Tube Rolling w/Crack

[JC]

Sounds like it might be of European heritage.  The flashing filaments were, for some years, part of their version of "controlled warm-up" for their heaters.  I've seen it most often in 12Axx series tubes, but they used it in others as well.

If this is the case, it is nothing to be concerned about.

Edit: I now see that Angela Instruments had some 12AU7s on E-Bay listed as "Pinnacle European Audio Tube", so I'd say the odds are better that you have a Euro-tube.

 

[hasafraker]

JC, thanks for the info! Yes this is in fact one of Angela's ebay tubes. I've purchased lots of random items from them over the years and the tube was pretty reasonable, $10 shipped I think so not much of a risk to give one a try. It seems to sound pretty good, at least as good as the other 12au7's I have.

 

[JC]

That certainly seems very reasonable, considering what new-manufacture ones go for retail.

As I've mentioned before, my first experience with this flashing phenomenon was in a vintage British guitar amp that just been purchased by the shop I was doing some repair work for.  We knew nothing about it at the time, so I think you can imagine the owner's face when four of those little flashes went off when he turned the amp on for the first time!  I don't think he could have got to that plug any faster on a bet!

 

[spear321]

Waiting for Crack to arrive, stuck in customs I think.

But have bought some 13D5 think these are 6.3V
Do I have to do any mods to the heater wiring, or will they just go straight in?

If have to mod, will a 12au7 work all right afterwards, don't want to have to keep swapping the wiring, I know you lot would put in a switch somehow, but I am afraid my buildings not up to that.

Thanks in advance for any help, did not think about this when I bought them, oh hum.

Cheers Paul

 

[Nocturnal]

Is the 6528 a plug in replacement for the 6080 and usable in the stock Crack?  I don't see it listed at the start of this thread.

http://www.radiomuseum.org/tubes/tube_6528.html

 

[Doc B]

No, a 6528 won't work - draws twice the heater current.

 

[Nocturnal]

No, a 6528 won't work - draws twice the heater current.

Dang, it apparently helps to lower impedance.  Thought it'd be interesting to try it with my Grado headphones.

 

[Doc B]

You can't lower the impedance of Crack close enough to the 32 ohm range to sound as good as it does with higher impedance headphones. IMO it will be nice, but not fantastic, even with a 5998 (which sounds great with Senns, Beyers, etc). However we are working on a new, different amp circuit that would specifically address 32 ohm headphones.

 

[Nocturnal]

You can't lower the impedance of Crack close enough to the 32 ohm range to sound as good as it does with higher impedance headphones. IMO it will be nice, but not fantastic, even with a 5998 (which sounds great with Senns, Beyers, etc). However we are working on a new, different amp circuit that would specifically address 32 ohm headphones.

  A modification to the Crack or a new product?

 

[hasafraker]

ok Doc you've let the cat out of the bag...

However we are working on a new, different amp circuit that would specifically address 32 ohm headphones.

Any idea when this might arrive? care to share any details?

 

[Paul Joppa]

The hope is to have a prototype running for the March 5 HeadFi meeting at BHQ. At this point I don't know if it will happen that fast, or even if it does, whether the amp will be broken in. It certainly won't be refined yet - we usually screw around with the design and parts a bit before releasing a product.

 

[hasafraker]

well that's awesome... my birthday is in march   I look forward to hearing more as it develops, who knows maybe I'll have something to compare to the Crack soon

 

[tdogzthmn]

Sadly, my 5998 went out on me today.  I lost the right channel after I powered the amp on after switching the 12AU7 to a 5814.  I was scared at first but I pulled out the 5998 and put in an a 6AS7G and got both channels back.  Sounds good now but I find there to be a noticeable difference in quality with the 5998 being very dark and detailed.

 

[hasafraker]

that's too bad at least it was the tube and not some other component but those 5998's are hard to come by unless you can afford what people are asking. I've been trying to get one off ebay but they're never cheap and always people wanting them... someday!

 

[hasafraker]

question, I saw in another thread PJ mentioned a tube I hadn't seen listed before 7802 as a sub for the 6080/6AS7, I happened a cross a NOS Tung-Sol 7802 pretty cheap so I picked it up, should this just drop in or will it need any changes, I've been looking for a 5998 to try and still haven't seen anything that didn't qualify as "stupid expensive" and I'm not going to spend the kind of money those tubes are going for, I figure if this guy is a drop in and I don't like the sound I won't have any trouble getting my money out of it, assuming it's fully serviceable.

 

[hasafraker]

well according to the data sheet I couldn't see a reason the 7802 isn't a drop in sub so I plugged it in and it's got about 28hrs on it now and sounds great.

 

[deltaunit]

You can add the CV2984 to the output tube alternative lists, it's a drop in replacement. I just picked a GEC one up to have as a spare. It seems good nothing really between it and my Mullard 6080 anyway.

 

[jrihs]

Thanks! Isn't CV2984 just the euro designation for 6080 though? Or am I misunderstanding something?

 

[deltaunit]

It's the uk military spec version of the 6080 which as far as I know is known as a 6080 here.

 

[MxT]

Hi guys.

Im not jacked on tube's at all. So if I had to get a suggestion of a drop in tube to try what should I look at??

thanks!!