Some hints about Dumble now

[VacuumVoodoo]

The solder is never supposed to be the electrical connection.

Other way round, solder is not supposed to be a mechanical connection in an electric circuit. i.e. you should not rely on solder to hold your wires together. Copper kettles were soldered but that's a different pot..

Also, one should not re-solder a connection without removing all of the old solder.
But spending 2 hrs on a single joint...never heard of one lasting that long

[Structo]

While that all sounds good in theory, how do you explain printed circuit boards that are wave soldered?

There is no mechanical connection, the component lead is just inserted into a hole then soldered.
The same with wires on a pcb.

[glasman]

Speaking of soldering. Here is NASA's spec. THere is also a complete manual on the subject from the Army.

http://workmanship.nasa.gov/lib/insp/2% ... inals.html

[Bob-I]

Speaking of soldering. Here is NASA's spec. THere is also a complete manual on the subject from the Army.

http://workmanship.nasa.gov/lib/insp/2% ... inals.html

excellent stuff. Is there a page on eyelets? I wrap the wire so that it contacts both sides of the eyelet but I don't know if this is correct/required for a proper connection. This is really difficult on repairs or changing components since you can't really get to the back of the board.

FWIW, if I spend more than 2-3 minutes on a solder connection it's a long time.

[glasman]

Speaking of soldering. Here is NASA's spec. THere is also a complete manual on the subject from the Army.

http://workmanship.nasa.gov/lib/insp/2% ... inals.html

excellent stuff. Is there a page on eyelets? I wrap the wire so that it contacts both sides of the eyelet but I don't know if this is correct/required for a proper connection. This is really difficult on repairs or changing components since you can't really get to the back of the board.

FWIW, if I spend more than 2-3 minutes on a solder connection it's a long time.

I have a small jewelers screwdriver to press and tighten the component lead or wire to the eyelet before I solder it. FWIW, I have not seen a document for eyelets. I

[Scumback Speakers]

I usually make a u-turn of the lead/wire that's slightly bigger than the eyelet, then push it in with a little pressure to make contact on two sides of the eyelet, then solder.

[VacuumVoodoo]

While that all sounds good in theory, how do you explain printed circuit boards that are wave soldered?

There is no mechanical connection, the component lead is just inserted into a hole then soldered.
The same with wires on a pcb.

The trick is in making hole diameters correct for the components lead diameter so you have little solder inside the hole but enough to fuse well with the leads and holes inside tin plating. It also makes the joint cool faster thus preventing cold grainy joints.

Above assumes double sided plated through PCB.
Soldering temperature and cooling time are especially crucial when you go unleaded ROHS.

To secure components on a single sided board it's usual to bend the lead stumps on the under side. But you wouldn't call an amp on a single sided board a high quality product today, would you?

Too many manufacturers try to make savings by normalizing to just a few hole diameters - PCB manufacturing cost goes up for every drill change.

Best way to attach stranded wire to a hole in a PCB is to crimp ferrules on the wire first. Ferrule keeps solder from creeping up into the strands and prevents breakage due to bending, vibration etc.
Soldered stranded wires with solder that crept up will break at the solder-copper strand transition.
Use solid wire only if you have a good quality adjustable insulation stripper that won't leave a nick in the wire - it will break off at the nick.

[David Root]

[quote="VacuumVoodoo"][quote="Structo"]While that all sounds good in theory, how do you explain printed circuit boards that are wave soldered?

But you wouldn't call an amp on a single sided board a high quality product today, would you?

quote]

If it's on a turret board or a similarly mechanically strong eyelet board, I don't see why not. If you're talking about PCBs that would possibly (not necessarily) be different.

[heisthl]

Best way to attach stranded wire to a hole in a PCB is to crimp ferrules on the wire first. Ferrule keeps solder from creeping up into the strands and prevents breakage due to bending, vibration etc.
Soldered stranded wires with solder that crept up will break at the solder-copper strand transition.
.

Or you can just run the wires through a hole in the board and then use a backing board so the wires don't vibrate or flex. Wait a minute - I think someone was known for that technique.

[Bob-I]

I have a small jewelers screwdriver to press and tighten the component lead or wire to the eyelet before I solder it. FWIW, I have not seen a document for eyelets. I

That's similar to what I do. I bend a 90 degree on the end, insert it through the eyelet and use a small sharp punch to press it against the eyelet while bending the top side.

[Aurora]

Soldering wires directly to a PCB is hardly a common production techniques these days - solder lugs or PCB connectors are always used in industrial production..
OTOH - there's absolutely nothing wrong with the turrets or eyelets used in hand production related to this forum - it's just not cost effective in an industrial scale. Sloppy soldering or wire stripping is quite another story, which sets a questionable quality mark on "hand made".....

[phsyconoodler]

Not to be argumentative,but after working on many older amps that were mil-spec soldered with all terminals wrapped,I found that even though the mechanical connection was solid the electrical connection often wasn't.
The solder is what supplies the electrical connection and the 'wrapping' is purely for vibration.
Case in point:I took a typical eyelet board and soldered a 20 gauge solid core wire to it.Then I wrapped the same wire around another eyelet and soldered it.I then lifted the 20 pound chassis by both wires and shook it a few times violently.Neither joint gave up the ghost.Now maybe with the right vibration the unwrapped joint might come apart but that test proves that most components soldered without a time-consuming wrap will not fail if the soldering is up to par.
And you have to ask yourself,when will the entire weight of that chassis be applied to that solder joint?Well?Never is the answer.
PC boards are considered more reliable that hand-wired as far as vibration is concerned,assuming it is soldered properly.No wrapping to be had with a PC board.
However,I have not heard any PC based amps that were as toneful as a similar hand-wired amp.I think that's more a design and component quality issue than anything else.

[Normster]

I always assumed that the reason for a good mechanical connection was to allow heat to transfer evenly between components when soldering and to immobilize the joint so it doesn't crystalize when cooling. To a lesser extent, I guess you could theorize that a good mechnical joint will also have less resistance, but I think that's getting pretty esoteric.

[Structo]

Nasa spec and Mil spec are all fine and dandy, but there is a lot of old Fender amps still pumping out good tone 50 years later.
I don't believe they were Mil spec.

I do agree in a perfect world, a good mechanical connection is preferred before soldering. That was how I was taught in trade school but sometimes it just isn't that practical, say when you are trying different valued components in an eyelet or turret board in an effort to get the tone you want.
I think as long as the solder joint is correct and not a cold joint or any of the other things we are taught to avoid when soldering, it will be sufficient.

Another thing if we want to take it to another level is to put a crimp in the component leads to allow for expansion and contraction so the component body is not stressed by tension on the leads.
I don't seem many amps being built with that detail.

[Max]

However,I have not heard any PC based amps that were as toneful as a similar hand-wired amp.I think that's more a design and component quality issue than anything else.

My personal experiences with Dumble amps with a PCB as preamp board are completely different. Perhaps because Alexander treats his PCB amps with the same attention to each tiny detail as his more usual boards.

Believe me, what's important is, that you precisely know how to achieve the sounds, articulation, dynamics etc. you want. If someone really knows his stuff in regard of building musical instruments, he's free to chose.

That's my personal believe. If cites would have banned European maple and spruce from import to USA, Jimmy D'Aquisto still could and would have built great guitars.