[buke9]

I'm in the first batch cool. Will be here in a week. Might have time to build it before the Dayton meet. Hopefully the led fixes my old one.

 

[Maxhawk]

  Has anyone ran 50-70uF value for the output caps? How'd it sound? I understand 100uF is recommended, but anywhere from half to twice the stock value should be sufficient. Experimentation is in order for those who wish to do so? That is, without hurting anything correct? I'm curious to try a few values of different caps I have, and the total would be 70uF for each channel. 
 
Happy listening,
 
-T
 
Edit:
Confirmed it is OK to go half to twice the value. What about going past that?

 
It's a simple first order high pass filter. With C in microfarads and Z = headphone impedance, you can calculate the -3 dB frequency with this formula:
 
f3 = 159000 / (C * Z)

 

[Tom-s]

  Pardon my lack of knowledge on this subject but are those the capacitors use the Mundorf  EVO 100 ufd caps for? If so going to a different value results in pretty good savings sometimes at the same voltage rating it would appear. That in itself looks like a good reason to try the other values.

 
I'm using 90uf (3*30uf) paper in oil caps. Costs were 35€ shipped for 10 pieces (only used 6).
 
Search MBGO 30uf on ebay.

 

[Hofy]

Thank you Doc. I have a tracking number.

 

[Paladin79]

I also have the tracking on my amp and one to build as a standard before I start modifications. I have to finish installing french doors today and then I hope to see if I can build a stock Crack amp in six hours. 

 

[i luvmusic 2]

Have fun!

 

[i luvmusic 2]

I just finished installing a top handle for my amp.
(Sorry for the crappy phone camera)

 

 

 

[attmci]

  I hesitate to say what I have spent so far on my modifications of two kits and I am not exactly done yet. I do plan to have added room inside the cabinets for any changes I make. The one I keep for myself may well have a row of brass toggle switches on one side with appropriate old school bulbs but I have not thought that all the way through yet. They may end up on the matching headphone stand I plan to build with a cable connecting it to the amp. I may hide a dac there as well. I do not want anything real modern looking noticeably hooking right to the amp. 
 
There is suddenly a new listing for a Crack on Ebay, $875 with walnut base. Pretty looking but I do believe the top plate is spray painted. I can definitely claim mine will be professionally assembled if I post one there but I have seen the Mundorf EVO caps for sale and $150 for those seems a little pricey but it has been a few weeks since I checked some out. Mine will most likely have dual Alps pots but those are one of three brands I will be testing. TKD makes a good volume pot but I always wonder when I see them selling for $100 out of Hong Kong, same with Alps when they are $10 out of China. I prefer going through known distributors for some parts.

deleted.

 

[Paladin79]

 
Crack is not as popular as before. I doubt that $875 one can be sold in the coming weeks. No one will purchase that broken one for sure.
 
To max out a Crack, you need GEC 6AS7G and driver tubes like a 7316 which cost a lot of $$ these days.

that is good advice. My purpose is not to make a killing on one and if I can get good results spending $30 on caps instead of $150, that is probably the route I will choose.
The electronics is easy for me so I am concentrating on building what I consider a pretty amp, headphone rack, and matching headphones...Steampunk style. It takes a lot to impress some scientists I hang with so I want something jawdroppingly cool looking when completed. I will strive for excellent sound as well. I am trying to insure my modified version does not sound worse than an original and I am paying attention to the advice of experienced builders on capacitors, volume pots, etc. I am doing individual left and right volume controls, I prefer that setup and want to try ladder pots along with more conventional pots.
 
I paid less for my extra Crack kit than the price the broken one is asking lol. 
 
Interesting handles Luvmusic. if all goes well I will only have two tubes and the transformer showing on the very top. I got my work done on the french doors so now I need to take time for a cold beer and some lunch then on to the crack build. 
Once again I will just do a stock build today and mark the top copper plate, final builds will come later once I receive more tools and more volume control pots. 

 

[Tom-s]

Experiment #242.4: Telefunken ECC81 (ribbed) in the driver seat for a few hours. 
Voltages are good with R1 = 470 Ohms (like E80CC, ECC40).
Sound is nothing special. Lean tight bass. Like the average 12au7 but less dynamic, more congested.
I like the 12au7 Telefunken's (ribbed) better.
 
Beware this type of tube has a lot more gain (no problem for me since i use Crack as a poweramp only).
And it might heat up your Speedball a bit. 

 

[Paladin79]

Power amp huh? So perhaps two could be monoblocks.

Too nice of a day to stay indoors but after three hours I am close to installing the speedball upgrade.

I just got a set of circle cutters in the mail so I should be attacking some copper plate soon. I also got more Alps potentiometers but I need to hear an original crack before I decide on all changes.

My second kit should be here in a few days from Bottlehead.

Tom

 

[nimmen]

 
Crack is not as popular as before. I doubt that $875 one can be sold in the coming weeks. No one will purchase that broken one for sure.
 
To max out a Crack, you need GEC 6AS7G and driver tubes like a 7316 which cost a lot of $$ these days.

I would suggest 5998 or WE 421A + good 6sn7(I use brimar cv1988) with adapter, at least that's what i'm using, but not all 5998 domino plates are the same, have two, they do differ a lot, but construction differences are very small and subtle... Crack is absolute beast(with correct headphones) when paired up with great tubes and modded with care, next step for me would be stax probably, but I don't think i'll leave my modded crack for a while as can't find anything that sounds same in 2-3x the price range...

 

[Timoteo80]

Just letting everyone know that the first big batch of sale Crack kits shipped out this afternoon. The rest will follow early next week. Thanks to everyone who ordered, we appreciate the support!

No thank YOU for the amazing Crack you designed!!

 

[MIKELAP]

Anybody ever tried a ECC31(NR73/1280) type tube in there Crack it is a very nice sounding tube used with an adapter, normally used in a 6SN7 socket in this case a 6SN7 to 12AU7is added .Only thing heater current is rated at .95A used with a 5998 which is rated at 2.4A .is it cutting it close or would it be ok .I am  using this tube already in a WA22 rated at 1A/Channel .

 

[Paladin79]

I just finished a basic Crack, I have yet to install the Speedball because I wanted to test the basic amp for a bit and make sure all was well before I proceeded. Total build time including some RCA cables about five hours but speedball is bound to add an hour or two. Currently I am using the preamp out from a Valhalla 2 as a source. I may end up using the tube sockets in my custom builds, I am having trouble finding matching octal and nine pin sockets and I already have dimensions for these.
I like the sound of the amp and it certainly has potential but I have not played more than six songs through it yet so it is a little early to form any opinions.