 701s are distorted it means that there is something wrong with them or that your amp isn't capable of driving them. If you can try them with a different amp, do. Otherwise, they might be defective. Certainly it is not what the 701 is supposed to do.

 

[gbx2006]

Thanks for all of the great replies.

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif Are you sure your amp isn't clipping? I just cranked up the K-701 (off head) to an unlistenable level and didn't hear any bass distortion. The K-701 is a fairly difficult load to push, anyhow. 62 ohms and requires a bit more voltage than most.

How can I tell if my amp is clipping, and would I notice it on other headphones besides the K701's?

Quote:

Originally Posted by cotdt Give it about +6dB of bass boost and any headphone will distort at normal listening volumes.

The distortion is not from using EQ or bass boost since neither is being used. I personally would rather buy new tubes or a new source, then have to mess with the EQ to change the sound haha.

Quote:

Originally Posted by b0dhi The K701 are a lot like a subwoofer outside of its enclosure. They have a very open design, and rely moreso on diaphragm displacement than enclosure resonance to generate bass, unlike many other headphones. If you're using an EQ to apply bass boost by ear until you get satisfying bass, you could easily cause it to reach its maximum excursion (i.e., distort). If you aren't EQing them, you probably have a faulty headphone, or you might have damaged the drivers in the past.

The headphones are brand new, and I have only played them for about 50 hours so far. Maybe I just need more burn in time?

Quote:

Originally Posted by milkpowder Definitely not. I've had the K701 play and extraordinarily loud levels (basically as speakers), and they don't distort. It's either the amp/tubes not being able to handle the power - unlikely, or something wrong with the headphones themselves (eg loose driver) - more likely. I'm not very tech-savy as far as my understanding of amp designs go, but it would seem unlikely that the Raptor cannot provide enough voltage or current to drive the K701. It could be a bad tube, but you would probably hear problems with your other headphones. Have you been able to replicate the problem with another source/amp?

I have tried to roll different tubes, and still have the same result. It is unfortunate, but I do not have access to any other source or amp right now. I used to have a nice portable setup but it is now sold.

As EtherealApril, olblueyez, ph0rk said, it might just be the Raptor and K701's just do not play well together. If the HD650's sound excellent though the Raptor, then I would think the problem is not that the amp can not drive the K701's, unless I am thinking about it the wrong way. I mean, isn't the HD650 harder to drive then the K701 is?

 

[Uncle Erik]

Quote:

Originally Posted by gbx2006 /img/forum/go_quote.gif How can I tell if my amp is clipping, and would I notice it on other headphones besides the K701's? If the HD650's sound excellent though the Raptor, then I would think the problem is not that the amp can not drive the K701's, unless I am thinking about it the wrong way. I mean, isn't the HD650 harder to drive then the K701 is?

You need to think about it in terms of how difficult something is to drive. And it's not just the headphones' stats. Headphones perform depending on how the amp performs. They're closely interrelated.

I couldn't find the output impedance on the Raptor, the site just says that it can drive a load as low as 32 ohms. But the amp does have an output impedance and that has a lot to do with performance. OTLs have a tough time driving heavy, low impedance loads. The K-701 is 62 ohms and the HD-650 is 300 ohms. IIRC, the Stereophile listing of headphones (it's out this month) says that the AKG needs a bit of voltage to run right. My guess is that the amp is struggling to deliver enough power at a fairly low (for headphones) impedance and is distorting or clipping as a result. Unless low impedance headphones are very efficient (like Grados) you're usually better off with a transformer coupled tube amp (with the transformers tapped for a low load), solid state, or an OTL with at least a couple watts of power to overcome the impedance mismatch.

 

[ph0rk]

K701's are low impedance, but low sensitivity - this means they need a lot of voltage swing - something SS amps with beefy 24-30v power supplies can do well.

I assume that there are tube amps that can manage this too, but I don't really do tubes - I do see many of the mid-lower end amps with minimum impedance numbers, so that might be something.

Then again, others seem to have used the k701 with the raptor, so that might be something too: http://www.head-fi.org/forums/f5/rsa...g-k701-267420/

 

[RuiCanela]

Change amplification and after you'll change your mind about it....

 

[Ajani]

Quote:

Originally Posted by gbx2006 /img/forum/go_quote.gif The headphones are brand new, and I have only played them for about 50 hours so far. Maybe I just need more burn in time?

Nope, burn in shouldn't have anything to do with distortion... I have a new pair of AKG K701s (probably just 14 hours on them), driven by a Benchmark DAC1 and there is no distortion at normal listening volumes or above...

 

[olblueyez]

Ditch the 701s and get the 650s, then you can tube roll and get whatever sound you like.

 

[gbx2006]

Thanks again for helping everyone! This is the best forum for 'learn about audio', worst forum for 'how to save money'.

I think will buy the HD650 and return the K701 for now. I may repurchase the K701 again, after I am running balanced from a solidstate amp, hopefully by spring. I hate the idea of having to go SS for a balanced system, but I really like my car, which is something I would have to sell in order to buy something like the B-52 haha.

 

[nikongod]

What tubes are you using? have you tried others?

The Raptor can drive R10 and grados to levels suitable for ray samuels (he listens loud), I seriously doubt IT is the limiting factor with a K-701.

 

[gbx2006]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif What tubes are you using? have you tried others? The Raptor can drive R10 and grados to levels suitable for ray samuels (he listens loud), I seriously doubt IT is the limiting factor with a K-701.

I have tried using these tubes with the K701:

12AU7 Amperex Bugle Boy Holland 1962

12BH7A RCA Black Plates D Getter 1950's

12AU7 Telefunken Germany Smooth Plates 1972

5687 WB Tungsol branded Raytheon 1950's

5687 WB Philips (These are the stock tubes that came with the Raptor. Not sure which year they are.)

 

[Peter Pinna]

I have never heard the K 701 distort. My best guess is that there is something else wrong in your audio chain. My second best guess is that the K701 you have is defective.

 

[ZephyrSapphire]

Every K701 I heard during meets distorted at the lower frequencies. But I blame the amps being unable to drive them. Tube amps make them even worse.

 

[hentai]

Quote:

Originally Posted by olblueyez /img/forum/go_quote.gif Ditch the 701s and get the 650s, then you can tube roll and get whatever sound you like.

Yes , tube roll and you still get hd650's sound.

If you like 701 alot, invest on a good solidstate amp. CI or Gilmore lite or EC/SS

 

[chobint]

I don't want to make a definitive statement, because the amp-headphone synergy could very possibly be the cause but...

I owned a pair of k701's previous to owning my current hd650's. I found the k701's to distort badly in the song Mayberry (go figure like one of the three country songs I can stand) when the mid-bass is rolling during the long held vocal notes ("...sunday waaa(distortion)aaas a day of rest..."). My hd650's do not present the same distortion as the k701s in this respect.

BUT...that said, I was also using an OTL tube amp (Cavalli Bijou), which means there is some possible bad voodoo between OTL and k701. Or perhaps the k701's just distort when the bass hits in the middle of a mid-high note.

Maybe some brave soldier with a k701 and an SS amp can crank Mayberry up for us and tell us if he/she notices any distortion.

 

[Shahrose]

i've never heard a high end headphone distort. if the K701 distort at bearable volumes, then that's quite surprising. with this many complaints, it can't just be blamed on "bad amp synergy." maybe the K701 are just weak at bass reproduction?