Replacing 9 pin tube socket with 8 pin octal socket

[TravAndAlex]

I'm doing a major Crack rebuild and since I have far more 6SN7 tubes (currently with the Garage1217 adapter), I'd like to just enlarge the 9 pin hole and replace it with an 8 pin octal socket that I have on hand.  Is there a guide or listing of what pin numbers will change from the 9 pin to the 8 pin?  Searches have found others that have done this, but not the specifics.

Also, can you run a 6SN7 without the Speedball upgrade?

Cheers!

[Natural Sound]

What I did was print out the datasheets for the 12AU7 and 6SN7 and put them side by side. Then make the necessary pin number changes.

http://tdsl.duncanamps.com/show.php?des=12au7
http://tdsl.duncanamps.com/show.php?des=6sn7

The only other thing you need to consider is where the LED's tie to the Center pin of the 9 pin socket. The 8 pin doesn't have a solder tab like the 9 pin does. I added a small terminal strip near the Octal socket. There was a photo I posted a while back but I think it was on the other (old) forum.

Yes, the 6SN7 will work just fine with or without the Speedball upgrade.

[TravAndAlex]

Thanks! 

So just to confirm that I'm not too stunned about the whole thing... I'm basically matching pin layout in the diagram?

9-pin   8-pin

1   2
2   1
3   3
4   7
5   8
6   5
7   4
8   6
9   -

[diynewbie]

I'm probably wrong, but I don't think that is correct.  It looks to me like you do not have a completed circuit for the heater.  I think 9 should go to 8 and 4/5 should go to 7 (or vice versa?).

[Natural Sound]

I'm probably wrong, but I don't think that is correct.  It looks to me like you do not have a completed circuit for the heater.  I think 9 should go to 8 and 4/5 should go to 7 (or vice versa?).

Good catch. You are correct.
Since the Crack uses AC heating the polarity isn't important.

9-pin   8-pin

1       2
2       1
3       3
4/5    7
9       8
6       5
7       4
8       6

[InnerTube]

Can I use an adapter to run the 6sn tube?  If so, do you know if there is such an adapter available?

[Chris65]

Yes. Available from various sources, including that famous auction site.

[InnerTube]

Thanks very much for your reply.  It will be quite helpful to me.  I have several 6sn tubes that I used in a Darkvoice 336 before the Bottlehead.  I will get an adapter right away.  Thanks again

[borism]

You should also look at this thread:
https://bottlehead.com/smf/index.php?topic=7742.0
Not all adapters are equally good. I got one of these and have had no issues.

[Chris65]

Never had any issues with any of the adapters I use . Possibly the nicest are the Teflon ones:
https://www.head-fi.org/threads/new-product-universal-teflon-tube-adapter.548267/

[Kitchener]

That forum thread is pretty dated by now, their website has them under Accessories.
Also, starting at $40 they seem to have a healthy percentage of audiophile tax applied! 

[TravAndAlex]

Thanks for the help guys!