Tube Rolling w/Crack

[Tom-s]

@cddc, for all the tube rolling. Just buy any tube you can find cheap.

Good catch on the ECC40's. Personally i liked the Eindhoven (only the early years of ECC40's were build there) and Hamburg manufactured Philips tubes best. Second is the Sittard plant, after that the French factories.

The difference between the exact same type off tubes is small but a lot of fun to explore. I've found the supertubes within a certain type of tubes are usually not exactly the same type, as they are electrically slightly different (the 5998, Bendix 6080 and CV2523 all are for 6080's par example). This is what attributes to their different sonic signature in my perception.

I have many driver tubes for Crack but the rules on this forum do not allow me to sell them to other members, otherwise i'd gladly help out.

 

[cddc]

Tom, thank you very much for pioneering the use of ECC40's and helping us with your findings there.

After reading pages of this thread, I kinda get lost :-\ There seems to be some widely agreed upon power tubes. But in term of driver tubes there are just so many different tube families (12AU7/6SN7/12BH7/ECC40/E80CC, etc) to choose from. It's like rolling a dice, I guess.

So far your opinions and recommendations have been great, I much appreciate it!

 

[attmci]

Tom, thank you very much for pioneering the use of ECC40's and helping us with your findings there.

After reading pages of this thread, I kinda get lost :-\ There seems to be some widely agreed upon power tubes. But in term of driver tubes there are just so many different tube families (12AU7/6SN7/12BH7/ECC40/E80CC, etc) to choose from. It's like rolling a dice, I guess.

So far your opinions and recommendations have been great, I much appreciate it!

Well, again this is all personal preference...........

 

[cddc]

I think that is the adapter that isn't noisy.  The Crack uses 6.3V heaters, so functionally that is the correct adapter.  The 12AU7 has a 12V heater with an extra connection in the middle.  If you tie the ends of the heater together and use the center connection, then you can heat the tube with 6V.

www.ebay.com/itm/GARAGE1217-6SN7-TO-12AU7-TUBE-SOCKET-ADAPTER-OUTSTANDING-BUILD-QUALITY/254027687944?hash=item3b253ae808:gYAAOSwOyJX-neh

Is this Garage1217 6SN7-to-12AU7 adapter ($33 shipped) any good?

I concern about the use of PCB instead of solid core copper wires in the Garage1217 one. I think PCB is inferior to wires in term of conductivity and capacitance (one of the many reasons why Crack sounds so good vs. a SS amp on PCB). So I searched eBay and found this cheaper one ($13.44 shipped) with solid core wires.

https://www.ebay.com/itm/1-6SN7-To-ECC83-12AX7-12AU7-Vacuum-Tube-Amp-Convert-Socket-Adapter-6-3V/312206555328?hash=item48b0f5f8c0:g:~rkAAOSwGDZbYVR3

Will the cheaper one work in Crack? I think 6.3v on 12AU7 sockets should make it work, right?

BTW, these 2 adapters should work for 6SN7 and its variants (like 7N7, 1633, Soviet 6Н8С, etc), right?

Many thanks.

 

[Tom-s]

I just use the cheapest china adapters. And until now (have about 20) never had any problems with them.
Only once ordered a 12v version instead of 6v, so just resoldered that myself.
I'd probably buy this: https://www.ebay.com/itm/201201010078

You can use all 6SN7 and pin-out equivalent tubes.
So 6SN7, CV181 (ECC32), 5692, 6H8C, B65 can be used in Crack.
7N7 is a loktal socket 6sn7 equivalent and won't work without it's specific adapter, but i've used it in Crack.
1633 is a 25V SN7, like 12SN7 is a 12V SN7 tube and 12SX7 is a 12V SN7 with a more rigid heater like 12AU7.

 

[cddc]

I just use the cheapest china adapters. And until now (have about 20) never had any problems with them.
Only once ordered a 12v version instead of 6v, so just resoldered that myself.
I'd probably buy this: https://www.ebay.com/itm/201201010078

You can use all 6SN7 and pin-out equivalent tubes.
So 6SN7, CV181 (ECC32), 5692, 6H8C, B65 can be used in Crack.
7N7 is a loktal socket 6sn7 equivalent and won't work without it's specific adapter, but i've used it in Crack.
1633 is a 25V SN7, like 12SN7 is a 12V SN7 tube and 12SX7 is a 12V SN7 with a more rigid heater like 12AU7.

Wonderful, thank you very much, Tom!

I initially thought all 6SN7 variants will work with the 6SN7-to-12AU7 adapters mentioned above,  except the ST shaped 6F8G/6C8G (just like most 12AU7 variants work with the 12AU7 socket). But now it seems lots of them won't work with the 6SN7-to-12AU7 adapter due to different voltages or socket shapes.

Tom, you mentioned "7N7 needs a special loktal adapter, but you've used it in Crack", I am a little bit confused here. Did you mean you used a 7N7 along with a loktal adapter in your Crack, or you just simply pushed it into the 6SN7-to-12AU7 adapter you recommended?

 

[Tom-s]

I've used 7N7 with it's specific adapter in Crack. It will not work in a 6SN7 socket.
And it sounded just fine with Crack. It's a cheap tube to find (especially in the USA).
That being said, personally i used a few short and tall bottle versions in my Crack to try.
The sound is similar to Sylvania 6SN7 variants.
6SN7 socket is more useful for tube rolling with Crack with a lot of tubes to try.
I've tried +- 20-30 versions of 6SN7 (RCA (American and EU factories), GE, Sylvania, Tung Sol etc), the ECC32 (CV181) Mullard versions, the 5692 RCA and CBS versions, the Russian 6N8S normal and 1578 variety.

The 6F8G/6C8G tube adapter is a more versatile adapter compared to 7N7 with more tube rolling / sound flavouring options (only tried +-10 different types in that).
Edit: 6F8G/6C8G's are generally a lot cheaper compared to their equivalent brand/type 6SN7's, with a very musical sound. But more prone to hum/microphony in my experience.

Edit 2: Warning! Don't get lost in tube rolling. Don't be like me  ;D .
The effect on sound is minor at best. It's seasoning / flavouring of the sound. If you want better sound, get S3X (it also gives reason to buy speakers (at least, it did for me)). If you want to be done with it, buy a Mainline (yes, it is that good). I have too many tubes to try in Crack, and with whatever tube, it's not a S3X and never close to Mainline. That said, Crack is next to Mainline on the desk and i listen to it 90% of the time vs Mainline 10% (both with HD800).  :-X

 

[cddc]

Super, thanks very much again for your opinions, Tom!

You are right 7N7s and 6SN7s are easy to find on ebay.com for decent prices. 6F8Gs and 6C8Gs seem much more expensive on ebay.com currently, maybe it's a different story in Europe.

For the tube rolling I just want to try it for fun - plan to grab several preamp tubes and several power tubes to try it first, hopefully will not end up being obsessed  ;D

I have 2 pairs of bookshelf speakers, one Sony and one Dynaudio - Dynaudio sounds way better than Sony IMO, with accurate presentation and spacious soundstage. Currently I'm 50/50 on speakers and headphones. Down the road will definitely consider getting some other amps to try, especially these DIY tube amps - amazing sound and lots of fun.

 

[cddc]

A quick question: just pulled trigger on a 12BH7 driver tube, does it need an adapter for the 12AU7 socket?

 

[Paul Birkeland]

A quick question: just pulled trigger on a 12BH7 driver tube, does it need an adapter for the 12AU7 socket?

Circuit changes.

 

[cddc]

Thanks a lot, PB.

By circuit changes you mean I should adjust the resistors/LED for optimal performance, but the pinout of 12BH7 should be the same as 12AU7 hence no adapter is needed, am I correct?

 

[Paul Birkeland]

The pinout is the same, but the plate voltage will drop considerably if you use it in the stock circuit.

 

[cddc]

Gotcha, thank you very much 

 

[attmci]

I, and many others on the other site, have plenty of problems............with cheap adapters.

Why not try some better 12au7s (designed for the circuit) first before using those adapters?? The best 12au7s are still much cheaper than top 6SN7s.

And a B65 for Crack????

Cheap Vt99/6f8g? Try these:

https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&LH_Complete=1&_udlo=&_udhi=&_samilow=&_samihi=&_sadis=15&_stpos=08820&_dmd=1&_ipg=200&_fosrp=1&_nkw=6f8g+tung+sol&_sop=13

 

[Paul Birkeland]

Gracious, when did the 6F8G get so expensive?

 

[Tom-s]

How could i rebuild my Crack to work with this tube? http://tdsl.duncanamps.com/pdf/a2900.pdf
Or could it be done by just raising the R1 resistor to 1k ohm?
Or should i use another LED color for correct bias?

As a don't have a volume control in my Crack, i'm ok with the higher gain.

Edit: I can imagine it being a no-go as the current would be to low for the LED to light up/function for getting it within save function. And lower bias would trow off the 6080 function.

 

[Paul Birkeland]

That tube has way, way too much amplification factor.  The extra 15dB of gain that you will get from using that tube will be very unwelcome.

 

[Tom-s]

Aside from the fact that it would be a problem in a Crack with volume control.
I'm ok with the extra gain. I just want to try this tube, and run it in optimal conditions for Crack (if possible).
Could i just make the R1 resistor in speedball a bit higher to get it to work?

 

[Paul Birkeland]

No, I mean when you move the volume control 5 degrees or so, you'll likely be near full output on the Crack.  In order to run that particular tube with the red LEDs on the socket providing bias, you'll run so little current that you'll be off in the weeds in terms of where the linear operating areas are. 

 

[attmci]

Gracious, when did the 6F8G get so expensive?

Because they are cheap comparing to these:

https://www.ebay.com/itm/173774749419?ul_noapp=true

Happy Easter!

And much cheaper than these rebranded Mullard. (Mullard had never made 6SN7GT tubes).

https://www.ebay.com/itm/2-pcs-new-NOS-NIB-6SN7GT-ECC33-CV2821-Mullard-matched-pair-/254196502387?nma=true&si=UDPVVJzJhpzUeUHL000cyhiFdV0%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557