Crack wiring options and tube socket PCB useage.

[Jim R.]

jrihs,

I am not sure I'm following you -- the transformer, pins 3 and 4 of the 9 pin socket are heater wires and those I wouldn't do silver or silver alloys with.  Copper 22 or 24 awg should be fine for the heater wiring.  Absolutely nothing wrong with the wire that comes with the kit.

As for silk, again, sme people don't like it as much as cotton and say it tends to sound more forward and can add glare, but I don't know because when I've used it, it was on top of cotton and mostly for some extra toughness as you say.  You can still easily poke the wire through it though.

As for the shielding, I myself wouldn't go that large, and I also don't know what covering half the signal wiring would be like.  A good opportunity for an experiement though.  Let us know how it goes :-).

Hey, I have yet to wire my crack inputs to the pot, and I really haven't decided what I'm going to do, but I'm leaning toward the cryo'ed mundorf silver/gold with cotton insulation, a silk jacket over those, and a length of 1/8" tin plated copper ground braid.

One more day of cleanup on my office/listening room/workshop, and I'll be ready to get the tools out again and get this puppy finished.

-- Jim

[Grainger49]

Thanks guys,

 . . .  

So how far do I take the signal / silver wire? through the heater wires to terminal 3,4 (?) on the transformer? Or just to the octal?  .  .  .    

The heater wires are not signal wires.  On the 12AU7 terminals 3 and 4 (As Beefy appropriately points out below heaters are 4 & 5, 3 is the first triode's cathode) are the heaters.  Don't waste silver wire there.

I don't have a Crack manual so I can't talk terminal numbers.  I'm looking at the picture of the Crack wiring.  The signal wire comes from the input RCA jacks (three braided) to the volume control, from the volume control to the 12AU7 driver tube grids (pins 2 and 7), from the plates (pins 1 and 6) of the driver tube to the grids of the output tube (don't know pins) and finally from the plates (correction, Cathodes) of the output tube through the output caps to the headphone output.  

I hope that is a leg up on identifying the signal wires.

[Beefy]

On the 12AU7 terminals 3 and 4 are the heaters.

That would be 4 and 5, plus 9 for the centre tap

[Paul Joppa]

And it's a cathode follower output, so the cathodes (not the plates) go to the output caps.

[Grainger49]

On the 12AU7 terminals 3 and 4 are the heaters.

That would be 4 and 5, plus 9 for the center tap

Yes, I left for something this morning and didn't have enough coffee to count terminals.  Thanks!

And thanks PJ, like I said I didn't know the circuit.

[Jim R.]

Where did our OP go?

-- Jim

[jrihs]

Sorry, been on travel. Thanks for the correct terminal info; I was going from faulty memory. So do you think the gold content may offset some of the need for shielding? Also, I was wondering if "bigger gauge" for upgrading the copper power path wire meant bigger # as in 24>22 or if it is convention is 22 gauge is > 24 gauge in diameter (probably the later I think). If so I was thinking of using Jupiter cotton clad 18 gauge. Thanks again guys!! I shouldn't obsess but what fun!

[Jim R.]

I doubt the 1% gold will have any noticeable effect on the magnetic susceptibility, in fact, I'm not even sure the silver wire will pick up any more hum in this amp as I've never tried it.

Yes, number two is right -- 22 gauge is larger than 24 gauge -- meaning larger cross-sectional area.

Not sure I would use cotton for power wiring though.

-- Jim

[jrihs]

Thanks, good point, though I'm not sure if its 1%. The z-wire was made by a now defunct company, and the seller on e-bay bought from a now defunct audio shop for $1500 a spool when it was going out of business. It sure looks higher than 1% in that its deffinately not silver in color! Should be interesting.

[jrihs]

How would I determine optimum gauge for power path? using upocc copper. Thanks

[Jim R.]

I'm not sure what an optimum gauge is.  The kit comes with either 24 or 22, and those are perfectly adequate.  Anything beyond that would have to be left to experimentation -- keep swapping power wiring until you hear something you like.  Not sure how much difference you'll hear with a headphone amp as it really doesn't draw huge current surges.

If it's any consolation, I used 20 awg neotech/FIM pvc OCC for power and filament wiring.

I have also decided to just go ahead with the mundorf 24 gauage silver/gold for my signal wiring up to the grids of the VA tube, and leave the teflon on it.  I will shield it with some small tinned copper braid between the RCAs and PEC pot though.

-- Jim

[Grainger49]

There are different philosophies about wire gauge at amplified voltages.  One says use a small path, high number gauge, for a pure sound.  The other says that a fat wire, 0 or 00 would be gook (that is a joke, 00 is as big around as a nickel), for best bass response.  

The fact is that 22 gauge (AWG) will carry all the current a Crack can supply.  The larger the wire the more current it will carry.  It has nothing to do with voltage, just current.

[Beefy]

Not sure how much difference you'll hear with a headphone amp as it really doesn't draw huge current surges.

The fact is that 22 gauge (AWG) will carry all the current a Crack can supply.  The larger the wire the more current it will carry.  It has nothing to do with voltage, just current.

And assuming that the Speedball is installed, one could argue that wiring is not going to be all that critical to current delivery......

[jrihs]

Thanks guys.  My signal wire (z-cable) is 22.5. I'll stick with the stock cable for power (mine is 20 awg)...or get some nice bare occ 20 awg from parts connextion since I got lots of extra teflon tubing with the z-cable. I'll leave my signal cable (AU&AG) in teflon for now,and see if its too bright, though the AU content may(?) help here.

[Colin]

How is the sound quality changed if all the crack's stock cable changed with pure silver core cable? I'm a newbie in diy, very interest when hear the silver core cable interconect sound character. But a little fatigue in high tone, its get sibilance and 'overload' in treble. So is it possible to get the best sound when apply all the stock cable with it? Any suggestion to remove the sibilance and overload treble?