Help! A question regarding soldering.

[Kuja]

Hi!

I'm restoring a pair of Acoustic Research AR-90 speakers.

I just finished the crossovers.
There is no PCB. They are made using direct point to point soldering of components.

An externally hosted image should be here but it was not working when we last tested it.

I have new caps, wiring and speaker binding posts.

At one point I got stuck when I had to solder two bundles of thick solid core wires to the speaker binding posts.

My soldering iron was not quite powerful enough. It couldn't provide enough heat, so I was not able to do everything in one go.

I was kind of building up things by adding solder partially to different spots. Finally I ended up kind of "sculpting" solder with my iron.

These are the binding posts in question:

An externally hosted image should be here but it was not working when we last tested it.

New internal wiring is solid core 14 and 16 AWG Neotech UPOCC (monocrystal copper) wire.

Here is the result.

An externally hosted image should be here but it was not working when we last tested it.

It looks kind of ugly, but I can assure you that everything is rock solid and that there are no cold solder joints.

My question is:
Are there any sonic penalties that can be heard with such a bulky solder joint in a speaker crossover?

I hope that I'm fine and that it won't sound worse compared to some nicer looking solder joints, but who knows?! I'm not an expert on these things.

On the internet, I can read a lot of audiophool voodoo stuff.
Some of it regarding crystal or submolecular metal structures and things like that.

In that light, those solder joints look really bad!

So, am I going to be able to hear it or not?

What do you think?

Thanks in advance,

Aleksandar

 

[Inductor]

It's a pitty that you left 3 inductors to close to each other. Like this they will keep warm for the winter. (hehe). You should rotate the middle one 90 degrees or the other two, so that they don't have the same axle direction (unless they are connected in series and there's no need).

 

[BarakaBloke]

Personally I wouldn't expect you'd hear any difference but I'd
still try to make a properly 'flowed' solder joint if possible.

With your approach you're in relatively uncharted territory,
whereas a conventionally 'good' solder joint's been tried
and tested for decades.

At the very least you need to successfully tin each wire
individually before 'glooping' them together.

Much better though, there are some very cheap powerful but
temperature controlled irons on eBay. I got one of these recently:
http://cgi.ebay.co.uk/QUALITY-VARIA...yZ106001QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
I wouldn't call it high quality but it's brilliant for the price.

Or borrow and use an additional iron for a bit more heat input!


BB

 

[Conrad Hoffman]

Like a lot of this audio stuff, whether you can hear it depends on whether you believe you can hear it. It would take a heap of confidence for most people to believe something that looked like that didn't have any sonic consequences. I'd get a bigger iron and reflow them just for peace of mind. Hint- for big lugs and such, I find my butane soldering iron is capable of far more output than its small size suggests.

 

[Dryseals]

Old soldering trick, Take a piece of solid wire about an inch or so long and solder it to the post so that it sticks out like an extension of the post. Wrap each wire individuallly around the extension in a row. Then bend back the extention to cover the row. Then solder.

 

[ttruman]

Old soldering trick, Take a piece of solid wire about an inch or so long and solder it to the post so that it sticks out like an extension of the post. Wrap each wire individuallly around the extension in a row. Then bend back the extention to cover the row. Then solder.

Good idea. Having done a lot of soldering in my day my instincts tell me vibration could cause micro fractures in that bundle which may eventually open up and come apart. Ideally you want the solder hot enough to flow across the entire joint.

 

[cuibono]

Good idea. Having done a lot of soldering in my day my instincts tell me vibration could cause micro fractures in that bundle which may eventually open up and come apart. Ideally you want the solder hot enough to flow across the entire joint.

I agree with this - you want your joints to be as reliable as possible - the wire extension is just what you want.

IMO, though, I would seriously doubt that your joint is 'audible', at least as it stands now. Even if there is some sort of distortion caused by it, how could it be anywhere near that of the drivers or amp, or the hundreds of other solder joints in the whole system? Not only that, but I seriously doubt anyone has ever done a scientifically valid investigation of solder joints 'audibility'. If someone has, I would very much want to see it. In lieu of any real data, I wouldn't worry too much about its 'sound'. But for reliability, I'd redo it.

 

[Dryseals]

Good idea. Having done a lot of soldering in my day my instincts tell me vibration could cause micro fractures in that bundle which may eventually open up and come apart. Ideally you want the solder hot enough to flow across the entire joint.

Way back when, I took an four week soldering course in the Navy, very intense and unforgiving. The Navy had completed a study and found that 80% of all failures in electronics where due to poor repair techniques. The normal course was a few weeks, I opted for the extended course which included micro soldering, joining multiple components together to make one circuit.

One of the things impressed upon us was the joint itself, if you tinned a wire and then bent it over for a loop and any of the wires separated, the joint failed, bird cage as they called it, improper tinning. Same with everything else.

Just as in soldering copper pipe, the solder will move to the heat, do not try and heat the solder to move it where you want it.

The same joint Aleksandar made with high heat, I can now make with a 40 watt iron, I use nothing hotter. Heat will separate the lead and the tin in the solder and cause a failure.

I have a web site I started a while back but have never found the time to add anything useful to it. I guess soldering should be the first thing as so many do not know the proper techniques.

Simple one and foremost, don't clean your iron, let it build up, clean only the very end tip. The trash that builds up on the iron helps the iron to transfer heat to the tip, acts like an insulator.

 

[Kuja]

Thank you all for your valuable answers!

I made this sketch to to explain better what I've actually done here:

An externally hosted image should be here but it was not working when we last tested it.

Before doing any soldering, I tried to make a good mechanical connection between the wires and the speaker binding post lug on their own, without any solder.
On the sketch you can see that this lug has a hole, so I had one wire going through it to the other side, where it made a loop around twisted bundle of other wires and then it went back.

After looping and tying the wires and the lug together, I squeezed everything together with pliers.

Only after that I started soldering.

Does this additional explanation makes those joints look better?

I hope so, since it would be a hell of a job to take everything apart, since I already poured a ton of hot melt glue over all joints and capacitors to prevent them from vibrating too much.

Thanks again!

 

[Dryseals]

You did good, run with it. The mechanical connection is by far the most important. The solder looks shiny which is a good thing. Practice on some other things and then redo at a later date IF you think the connection may cause some problems.

 

[cuibono]

nice diagram! I wouldn't redo that joint, it looks pretty solid with the wires wrapped together like that.

 

[Ray Collins]

Try solder lug terminals. They were used during the days of point to point wiring...prior to PCB's.

Ray

 

[Andersonix]

In addition to the advice already given, I would strip the insulation back far enough so it doesn't melt and contaminate your joint. You could also use some heat shrink sleeving to cover up some of that blob and add an extra level of clamping if things go wrong.