Crack and Grado SR-60

Nocturnal · 4601

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Offline Nocturnal

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on: September 29, 2010, 05:36:03 AM
  Howdy folks, I'm very interested in purchasing and building a tube kit and the Crack seems the perfect kit for a beginner.  However, I've seen some postings re its limitations with 32 ohm headphones, I have a pair of Grado SR-60s.  How poor is the performance with these headphones?  Many thanks for any replies!




Offline Grainger49

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Reply #1 on: September 29, 2010, 06:02:33 AM
They explored this a little while ago:

Crack Performance With Low Impedance Headphones




Offline ironbut

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Reply #2 on: September 29, 2010, 07:54:47 AM
Hey Nocturnal,

If you've read the thread that Grainger linked to, I think you can see that the main issue would be a higher bass roll off. With some cans which are low impedance and low sensitivity, the issue becomes more pronounced.
That said, I used to own a pair of SR-60 (or 80's?) and I found them to be very easy to drive. In fact, I used them almost exclusively directly out of a Walkman (portable CD/cassette).
If it's only the SR-60's that you're worried about driving, I'd build the amp stock and try it that way for a bit. If you listen to a lot of music with significant low bass, you might want to change the output caps to a larger (330uF) Panasonic ED series cap. Take it from someone who usually cap rolls to excess, those electrolytics sound very good in that position.

BTW, I listen to my Audio Technica AD2000's on my Crack all the time and love it. The AD2000 are 40 ohm and the output caps are 100uF. I'm sure that the lower bass is more rolled off than it should be but I don't really notice it (iron-ears?).

steve koto


Offline Nocturnal

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Reply #3 on: September 29, 2010, 10:05:35 AM

If it's only the SR-60's that you're worried about driving, I'd build the amp stock and try it that way for a bit. If you listen to a lot of music with significant low bass, you might want to change the output caps to a larger (330uF) Panasonic ED series cap. Take it from someone who usually cap rolls to excess, those electrolytics sound very good in that position.

BTW, I listen to my Audio Technica AD2000's on my Crack all the time and love it. The AD2000 are 40 ohm and the output caps are 100uF. I'm sure that the lower bass is more rolled off than it should be but I don't really notice it (iron-ears?).


  Great info, guess I'll be getting something to build for my birthday :)  Thanks!



Offline crappyjones123

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Reply #4 on: October 04, 2010, 04:30:10 AM
I have a pair of iGrados that i use for testing stuff. it uses the same drivers as the sr 60 - volume wise no issues. plenty of juice with the original caps. the bass itself is pretty muddy on the headphones to begin with. the amp helps accentuate the mids and highs but makes the lows pretty boomy. not necessarily anything but but the amp sounds MUCH nicer with my 650s. obviously the igrados are 50 bucks vs the 300 for the 650s but thought i would mention it just for a comparison.

forgot to mention im using a 421a and amprex 12au7.
« Last Edit: October 04, 2010, 04:31:44 AM by crappyjones123 »