Tube Rolling w/Crack

[Grainger49]

Could someone maybe list the different variants of the two tubes that can be used?
I'm familiar with some of the 12AU7 versions, but I guess I don't know all of them (5963? 5814a?) and I know nothing about the 6080/6AS7's.

Thanks!

And yes, I only just ordered my kit today and I'm already looking for tubes
All I have are 12AT7s in my speaker rig

Wouldn't a straight swap tube substitute list make a good sticky in each product area?

A list below that could be those that require pin changes and or circuit changes.  Certainly not instructions just a list.

[levlhed]

agreed!

[tdogzthmn]

I would like to see a beginners guide to tube rolling.  I dont have a background in electronics so most of this is foreign to me. 

[Paul Birkeland]

Buy tube,remove old tube, plug new tube in, listen to tube. Rinse and repeat...

[ironbut]

Just like headphones, what's worth the money is in the eye of the beholder.
There's always plenty of folks who'll be happy to spend your money by stating that this tube or that tube is the only one to use in a particular amp and it's difficult when you're new at this to separate the wheat from the chaff.
My advice is to start by buying from a good dealer and avoid the auctions till you have a better idea what you're looking for. An established dealer has a stake in keeping his customers happy and well informed. They may be a little more money for a given tube, but they stand behind what they sell and do proper testing. Some even do some grading for low noise if you need some tubes for something like a phono preamp.
So, start small and don't be reluctant to buy used tubes from a trusted seller. When I start with a tube type that I'm unfamiliar with, I try not to spent top dollar on new old stock when there's a chance that that tube won't be the "holy grail" that other's seem to think it is (at least half the time, but that's just me). And if I do end up loving it, I can spend the money then. But there are lots of used, tested tubes that'll sound fantastic for years that you can get for a fraction of the cost of NOS.

Another thing to bear in mind is that current production tubes seem to be getting better and better. Some cost almost as much as fabled NOS tubes but don't overlook them just because they aren't as hip.

Finally, give tubes a chance to settle in. I know that it's hard to resist switching tubes after just a few hours, but I always give every tube at least 25 hours of burn in before I start to listen critically. Then I'll give it several days of regular listening with different sources and music genres. If I can't hear a difference without A/B'ing, the cheaper, easier to find tube wins.

[Grainger49]

I would like to see a beginners guide to tube rolling.  I dont have a background in electronics so most of this is foreign to me.  

Paul Birkeland's explanation covers most of it.  If you buy a tube with the exact same tube number you are fine.  

This is a quote from the Product Page, "And of course you can tweak to your hearts content tube rolling different 12AU7 and 6080/6AS7 variants."  What Doc means is that there are "equivalent" tubes out there.  Some are a drop in replacement, like the CV4003 Mullard is exactly the same as a 12AU7 but sounds nicer.  Others are very similar but won't work for some reason or another.  In the case of the 6DJ8/6922/7308 that is used in the Seduction the Russian 6N1P is the same except it needs more current for the heater.  Using it in the Seduction will either blow the fuse, we hope, or burn out the heater winding in the transformer, we hope not.

Look two posts above yours, I suggest that usable tubes like the CV4007 be listed as a "Sticky" for each product.  That would take the guessing out of it.  And maybe I will start a thread that others can correct and add to and Doc can make it a Sticky.  

The OP, Dr Toobz could collect the equivalents for the crack and edit ("Modify") his first post for the Crack.

For the input tube, the 12AU7 I have a list of tubes that I believe are usable equivalents.  I do not know that all use the same or lower heater current, a common problem is higher current.  But this is a start for the 12AU7:

12AU7(A)(WA)
ECC186
ECC82
ECC802(S)
E8025
E82CC
CV4003
CV4122
CV491
5814(A)
6189(W)(WA)
6680 (WL6680)
6067
7489
7316

I will be happy to correct this list if anyone can help.

[tdogzthmn]

Has anyone tried using a Western Electric 421A?  I saw some for sale but they are quite pricey. 

[Jim R.]

How about the 5670/2c51?  Will this tube work in the amp if the front socket is rewired?  I don't have a pinout chart so I can't tell if it is the same as a 6cg7.  I also don't have access to the curves so I can't tell if any changes to bias would be needed at the 75v operating voltage.  I realize there will be 5 dB more gain, but is there anything else I should be considering?

Thanks,

Jim

[Paul Birkeland]

You could indeed use this tube, but it would be easier to do with the Speedball upgrade. If you're planning to go that route, I can post the R1 value for the driver C4S boards.

Honestly, I'd go for the 5687 instead.

[mrarroyo]

A good site to find information on tubes and their equivalets is: http://tdsl.duncanamps.com/tubesearch.php

[Jim R.]

Thanks, Paul.  If you can post the resistor value, that would be great as I may just give this a try at some point.  I only thought of the 5670 because I have a few of the super nice, 1950s Ericsson/simens gold pins and no 5687s in house, and no money to buy more tubes right now.  Any particular reason for one over the other?  The interelectrode capacitance values of the 5670 seem decent to me.

Marroyo, I do use that site, but I'm blind so the graphs and graphical pinouts are of no use to me, but the TDSKL page often gives me links to other html pages where the electrical data is published in text.  I still haven't found one that identifies pinouts though.

Thanks anyway,

Jim

[ironbut]

Hey Jim,
The pin assignments for the 5670 are;

1-heater
2-cathode (2)
3-grid (2)
4-plate (2)
5-shield
6-plate (1)
7-grid (1)
8-cathode (1)
9-heater

Heater-6.3V, 350mA

Class A
plate voltage 150V
cathode bias resistor 240 ohm
amplification factor 35
plate resistance 6400 ohm
transconductance 5500 micromho
plate current 8.2 milliamperes
grid current -8V (Ib=10 milliamperes)

[Dr. Toobz]

Ok, here's a theoretical question, just out of curiosity: is the lowly 6AS7 and its many variants we're playing around with like a sort of indirectly-heated twin 2A3? I remember somebody claiming someplace else that a 6AS7 is similar to two 6B4's, or at least close. 6B4's are the octal version of the 6A3, which is a 6-volt heater version of the 2A3. Correct? So, might a 6AS7, the lowly regulator tube now finding use in many headphone and P-P amps, actually be an indirectly-heated cousin of the 2A3? This tube certainly sounds a lot better than it has a right to....

(One problem I found, though, is that the 2A3's mu is higher than the 6AS7, which I think is around 2, correct? So,maybe distant cousins....).

[Dr. Toobz]

I've started to compile a list of tubes on the original post as a reference. Would you guys who actually know something about tubes double-check it for accuracy, and PM me with any additions/corrections? There's one input tube, for example, that I left off, the ECC80, as I don't know if it's a drop-in replacement or needs the heaters rewired (don't have specs handy ATM).

[Paul Birkeland]

Wow, the 5687 does indeed look like an interesting tube to try.  Of course, the pinout is different, so that has to be addressed first.  After that, I would change the R1 on the green PC boards to 52 ohms.  This will set the forward current to around 15ma, and should keep the plate voltage around 75 volts.  Of course, 150-75=75 volts across the CCS, then .017A*75v=1.275 watts, so use a small clip on heatsink for each transistor (it won't require anything significant). 

The 5687 has similar gain to the AU7, and the extra plate current should really sweaten the sound!  Based on the extra current drawn, I would go to a CLC power supply at the same time to ensure that the B+ rail stays up over 150v.