[JTori]

You made me realise I never put the badge on mine. Thx.

Interesting build. I'd like to know more about the input tube and any other mods you've made to your Crack. Mine's a little more pedestrian, save for some tube rolling.

Best,

Joe.

 

[m17xr2b]

The input tube is a CV1102, I really like it and decided that's to only input tube I'll use in the crack and just roll output. Can't be used in a stock crack due to 1.3A of heater requirement and different pin config
The more notable things I've put in it:
Jensen 220uF x2 audio electrolytic caps
Jensen 50uF oil x3 for the last cap in the PSU
Mundorf 100uf evo oil for output
Dual UK made choke
Battery bias instead of LED for the input tube
No Speedball
Custom overspeced transformer - this runs really cool compared to stock.
Duelund 26AWG wiring
TKD volume pot
Charcroft Z-foil resistors where I could.

 

[JTori]

The input tube is a CV1102, I really like it and decided that's to only input tube I'll use in the crack and just roll output. Can't be used in a stock crack due to 1.3A of heater requirement and different pin config
The more notable things I've put in it:
Jensen 220uF x2 audio electrolytic caps
Jensen 50uF oil x3 for the last cap in the PSU
Mundorf 100uf evo oil for output
Dual UK made choke
Battery bias instead of LED for the input tube
No Speedball
Custom overspeced transformer - this runs really cool compared to stock.
Duelund 26AWG wiring
TKD volume pot
Charcroft Z-foil resistors where I could.

Wow! Very interesting build! I'm sure it sounds awesome. Did you construct a new, larger base to accommodate everything?

 

[m17xr2b]

Yes, custom plate and wood base, actually there's no bottlehead kit part in it, not even a nut.

It does sound pretty baller, but then again it's a 1K amp at this point. Still, there's something about the crack circuit that hits the sweet spot. It's my daily amp but might as well be end game. My main amp is the DNA Stellaris.

 

[JTori]

Very impressive and well thought through! I agree with you, the Crack circuit is elegant in its simplicity; BH has taken time to distill the design to its essence, not always easy to achieve. I don't know how many Crack kits they sell per year, but in my opinion it's not as many as they should. And, the company is a prime example of how to build a loyal customer base: highly responsive to DIY'ers' inquiries and a thriving discussion forum. I've built both the Crack/Speedball and the Mainline. My Crack is bone stock, while I did pop a pair of 10uF Mundorf Supremes in the Mainline. I love both amps. I'm not contemplating replacing my longtime ARC/Magnepan/Vandy sub rig with a pair of Kaijus, a BeePre, an Eros 2 and a pair of Jagers.

Once more, nice work!

 

[Toad_of_Toad_Hall]

.

 

[DenverW]

Here’s an adapter question for the tube experts! I have multiple adapters for a 6sn7 based darkvoice amp. Things like 6f8g and 7193 adapters. Rather than purchase multiple adapters for these going into 12au7 would I be able to use two adapters at once? For example, 6f8g to 6sn7 adapter —> 6sn7 to 12au7 adapter—> crack w/speedball?

May not be the prettiest, but if it would work it would save time and money! I would thiiink it should be ok?

 

[m17xr2b]

Did you pay Bottlehead for the use of their design? I wonder how Doc & co would feel about this build. At what point does a Crack stop being a Crack?

The right question is if I ever bought a new crack before to have access to the manual. The answer is yes and other kits as well.
Why did you feel the need to post this question? Go back to the swamp.

 

[Toad_of_Toad_Hall]

.

 

[m17xr2b]

Not being rude, just making fun of your nickname, because you're a toad. Still, your accusation is quite severe and in a public forum yet you failed to mention exactly what I did or what I shared that not already public.

Why are you picking on my build, who are you? Are you really a toad? If DocB wants me to redact anything fine by me, I love bottlehead and learned to do this because of their kits especially the BeePre.

Crack modding is a culture by now and I couldn't use anything from the kit for my purpose not even the transformer and top plate, I don't get the SJW attitude.

 

[Wes S]

Not being rude, just making fun of your nickname, because you're a toad. Still, your accusation is quite severe and in a public forum yet you failed to mention exactly what I did or what I shared that not already public.

Why are you picking on my build, who are you? Are you really a toad? If DocB wants me to redact anything fine by me, I love bottlehead and learned to do this because of their kits especially the BeePre.

Crack modding is a culture by now and I couldn't use anything from the kit for my purpose not even the transformer and top plate, I don't get the SJW attitude.

I would love to hear that thing, and bet it sounds awesome! Really cool to see different builds! Thanks for posting

 

[m17xr2b]

Here’s an adapter question for the tube experts! I have multiple adapters for a 6sn7 based darkvoice amp. Things like 6f8g and 7193 adapters. Rather than purchase multiple adapters for these going into 12au7 would I be able to use two adapters at once? For example, 6f8g to 6sn7 adapter —> 6sn7 to 12au7 adapter—> crack w/speedball?

I did chain adaptors for other amps, not pretty but it does work, you will increase the chance of static and noise but if it works fine you should be good to go.

I would love to hear that thing, and bet it sounds awesome! Really cool to see different builds! Thanks for posting

If you're ever in London...

 

[audiowize]

For those who may consider a larger/cooler running transformer to be some kind of improvement, it's worth remembering that underloading a transformer leads to poor regulation, and poor regulation can leave your 6.3V heater winding putting out far more than 6.3V, which can reduce tube lifetime.

I had someone bring by a Singlepower MPX3 that someone had "improved" by adding a really heavy duty power transformer. The heater winding was putting out over 7V, and this is not so great for tube life.

 

[m17xr2b]

For those who may consider a larger/cooler running transformer to be some kind of improvement, it's worth remembering that underloading a transformer leads to poor regulation, and poor regulation can leave your 6.3V heater winding putting out far more than 6.3V, which can reduce tube lifetime.

I doubt anyone would consider a larger transformer but you are right. Normally my transformer would run at about 6.7V but brought down to 6.3V. This is detail a bit beyond the typical DIYer for the crack. I do like a load of 60-70% of the rating.

 

[audiowize]

The stock transformer is spec'd at about 105VA and runs under 50VA.