Tube Rolling w/Crack

[Doc B.]

Like with a lot of things the people who are ignorant about how this stuff works are paying the stupid money. There are lots of good sounding tubes out there and the "best" ones are seldom 10-100X better than the next one down the ranks. I could have taken advantage many, many times over on this front. But it kind of grates to see guys jack prices for tubes that weren't worth shit before we or someone else made an amp that uses them.

We have conversations every so often that go something like "lets buy all of the 6whateverKs in the world for 50 cents each, and make a $99 amp that can only use four of them and no other tube will work. Then we sell 'select polytonic transgender lofi upgrade tubes from the Stechner-Weissen radar and lawnmower factory (palladium pins, rhombic deuterium plates, 13.5 micas, kanji getters)' for $250 each."

My advice is listen to a tube before you pay big money. Some of the higher priced stuff is good, and some is just not worth it.

[2wo]

Man I have been looking for those Kanji getters forever, sure you wont sell me a pair?

[Guy 13]

Hi all,
many times I did tube rolling with different makes and models of tubes for my Crack
and all times I was wondering if my soon to be 67 years old ears
where responsible for not been able to ear big differences
between different makes - models of tubes.
With my Crack (6AS7G-6080/12AU7), Decware SE84C+ (5AR4-5U4/6922/EL84)
and Bellari VP-129 (12AX7) I never pay more than 35 USD each and most of the time,
the price I pay for one tube is 15 - 24 USD.
I will never pay more than 50 USD for a tube,
regardless of what the reviews by customers says.
Paying 250 USD for a (Rare or not) tubes is good, yes, it's good,
if you don't know what to do with your money or if you think it's worth,
until you find out  it was not worth...
It's my opinion and you don't have to agree with it.

Guy 13

 

[Adelz]

Hey, I'm finally getting around to buying some new tubes for my Crack. Before I buy, I was wondering if this listing on Ebay would be a wise purchase; how do I get the ability to post links in this forum? Thanks!

[Grainger49]

You can post links by cutting from the browser and pasting in your post.

[Adelz]

http://www.ebay.com/itm/Mullard-12AU7-double-triode-Vacuum-Tube-CV4003-ECC83-/271757525740 Here is the link. Upon having it in my post earlier an error popped up saying that I did not have permission to post links.

[Blkout]

Question regarding the Tung Sol 5998.

I read that the Tung Sol 5998 is a great tube and often recommended but also read somewhere, maybe it was Doc B on another forum that the specs are slightly different but still works fine in the Crack. What difference if any does the 5998 make in the Crack and is it because the specs are slightly different that causes the change in sound?

I am able to get my hands on a 1957 Tung Sol 5998 right now but it's around $100 so I was wondering if its even worth bothering with since it seems input tubes seem to make the most difference based on most user opinions.

[Paul Birkeland]

What difference if any does the 5998 make in the Crack and is it because the specs are slightly different that causes the change in sound?

The 5998 generally speaking has more transconductance than the 6080.  In the Crack circuit, you'll get slightly lower output impedance.  On the other hand, the insulation of the 5998 between heater and cathode is not anywhere close to as robust as the 6080, and this is pushed to the limit in the Crack design.

-PB

[Blkout]

The 5998 generally speaking has more transconductance than the 6080.  In the Crack circuit, you'll get slightly lower output impedance.  On the other hand, the insulation of the 5998 between heater and cathode is not anywhere close to as robust as the 6080, and this is pushed to the limit in the Crack design.

-PB

So technically speaking, the 5998 will very likely not last as long as the stock 6080, and with the lower output impedance I should get slightly better damping if I was using low impedance cans, which I'm not so it sounds like a moot point to use one in the Crack for my application. Sound about right?

[Paul Joppa]

At least some 5998s seem to have a better sound - nobody knows why, though I suspect better (quieter) cathodes because it's a premium tube. Or maybe it's just Western Electric brand-name stardust from the WE421 prototype. Be aware that there were never that many made, so a disproportionate percentage of what's available are samples that have been rejected before for one reason or another.

[Adelz]

I'm also leaning toward purchasing a 5998 tube. Would it perform well coupled with a Mullard CV4003? (also, would this listing be a good buy? http://www.ebay.com/itm/Mullard-12AU7-double-triode-Vacuum-Tube-CV4003-ECC83-/271757525740)?

Edit: Other than ebay, where would be the best place to get a Mullard CV4003 at a reasonable price? Upscale Audio has them for $95 while Mullard's site carries a matched pair for $125. There are also multiple listings on Tube World. Should I just go with the lowest price for a NOS tube or is it worth paying extra for top-notch tubes?

[orson]

I purchased a Brimar 12AU7 on ebay and got it today.
It has a metallic area on the glass that no other of my 12AU7s has.
Does anybody know what caused this?
Should I try that in the Crack or is it dead?

[Adrian]

orson:
Perhaps this Brimar 12AU7 was constructed with a "side getter" and what you are seeing is the remnants of that.  If so, then based on the apparent color of the "stain" on the glass,  the tube should be fine.  Many 6DN7s have this characteristic.

[fullheadofnothing]

Maybe someday the avid tube rollers will come up with a term to describe tubes that are transparent at their apex. Until then, listen and enjoy.

[borism]

Isn't the designation "clear-top" as in 12au7 clear-top used for this purpose?