Crack;Bottlehead OTL
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maxpudding
100+ Head-Fier
Yeah you could do that and roll different tubes.
With adapters (make sure they are the 6.3V type) in the driver slot, you could try the 6SN7, or the 6J5s (you'll need two of these because each 6J5 is 1/2 of the 6SN7).
I'd only recommend changing the inner stock parts if you are confident enough to do the mods, or probably you could send your stock crack to someone who could do the mods for you.
Congratulations on building your Crack. I can understand where you're coming from with your hd800 I use them as well and have built a number of Cracks in the past. The Crack is a fun amp it's reputation is essentially built off of its pairing with the Senn 600 & 650.
it's possible with premium tubes and some straight forward modifications to make noticeable gains in its sonics with the hd800 that's probably the route that the majority of Crack users take no matter what headphones they use with it.
Ultimately though the thing to bear in mind is even when spending on expensive tubes and upgraded components and modifications your hd800 performance is still going to be restricted by the Cracks technical ability.
What you will end up with taking that path will sound very nice and you will end up with a unique to you amp.
However its of importance to understand that while that is a enjoyable journey to undertake with the Crack it would be more financially economical to just go with one a more capable amp than spend time and money upgrading a Crack.
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I put in one of my 7N7 tv tubes with two adapters. I have the 6sn7 adapter then Woo's 7N7 adapter. The tube is sitting almost as high as the RCA 6AS7G very good sound. I'm waiting on more RCA 6AS7G tubes of different decades and hopefully a replacement to my current one which has noise heard in cathode tube tv's so not a hum more midrange pitch only coming out of the right channel.
Here's the crack two adapters and 7n7 Westinghouse.
What are the stock tubes you have now?
ColdsnapBry
500+ Head-Fier
Is there a good resource on Crack + Speedball upgrades a first time builder can do while making the thing? I want to do my first build, but also have a bit of extra money where I can do the upgrades during the build.
Bottlehead recommends not doing upgrades during the initial build and I completely agree. It just gets harder to diagnose any issues.
Down the road there is a speedball upgrade, switching to film caps, adding a choke, and switching to Cree diodes.
cddc
1000+ Head-Fier
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I agree, from my personal experience.
Do the basic Crack build first, not even with the Speedball upgrade, so that there will be less trouble for beginners. Otherwise, too much frustration could lead to give-up.
Once the basic Crack is successfully done, you can then add SB, and mods later.
cddc
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The Bottlehead forum is a good resource...though I haven't been there long time (here Head-Fi as well).
cddc
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I am glad that you are ok, I think i have the same adapter bought from Garage 1217 on Ebay. The first thing that i noticed the metal that exposed at the bottom, it is hazardous to your health so i hacked it by cutting a part of plastic tube for medicine to cover it. It fits perfectly and prevent you from touching the base.
I have said many times here on the Crack thread - don't buy these Garage 1217 adapters, they are half done products. The exposed metal contacts on these Garage 1217 adapters pose huge hazards to safety, they could lead to shorts, shocks, or even death. Keep your kids away from these adapters!
Agreed, the first crack I ever owned was purchased instead of built by me, and the input socket was slightly recessed. The garage adapter shorted the amp, while the eBay adapter from xulingmrs worked fine.
cddc
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Yeah, your case is the second case of Garage 1217 adapter shorting Crack chassis that I've seen here. Some Crack builders like to keep their 12AU7 socket low-profile, so they choose to mount it from the bottom of the chassis instead of to the top. Then, there won't be enough clearance for these exposed solder joints at the bottom of these Garage 1217 adapters, they will touch the metal chassis/screws and cause shorts.
Adding a plastic/rubber cylinder will protect against the exposed metal legs on top of the Garage 1217 adapters, but still the exposed solder joints at the bottom pose another threat to safety.
All in all, these Garage 1217 adapters lack of basic safety considerations (tubes are high voltage stuff in general, hence the exposed metal contacts pose huge threats), they are half-done products and should be avoided IMO.
Adding a plastic/rubber cylinder will protect against the exposed metal legs on top of the Garage 1217 adapters, but still the exposed solder joints at the bottom pose another threat to safety.
All in all, these Garage 1217 adapters lack of basic safety considerations (tubes are high voltage stuff in general, hence the exposed metal contacts pose huge threats), they are half-done products and should be avoided IMO.
Galapac
1000+ Head-Fier
Yep…either of these are better and insulated.
You want 6.3 volt version when buying these for standard BHC.
https://www.ebay.com/itm/203513997654?hash=item2f62612956:g:olsAAOSw5VFWLiss
https://www.ebay.com/itm/294212319817?hash=item44806bba49:g:G14AAOSwXuRe5Ey3
Deyan also can make you one and is a member here.
You want 6.3 volt version when buying these for standard BHC.
https://www.ebay.com/itm/203513997654?hash=item2f62612956:g:olsAAOSw5VFWLiss
https://www.ebay.com/itm/294212319817?hash=item44806bba49:g:G14AAOSwXuRe5Ey3
Deyan also can make you one and is a member here.
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Just to strengthen the recommendation - I had Deyan build me several adapters and I am very, very satisfied with the products and entire process. Highly recommended instead of what I am reading above about dangerous, half-finished adapters.
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