Tube adapters??

[danosol]

I just got one from Lowther club and one of the pins had a glob of solder on it and the socket is crooked.  Junk! I 'm in the process of a dispute with them on e-bay. 

Hopeful,

Check your lighting in the room where your Crack is being used I got some audible noise on my crack and then isolated it to a dimmer on that circuit.

[dubiousmike]

Thanks for the suggestion danosol.  I don't have any dimmers in that room, but it is full of other electronic equipment that couldn't potentially be causing issues.  Anyone have a suggestion for a cheap power conditioner/isolator?  I used to run my crack from an audio port on my belkin pf60 - which worked reasonably well, but we moved and my amp migrated from my family room entertainment area to our guest bedroom/office.

I get no noise at all when I'm running 12au7's/12bh7's - so it seems like it has to be an adapter issue, but cleaner power couldn't hurt.

[danosol]

You can pick up Furman stuff for cheap on craigslist like the PL-8 Plus.  Look for the stuff with Lift technology if you decide to used (all the new stuff has it).  It should be around $80 used.  Kinda  big because it's rack mountable stuff but it's well made stuff. 

Someone else will probably chime in with another suggestion I'm sure.  I'm just familiar with Furman as I use it on my guitar rig.  You can always call Rob at Furman and tell him I recommended you.  Rob  and the rest of the team are great guys and know their stuff.  By the way my name is Ajay.

[Aeolus Kratos]

Hi everyone,

Can anybody confirm if the tube adapter in the picture below works on the Crack or not? I'm confused because the white words printed on the base of the adapters indicate that this one is to convert the 6SN7's to 12AX7's, not 12AU7's, I called the seller and he said that this would work just fine with the 12AU7's. These adapters are sold in the local audio shop, so it doesn't take too much time for me to drive there, give them cash and bring them home, much faster than buying and waiting for shipping on Ebay 


(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi148.photobucket.com%2Falbums%2Fs36%2Fdungaudio97%2FIMG_9539.jpg&hash=a041b864c74bb6ad0326bb9c5f9ba32246be9ffc)

( Adapter number 03 )

Thanks in advance!
Kratos.

[Grainger49]

Ok, the tube pin assignments are the same for a 12AX7 and a 12AU7.  The tubes are not equivalents. 

The reason the adapter says 6SN7 to 12AU7 is that they are equivalent tubes, one octal one noval.  If you use a 6SN7 where a 12AX7 was you will not be setting the 6SN7 up properly.

Does that make sense?

[Aeolus Kratos]

Ok, the tube pin assignments are the same for a 12AX7 and a 12AU7.  The tubes are not equivalents. 

The reason the adapter says 6SN7 to 12AU7 is that they are equivalent tubes, one octal one noval.  If you use a 6SN7 where a 12AX7 was you will not be setting the 6SN7 up properly.

Does that make sense?

Hi Grainger,

Thanks for your reply.

I'm sorry, but my English is not so good, so I don't understand what you mean very well. I consider that the tube adapter number 03 in the picture I posted above can be used perfectly for the Crack, because the function of tube adapters is just for converting the tube pin assignment from the 8-pin 'octal' of the 6SN7's to the 9-pin 'noval' of the 12AX7/12AU7/12AT7, etc, and it does not matter what kind of 'noval' tube your amps are using?

Thanks again,

Best regards,
Kratos.

[Paul Birkeland]

The 6SN7 to 12AX7 6.3V adapter in the photograph would be the correct one (by specification).

Grainger is very correct - the 12AX7 and 6SN7 would not be operationally interchangeable.

[adamct]

FWIW, I have two 6SN7-->12AU7 adapters that would appear to be from the same manufacturer. Both are VERY, VERY noisy in my Crack, which is generally silent with my 12AU7s, 12BH7s, and E80CCs.

[Paul Birkeland]

FWIW, I have two 6SN7-->12AU7 adapters that would appear to be from the same manufacturer. Both are VERY, VERY noisy in my Crack, which is generally silent with my 12AU7s, 12BH7s, and E80CCs.

Did you ever end up trying a 6V DC wall power supply to feed the 9 pin socket?

[adamct]

No. By the time I saw your suggestion, I had already ordered another (i.e., 3rd) adapter. I'll wait for that to arrive. And frankly even if that one is still noisy, I'm not sure that it is worth the effort for me to explore using a separate power supply. Are 6SN7s really all that likely to sound better than the various 12AU7s and 12BH7s available?

[Paul Birkeland]

It's not a matter of better or worse IMO, there are just a lot of different varieties of 6SN7.

[adamct]

Yep, I already have more of them than I know what to do with...

My next step for my Crack will be to install those 200uf Icar films caps in place of the first two power supply caps, and the two 100uf motor run oiler caps in place of the stock electrolytic (currently bypassed with a film cap) for the last power supply cap. After that, I think I will be tapped out on Crack mods...

[Grainger49]

Paul Birkeland said it.  The 6SN7 and 12AX7 are not interchangeable tubes.  They are not equivalent.  They don't have the same gain, need different voltage and current to operate properly.  But the 12AU7 and 12AX7 have the same pin assignments.  That means that the plates, grids, cathodes and heaters all use the same pin numbers. 

But just because they have the same pins and holes to go in it does not mean that they are the same.

The tubes will work but not well and not as designed.

Does that make sense?

Grainger

Ok, the tube pin assignments are the same for a 12AX7 and a 12AU7.  The tubes are not equivalents. 

The reason the adapter says 6SN7 to 12AU7 is that they are equivalent tubes, one octal one noval.  If you use a 6SN7 where a 12AX7 was you will not be setting the 6SN7 up properly.

Does that make sense?

Hi Grainger,

Thanks for your reply.

I'm sorry, but my English is not so good, so I don't understand what you mean very well. I consider that the tube adapter number 03 in the picture I posted above can be used perfectly for the Crack, because the function of tube adapters is just for converting the tube pin assignment from the 8-pin 'octal' of the 6SN7's to the 9-pin 'noval' of the 12AX7/12AU7/12AT7, etc, and it does not matter what kind of 'noval' tube your amps are using?

Thanks again,

Best regards,
Kratos.

[adamct]

To summarize:

12AU7 and 12AX7 are not interchangeable, because they have different gain, etc. You generally can't use a 12AU7 where a 12AX7 is called for. BUT, they do have the same pinouts. So a 12AU7 will fit in a 12AX7 socket, even if it shouldn't be used there.

6SN7 and 12AU7 are sonically interchangeable. In theory, you can use a 6SN7 where a 12AU7 is called for, and vice versa. But the problem is that they have different pinouts and sizes. So you have to use an adapter.

Because 12AU7s and 12AX7s are the same size and use the same pinouts, you should be able to use a 6SN7 --> 12AX7 adapter in order to use a 6SN7 tube in place of the 12AU7 in your Crack (provided you get a 6.3V version of the adapter, not a 12V version). This is because an adapter doesn't (or rather, shouldn't) have any characteristics of its own, it just rewires the pins assignments, which are the same for a 12AU7 and a 12AX7.

See, isn't that simple? 

Best regards,
Adam

[Aeolus Kratos]

Paul Birkeland said it.  The 6SN7 and 12AX7 are not interchangeable tubes.  They are not equivalent.  They don't have the same gain, need different voltage and current to operate properly.  But the 12AU7 and 12AX7 have the same pin assignments.  That means that the plates, grids, cathodes and heaters all use the same pin numbers. 

But just because they have the same pins and holes to go in it does not mean that they are the same.

The tubes will work but not well and not as designed.

Does that make sense?

Grainger

Hi Grainger,

Thank you for clarifying.

But I have one more question, you said that the 6SN7 tubes will work but not well and not as designed because 6SN7 and 12AX7 are not interchangeable, so what are the 6SN7-12AX7 tube adapters used for? They are not equivalent, so in theory you can not use a 6SN7 where a 12AX7 is called for. Why do people make the adapters which sonically can't be used because of the tube characteristics?

Thanks again, and sorry if my question is too silly 

Best regards,
Kratos.
 

To summarize:

12AU7 and 12AX7 are not interchangeable, because they have different gain, etc. You generally can't use a 12AU7 where a 12AX7 is called for. BUT, they do have the same pinouts. So a 12AU7 will fit in a 12AX7 socket, even if it shouldn't be used there.

6SN7 and 12AU7 are sonically interchangeable. In theory, you can use a 6SN7 where a 12AU7 is called for, and vice versa. But the problem is that they have different pinouts and sizes. So you have to use an adapter.

Because 12AU7s and 12AX7s are the same size and use the same pinouts, you should be able to use a 6SN7 --> 12AX7 adapter in order to use a 6SN7 tube in place of the 12AU7 in your Crack (provided you get a 6.3V version of the adapter, not a 12V version). This is because an adapter doesn't (or rather, shouldn't) have any characteristics of its own, it just rewires the pins assignments, which are the same for a 12AU7 and a 12AX7.

See, isn't that simple? 

Best regards,
Adam

Hi Adam,

That is a superb detailed and helpful reply and explanation. I guess I'll come to the local audio shop and try this adapter out. I can't stand the fact that I'll have to wait for nearly a month to get the adapter on Ebay 

Thanks in advance!

Cheers,
Kratos.