Texas Crack

[InfernoSTi]

I was one of the guys who bought the "PBS Inspired" Crack Amp sale (I bought two, actually).  

Having a poor weekend last week (my upstairs neighbor had a 1" water line break and flood her and my apartments for three hours before it got turned off), I was in need of some good vibes. So I threw together one of my Crack kits.  Emphasis on "threw" as I managed to toast a few parts in the process.  But I got it built while the carpet was being pulled back/pad being removed, drywall having holes cut in it, and blowers installed for four days.

I mangled some LEDs, a resistor (thanks Doc and Queen for replacements), and a cap and diodes (didn't realize this when I got my replacement parts...and some badges I was meaning to order).  Note to self: self, don't work on amps when upset, lacking sleep, and generally in a poor mental state.  On the other hand, it was great therapy and I managed to make a working headphone amp!  

Well, kind of working...it sounded GREAT but there as a ton of noise. It sounded great but for the hum/buzz/whine.  I couldn't figure that part out...everyone said it was pretty silent so I was perplexed.  Swapped tubes. No help.  Then I took some time off this weekend and came back to the obvious solution: rework my rectifier/first cap and see if that helps. Well, it did help.  Now the Crack amp is silent and still sounds GREAT!  

I built it without a volume pot because I use an optocoupler pre amp.  I substituted the 100K pot with Kiwame "green" resistors but will probably swap them out for some PRP "reds" which I really like.  The "greens" sound good...smooth and nice...but the "reds" are so clean and transparent.  It's like they aren't even there.

I have two headphones that I'm able to use with the Crack: Sennheiser HD600 and MB Quart QP400.  They both sound great...and different from each other, which is nice to be able to roll headphones.  

I have to say this is the nicest headphone amp I've owned.  I've got/had a couple of simple headphone amps, nothing special, so I'm no expert. But like you guys already know, this is something special when matched with proper impedance 'phones.  

Once I get done with my move (yep, I'm moving next week...the flood? Missed moving by THAT much), I'll stain the base "Miniwax Ebony" and finish it up with a "Miniwax Satin Poly" both wiped on by hand and several layers of each. That will match my Stereomour very nicely.  I also got a couple of BH badges, one for the Crack and one for the Stereomour.  

What a great headphone amp and what a fun project to build!  Just what I needed to make the raining day (inside) go away...

Cheers,
John

P.S. I've got two tubes I'm going to roll in place of the stock 6080s: first up, a 5998A GE JAN that should sound sweet, and, second up, a 1963 metal base 7236 Sylvania that I hope to be the bomb!

[Jim R.]

Hi John,

Wow, sorry about the indoor storm -- I hate it when that happens :-).  Glad you got a Crack and both those sets of headphones should be great withit, especially with the outboard LDR atttenuator and no pot in the amp itself.

Congrats on another BH amp and a a new place to live.

-- Jim

[matthewmckay]

"Note to self: self, don't work on amps when upset, lacking sleep, and generally in a poor mental state. "

Ha Ha ...  so true.

[Bolivar]

"Note to self: self, don't work on amps when upset, lacking sleep, and generally in a poor mental state. "

Ha Ha ...  so true.

Indeed.

When I sit down to build something, I'm often unable to stop until I'm finished. No matter how tired and frustrated I get, I have to keep going and the workmanship suffers. Which leads to revisiting ugly solder joints that were done in anger.

By the way I have the same 7236 Sylvania. Very tight and articulate, would do well when paired with a warm sounding driver tube.

[InfernoSTi]

Thank you, guys, it's been really a fun project.  I recommend to anyone wanting to get started with DIY or who is looking for a headphone amp. 

Jim, I appreciate your wishes on the move...I'm a bit unsettled until that happens but am looking forward to being in a house where I can start to settle in a little more.

Matt...you've been there, too it sounds!  Hindsight is always 20/20, right?

Bolivar, I'm exactly as you described. Once I committed to starting, I wasn't going to let up until I was done.  Your description of the 7236 Sylvania...light and airy...is so right.  I would add this is the quietest of the three tubes.  Do you have a suggestion on a complementary driver tube to match?

John

[Bolivar]

I'm still going through my stash of tubes, but a GE 5963 seems nicest so far.

[InfernoSTi]

I'm still going through my stash of tubes, but a GE 5963 seems nicest so far.

Interesting...please feel free to post any other suggestions as you come across them.  I have really enjoyed rolling my driver in my Stereomour 2A3 amp...what a sonic difference it can make.  Oh, and I noticed I miss read your comments...tight and articulate somehow became light and airy!  I don't know where my eyes were...not on the post, that's for sure.  And yes, tight and articulate is right...they don't have a lot of color or midrange bloom.  I like it very much.