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Crack;Bottlehead OTL - Page 339

post #5071 of 8083

My neighbour, who never ever goes out, went out despite my best bribery, so no brown base today but I'll be at the Post Office tomorrow for 6am, sharp!


Meanwhile, I'm really happy with how these these Mundorfs are changing as the hours go by. On day two, they were almost too bright, almost thin in the mids, there was so much detail. They're filling out again now, the bass is superb but the mids have come back with detail and, crucially, that lushness that makes the HD650s.


Listening to something like Random Access Memories, there are so many layers of keys and synths and choppy guitar, adding colour and groove. I knew it was an incredibly well-produced record but I'm peeling back further and further.

post #5072 of 8083

Just got my ts5998 from vacuumtubes.net.  There are three small chips of glass floating inside. :angry_face:  That can't be good. Is it toast? Won't have the crack ready till tomorrow so I can't test it today. 

post #5073 of 8083
Here's a pic. Not sure if it will show visibly.
post #5074 of 8083

I have had several tubes including 5998s with glass chips in all have worked perfectly. Its something that sometimes happens during manufacturing  apparently.

post #5075 of 8083

Mine evidently has a microscopic chip somewhere because I can hear it gently rattle but can't see it!

post #5076 of 8083
Okay. Maybe there is hope afterall.
post #5077 of 8083
Originally Posted by MattTCG View Post

Okay. Maybe there is hope afterall.


Apparently it is totally normal to have glass chips in a 5998.  All 4 that I've had had them...  All 4 had problems mind you...  :confused:

post #5078 of 8083

I've had two other 5998's with no glass. One developed a slight hum during warmup but then was dead quiet. The other was perfect...


Great job by vacuumtubes though. Very quick shipping and well packed in the box. Very friendly on the phone as also. I'd do business with them again even if there is a problem with this tube. 

post #5079 of 8083

is there supposed to be buzzing/humming at low levels with my crack/speedball?


If not what could be the problems. I had this with other amps and know its common but its a little bit louder on the crack/speedball.


I am thinking its the kind of tube I am using "RCA 6AS7G JAN Black Plates". The stock 6080 did this even worse. 

Edited by grizzlybeast - 5/21/14 at 12:26pm
post #5080 of 8083

In short, no, no hum at listening levels. If you've identified whether or not it's the tube, your best bet is to ask on the Bottlehead forums and there will be some very helpful chaps there to help you isolate the problem.

post #5081 of 8083

no, there shouldn't be a hum.. Now, if your using low impedance cans, then yes, you will hear a hum.


I had this same issue.  if its not the tube itself, (I had 2 stock tubes that were both noisy) then double check your wire routing around the tubes.  I had routed a wire under a tube instead of around it, and it caused hum.  also make sure you do all the corrections on the crack support page.  all that will help.

post #5082 of 8083
Originally Posted by MattTCG View Post

Dang, nice find!! Today I'll be setup again on my favorite chain. uberfrost>quickie>crack>650. biggrin.gif
Quickie>Crack combo is from now on called Crackie, okay? :P
post #5083 of 8083

Crack should run dead silent.  I've only tried mine once with low Z phones, and frankly I don't recall hearing any noise then either.


I believe Doc posted something a few pages back about a suspect batch of transistors that may have been included with certain speedball orders.  Did your crack make this noise in its stock build?  If not, I believe BH said they would supply the replacement transistors free of charge.  


Alternatively, if it did buzz or hum in stock form, I would try the following: (1) plug it in in a different room to see if it might be some other appliance polluting your AC and causing the issue (like a light with a dimmer); (2) swap in a new 12au7 to ensure that isn't the culprit; (3) check that the input wiring from your rca's to pot are braided as tightly as recommended in the manual; and (4) touch up your solder joints on ground - although honestly, in my experience, a bad connection here makes a much louder buzz than what you're describing.  Hope this helps!

post #5084 of 8083
Originally Posted by JamieMcC View Post

Latest caps rolled in the Crack.


A pair of pre-loved EPCOS (Siemens) 750v100uf polypropylene in oil films (non audio caps).


These are very nice sounding caps imho and seem to be the equal to any of the audio branded mkp films I have tried to date while also providing that liquid effortlessness in presentation that only the pio's can do yet combined with plenty of details and rich smooth vocals.


I later tried bypassing them with a pair of Hovland Supercaps 1uf/400vdc with good effect. Increased detail and clarity a sense of intimacy in vocal presentation with some familiar tracks. With the Hovland's added the presentation also felt slightly faster than that of Epcos PIO's on their own. 




Pretty cool!  Those bad boys are giving me flashback's to adamct's crazy: http://www.head-fi.org/t/679064/maxxximum-capacity-crack


Somewhat seriously....I hope his absence from the crack thread in recent months is due to a new hobby and not inadvertently touching the exposed leads on those PSU caps....


post #5085 of 8083
Originally Posted by .Sup View Post

Quickie>Crack combo is from now on called Crackie, okay? :P


Good one..."crackie" it is. :D

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