A few days alone with Crack

[John EH]

Well I've had my Crack together a few days now and am ready to do a review of sorts.  I have the Crack with Speedball upgrade.

One of the first things I've noticed with this amp is that tube rolling affects it more than any other amp I've ever seen.  Probably because the sound is getting pumped right into your ears but the difference in tubes is not subtle. 

Best combo I've stumbled across so far is a Mullard CV4003 and Sylvania 6080.  The CV4003 sounds better than my Telefunken smooth plates A LOT. A whole lot. 

Next 12au7 to roll in will be a Philipps 7316 that I just got not too long ago.  Currently in one of my Foreplay 3's.

Still have a little floor noise at max volume after the Speedball upgrade.  Easy fix.  Turned the volume down 3 or 4 clicks (I have a 100K Goldpoint) and went into my Raspberry Pi system and went to "alsamixer" and maxed the source volume which gave me a little more headroom.

So the floor noise issue is resolved.  The stock Crack was dead silent at highest volume.

I use Squeezeplug (same as a Squeezebox on Raspberry Pi computer) and I control the volume and music via iPhone using a program called iPeng.  Also use Logitech Media Server on my Mac as well.  Headphones are Sennheiser HD650.

Regarding sound quality of the Crack, suffice to say it is just awesome.  As I type this I'm listening to Taj Mahal "Celebrated Walking Blues".  Never heard it this perfect before.  The blues guitar and wailing harmonica is enough to make a fella cry.

If you like listening to music through headphones I'm not sure you can do better than this.  I don't have a lot of headphone sources but I whooped out the Fisher 500C from the closet.  Crack is better.  I have the Sex 2.0 with C4S upgrade.  Crack is better.  I have a couple DAC's with headphone out.  Crack is better.  Plugged some USB DAC's into my Mac.  Crack is better.  Crazy better.

I just don't see how it gets better than this.  A few hundred bucks, and you get the joy of building it and customizing it yourself.

Couple of other observations.  As a conversation piece when people see my SEX amp in the office I'll grab the tranny and pick it up so they can see the guts.  You ain't comfortably picking up the Crack.  It's hot!

Turn off the amp to roll a 6080.  Better wait or get gloves.  It's really HOT!

And if you're serious about the sound ditch the stock volume control.  Get an ALPS Blue Velvet, get a DACT, get a Goldpoint, go to ebay and buy a Chinese ladder attenuator with Dale resistors but ditch the carbon pot.  Or buy the Bottlead attenuator, even better!.   Yeah they gotta keep an affordable price point.  Hell my Goldpoint was $150.  Kinda crazy but I'm glad I did it. 

John

[palmfish]

Thanks for the goodmwrite ups John! Can you tell memhow your upgraded volume pot sounds compared to the stock one? Im getting ready to build and was planning on keeping mine all stock.

[John EH]

Thanks for the goodmwrite ups John! Can you tell memhow your upgraded volume pot sounds compared to the stock one? Im getting ready to build and was planning on keeping mine all stock.

Never heard the stock one so nothing to compare it to.  I have another Crack here due any day now.  I've yet to buy a volume control for it.  It'll probably be built stock.  However if I can get down to Hiroshima I'll try to get an Alps Blue Velvet or something similar.  I have a DACT in my SEX amp and I'm considering removing it and putting it in the Crack because the SEX amp is at work and high fidelity is not really important at the office. We just use it for background noise.

John

[earwaxxer]

Hey John, this modding thing can get a bit crazy, its good to keep a level head about it. Everything makes a difference. Its more about enjoying what you have. I wouldnt mod anything unless I felt I had a "reason" to. In other words, there is something that I would like to improve upon, and I'm motivated to solve that problem. Without identifying a problem, its a bit like shooting in the dark IMO. ALL of our systems can be improved on. Thats what makes the hobby fun, and unlimited, kind of like chess...

[palmfish]

"if you're serious about the sound ditch the stock volume control."

"Never heard the stock one so nothing to compare it to."

Um, ok...

[earwaxxer]

Upgrading the pot is a no brainer. You just have to get your wallet out... I guess that applies to most/all mods! Gota love it.

[adamct]

An Alps Blue costs $15 or less. A VALab "ladder-style" stepped attenuator costs $25. I personally wouldn't spend more, since I think both options are outstanding value for money.

[earwaxxer]

Agreed... the VALab stuff looks very attractive! Gota love China.... at least for something!

[adamct]

More specifically, Taiwan... 

[John EH]

"if you're serious about the sound ditch the stock volume control."

"Never heard the stock one so nothing to compare it to."

Um, ok...

I've built lots of Bottlehead gear and a volume pot upgrade has always been .....errrrr an upgrade to me.  Just hadn't heard the Crack with the stock pot.   Attenuators with good resistors are almost always going to sound better than carbon pots.

John

[palmfish]

Interesting, I had no idea the pots where so easily swapped!

The Alps pots look like it is pinned for mounting on a PCB but the VALab stepped attenuator looks similar to the stock one. Do I just get the "100K stereo log" as a direct replacement? How do I know which wires go where? I'm a complete rookie first time builder...

EDIT: I also see from a photo that the shaft on the VALab is "D" shaped and the stock shaft is round. Is that a problem?

[adamct]

1. Make sure you get the "ladder-style" attenuator from VALab, they have a couple that sound similar, so make sure you get the ladder-style.

2. The pictures are out of date. The attenuators come with a green lead terminal on the end that is clearly marked "IN", "OUT" and "GND" for each of left and right.

[palmfish]

This one?

http://www.ebay.com/itm/Valab-23-Step-Attenuator-Potentiometer-100K-Stereo-Log-/281034318355?pt=US_Amplifier_Parts_Components&hash=item416ef36213

[adamct]

No, this one. But again, the unit that will ship will have an extra bit on the end that makes it very easy to attach the wires.

[palmfish]

OK, I see the difference. Thanks for the help, I think I'll pick one up!

The plastic nub that sticks up fits into the same hole used by the stock unit as a stop?