Hi Skip, Pre amp build thread is over here
http://www.diyaudio.com/forums/anal...me-differential-preamp-build.html#post4686672
Modushop case
I ordered a case from Modushop with a custom drilled back panel. During the ordering process I had many email conversations with Gianluca at Modushop. All were very pleasant, clear and very helpful.
It arrived three days after they shipped it. Their packing is outstanding and the case is perfect.
I strongly recommend them and I'm not connected with in any way. Just a very pleased customer.
henrylrjr
I ordered a case from Modushop with a custom drilled back panel. During the ordering process I had many email conversations with Gianluca at Modushop. All were very pleasant, clear and very helpful.
It arrived three days after they shipped it. Their packing is outstanding and the case is perfect.
I strongly recommend them and I'm not connected with in any way. Just a very pleased customer.
henrylrjr
Wiring the Mod86
I just learned about Bleden 1192a star quad cable. It's description leads me to believe it is a very good cable. I'm using it to connect the Mod86 to the XLRs in the Modushop case. It's spec.s seem more than good enough to use it as interconnect cables. Anyone have an opinions?
I just learned about Bleden 1192a star quad cable. It's description leads me to believe it is a very good cable. I'm using it to connect the Mod86 to the XLRs in the Modushop case. It's spec.s seem more than good enough to use it as interconnect cables. Anyone have an opinions?
Starquad is good. Better than you are likely to ever need, but overkill in a good way. It is often used in theatres where there is a lot of grot from lighting circuits. I'm planning to use it mainly because its only 50p a metre more at the local Maplin but gives and actual measurable reduction in pickup.
Now mod86 has such good CMRR in a domestic setting you could use wet string, but its nice to know you've done your best for the signal. in the mind that is worth something
Now mod86 has such good CMRR in a domestic setting you could use wet string, but its nice to know you've done your best for the signal. in the mind that is worth something
Belden is great stuff. I'm using some kind of Belden coax (can't remember exact model name) with BNC for digital interconnects.
That star quad looks like great stuff. Where are you getting it? I imagine that unless you're buying 500 or 1000 feet of it, that you may be paying up to $2.00 per foot, or a little less.
I ordered from Redco some Mogami W2549, it's only $0.80 per foot, and it's reputed to be excellent quality, probably more than I need. I needed about 20 feet for interconnects + a few inches for inside the Mod86 chassis. I guess the more feet of it you need the more significant the price difference is.
That star quad looks like great stuff. Where are you getting it? I imagine that unless you're buying 500 or 1000 feet of it, that you may be paying up to $2.00 per foot, or a little less.
I ordered from Redco some Mogami W2549, it's only $0.80 per foot, and it's reputed to be excellent quality, probably more than I need. I needed about 20 feet for interconnects + a few inches for inside the Mod86 chassis. I guess the more feet of it you need the more significant the price difference is.
It's $1.49 per foot on Markertek. Audiophiles are paying into the $1K range for interconnector cables. Why? Parts express has top level Switchcraft and Neutrik connectors for about $4 each. That's would make a low priced IC.
HeatsinkUSA,s prices are also very reasonable. AnTek transfomers, in the $40 range ,are also good buys. And Modushop seems to beat all the "from china cases", and the one I got is great.
HeatsinkUSA,s prices are also very reasonable. AnTek transfomers, in the $40 range ,are also good buys. And Modushop seems to beat all the "from china cases", and the one I got is great.
use eutectic solder, preferably leaded. try 63/37 as your very available and cheap starter solder.
2% silver is also a eutectic, as is 1% copper.
These are refered to as triple eutectic. All three are great for electronics work.
https://en.wikipedia.org/wiki/Solder
Note that 1% copper is not recoomended for silver, nor gold overlays and that both the triples are not recommended for gold overlays.
This table does not reveal the existence of a quad eutectic, which is probably silver AND copper along with tin and lead.
Be wary of Cardas. There is recent discussion that they changed their formulation and that has given problems. Their old quad was reputed to be excellent.
Last edited:
I've forgotten most of my solder geek stuff from 20 years ago, but ISTR that tin/lead and gold flash are not good bedfellows. As Andrew point out multicore today has copper, so similar melting point to lead free.
of course having the right temp iron for the solder you have is more important than anything else. Since I got a cheap metcal it almost looks like I know what I am doing!
of course having the right temp iron for the solder you have is more important than anything else. Since I got a cheap metcal it almost looks like I know what I am doing!
Now mod86 has such good CMRR in a domestic setting you could use wet string, but its nice to know you've done your best for the signal. in the mind that is worth something
You may have to soak the string in salt water periodically, but yeah... Pretty much.
Personally I use microphone cable. I find the least expensive way to buy mic cable without having to buy a 1 km spool of it is to pick up an XLR cable. GLS make some pretty decent ones. I just lob the XLR connectors off and use the cable.
To start at the beginning: You want to use solder intended for use in electronics - not plumbing solder. In plumbing you apply the flux with a brush and the solder itself has no flux in it. Not useful for electronics.
You'll want to use solder with flux in it. The flux used to be rosin based. I'm not sure what they use these days. In any case, the solder should have flux in it. There are at least two kinds of flux: Regular and no-clean. The difference is the solvent used to remove the flux after soldering. The regular flux can be cleaned off with acetone, though an actual flux remover is useful here as acetone is rather hard on many types of plastics. Personally, I use Chemtronics Flux-Off, which you can get from Mouser in the US. It does not ship via airmail due to flammability. MG Chemicals (and likely many others) make flux cleaners as well. The no-clean flux should in theory require no cleanup.
Some may ask, "Why the fuzz? I've been soldering for 35 years, never cleaned the flux, never had a problem!" That may be true. And so have I, by the way. However, I've also worked in a production environment where reliability was a concern and I learned a thing or two doing that. The trouble with flux is that it's hydrophilic, i.e. attracts water. This means any flux residue on the PCB will cause significant leakage currents on a wet day. You may have a circuit that works well in a dry climate but fails in a coastal climate. Water is also known to be corrosive, so allowing a substance to attract water to your electronics is a recipe for failure. Supposedly the no-clean fluxes are not hydrophilic, hence don't require removal. I'd still clean the boards, though.
Now, to be clear, the Modulus-86 is a rugged circuit. It will perform well regardless of whether you clean off the flux. However, in a production environment I would clean off the flux for the long-term reliability concerns mentioned above. Any board I send out to a customer will have the flux removed.
Alright! Enough about flux. Now to the solder part of things: In The Good Old Days™, 60/40 tin/lead was the standard. 60/40 means 60 % tin, 40 % lead. These days lead-free solder is all the rage due to environmental concerns - and justly so.
Lead free solder does not have the best reputation. Some of that is related to good old-fashioned stubbornness and resistance to change, but some of it is related to technical issues with the soldering process. Most lead free solder alloys melt at a higher temperature (about 225 ºC) than tin/lead solder (about 180-190 ºC), so if you are using your leaded setup to solder with lead free solder, you'll likely experience cold solder joints. The typical tip temperature for leaded soldering is 320-370 ºC (600-700 ºF). For lead-free, you need to turn the dial up to 370-425 ºC (700-800 ºF), or if you're using a METCAL or Weller TCP/WTCP setup, you may have to change the tip to one with a higher temperature.
If you do go the lead-free route, tin-silver-copper (SnAgCu) solder is the stuff to get as it is the alloy which is the most likely to result in good results for hand soldering.
In the leaded world, you'll be looking at 60/40 (Sn/Pb), 63/37 (Sn/Pb), or 62/36/2 (Sn/Pb/Ag) "silver" solder. At the time of writing, the main functional difference is cost. A 1 lb spool of 60/40, 0.8 mm diameter at Mouser is $43. 63/37 $50, and 62/36/2 $60.
The difference between these alloys is their plastic temperature ranges, i.e. the range of temperatures where the solder is pliable but not quite melted. 60/40 solder becomes plastic at 183 ºC and melts at 188 ºC. 63/37 solder is the eutectic alloy, meaning that it goes directly from solid to liquid without plasticity. 63/37 solder melts at 183 ºC. The 5 degree plastic range of 60/40 has no implications in practice and the two solders can be used interchangeably. The solder joints made with 63/37 solder may look a little shinier than those made with 60/40, but that's purely a cosmetic effect.
If you are soldering to silver wire, including some ceramic caps and silver-on-steel RF cables, you may want to use 62/36/2 (Sn/Pb/Ag) solder. This is because regular Sn/Pb solder will dissolve the silver over time. The silver in the 62/36/2 prevents this from happening.
In terms of conductivity, the three types are within a few percent of each other. The tensile strength of 62/36/2 solder is about twice that of 60/40, but whether that actually translates into mechanically stronger solder joints depends on the joint geometry.
Needless to say, when I'm out of the spool of 60/40 solder I've been using since the late 1980ies, I'll be buying more 60/40 or 63/37 depending on what's on sale.
I hope this answered your question about solder.
I should probably put this on my website as it's a pretty common question.References:
AIM: Comparison of lead free solder alloys.
Kester: Lead free hand soldering.
Multicore: Properties of solder.
Tom
It has to do with the flux not the alloy. You can read about it in the Kester write-up I linked to above.
Tom
Great write up about solder. I've been real happy with Kester "44" Rosin Core Sn63Pb37. I especially like that it's a small diameter .50MM (.020).
I also have a small amount of Cardas Lead Free Tri Eutectic. I don't like it as much, it seems harder to use. After reading the above, maybe I just need to try again with a higher temp? I do have a more than half decent Weller now.
The Cardas that I have is a larger diameter, and I prefer the smaller diameter especially on the Mod86 as the pin density is tighter than previous projects I've done. I'm pretty inexperienced, but it just seems easier to me that way.
Edit: forgot to ask. I've been taking an old tooth brush with a little bit of 91% Isopropyl Alcohol to scrub flux off boards. It seems to work okay. Is it a bad practice for any reason?
I also have a small amount of Cardas Lead Free Tri Eutectic. I don't like it as much, it seems harder to use. After reading the above, maybe I just need to try again with a higher temp? I do have a more than half decent Weller now.
The Cardas that I have is a larger diameter, and I prefer the smaller diameter especially on the Mod86 as the pin density is tighter than previous projects I've done. I'm pretty inexperienced, but it just seems easier to me that way.
Edit: forgot to ask. I've been taking an old tooth brush with a little bit of 91% Isopropyl Alcohol to scrub flux off boards. It seems to work okay. Is it a bad practice for any reason?
Last edited:
Thank you.
I use 0.7-0.8 mm for leaded and 0.5 mm diameter for SMD work.
Sounds like cranking up the temperature a bit will do the trick.
Cleaning the flux off is always good practice. To be anal about it, you really should use an ESD safe brush (so an electrostatic dissipative or mildly conductive one) rather than a toothbrush. I suspect the alcohol solution is conductive enough that ESD is not an issue, but if you were ever to get audited in a production environment they'd probably flag the nylon toothbrush. Looks like Mouser P/N 485-1209 would be just the ticket. Of course it's out of stock. How could it be any different... Grr!
Tom
I don't know why you looked up Kester and lead free.
Here is Farnell's copy of the Multicore datasheet.
http://www.farnell.com/datasheets/315929.pdf
It shows on page 1: