The Crack - BAC version.

[ALL212]

I've been thinking about doing this for some time and finally got the plate cut and all the parts in.  This is a Crack/speedball on a 10" x 12" plate.  Lots of room to throw some big stuff around. 
Changes:
Replaced the last power supply resistor with a choke.
Cap #1 and #2 are JJ caps.  The first tipped with a 4.5uf Solen, the second tipped with a 1.0uf Clarity cap.  Values were not "chosen" but I happened to have these laying around.
Cap #3 is a 220uf Solen.
upgraded the RCA's.
GoldPoint 24 step attenuator.
Replaced the 9 pin socket with an 8 and wired it for 6SN7 use.
Moved the power switch to the front.
upgraded wiring - Teflon coated silver plated stranded copper for most of the signal path.  Mogami W2534 between the RCA's and volume.

Plate painted - I used black hammered rattle can but heated the plate.  It made a nice matte finish.


Parts installed.  I made a mistake on my drawing in that when I replaced the 9 pin socket I centered the 8 pin.  That moved the screw hole just a bit closer.  Large speedball board still mounts but not with both screws.

Towards the end of the base build I broke the lead off of one of the big clarity caps.  It had been repurposed from a prior build and the lead had been bent too many times.  I installed the stock caps and it tested good.  I then realized that if I had installed the large caps I would have had a very difficult time installing the speedball.  So while waiting for the new caps to arrive I've installed the speedball.

Build sequence.













Original plate Crack next to the larger plated Crack.  It is much easier to put the big stuff in under this larger chassis.

 

[Dnorris]

Looks fantastic, nice work. How do you like the 6SN7 in the circuit compared to the stock Crack/Speedball.

 

[ALL212]

I bought socket adapters from the 'Bay to try out the 6SN7 on my original Crack.  Loved them immediately.  Seems like a much smoother, more balanced tone to them. 

New caps came in very quickly so she's done. 

 

[grausch]

Love the way that looks...really clean way to get all of the desired upgrades in there.

 

[Karl5150]

Myyyy...that's a big one! You fabricated the plate yourself? Very Nice

 

[ALL212]

I used a scan of the Crack plate in Visio and added the rest.  Then had it cut on our laser at work.  This burn failed as the power connector piece didn't fall through clean.  At the beginning it goes over to the left and picks out the correct head for this material.

 

[malloy]

Whoa! Very impressive indeed.  Is that a Wireworld power cord? How did the Crack respond to that?

 

[ALL212]

Wireworld on the Crack - it's better than a stock cord.  But to what degree the improvement is (over my imagination) is hard to say.  I like their theory on how they build the cords and I stay in the low end of the model line.  I did go through a phase of replacing all my power cords with Wireworld and I've found no reason to go back...or forward.

 

[ALL212]

The last modification...or is it?  :

I could get the volume from 6 to 9 but that was it.  Higher than 9 and my ears were bleeding.  I tried 20b of attenuation but that was too much.  This setup is closer to 10db.  I can swing the volume past 3 now and depending on the recording level a bit past that.  Dropping down to 7 or 8 db would probably be better but this works.  One of them is a 51k ohm, the other a 56k ohm.  This is close to what GoldPoint recommends for their 50k volume control.

These are Takman REY 1 watt metal film resistors.  The leads are heavy enough to use as solder points. I understand I don't need this big a resistor but the 1/4 watt leads are too fine to use for as additional solder points.  In order to get all that ground wire in I used a heavy lead from some component and made a ground "post" from left to right channel.

I'm not sure if it's because this is breaking in or because of this mod but I feel the bass came up a bit.  It's nice.

Overall the sound is the best I have here.  I can have headphones on for hours, no fatigue.  Soundstage is amazing.

 

[i luvmusic 2]

One NICE big A55 CRACK......... ;D

 

[HF9]

Looks fantastic!! Having the caps peak out is a nice touch. Be sure not to overtighten those babies, otherwise you'll have electrolytic fluid leak out!