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Crack;Bottlehead OTL - Page 498

post #7456 of 7714
Quote:
Originally Posted by grausch View Post
 

Even if you switch off your power at the wall, I believe it only switches off live (could be neutral - I can never remember). Thus, as long as the Crack is plugged in you run the risk of being shocked. The only way to avoid that risk is to a) unplug the Crack completely, b) switch the power off at the circuit breaker or c) don't touch any exposed wires when touching the Crack "down under". The shock you experience would not have been capacitors discharging nor would it have been from the tubes. When you touched the exposed wires, you simply grounded the electricity coming in from the wall and got shocked.

 

Not sure why only one channel worked after that incident. I have been shocked the same way you were once or twice and I have been shocked once from the caps discharging when I touched them immediately after unplugging the power from the wall. My Crack worked fine thereafter although it took me some time to recover - it was less than 3 months though ;). I am assuming you have a bad solder joint somewhere that is now making proper contact again.

It's such a freaky feeling >.< 

 

Anyway now there is constant hiss more on the left channel than the right, i have a feeling it may be dust and or that bad solder joint, or maybe tubes? Ugh wish i was in the US would just send it back to bottlehead to redo it for me, lol

post #7457 of 7714
Quote:
Originally Posted by platinumbird View Post
 

It's such a freaky feeling >.< 

 

Anyway now there is constant hiss more on the left channel than the right, i have a feeling it may be dust and or that bad solder joint, or maybe tubes? Ugh wish i was in the US would just send it back to bottlehead to redo it for me, lol

Yes, being shocked by electricity is no fun and realising how I stupid I was even less. Being shocked from the caps discharging is even worse. Before I start working on the Crack nowadays (and especially during voltage checks), I always check to ensure that the PS caps have discharged before I even start. 

 

The best place to solve the issue would be the Bottlehead forums. Check your resistances and your voltages and post any that seem out of line there. They can help guide you through the process of fixing the problem much better than we can here.

post #7458 of 7714
Quote:
Originally Posted by grausch View Post
 

Yes, being shocked by electricity is no fun and realising how I stupid I was even less. Being shocked from the caps discharging is even worse. Before I start working on the Crack nowadays (and especially during voltage checks), I always check to ensure that the PS caps have discharged before I even start. 

 

The best place to solve the issue would be the Bottlehead forums. Check your resistances and your voltages and post any that seem out of line there. They can help guide you through the process of fixing the problem much better than we can here.

Just turned it over and gave it a good dusting.

 

Now the hissing is gone, but only right channel is working  "sigh"

 

Guess i should get out my multimeter :( I have no idea wehere to start... how do i know if a solder joint is bad or not?

post #7459 of 7714
Quote:
Originally Posted by platinumbird View Post
 

Just turned it over and gave it a good dusting.

 

Now the hissing is gone, but only right channel is working  "sigh"

 

Guess i should get out my multimeter :( I have no idea wehere to start... how do i know if a solder joint is bad or not?

You can find bad solder joints by doing the chopstick test, namely taking a chopstick (any non-conductive object will do) and systematically giving all solder joints a push or shove. If you listen to your headphones, you will usually hear a crackling noise to indicate something is loose. I would first check resistances. If those check out, check voltages. If everything checks out at this point, you could do the chopstick test, but I would still recommend contacting the team at the Bottlehead forums before you start poking in there with the chopsticks and run the risk of further damage to your amp.

post #7460 of 7714

Get over to Bottlehead crack forum, post your resistnances and if ok, then post all your voltage measurements...the guys over there are "bottlehead" and will quickly respond and help you get things working correctly!!

 

Alex

post #7461 of 7714

If one wanted to bypass the final power cap in the Crack with a film capacitor, does the actual capacitance value of the film cap matter? The only thing I could find on that mod, which I know I've seen in multiple places, was someone using a WIMA 2.2uf cap. Just curious whether or not the capacitance value matters, and what effect increasing/decreasing that value might theoretically have on the sound

post #7462 of 7714

It's fairly standard for bypass caps to be 1% of the value of the larger cap being bypassed, but that's not the only "correct" or magic value. I doubt you'd hear much difference within an order of magnitude of that range. IIRC the theory has mostly to do with resonant frequencies (which I read about a while ago and have since forgotten) and the fact that two caps in parallel will have a lower ESR than just one.

 

I've hot-swapped a variety of bypass caps (values, as well as material/construction type) over the 100uF output coupling caps, where my naive understanding says I'd be more likely to detect audible differences than in the PS section. Even in sighted, biased tests where I had bypass caps alligator-clipped in and was disconnecting them on the fly (if anyone has a better experimental method, I'm all ears) I struggled to hear differences. With "a bypass cap" in place the highs were perhaps a touch more open and airy. Maybe. Could have been imaginary. I was working within a range of 0.1uF to 3uF (0.1% to 3% of the larger cap's value). So I wouldn't lose sleep over bypass cap value provided it has an appropriate voltage rating.

post #7463 of 7714

Speaking of those damn output caps, I just got done replacing them entirely earlier today. I put in a couple of Dayton Audio 100uF 250V polypropylene caps in their place. IMO there is a significant gain in clarity that I would recommend.

post #7464 of 7714
Quote:
Originally Posted by ohcrapgorillas View Post
 

Speaking of those damn output caps, I just got done replacing them entirely earlier today. I put in a couple of Dayton Audio 100uF 250V polypropylene caps in their place. IMO there is a significant gain in clarity that I would recommend.

 

Mmmm yes I got those too on my Crack. There is definitely a big change in clarity that I believe is very noticeable.

post #7465 of 7714
So I was looking this up, and I found a lot of information from a few years ago. I'm sure it's still relevant, but I might as well ask again.

I am interested in building the Crack and don't have any equipment (iron, solder etc.). With a $50 budget, what equipment would you suggest? Or do I need to extend my budget?
post #7466 of 7714
$50 is enough
Soldering iron, solder, multi meter and maybe some desoldering wick for when you mess up.
Edited by audiojun - 2/20/16 at 11:24pm
post #7467 of 7714

I just bought the legendary HD600, having a Hifiman He-500 before i'm just happy with the more accurate sound of the HD600, even though it's more polite.

 

I used to drive my Hifiman with the Project Polaris from Garage1217 wich is a SS amp with some harmonics tube distorsion. I'm now considering to upgrade with the very renowned Crack, but i'm wondering if it's worth it considering the fact that the Polaris is already a very good amp pairing with the HD600, i have no idea of how the HD600 could improve upon such a good match with the crack...


Edited by Drrizzt - 2/21/16 at 7:43am
post #7468 of 7714
Quote:
Originally Posted by saxophone View Post

So I was looking this up, and I found a lot of information from a few years ago. I'm sure it's still relevant, but I might as well ask again.

I am interested in building the Crack and don't have any equipment (iron, solder etc.). With a $50 budget, what equipment would you suggest? Or do I need to extend my budget?

 

I would also recommend a solder wire sponge. It beats having to use a paper towel after each solder. It's just more neat that way. You'll definitely need a soldering iron, solder, and either a desoldering pump (takes practice using it) or desoldering wick. I like using the pump better, it's just faster and easier when you get the hang of it. Not sure if $50 will cover all of it but I'm sure you can get close to around that price.

post #7469 of 7714

Well, I understand that I need those items. Some people suggested getting a soldering iron that can run 600 degrees Farenheit and others said I need an iron that can run 600 degrees Celsius. That's a pretty big difference, and I still haven't figured out which one is correct, although 600 F makes a bit more sense. I didn't consider purchasing a multimeter, so I added that into the equation. I saw that soldering stations were available and a bit cheaper, but they didn't have a desoldering pump/wick.

 

This is what I have so far in my cart:


Besides solder, are there any other things I will need? Also, do you have any suggestions on modifications to this list (brands, cheaper products available, etc.)?

post #7470 of 7714
Quote:
Originally Posted by saxophone View Post
 

Well, I understand that I need those items. Some people suggested getting a soldering iron that can run 600 degrees Farenheit and others said I need an iron that can run 600 degrees Celsius. That's a pretty big difference, and I still haven't figured out which one is correct, although 600 F makes a bit more sense. I didn't consider purchasing a multimeter, so I added that into the equation. I saw that soldering stations were available and a bit cheaper, but they didn't have a desoldering pump/wick.

 

This is what I have so far in my cart:


Besides solder, are there any other things I will need? Also, do you have any suggestions on modifications to this list (brands, cheaper products available, etc.)?

 

a long nose pliers and a cutter too. not forgetting a wire stripper this would be for the electronics component. For the wooden base you will need wood glue and some tape.

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