Tube Rolling w/Crack

[Koop]

Rolled in a 6AS7 using an adapter. I really like what I'm hearing with my 650's. More space between instruments and effects. Vocals sound really great as well.

[Doc B.]

A 6AS7 does not need an adapter, it plugs right into the 6080 socket. If you are trying to use some sort of adapter to replace the 12AU7 with a 6AS7 you will smoke your power transformer.

[cddc]

Rolled in a 6AS7 using an adapter. I really like what I'm hearing with my 650's. More space between instruments and effects. Vocals sound really great as well.

Did you mean 6SN7 input tube? And which 6SN7 tube it is?

6AS7 should work in Crack as power tube without any adapters as far as I read.

[cddc]

Got some questions:

Someone mentioned earlier in this thread that the 6080 power tube in Crack is only a cathode follower and no voltage amplification is done by it (only losses, so max amp factor is 1.0).

Does that mean the 12AU7 driver tube has much more sonic importance than the 6080 power tube does in Crack (because 12AU7 does the main amplification work in Crack)?  And so it's much more important to find a good driver tube first (i.e. roll 12AU7 first before 6080)?

But now so many people here are obsessed in finding a power tube, why is that?

[Paul Birkeland]

Someone mentioned earlier in this thread that the 6080 power tube in Crack is only a cathode follower and no voltage amplification is done by it (only losses, so max amp factor is 1.0).

Does that mean the 12AU7 driver tube has much more sonic importance than the 6080 power tube does in Crack (because 12AU7 does the main amplification work in Crack)?  And so it's much more important to find a good driver tube first (i.e. roll 12AU7 first before 6080)?

But now so many people here are obsessed in finding a 5998 tube, why is that?

Someone mentioned that the 12AU7 tube in the Crack is only a voltage amplifier, and that no current amplification is done by it (assuming the Speedball is installed).  Does that mean that the 6080 has much more sonic importance than the 12AU7 driver tube in Crack? (because the 6080 does the main amplification work in Crack)?

Both questions are valid!

[cddc]

Someone mentioned that the 12AU7 tube in the Crack is only a voltage amplifier, and that no current amplification is done by it (assuming the Speedball is installed).  Does that mean that the 6080 has much more sonic importance than the 12AU7 driver tube in Crack? (because the 6080 does the main amplification work in Crack)?

Both questions are valid!

Thanks a lot for the answer. I am still confused because of my innocence in electronics.

I reviewed page 22 where Nick said no voltage amplification in Crack while Beefy said 12Au7 amplifies the voltage. I guess in this case Beefy was correct from your answer.

But somewhere (could remember which page now) I read there is only loss to the cathode follower and the max amp factor is 1.0. So 5998 has more gains than 6080 does, because it has less loss.

From above I reasoned that the amplification job is mainly done by 12AU7, as cathode follower can only produce losses.

I guess you are correct that 6080 does the main amplification job - the name "power tube" just sounds right to me in term of amplification. But I couldn't figure out where I made the mistakes regarding the losses on cathode follower and 5998vs6080 in my previous post. 

[Koop]

Did you mean 6SN7 input tube? And which 6SN7 tube it is?

6AS7 should work in Crack as power tube without any adapters as far as I read.

DOH - my bad, yes I meant 6SN7. It's a zenith , late 50s I believe. These are rebranded Amperex correct?

[Paul Birkeland]

as cathode follower can only produce losses.

You could make a sub-unity voltage gain Crack with no 12AU7, but you couldn't make anything useful for driving headphones with just a 12AU7. 

If you switch your thinking to current, then things change significantly.

[cddc]

You could make a sub-unity voltage gain Crack with no 12AU7, but you couldn't make anything useful for driving headphones with just a 12AU7. 

If you switch your thinking to current, then things change significantly.

Found PJ's comments on Page 30, "The output tube is used as a cathode follower, so the gain of that stage is always a bit less than 1.0. Into a high impedance, the 6AS7 might have a fain of 0.65, vs. 0.8 or so for a 5998." So I guess "gain less than 1.0" doesn't necessarily translate into "amp factor less than 1.0 (i.e. no amplification)".

It's becoming too technical now for an electronics novice like me, so I gave up...LOL

So I only take the conclusion that power tube has more sonic impact, and 5998 sounds louder than 6AS7.

Anyway, thanks a lot for the reply, PB!

[Paul Birkeland]

So I only take the conclusion that power tube has more sonic impact, and 5998 sounds louder than 6AS7.

The 5998 has a little extra transconductance and will have slightly lower output impedance than a 6AS7.  Personally I think the 12AU7 matters a whole lot more.  The 5998 shouldn't be audibly louder than the 6AS7.

[cddc]

Jamie, It's rare that I ever hear anyone mention Eva Cassidy. "Live at Blues Alley" is probably my all time favorite album. So sad that such a remarkable talent passed away at such a young age. She sounds great on my Crack with 5998 and a Ken Rad 5814 ( 1948).

It's not so rare, i think. 

Eva Cassidy's "Live at Blues Alley" is also one of my favorites. "Autumn Leaves" is a blessing.

[attmci]

They appear to have a winged C on the photo's. So they'll be fine.

I only have one 6H13C and one 6H5C in my collection.
With +- 30-50 output tubes for Crack i've plenty of variety, no need to buy different date codes to try different sound. I just put in a different 6080/6as7 and discover a new sound every time.

From personal experience with tubes, the date code makes minor difference in sound compared to just putting in another brand of tube.

I agree with Tom. Try different tubes, then buy backups of the ones you like.

Hard to get rid of those W-Cs.

BTW, all tubes (driver, power, rectifier) have "sonic impact". But everyone has his/her own taste.

[cddc]

I loved my 5998.  Unfortunately, it died on me the other day.  I was switching out the 12AU7, and I didn't let it cool down long enough.  Turned it back on, and I get very little output.  Now I'm running a Bendix 6080WB graphite plate.  It's not as pretty as the 5998, but it does sound great.

Sorry to hear the tragic...but I don't understand why the tubes need to cool down?

I remember Doc B. said earlier that all you need to do is just to power off the Crack and then roll tubes.

[cddc]

NVM, found the answer.

[adydula]

Eva Cassidy!!

Really great talent, that passed away...so young....

I have most of her albums and they all are awesome.

The Live at Blues Alley is really superb!

Alex