Tube Rolling w/Crack

[L0rdGwyn]

Thanks again! The 3 Stromberg Carlson 6080s from eBay arrived the other day. I'm going to contact a local dealer that has the equipment to test tubes here in Raleigh. Going to make sure they are in good shape. They definitely look NOS and unused but I bought them untested so I want to be sure. I'll probably see if he wants to buy 2 of 3 off me if they test well since he could easily sell them as a pair on his eBay store. I could totally hold on to one for you if you want! They are hard to come by at a decent price :\ I don't want much for them since I got such a good deal on them! Just let me know. The Chatham 6AS7G arrived from vacuumtubes.net the other day too! So between those and my stock winged "c", I'm all rounded out! Thanks again everyone for the help.

Hey bud - just saw this post, if they pass your testing and you want to hold onto one for me, I would definitely take it off of your hands if it's too much of a hassle, I'll look for your local dealer's Ebay listing.  Would shoot you a PM, but I can't seem to figure out how on the BH forums lol am I missing something here guys?

[attmci]

I've read dozens...actually probably hundreds...of posts across the web. Didn't think it would hurt to consolidate a few questions in one reply here. Still don't think it's a problem.

Well, then you should already know the answers.

[attmci]

I've rolled 100's of tubes in my Crack. I can only recommend the "Russian combination" for a reasonable price.
6H13C (Svetlana winged C, OTK)old stock for the power tube.
ECC82 Gold Lion new production for the input tube.

On the other end of the spectrum, for just marginal gains over the above mentioned combination (but have heard none better to date), there's the not so reasonably priced/unobtanium "English combination".
A1834 GEC power tube.
ECC32 Mullard input tube.

See, everyone has  different options. I will never use these two tubes in my amp.

BTW, Tom's crack had been heavily damaged, I mean modified. LOL

[JLDub]

Hey bud - just saw this post, if they pass your testing and you want to hold onto one for me, I would definitely take it off of your hands if it's too much of a hassle, I'll look for your local dealer's Ebay listing.  Would shoot you a PM, but I can't seem to figure out how on the BH forums lol am I missing something here guys?

Hey Gywn, I also don't see a PM option. I'm having a hard time getting in touch with VTubeaudio here in Raleigh. He answered my first email when I was looking for some tubes, but that's about it :\ his site says he'll list tubes on his eBay store (surely for a fee) which would be ideal, and in turn they'd be tested. Anyways, I've run across you on Head-fi so I can PM you there. FYI the 6080s look to be in great shape and not used. It will be some time before I can actually try them out in my crack though. Work and family life has taken up most of my time lately. I plan to start my build tomorrow! I can always mail them and accept PayPal, not a trouble at all.

[Doc B.]

Click on the user's name, then click on send PM. If the send PM selection doesn't show, the user has opted out of accepting PMs.

[JLDub]

Thanks Doc, I had to go to my account and check allow users to email me.

[Tom-s]

Yes my Crack's been heavily damaged. 

But that's what the kit is all about. For me, the fun is in modding it, playing with it, trying every tube i can.

It's on about 8 hours a day, now mostly used with HD800's.

Currently looking into other Russian tubes: http://klausmobile.narod.ru/testerfiles/6n30p.htm
6n6p and 6h30p, PB/Doc any comments on these, which would be better?
I think both could work in Crack (with speedball).
Closest tube i've used in Crack (with a few corrections) is 5687 and 7119.

[Paul Birkeland]

Currently looking into other Russian tubes: http://klausmobile.narod.ru/testerfiles/6n30p.htm
6n6p and 6h30p, PB/Doc any comments on these, which would be better?

The 6H30, in a Crack with Speedball, will develop about 29V on the plate instead of the 80V we'd like to see.   10mA/4.5V of bias would make the 6H30 work.  The MJE350 would need to come out and the MJE5731A installed in its place.  The R1 resistor would, of course, need to change as well.

The 6H6P will make maybe 40V with the stock Speedball.  4mA of plate current and 3V of bias would get you up and running there.

[Rossputin]

Other than the obvious "supply versus demand", can anyone tell me why the Tung Sol 6AS7G tubes can be had for something like 10% or 20% of the price of the 5998, and whether you think the 5998 is worth the higher price?  In other words, are the 5998s much better, much rarer, or both?

Also, in the very first post in this excellent thread, I don't see 421A listed as a substitute for 6080. But I do see lots of folks talking about them on the board and selling them as substitutes. Is it a straight-up substitute for the 6080 or would using it require other modifications to my Crack (with Speedball)? Thanks!

[Paul Birkeland]

The 5998 is a completely different tube than the 6080, but they work interchangeably in the Crack circuit.  They are in demand and quite rare, so prices are high.

The WE 421A is a rebranded Tung Sol 5998, so there aren't any issues there.

[L0rdGwyn]

The 5998 is a completely different tube than the 6080, but they work interchangeably in the Crack circuit.  They are in demand and quite rare, so prices are high.

The WE 421A is a rebranded Tung Sol 5998, so there aren't any issues there.

PB, I think I remember reading the WE 421A is a similar but distinct tube from the TS 5998.  Transconductance is 20,000 and mu of 6.1 compared to the 14,000 and 5.5 of the the 5998.  Is it just a rebrand?  Regardless, they both work in the Crack

http://www.westernelectric.com/static/library/specifications/tubes/5998.pdf

http://www.tubebooks.org/tubedata/5998_TS.PDF

[Paul Birkeland]

The "Western Electric" datasheet is named "5998.pdf". The Western Electric datasheet also says "Western Electric 5998" on the first page.  The two tubes are identically constructed.

The 5998 lists 120V plate, 125mA, 17,000uMhos, and an amplification factor of 6.2.
The 421A lists 110V plate, 125mA, 20,000uMhos, and an amplifiaction factor of 6.1.

For lower plate voltage and the same current, grid bias will be lower, and that change in operating point will increase transconductance a little.

[L0rdGwyn]

The "Western Electric" datasheet is named "5998.pdf". The Western Electric datasheet also says "Western Electric 5998" on the first page.  The two tubes are identically constructed.

The 5998 lists 120V plate, 125mA, 17,000uMhos, and an amplification factor of 6.2.
The 421A lists 110V plate, 125mA, 20,000uMhos, and an amplifiaction factor of 6.1.

For lower plate voltage and the same current, grid bias will be lower, and that change in operating point will increase transconductance a little.

Got it, thanks for the insight!

[L0rdGwyn]

If I have a power tube that arcs on start up, do I run the risk of damaging my amp?  It isn't every time, I've tried "cooking" the tube for probably around 5-6 hours, but still arcs.  After it warms up, it sounds great and has no other issues, just don't want to damage anything.

[Tom-s]

The 6H30, in a Crack with Speedball, will develop about 29V on the plate instead of the 80V we'd like to see.   10mA/4.5V of bias would make the 6H30 work.  The MJE350 would need to come out and the MJE5731A installed in its place.  The R1 resistor would, of course, need to change as well.

The 6H6P will make maybe 40V with the stock Speedball.  4mA of plate current and 3V of bias would get you up and running there.

Thanks for the reply. Tried 6H6P first. Running at 2V bias, 150Ohm R1 -> 90V on 1 and 5. Sound ok, small 50Hz hum for now.

Edit: I do have a MJE5731A on my speedball small board.

Edit 2: For anyone interested. The 6N6P is an excellent performer for the Crack. The detail retrieval is up there with the best 12au7's. Is has the holographic extra layer like a Telefunken. The soundstage is not of the best. For me it performs as good as other "supertubes" E80CC/12BH7/7119.
To use it in Crack, it uses same setup as 5687 tubes (blue LED bias, 150Ohm R1), only different pinout.