Tube Rolling w/Crack

[luczamic]

I don’t Paul, I’ve already ordered the one you’re liked.

Thank you for that!

[monsterdonkey]

Tube rolling can be fun and costly and all that, but as the differences can be quite subtle (I’ve found I like tubes I thought I didn’t like on different days) why not try adjusting the tone controls or equalizer on your source machine and see if you can get it closer to your preference that way?

[Souldriver]

Hey all, i finished my kit a few weeks ago and am looking to roll around. I want to start with some of the tubes i yave left over from my guitar days and when searching i came across this guy.

A JAN Philips 5751

Since this is a 12ax7 type normally i would try, but here is an interesting thing about it:
The 5751 is not a true 12AX7, but is often used in place of a 12AX7. They should have approximately 70% of the gain of a 12AX7, and are often used to quiet down guitar amps that have too much gain. If you have gain to spare using a 5751 tube will greatly improve your overall tone without making your preamp excessively clean.

With this said, is this something that can be safe on a BHC + SB or is it still going to be too much?

Thanks for the help!

[Paul Joppa]

The 5751 requires a much higher plate voltage than is available in the Crack.

[Paul Birkeland]

Other than the plate voltage problem, more gain in the Crack is not something considered desirable.

[Souldriver]

Thanks for confirming guys, I figured the lower gain 5751 would still be too far off.

I bought a few of these for $15-20 a piece and now they are much rarer. I most likely will sell them and grab what i need.

[ipetruk]

Re: crackling in tubes, what's your opinion on reflowing the solder inside of the pins? Let's say I have a power tube with thick pins that crackles and other tubes don't (so it is not an amp issue). Cleaning pins does not help

Is sucking the solder with vacuum and putting a new one a good idea? I've heard some people do it.

[Paul Birkeland]

If only that tube presents problems and you have many others that work fine, I wouldn't focus so hard on the amp.

[Doc B.]

Reflowing tube pins is done more often with older four pin DHTs, as they were more susceptible to the joints inside the pins oxidizing with time and the glass coming loose in the base, allowing stress on the pin connections. I might be inclined to install the 6080, invert the amp, fire it up and wiggle the socket connections at each pin while listening for the noise. Obviously you want to use headphones you can afford to sacrifice for this kind of test. If you can make it happen by working the contacts it might be worth attempting a reflow - or you may have located a bad contact between the pin and the socket. Chances are good that the crackling is due to some other internal, mechanical issue in the tube.

[Paul Birkeland]

Oh, the solder in the pins themselves?  I have done this a bunch on 4 pin tube bases, but never on an octal that I can remember.  You could touch the tip of your iron to each socket pin and let the solder reheat and flow out a bit more. 

[ipetruk]

I have a Garage 6SN7 to 12AU7 and it works perfectly. I've rolled many 6SN7 tubes.

I have Siemens C3G tubes. https://www.tubedepot.com/products/siemens-c3g-pentode

Can I use https://www.ebay.co.uk/itm/201814708334 to adapt it to 6SN7 and then to 12AU7 via Garage adaptor? Or does it look unrealistic?

[Paul Birkeland]

I have a Garage 6SN7 to 12AU7 and it works perfectly. I've rolled many 6SN7 tubes.

I have Siemens C3G tubes. https://www.tubedepot.com/products/siemens-c3g-pentode

Can I use https://www.ebay.co.uk/itm/201814708334 to adapt it to 6SN7 and then to 12AU7 via Garage adaptor? Or does it look unrealistic?

We use both halve of the 12AU7, so a triode strapped C3G will not be a suitable substitute. Depending on what's going on in the adapter, you could cause serious damage to the amp or the 6080 if you tried this.

The C3G has way too much gain for the Crack circuit anyway. 

[th3p3r50n]

Hey all, recently bought my first tube to try tube rolling with, a Tung Sol 6520 with the domino plates on ebay. The seller said it had plenty of life in the listing, however when I plug it in the left channel is there but almost inaudible. If I crank up the volume all the way I can hear it better but then the right is way too loud. Volume is fine in both channels with the original 6080. Does this mean one of the triodes is dying and it's a bad tube, or is there something I can do? Thanks

[Paul Birkeland]

I would return that tube.

[gonzoznog]

Hey there! I recently sold a working Crack w/ SB. The buyer says that he is getting very low volume. I was wondering if this could be a bad tube? I did give him extra power and input tubes that he could try. I'm guessing I should ask him to try all tube configurations to see if that helps? Any other suggestions? As mentioned, I know this amp worked fine when I listened to it before selling it last week. I am wondering if one of the tubes went bad or was damaged in shipping. Makes me nervous as I have never sold anything that didn't work as intended! The Crack came pre-assembled to me, so I have zero knowledge or skills in diagnosing anything wrong with the electronics but I suspect that it's either tube-related or maybe a configuration error. Any help would be greatly appreciated!