[j123my]

Looking at the undersides of the amp, the top arrow hows a loose connection. Tapping this will cause the LED's in the SB to turn off/on.

 
Sounds like bad solder joint(s) to me.. Easiest fix would be to send it back to the original owner and ask him to fix that 

 Or you could try to reheat the solder joints and see if that fix the intermittent LED problem. Swapping both tubes is also a good idea, since most problems can be traced to a bad tube.
 
BTW you might have known this, but be careful when tapping on things while the amp is on! There are high voltages there. If I have the correct picture in my mind, you are pointing to the first cap in the power supply just next to the diode bridge, and if I remember correctly that cap has about ~200V on it.
 
 
 

I do not have any schematics or assembly manuals, not sure if these are available online.
Any advise woudl be appreciated.

Again, the previous owner is your best bet here. As far as I know, the manual is only distributed in a CD when you buy the kit and is not available online for copyright reasons.

 

[TheKillerPiglet]

Thank you for the reply.
 
This amp was originally assembled by BH, my understanding is that it was the first to use the speedball.
 
To clarify, the set of LED's near the lower heat sink never turn on even when the other do. The bad solder joint seems simple enough, the dead right channel less so unless it's a bad tube.
 
KP
 

 

[j123my]

my understanding is that it was the first to use the speedball.

That sounds familiar.. 

 
Well, I'd do the following (in order, proceed only if the previous step did not solve the problem):

• Reflow all suspicious joints (if you have the manual, you can do the resistance check to narrow down the potential problematic joints)
• Swap the driver tube when you have it with you.
• Get the manual, do voltage checks, and post the results on BH forum. The experts there should be able to tell you what went wrong by looking at those numbers.
• If the issue is still not solved, cry. 
  

 

[TheKillerPiglet]

I don't know if it sheds any light but the right channel went out when I swapped cans. Hopefully the tube just shorted.
 
KP
 

 

[Jmstrmbn]

 
 
Top View: Copper Hammertone with a Golden Oak Finish
 
 
 

 
Under the hood: totally stock except for some heat shrink over some of the exposed leads.
 
Can't believe how great this sounds with the HD600s.  Compared to the Nuforce HDP they sound like a totally new headphone, I didn't expect this kind of difference for this price.  

 

[ben_r_]

Quote:

 
 
Top View: Copper Hammertone with a Golden Oak Finish
 
 
 

 
Under the hood: totally stock except for some heat shrink over some of the exposed leads.
 
Can't believe how great this sounds with the HD600s.  Compared to the Nuforce HDP they sound like a totally new headphone, I didn't expect this kind of difference for this price.  

Are you using the HDP as a DAC for the setup now?

 

[Jmstrmbn]

Yes I have it pre-amping the Crack now and it works well but I can't but feel a dedicated DAC would perform better.

 

[ben_r_]

Quote:

Yes I have it pre-amping the Crack now and it works well but I can't but feel a dedicated DAC would perform better.

I hear ya. I Have the HDP and an ASUS Xonar Essence ST now and am thinking about buying an HRT Music Streamer II and an ODAC so that I can do a little comparison of my own.

 

[TheKillerPiglet]

Ebay seller shipped like greased lightning, turns out to be bad tube.
Thank you, j123my.
 
Yay.

 

[j123my]

Ebay seller shipped like greased lightning, turns out to be bad tube.
Thank you, j123my.

You should thank the ebay seller instead 

Bad tube is a very common problem. It is a good idea to have some spare tubes lying around, just in case..

 

[TheKillerPiglet]

Quote:

You should thank the ebay seller instead 

Bad tube is a very common problem. It is a good idea to have some spare tubes lying around, just in case..

Oh I did.
I have stockpiles of various tubes but this 6080 family is new to me. Let the hoarding begin.
 
KP

 

[greyhorse]

Does anyone know how the Crack compares with the Bijou for use on HD650s?
I already have all the parts to build the Bijou, so this will get built for sure, but I am wondering if I need to try the Crack as well.
So far I am listening with the EHHA, and the HD650s sound boring.  Thanks for any info.

 

[eganz]

dpipple - To change the range of the volume pot, a simpler solution is to install some padding resistors before the volume pot. 50 Or 100 kohm Should do the trick.

 

[Beefy]

Quote:

dpipple - To change the range of the volume pot, a simpler solution is to install some padding resistors before the volume pot. 50 Or 100 kohm Should do the trick.

 
You don't want to just increase this too much though, because it introduces noise. My solution was to use a 50k pot with a 50k resistor, for the same 100k input impedance.

 

[swmtnbiker]

Quote:

dpipple - To change the range of the volume pot, a simpler solution is to install some padding resistors before the volume pot. 50 Or 100 kohm Should do the trick.

 
I'm no DIYer, have no tools, and no electronics fabrication or soldering skills. My Crack was built by someone else (who did a supreme job BTW!). My solution was to buy a pair of Harrison Labs 12dB line-level attenuators. They'll be here on Friday, so I don't have long to wait to see if they do the trick without compromising sound quality.