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Crack;Bottlehead OTL
Aug 15, 2013 at 4:39 PM Post #2,341 of 12,335
Quote:
doc b. said:
With all due respect, it would be unfortunate if this turned into an internet legend of 5998s regularly blowing up headphones all over the planet. This stuff is DIY, and we do it for the reward of great sound at a reasonable cost and a sense of accomplishment. Sometimes it is easier to blame some particular item for all of our problems based upon one or two occurrences rather than looking at the probabilities of the cause of it happening. One can screw up their equipment lots of ways - hot plugging, bad solder joints, miswires and yeah, occasionally, flakey tubes. It's just part of the learning experience. As my old bud John Tucker used to say when we were building (and occasionally blowing up) circuits - "no balls, no fly medal".
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All well and good when your blowing up 20 cent resistors, but $400+ headphones and $100+ tubes is a different story to which would never want to try and justify with "just part of the learning experience".
 
Aug 15, 2013 at 5:09 PM Post #2,342 of 12,335
Well, we seem to agree that you have to decide for yourself what the reasonable cost to learn something is. I won't upset you by stopping to figure out how much stuff I have blown up over a lifetime of DIY audio 
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Aug 15, 2013 at 5:09 PM Post #2,343 of 12,335
I really don't think that is what Doc was saying. As I read it, his point was: don't blame the 5998 and claim that it is prone to blowing up headphones. There may have been one or two 5998s that were bad, but that could just as easily have been due to some sort of problem with the relevant amp. Or it could have been those specific 5998s that were bad, but it isn't as though there are no bad 6AS7Gs or 6080s or whatever. Absent some sort of statistical evidence from a large sample size over time using a variety of amps, it seems irresponsible to claim, based on anecdotal evidence, that 5998s are particularly dangerous and should be avoided. Best regards, Adam
 
Aug 15, 2013 at 5:11 PM Post #2,344 of 12,335
And to further clarify: yes, Doc was making the point that you can't make an omelette without breaking a few eggs, but I consider that a separate point from the question of whether 5998s are fault-prone.
 
Aug 15, 2013 at 5:17 PM Post #2,345 of 12,335
Quote:
amcananey said:
 Absent some sort of statistical evidence from a large sample size over time..., it seems irresponsible to claim, based on anecdotal evidence, that ... are particularly dangerous and should be avoided. 
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Don't tell CNN or FOX that.
 
Aug 15, 2013 at 5:31 PM Post #2,347 of 12,335
This is not really a 5998 specific issue. Any tube at any time can fail in an arc-over mode. Most of the time, your ears ring and the driver is fine. In an OTL amp using CCS, the current gets limited and the event is pretty much a non event. For OTL with just a resistor in cathode, the pop can be much louder. I'm only aware of a couple on the forum that have stated they've lost a driver....I believe this is a very rare occurrence. I've had a number of arc-over events and none have damaged my HD558. Specifically, I've had 2399, TS7236 (box plates), and 5998A do this....all high transconductance tubes. It's almost always used tubes from unknown sellers (cheap ebay) and none of mine were NOS failures. Also, they all did it within a few minutes of warmup. My standard procedure now is to treat questionable tubes with caution and let them warm up for a few minutes without my headphones plugged in to be sure they are good.

ben_r_ said:
This is the first I have heard of the 5998's causing literal blowouts. How often does this occur? Is it only used ones or has it happened to NOS or something like a new Chatham?
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Aug 15, 2013 at 5:52 PM Post #2,348 of 12,335
Quote:
grindingthud said:
It's almost always used tubes from unknown sellers (cheap ebay) and none of mine were NOS failures. Also, they all did it within a few minutes of warmup. My standard procedure now is to treat questionable tubes with caution and let them warm up for a few minutes without my headphones plugged in to be sure they are good.
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Sage advice indeed. I have had similar experiences with ebay tubes, and a couple of scares with my speakers. 
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Aug 15, 2013 at 10:41 PM Post #2,349 of 12,335
Quote:
Originally Posted by Doc B. /img/forum/go_quote.gif
 
"no balls, no fly medal".
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fly medal?
 
(the reference is lost on me)
 
Aug 15, 2013 at 11:40 PM Post #2,351 of 12,335
Quote:
armaegis said:
 
fly medal?
 
(the reference is lost on me)
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It sounds to me like an air force reference or similar, but I don't know for sure. I figure it's something along the lines of "no guts, no glory"... maybe "no broken drivers, no awesome amplifier"?
 
Only kidding, I actually think Doc's comments seem reasonable given that we're in the DIY world here and it just makes me think that I'll plug in my cheap, old and worn-out AKGs to test any new tubes before firing them up with my HD650s or T1s.
 
Aug 16, 2013 at 12:01 AM Post #2,352 of 12,335
I just want to mention as a counterpoint, I've smoked more headphones with DIY solid state amps than I have tubes. 
 
Aug 16, 2013 at 2:12 AM Post #2,353 of 12,335
Quote:
rosgr63 said:
The 5998's have been known to pop and damage headphones with some amps and I am not referring to Bottlehead amps.
Be careful it could happen again at random.
 
The 6AS7G are usually safer.
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frown.gif
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. Looks like I have to go for a GEC 6AS7G Brown base, right?
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Quote:
amcananey said:
I really don't think that is what Doc was saying. As I read it, his point was: don't blame the 5998 and claim that it is prone to blowing up headphones. There may have been one or two 5998s that were bad, but that could just as easily have been due to some sort of problem with the relevant amp. Or it could have been those specific 5998s that were bad, but it isn't as though there are no bad 6AS7Gs or 6080s or whatever. Absent some sort of statistical evidence from a large sample size over time using a variety of amps, it seems irresponsible to claim, based on anecdotal evidence, that 5998s are particularly dangerous and should be avoided. Best regards, Adam
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You had some very good point, Adam.
Quote:
kozmos said:
that's why i bought Sennheisers, if i blow a driver i can always buy a new one and replace it :)
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Hi kozmos,
 
Does Sennheiser sell their headphone drivers separately? And where I can buy them?
 
Thanks.
Quote:
skeptic said:
Being the generous and helpful guy that I am, I will save you all from your dangerous 5998's by taking them off your hands for $10/each 
wink.gif
 
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LOL
 
It is my pleasure to take all of your very dangerous 5998's off you for $20/each.
Now I guess I'm twice as generous and helpful as you
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Quote:
ben_r_ said:
This is the first I have heard of the 5998's causing literal blowouts. How often does this occur? Is it only used ones or has it happened to NOS or something like a new Chatham?
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I don't know about you guys, but my Crack actually KILLED my Panasonic HTF-600 about a month ago. But it was not due to the 5998's as I still have not had a 5998 back then. It was the bad stock 6080 tube.
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I only had this popping happen once two days ago, but it has not happened again since. I'm using NOS Chatham 2399 by the way.
 
Kratos.
 
Aug 16, 2013 at 9:08 AM Post #2,354 of 12,335
Stupid question.  Just ordered the crack, but am hearing the end of this forum where people are talking about amps busting headphones.  Are you guys modding the crack?  Or do I not have to worry with the stock crack?
 
 
Aug 16, 2013 at 9:15 AM Post #2,355 of 12,335
Quote:
thunkerdo said:
Stupid question.  Just ordered the crack, but am hearing the end of this forum where people are talking about amps busting headphones.  Are you guys modding the crack?  Or do I not have to worry with the stock crack?
 
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This is a rare occurence and typically only happens if youre not paying attention to the manual. Had to put that in perspective. All is well.
 
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