donvan wrote: ↑Tue Jun 18, 2019 7:25 pm
Taylor,
Very nice looking work as usual.
I've always wondered how people clamp the coax braid against the case of a pot to hold it steady while soldering the braid to the case. I see that you used some sort of high temp epoxy to fasten the non-stripped portion of the coax to the pot case. Then, after it dries you must have soldered the braid to the case of the pot. I like that idea!
What kink of epoxy do you use?
Does everyone do this or are there other tricky ways of clamping?
Thanks,
Don
Thanks Don!
No that’s just left over flux. The trick I use is to rough the back of the pots with sandpaper, clean with alcohol, then I use a rosin flux pen on the back of the pots and tin with Kester 44 solder (which is also loaded with flux). I also tin the braids of the coax with 44. Then i usually can do it by hand, but sometimes I have to hold with my needle nose pliers because it just gets too hot!
Looks great taylor, I've never managed to perfect this method I usually end up tying the shields to the bus bar as my attempts at doing it your way end up look very messy.
amplifiednation wrote: ↑Thu Jun 20, 2019 3:01 am
The trick I use is to rough the back of the pots with sandpaper, clean with alcohol, then I use a rosin flux pen on the back of the pots and tin with Kester 44 solder (which is also loaded with flux). I also tin the braids of the coax with 44. Then i usually can do it by hand, but sometimes I have to hold with my needle nose pliers because it just gets too hot!
Ok, so pre-tinning is how you free up one of your hands to hold the coax wire in place. Thanks for clearing that up!
amplifiednation wrote: ↑Thu Jun 20, 2019 3:01 am
The trick I use is to rough the back of the pots with sandpaper, clean with alcohol, then I use a rosin flux pen on the back of the pots and tin with Kester 44 solder (which is also loaded with flux). I also tin the braids of the coax with 44. Then i usually can do it by hand, but sometimes I have to hold with my needle nose pliers because it just gets too hot!
Ok, so pre-tinning is how you free up one of your hands to hold the coax wire in place. Thanks for clearing that up!
Yeah. Then once the coax is attached you can go back and add solder if you need to. Tricky though for sure to do it without getting your fingertips burnt!
amplifiednation wrote: ↑Thu Jun 20, 2019 3:01 am
The trick I use is to rough the back of the pots with sandpaper, clean with alcohol, then I use a rosin flux pen on the back of the pots and tin with Kester 44 solder (which is also loaded with flux). I also tin the braids of the coax with 44. Then i usually can do it by hand, but sometimes I have to hold with my needle nose pliers because it just gets too hot!
Ok, so pre-tinning is how you free up one of your hands to hold the coax wire in place. Thanks for clearing that up!
Yeah. Then once the coax is attached you can go back and add solder if you need to. Tricky though for sure to do it without getting your fingertips burnt!
I've found the problem to be melting the insulation under the coax when getting enough heat in to hold it to the pot, or even when tinning. Maybe you have different coax to the stuff i tried.
norburybrook wrote: ↑Sun Jun 23, 2019 10:19 am
I've found the problem to be melting the insulation under the coax when getting enough heat in to hold it to the pot, or even when tinning. Maybe you have different coax to the stuff i tried.
M
The secret of soldering such places in the use of a large power soldering iron with a thick tip, or soldering iron with very fast temperature stabilization. This reduces the soldering time massive parts and the insulation does not have time to melt. And of course the wire must be in teflon insulation.
If your coax is all-PTFE, it won't have the melting problem. I'm not a fan of this technique, though. I don't like applying that much heat to the pot, and then if the pot does fail, it's harder to replace. In addition, the ground connection for the coax shield depends upon the pot bushing contact, which may deteriorate over time. I like wrapping and soldering a short wire to the braid, and connecting that to the ground bus.
martin manning wrote: ↑Sun Jun 23, 2019 12:02 pm
If your coax is all-PTFE, it won't have the melting problem. I'm not a fan of this technique, though. I don't like applying that much heat to the pot, and then if the pot does fail, it's harder to replace. In addition, the ground connection for the coax shield depends upon the pot bushing contact, which may deteriorate over time. I like wrapping and soldering a short wire to the braid, and connecting that to the ground bus.
which is exactly the method I came by just by a similar set of thoughts and not liking the results of melting coax Martin. There's a bus bar right above you at all these points, seemed a lot simpler and 'better' from the points you made than the back of the pot method.
I also used the bus bar method for my coax grounding and I see the advantages that have been mentioned above. But, I also see advantages in the way that Taylor (and Dumble) do it. By soldering right to the pot case you get some really good strain relief and if it's done well it looks really good.
I've had too many pots go bad, mostly because I suck at soldering on them and ended up with too much heat, killing them. (in my early days) it does seem, though that modern pots don't have as much durability as the older ones did, and therefore I've always opted to have a bus bar behind the pots not soldered directly to them for grounding things. I use sluckey's or doug hoffman's (not sure which) method of pulling the braid away, and soldering a wire to it and connecting that to ground then putting shrink tube over it to make it look nice.
Looks way cleaner soldering to the pots, plus gives a killer mechanical connection.
I agree it’s a pain to swap pots, but if you build enough amps, all that extra time spent soldering leads onto the braid and then heatshrinking surely takes more time.
And yes only Teflon wire will work. But why would you use anything else?
norburybrook wrote: ↑Sat Jun 15, 2019 11:33 am
Lovely build. You need to change those epoxy ceramic caps though as it won't sound good with those
M
What do you recommend?
The epoxy coating doesn't tell you what ceramic was used in the cap(NP0, Z5U, etc), but it should be labeled on the cap. Back in the day, I used to work at a place called Dielectron that made ceramic caps. I won't make value judgements on how the different caps sound, but some of the ceramic formulations had very poor temperature stability. C0G and NP0 seem to be best in that regard, based on the literature. Nothing earth shattering, just my 2 cents
Actually that was a sarcastic snip at a comment I made about the epoxy coated ceramics. The ones I was specifically referring to are the yellow Panasonic ECK and the Vishay Ceramite. They are labled Y5F, so a good cap, they just don't seem to like the OD mode as much as the(older) tan Xicon or NTE ceramics. At least to my ears, in a leaner circuit like a Classic.
CW
I usually end up tying the shields to the bus bar as my attempts at doing it your way end up look very messy.
The ones I was specifically referring to are the yellow Panasonic ECK and the Vishay Ceramite. They are labled Y5F, so a good cap, they just don't seem to like the OD mode as much as the(older) tan Xicon or NTE ceramics. At least to my ears, in a leaner circuit like a Classic.