Crack build impressions

[gwompki]

So I built my Crack about 3 weeks ago and have been enjoying it immensely.  Thought I would share some build and listening impressions.

First of all the instructions were fantastic.  I've built a lot of audio related kits over the years and these were some of the best instructions I've ever come across.  I'd say it took me about 6 hours with a couple of breaks in between to wire everything up.  Add on about 30-45 minutes of troubleshooting nasty hum that turned out to be a cold solder joint  on the ground for the headphone out. 

Now, on to the wood work.  I was dreading this part. I have zero experience working with wood and thought I would most definitely screw something up.  The cabinet assembly was very straight forward and took about 15 minutes.  The finishing on the other hand took a solid week to get it to where I was happy with it.  Once the cabinet was assembled I borrowed a random orbital sander and sanded with a 220 grit pad.  After a lot of reading, I decided to go with an ebony Minwax stain due to its availability.  I also got the Minwax pre-stain treatment and Minwax poly for the clear coat.  I found the pre-stain to be very effective on some old pieces of 2x4 I had laying around from when my house was built, so I would highly recommend that for any n00bs like myself.  I applied the ebony stain very lightly, and wiped it off quickly.  Surprisingly it came out half way decent IMHO.  Much more dark brown than ebony which is what I was hoping for.  After waiting 24 hours I began applying the poly.  I did 3 or 4 coats of poly waiting 24 hours between each coat.  After the first coat I did a light sanding with 300 grit sand paper, but I did not do that after the 2nd or 3rd coats.  All in all I am pretty happy with its appearance.  Oh yeah I hit the bell cover with 2 coats of gloss black Krylon and it looks pretty good I must say.

A couple of other changes I have made initially were to use an Alps Blue Velvet pot and a new knob to accommodate the longer shaft of the Alps.  I rolled the dice and bought an Alps pot from a Chinese Ebay seller and I think I lucked out.  It very well could be fake but I checked resistances before installing and both channels were very closely matched.  I listen at fairly low volume so this was important to me. 

Now as for listening impressions, all I can say is the hype is real.  Incredibly good match for the HD-6XX.  The first time you fire it up with the stock tubes is a magical experience.  It truly is an addictive sound.  I had to be torn away by my family the first night I was listening to it and several evenings since. 

I've been rolling several budget tubes (have not paid over 10 dollars for a single tube) I scored from eBay while waiting for the kit to ship. Here's what I have tried so far:

6080/6AS7G variant:
Tung Sol 6080 - Pretty good, a bit light on the bass, but rather involving.
Tung Sol 7236 - Wow, exciting sound, definitely solid state sounding.  Very punchy, but you lose some of the tube magic imo.  As good as it sounds, I haven't spent a ton of time with it due
                        to not being "tubey" enough
Stock JAN 6080 - Weighty tube, both physically and sound wise.  I very much like this paired with an RCA clear top
GE 5998A - This thing gets hot...really hot, hotter than the other tubes which are hot!  Sound is similar to the 7236, maybe a bit warmer around the edges
Winged C 6H13C - Super cheap, very readily available.  I really like this tube.  It pairs well with almost all of my 12AU7 tubes.  Very good bang for your buck.  Its not perfect, is a little
                          woolly in the bass, maybe a tad bass light, but an incredibly good value.

12AU7
Stock Tube - Can't tell the brand
Tung Sol - Pretty good.  Warm, soft sounding, some detail lost.  Very cheap and readily available.
Mullard 12AU7WA - Great tube.  Very good balance of detail and warmth.
RCA clear top - I love this tube.  Maybe a bit brighter but pairs well with all of the 6080/6AS7G variants I have.  Lots of detail, increased sound stage.  Great bang for your buck here. 

I think overall my favorite pairing so far is the 6H13C and RCA clear top.  I want to try a Tung Sol 5998 but I'm a cheap skate and holding out for the right deal.  Yes I realize I  could have bought a 5998 by now with all of the other tubes I've bought, but I enjoy tube rolling too much

I plan to install the speedball over the holidays and looking forward to hearing what sort of changes that brings to the table. 

 

[Paul Birkeland]

The base came out nicely.  I wonder how a SEX amp would sound on those Overnight Sensations!

 

[gwompki]

Don't you tempt me! My wife would have my hide.  ;D Hopefully some day soon though.  I'm actually taking delivery of a fairly nice set of floor standing speakers tomorrow and the wheels are already spinning about which bottlehead amp to drive them with.

My dad actually made those (overnight sensations)for me.  He is an avid woodworker and super talented.  I didn't inherit that gene unfortunately.

 

[Paul Birkeland]

I ended up making a soundbar based on that design:

 

[gwompki]

I ended up making a soundbar based on that design:

That looks awesome (as does that impressive looking rack of gear to the right). . I imagine it sounds as good as it looks. Is it integrated into the mantle or did you replace the mantle with the mega OS sound bar?

I would love to try to tackle a set of the Jager speakers some day.  They look amazing.

 

[mcandmar]

I like how you found the sweet spot in three weeks, RCA clear top and a 6H13C.  You can spend a whole lot of money chasing rare and interesting tubes and never find much of an improvement.

...those speakers are crying out for a S.E.X amp

 

[kgoss]

Great job finishing the base!  The pre stain or sanding sealer step is the key to getting an even color on open grain wood.  A lot of people skip that step and end up with a blotchy finish with dark spots where the wood grain absorbed more stain.  For someone with no woodworking in their genes you did an outstanding job!  The amp and base both look great, enjoy the fruit of your labor!

 

[gwompki]

Great job finishing the base!  The pre stain or sanding sealer step is the key to getting an even color on open grain wood.  A lot of people skip that step and end up with a blotchy finish with dark spots where the wood grain absorbed more stain.  For someone with no woodworking in their genes you did an outstanding job!  The amp and base both look great, enjoy the fruit of your labor!

Thank you for the kind words.  It actually makes me want to take on more wood working projects because of how enjoyable it was.  I never got it as a kid hanging out in my dads shop...I always wanted to bang around with his soldering iron and could care less about the wood.  Now I understand the appeal 30 years later lol. 

 

[gwompki]

I like how you found the sweet spot in three weeks, RCA clear top and a 6H13C.  You can spend a whole lot of money chasing rare and interesting tubes and never find much of an improvement.

...those speakers are crying out for a S.E.X amp

Yeah I'm trying to resist the urge to buy more and keep playing with what I have now.  Unfortunately I can definitely see a 5998 in my future. 

 

[gwompki]

Hey guys.  I wanted to post a quick update.  I installed the speed ball about 10 days ago and listening off and on with it.  All of my voltages were within range except for OA and OB were about 5V higher than what the spec called for, and all LEDs lit up with no problem.  I've been listening to it and rolling tubes almost every day during that time to try and let my ears adjust before I made any comments.

The sound has become fairly bright and detailed, but it seems that this is at the expense of a diminished low end and slightly recessed mids.  According to everything I have read about the improved bass response from the speed ball, makes me think I might have something out of sorts here.  Is it possible something is wrong or is it just a case of the sound of the speedball just isn't for me. If there is anything obvious I might be missing let me know.

Thanks!

 

[Paul Birkeland]

My suggestion would be to listen to the amp for another 2 to 3 weeks, then remove the small board and put the 22.1K resistors back.  The Speedball will reduce the harmonic distortion produced by the 12AU7 front end, and this reduced distortion will appear to remove some bass (it is reducing bass harmonics), but without the added distortion, the bass is significantly clearer.

 

[gwompki]

Sounds good Paul.  Will give that a shot.  Thanks!

 

[gwompki]

So I got impatient and went ahead and removed the board feeding the 12AU7 last night and things are better.  Definitely more low end.  Actually I have found that it sounds fantastic, but I'm having to turn the volume up a good bit more to get that "magic" sound.  Pre-speedball I would typically keep the volume at about 9 o'clock and now I'm up around 10-11.  I typically prefer to listen at lower volumes so its taking some adjustment.  Definitely not ear splitting loud by any means.  I feel like previously I was able to get great sound across the whole spectrum at lower volumes, but now if I keep it at the same volume then the sound is wonky.  It's almost like as I turn the volume down the mids/bass get quieter and the highs stay the same volume.  As I begin to turn it up towards 10 o'clock the bass and mids fill in again and the highs don't sound so shrill anymore. 

Is there any science to explain why the speedball would cause such a phenomenon or is it entirely psycho-acoustics at play?  Feel free to tell me I'm crazy...you won't be the first person to do so lol  ;D

 

[Paul Birkeland]

You  prefer the presence of some additional harmonic distortion (usually mostly 2nd order with triodes).  The added distortion may be filling in the low end a bit, and on some headphones this can be helpful.

 

[gwompki]

Good stuff.  I'm really enjoying it now.  I still might switch back the stock build eventually as my favorite time to listen is in the mornings with a cup of coffee when my ears aren't fully awake.  I think the stock sound is more friendly for that type of listening  vs the more bombastic and engaging speedball.

BUT...I'm going to give it at least 30 days in this config before I go making any more changes.