Heaphones - lowZ ... and, maybe higher Z.

[Laudanum]

First off, Happy Easter.

Im sure that some of this has already been brought up numerous time but Im no guru at this stuff and can use all the advice/input that I can get ...

I recently ordered the Crack kit and patiently await it's arrival.  Want to use it in a table-top set up right beside the old recliner. 
I have a couple pairs of relatively low-z phones and I have read about possibly changing the stock 100uF output caps to 330 - 470uF and resistors at the phone-out jack to 1K in order to lower -3db point for lowZ phones (at the cost of some power output, right?)
Is this still considered a potentially viable option for lowZ phones?  If so, I'll pick up the parts to have on hand.  I have read that the Panasonic ED series caps are the recommended choice. What about resistors, any preference? 

That aside, Crack may be a good excuse to purchase some barely used 250 ohm Beyerdynamic 990's that were offered to me a while back and still are available.
I havent been interested in the Beyers because they are 250 ohm and havent had anything that I thought would be well suited to drive them.
In fact, I wasnt even thinking about them before purchasing the kit.  But now it's got me thinking about the Beyerdynamics again.

Has anyone used the Crack with 250 ohm Beyers?  Better question may be, in general, would 250 ohm Beyerdynamics seem like a good match for the Crack?

Sorry if my first post here is too much but I appreciate any advice and input anyone has to offer.

Thanks.

[JC]

OK, I'll take a shot at your general question: I think  250 Ohm phones sounds about ideal considering the output impedance of the Crack.

But, what would probably most helpful to those who know better than I would be if you could list both the impedance and the sensitivity of your current phones, along with any you think you might want to try.  That, hopefully, will give someone enough info to really answer your questions authoritatively.

[Laudanum]

Wow, didnt expect a reply today, I appreciate it.

Actually, one of the Headphones is a cheaper Sony on the ear that my wife uses.  I believe that they are 32 ohms.  They are 20 or 25 dollar phones so I wont even count those.  
I have a Senn HD 555.  Not bad for the money but not very extended up top but I have been using them mainly with a Cowon J3 lately when Im not using the IEM's.  I guess they are discontinued by Senn as I had to find their specs in the archives.  50 ohms and a rated 112db (at 1Khz 1V).  The J3 drives them pretty well so they must have decent sensitivity, stated spec not withstanding.  

Thinking about it, at 50 ohms, they may very well be fine with the amp as is.  -3db should be around 32hz with the 100uf caps according to ... http://www.bottlehead.com/smf/index.php?topic=789.0 .
I dont listen to much of anything with low, low bass and not sure the 555's would do much, if anything, with 32Hz.  But if Im missing anything here or if Im just dead wrong, please let me know.

Other than that I have some old AKG 141's from the 80's ... 600 ohm.  I havent had anything that could drive them since an early 1980's Sansui integrated died in the late 90's.  They need to go into AKG for everything but new drivers.  I used to love those phones but find them a bit boring now although, as I said, I have nothing currently that can drive them to any decent listening level.  Crack will be a good excuse to get them re-furbished, may as well see what the Crack can get out of them.

So really, just the Senn HD 555's at 50 ohms.   And, of course the 250 ohm Beyerdynamic 990's, which you already helped with.


Thanks

[Doc B.]

Yes, you will be better off with 250 ohm headphones than trying to make the amp work with low Z phones. You can increase the coupling cap size but the bass control still won't be as good as with higher Z headphones.

[Laudanum]

Yes, you will be better off with 250 ohm headphones than trying to make the amp work with low Z phones. You can increase the coupling cap size but the bass control still won't be as good as with higher Z headphones.

Thanks very much for taking the time to reply today.

I think I'll snatch up those Beyerdynamics then.   I'll leave the amp alone, and see how it sounds with the Senn. 555's.  They dont thrill me much so I wont be dissapointed if the turn out to be a poor match.

Doc, how do you think the old 600 ohm AKG 141's would fare?  I dont believe they are very efficient but worth re-furbing you think, to try on the Crack?

Thanks

[Paul Joppa]

The AKG 141 (98dB sensitivity) needs only a bit more voltage than the Beyer 990 (101dB), according to specs I can find. I'd expect the Crack or S.E.X. to drive either quite loud.

The Beyer impedance plot (at headroom) shows a distinct peak at 100Hz, so Crack may give a bit of bass emphasis - a couple dB perhaps? I couldn't fin an impedance plot for the AKG, but its higher impedance makes it less sensitive to this.

My 2 cents - this is theory, not listening!

[dubiousmike]

The crack will handle those Beyers with ease.  I have a pair of 250 ohm DT880's (similar to the 990's but with a flatter FR curve), and they are driven very nicely via the crack.

My personal preferences tend to run towards the Sennheiser house sound.  So if you happened to find a pair of used HD600's or 650's in the same financial ballpark as those 990's, that's where I would spend my money.  Subjective preferences aside, the 250 ohm Beyers are also an excellent match with this amp - and their comfort is unparalleled.

[Laudanum]

The AKG 141 (98dB sensitivity) needs only a bit more voltage than the Beyer 990 (101dB), according to specs I can find. I'd expect the Crack or S.E.X. to drive either quite loud.

The Beyer impedance plot (at headroom) shows a distinct peak at 100Hz, so Crack may give a bit of bass emphasis - a couple dB perhaps? I couldn't fin an impedance plot for the AKG, but its higher impedance makes it less sensitive to this.

My 2 cents - this is theory, not listening!

990's arent exactly bass heavy and while I am not a bass head by any means, I actually dont mind a little more low end than what would be considered completely accurate.  I know they dont have as flat a curve as some of the other Beyers.  They seem to have a little more energy in the bass/midbass but I dont think a couple more db's will hurt.  But this is from my listening to other folks Beyers, I dont own a pair myself to be really familiar with them ...yet.   But it probably is what has made me a bit partial to the 990's.   

Thanks for the info Paul.

[Laudanum]

The crack will handle those Beyers with ease.  I have a pair of 250 ohm DT880's (similar to the 990's but with a flatter FR curve), and they are driven very nicely via the crack.

My personal preferences tend to run towards the Sennheiser house sound.  So if you happened to find a pair of used HD600's or 650's in the same financial ballpark as those 990's, that's where I would spend my money.  Subjective preferences aside, the 250 ohm Beyers are also an excellent match with this amp - and their comfort is unparalleled.

The incentive to send those AKG's in (and spend some more money in the process) keep's on coming.  Definitely need to get them refurbed then.
I really used to love those phones.  Maybe I will again, maybe not but they are good phones and worth fixing.

As I mentioned, I do have the Senn 955's.  They are really the only full size phones I have been listening too lately (I forgot that I have the M-audio Q40 as well but I havent listened to them in a while ... bottom heavy but ok as a different flavor every once in a while).  The 555's arent in the league of the high end Senns but do give a taste of the Senn sound.  I like them well enough.  I seem to have an affinity toward those Beyers though.  But again, without living with them I cant be sure.  These are the 990 pros by the way, not the premiums.  A friend of mine owns them.  He finds them uncomfortable (skullcrushers).  They do fit more snugly than the premiums from what I hear.  Not sure if they sound any different.  I havent heard the 990 premiums I dont think.  I have heard some of the others though.  Anyway,  I find the pros very comfy, as you mention ... probably due to my small egg-head :-).  For $120 bucks, it's worth it to me to find out if it has just been an infatuation or not.   The 990 Pros can be had new for around $170 if one shops around a little.  I dont even think these are burned in, they look brand new.

I kind of jumped at this thing but seems to be coming together for the good with the AKG's just needing a makeover and the deal on the Beyers.

Thanks for the input, I appreciate it.