Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: TravAndAlex on March 16, 2018, 02:07:20 PM

Title: Replacing 9 pin tube socket with 8 pin octal socket
Post by: TravAndAlex on March 16, 2018, 02:07:20 PM: 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!
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: Natural Sound on March 17, 2018, 10:52:52 AM: 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=12au7)
http://tdsl.duncanamps.com/show.php?des=6sn7 (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.
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: TravAndAlex on March 17, 2018, 01:12:20 PM: 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 -
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: diynewbie on March 18, 2018, 03:09:00 AM: 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?).
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: Natural Sound on March 18, 2018, 10:07:59 AM: Quote from: diynewbie on March 18, 2018, 03:09:00 AM
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
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: InnerTube on March 18, 2018, 10:36:19 AM: Can I use an adapter to run the 6sn tube? If so, do you know if there is such an adapter available?
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: Chris65 on March 18, 2018, 11:43:10 AM: Yes. Available from various sources, including that famous auction site.
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: InnerTube on March 18, 2018, 02:41:36 PM: 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
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: borism on March 18, 2018, 02:47:37 PM: 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.
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: Chris65 on March 18, 2018, 02:56:40 PM: Never had any issues with any of the adapters I use :D. Possibly the nicest are the Teflon ones:
https://www.head-fi.org/threads/new-product-universal-teflon-tube-adapter.548267/ (https://www.head-fi.org/threads/new-product-universal-teflon-tube-adapter.548267/)
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: Kitchener on March 19, 2018, 12:38:12 AM: 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! ;D
Title: Re: Replacing 9 pin tube socket with 8 pin octal socket
Post by: TravAndAlex on March 20, 2018, 06:22:51 AM: Thanks for the help guys!