Tube Rolling w/Crack

[m17xr2b]

For ECC40 with an adaptor is the same resistance value as E80CC(470ohm) the correct value?

[Tom-s]

Yes. The ECC40 functions with the same parameters as the E80CC. It was it's predecessor.

[airofu]

Just wondering what are some recommended power and driver tubes in the lower sub $30 price range that are more readily available and rated good for the money (better then stock)?

Going off some reviews I am looking at the 6H13C Winged-C power tube and driver tube the 12AU7 Mullard/Brimar CV4003 or ECC82 Mullard? I'm hoping these are better then stock for fairly little outlay?

[tim273]

Would this work for a 6sn7 to 12AU7 adapter: h t t p s://www.ebay.com/itm/GARAGE1217-6SN7-TO-12AU7-TUBE-SOCKET-ADAPTER-OUTSTANDING-BUILD-QUALITY/254027687944?hash=item3b253ae808:g:-PYAAOSwOyJX-neh

It specifically says this: 

This adapter allows you to use a 6sn7 tube in place of a 12au7 in certain designs (heater voltage must be 6.3V on the 12au7 / center tap used) Do not use this adapter if you amplifier runs at a true 12.6V on the heater circuit. Also, do not use this adapter if your 12au7 socket is flush with or sitting below a metal chassis plate

Looking at the manual it appears as though everything checks out, I'm just not sure about the "center tap used" part.

[Paul Birkeland]

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.

[azeendeen]

Can anybody recommend me tubes to get with a budget of 100usd? I would like a slightly v sound with bigger sound stage.  It's just that I don't much about tubes since this is my 1st tube amp .

[attmci]

Can anybody recommend me tubes to get with a budget of 100usd? I would like a slightly v sound with bigger sound stage.  It's just that I don't much about tubes since this is my 1st tube amp .

Do you mind to use an adapter?

[cddc]

The ECC32 is a 6SN7 and should work with the stock Speedball.

Curious about tube rolling.

So when you plug in a 6SN7 tube and adapter to replace the 12AU7 tube on a stock Crack with Speedball, you don't need to make any other changes?

Someone said you need to change the resistors on the speedball. Is that true, or is it as simple as "plug and go"?

Thanks.

[cddc]

Hi, BZ58, the Syl 6SN7W is one of the best 6SN7 tubes (military grade tube, long life, very very quite). They can be used as driver tubes with an adapter on Crack (same gains, but draw 0.6A).

http://www.fourwater.com/files/hist6sn7.txt

Hi attmci,

So 6SN7 doubles the current, right? Do we need to change the resistors in Crack w/Speedball, or it's just fine?

Will there be excess heat?

Thanks!

[Tom-s]

A 6SN7 (w) will work just fine with the stock speedball setup. No need to change resistors.
The 0.6 amp heaters are ok for Crack. Max is 3.5 amps for all tubes together. Output normally uses 2.5A.
That said, the ECC32 is not an exact 6SN7. See: https://www.tubeworld.com/ecc32ecc33.htm
It works fine in the stock speedball Crack, though the E80CC resistor change helps to optimize the voltages.
The ECC32 is unobtanium and overpriced. Tried a few, and they are somewhat suspect to hum from the PT.
They do sound great, but can't recommend them for the price. Do mind the 0.9A heater current.
I've tried many 6SN7 and variants and they all work fine with Crack.
Right now using RCA 6as7g with 5692, also not a 6SN7 but close enough and functioning perfectly in Crack.
Also bit pricey for Crack, but extremely well build. If i ever build a tube amp for my car, this i'd use.

From my personal experience, don't buy expensive tubes. Better learn a thing or two by making modifications to your Crack and save the money for a better amp. The best Crack is not a S3X and a Mainline is in a entirely different league.

[cddc]

Thank you very much Tom-s for your detailed explanation and insight into the 6SN7 tubes! It's very helpful.

Very glad to know that 6SN7 is as simple as "plug and go". I built my Crack w/speedball with great care. It sang amazingly for me from the moment it was completed. So really don't want to screw it up accidentally when changing something like resistors on the SB circuit board.

I haven't really looked into tube rolling yet. Just quickly looked up the 6SN7GT tubes the other day, and found lots of them could be outrageous in price.

Do you have any good value 6SN7 tubes to recommend (i.e. sound good but do not break the bank)?

[cddc]

Regarding the additional heat caused by doubling the current for 6SN7, it could be a problem for a Crack without Speedball, because the wirewound resistors under the heat sink might generate excess heat. However, with the removal of wirewound resistors during Speedball installation, there won't be heat from the 2 wirewound resistors anymore, hence it is no longer a problem to Crack with Speedball, right?

Not sure whether my poor reasoning on the possible heat issue is correct or not?    My knowledge in electrics is very limited.

[Tom-s]

The 6SN7 is plug and go in a Crack with speedball (with adapter).

Don't get into tube rolling. It's a trap. 

The heater current has nothing to do with the heat from the 5w bias resistors.

Edit: It will function just fine. Heat will not be an issue.

[cddc]

Cool.

I don't remember where I read it, but someone reported the wirewound resistors under the heat sink became very hot and wires next to them turned brown after rolling in a 6SN7. So I was kinda concerned about 6SN7 tubes. But it's okay now. Thanks very much.

Hopefully I won't get into the trap, or at least not too deep into the trap. We'll see. 

[Paul Birkeland]

I don't remember where I read it, but someone reported the wirewound resistors under the heat sink became very hot and wires next to them turned brown after rolling in a 6SN7. So I was kinda concerned about 6SN7 tubes.

Maybe he used a really dead 6SN7 or had other issues with the amp.