Tube Rolling w/Crack

[JamieMcC]

For tube rolling other tubes than 12au7's, what would you guys suggest?
Any drop-in options that work good via adaptors?
With the R1 resistor mod on speedball boards optimization for the E80CC and 12bh7 is possible, but there must be other options besides these?
Also saw the 5687 switch mod. More options?

You can have lots of fun with 6sn7 and 6F8G  variants there are some great sounding tubes but you will need the relevant xyz to 12au7 socket adapter.

 

[i luvmusic 2]

6CG7 is a nice tube too i prefer these tube over 12AU7's at least for me anyway.

 

[mcandmar]

6CG7 / 6FQ7 is my favorite too, one of the cleanest sounding of the 9 pins.

 

[Tom-s]

Thanks guys! Bought the needed adapters (4 weeks in transit).
What are the R1 resistances on the speedball boards to use with those?

 

[Johnny lolo]

Hi all, just joined the Bottlehead crack club

I'm curious what power tube my amp came with. It was bought a few months ago and the label says USA with 6080  in an octagon below it. No other text. It sounds pretty good! Thanks

 

[mcandmar]

An octagon around the part number means its an RCA tube.

 

[Johnny lolo]

Good to know, thanks

 

[i luvmusic 2]

6CG7 / 6FQ7 is my favorite too, one of the cleanest sounding of the 9 pins.

Do you have any particular brand of 6CG7 you prefer?



Thanks!

 

[mcandmar]

Cant say that i do, from the few i have tried they seem to be very similar to each other unlike the 12au7 variants which vary wildly.

 

[moriez]

Hey gang. Another very happy Crack owner reporting  :-*

Besides the wealth of info I think this thread also lends itself for some tube trading perhaps? I haven't the slightest interest in stacking 'em if they don't please me.

Anyone preferably in Europe who's interested in a TungSol 6080WA (solid graphite) or Mullard CV4003 (M8136)? Very low hours on both.
I'm especially after quality (JHY) CBS Hytron 5814a or something very, very similar. Could be interested in a TungSol 7236 as well.

 

[Paul Birkeland]

It's a bit of a slippery slope when you have a forum like this and you allow trading.  The one time Doc B will allow it is when somebody would like to sell a kit they have to upgrade to a new one.

Having said that, here is a place where you could likely find what you're looking for:
https://groups.yahoo.com/neo/groups/BHExchange/info

 

[moriez]

Oh ok. Didn't know and didn't read the rules if there are any. In my opinion there'd be nothing wrong with having,  if it need be a subforum that allows for trades. Have this-Want that kind of thing. No biggie though. It's probably not worth our energy to discuss as there are enough other options out there.

Cheers 

 

[fullheadofnothing]

The forum rules are the first section of the forum...

http://bottlehead.com/smf/index.php?board=11.0

 

[Tom-s]

You can have lots of fun with 6sn7 and 6F8G  variants there are some great sounding tubes but you will need the relevant xyz to 12au7 socket adapter.

Thanks Jamie! Using your advise i bought my first NOS tubes for the crack Let's start rolling.
Using this advise i now have a 6sn7 1578 tube in transit (but already got the adapter).
For the 6F8G i found a pair of Tung Sol black glass round plates (but for those i'm still waiting on the adapter).
Can't wait to get these going. Any tips on optimizing the crack for this sort of tubes?

 

[Wizzie]

Need a little help identifying a 12au7 tube that came with my crack kit

any feedback would be appreciated

Thanks

 

[ju29]

Hi everyone,

I have to possibility to try a 12Bh7 tube (12BH7A Raytheon from the 50s) with my Crack (with speedball installed).
Before doing this I just wanted to be 100% sure if it was safe.

So here is my question : Does a 12BH7 tube work properly with a Crack (with speedball) OR does it need more mods to run ?

(For now I have the 6080 stock installed but will plan to try the 12BH7 with a TS 5998 that is on its way).


Sorry if it has been discussed on the older posts. I made my researches but I still have a doubt about it...

Thanks for your answer !

 

[lth1]

According to the post Tube Rolling w/Crack (which has been read 230,518 times; an amazing number) the 12BH7 is "Sort-of-a-Drop-In (but not equivalent - for best results, replace plate resistors with Speedball boards)".  It just means that the 12BH7 will work but may sound better if one installs a proper valued plate resistor.  I have had no problem tube rolling and listening to the 12BH7, very nice sounding tube even without changing the plate resistor.

I have considered installing a switch that would allow the use of the stock and 12BH7 resistor, but didn't think it was worth the effort, the 12BH7 can be an extremely good sounding tube in the Crack.

 

[ju29]

Yeah the first page of the Tube Rolling w/Crack is one that I refer the most. I wasn't sure about the meaning of "drop in" + about the plate resistors change (if that meant only to have the speedball update installed or if that meant to have to SB installed+others resistors mods on the SB).

I don't know if I'm clear about what was unclear in my mind.. But anyhow with your answer you confirm me it's safe so I'll try the 12BH7. Thanks !


About the switch, I think it probably will take me too much time only to understand what I should do so. So not really an option for me...

Thanks again

 

[Maxhawk]

It would help if you could provide photos that clearly show the markings. It's difficult to tell by the internal construction alone.

 

[Wizzie]

It would help if you could provide photos that clearly show the markings. It's difficult to tell by the internal construction alone.

Thank maxhawk

However the printing on the tube itself is difficult with the naked eye

The writing reads on the 1st line is 12, 2nd reads AU7A and 3rd reads U.S.A.

There are no other marking on the tube