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DIY 89259/89248 interconnect questions: Jon & all

205.188.199.33

Posted on July 10, 1999 at 08:34:00
Rob


 
Jon...I have read through your faqs and all the info from your site - I still have a few questions:

- I'm not really certain if you advocate a shield or not - I understand the concept of spacing it adequately from the two center conductors using sheet foam, or teflon tubing/cut up inner core dialectric. It has been written in a reply that we would already know if RFI/ EMI is a concern in our area but I'm not really sure what to listen for/ what it sounds like. I currently live in an apartment and am moving in 3 weeks to a townhouse.

- if no shield is used....does that mean that there is only a positive connection? I am referring to the twisted pair combo 89259/89248 - based on what I've read I'm assuming that I would twist the ends together and connect to the positive "nubbin"?

- I ordered 12 pairs of the sonic frontiers rca's. I specified solder type - I realized after I received my order that someone else had posted and recommended the "tiffany" style. These are actually modeled after the WBT locking rca's. They look really nice and were only $10 a pair. Here's the question - on the positive "nubbin" it has a set screw. I called them and they told me that I did get the right one - there is no difference between the two except that the solder type didnt have the set screw in it....just a hole where I guess you would apply the solder. Will I get a better connection from using the set screws (all 12 pairs I received have them) or is solder really necessary in this case? If solder is not a need now, it certainly would reduce the assembly time, and would be easier as well add a shield later if needed.

- am I right that ersin multicore solder is better? I have paid close attention to posts pertaining to this as well as manufacturer's recs....
however - what core size? what is the best place to get it? (it seems that a lot of companies carry the more common ones, but obscure ratios are more difficult) what exact ratio?

- I dont own a soldering iron....any recommendations for a multipurpose iron that won't set me back too much? I would say that the majority of my use of it will be fiddling with electronics.

- I have seen co-ax cable rotary strippers....is this something that is necessary? Or is an exacto knife just as good? Most of the strippers are $14-$18...kind of expensive for the limited application I would use it for.

So far I have 50ft each of the two belden cables, and sufficient amount of 3M EPS200 heatshrink and am eager to get started.

Thanks for your help

- Rob

 

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Re: DIY 89259/89248 interconnect questions: Jon & all, posted on July 10, 1999 at 11:49:37
[ I'm not really certain if you advocate a shield or not - I understand the concept of spacing it adequately from the two center conductors using sheet foam, or teflon tubing/cut up inner core dialectric. ]

Most people need a shield, and I recommend this over getting zapped by a CB or RFI. The shield introduces compromises in the sound, a slight dulling of transients, a loss of some air and space (no readily measurable effects on large signal amplitude response either) IF it is right next to the cable cores used for the twisted pairs. Spacing the shield away will reduce the worst of these effects to a point where it would be silly not to use the shield. See my post about McMaster-Carr DIY items over in the Tweaks section:
/audio/tweaks/messages/2708.html
for materials that can be used to space the shield away, and for copper braid to use for such larger shields (you can't re-use the oprioginal coax shield, as it will be too small).

[ It has been written in a reply that we would already know if RFI/ EMI is a concern in our area but I'm not really sure what to listen for/ what it sounds like. I currently live in an apartment and am moving in 3 weeks to a townhouse. ]

The fact that you can't always tell, and that you are moving too, augers for incoprporating a spaced shield up front. Yes, you could try them without a shield, but they might sound terribly dissapointing, and you might never know how good they could sound.

[ if no shield is used....does that mean that there is only a positive connection? I am referring to the twisted pair combo 89259/89248 ]

If you just make a twisted pair without shield, then you use one wire for the hot, and the other wire for the ground. Even on unbalanced/single-ended interconnects (coaxial using RCA's), the ground connection carries the signal just as much as the center wire does, there must be a 'ground return path', or no current will flow, and since none of our audio cables work on pure electrostatic principles, there must be some current flow, however minute, in order for the signal to be transfered.

One question I get asked is: which center core do I use for the hot connection, and which for the ground? Theoretically, it should not matter, but with real world systems, and the possibility of differences in the ground potentials of different components, it makes sense to use the heavier gauge for the ground connect, in this case, the 89248 is the heavier of the two, so use it for the ground connection. It should not make a huge difference, but can't hurt.

[ I ordered 12 pairs of the sonic frontiers rca's. I specified solder type - I realized after I received my order that someone else had posted and recommended the "tiffany" style. These are actually modeled after the WBT locking rca's. They look really nice and were only $10 a pair. Here's the
question - on the positive "nubbin" it has a set screw. I called them and they told me that I did get the right one - there is no difference between the two except that the solder type didnt have the set screw in it....just a hole where I guess you would apply the solder. Will I get a better connection from using the set screws (all 12 pairs I received have them) or is solder really necessary in this case? If solder is not a need now, it certainly would reduce the assembly time, and would be easier as well add a shield later if needed. ]

You can use the set screw IF you have the means to tighten it very firmly, and then I would use it only on the soilid wire, which means reversing what I said just above here. Remember, using the 18 gauge 89248 as the ground side is not that important, and in your case, using it for the set screw is the better way. NEVER tin a stranded wire and then try to crimp or use a set screw with it, the tinning will not allow the crimp or the set-screw to funtion properly. You should consider getting the proper screwdriver or tool to tighten the set screws firmly, or the connection will compromise the sound.

[ am I right that ersin multicore solder is better? I have paid close attention to posts pertaining to this as well as manufacturer's recs.... ]

Yes, Ersin is good stuff. I have used and recommended the Kester 63/37 tin/lead eutectic for years, with the "44" flux, and this is readily available, but the Ersin is also a really good solder, much better than any RS solder, or no-name 'electrical solder' found at the hardware store.
Is it the very best? Who can say for sure? Half the time, the flux makes as much difference to the sound as the solder alloy and purity does.

[ however - what core size? what is the best place to get it? (it seems that a lot of companies carry the more common ones, but obscure ratios are more difficult) what exact ratio? ]

0.031 to .040 is fine, anything larger gets unwieldy, anything smaller , and you must feed alot of it into the joint, which can be difficult when soldering plugs. Various nationwide electronics distributors carry the major name brand solders, including Newark, etc.

[ I dont own a soldering iron....any recommendations for a multipurpose iron that won't set me back too much? I would say that the majority of my use of it will be fiddling with electronics. ]

RS # 64-2055 for $10 is dual heat hand held pencil style iron, 15W for Integrated Circuits, and 30W for everything else. You need at least 30-40W for everyday electronics use, and should not use more than about 15W for Integrated Circuit soldering. I would not get a gun style iron, too heavy.
[ I have seen co-ax cable rotary strippers....is this something that is necessary? Or is an exacto knife just as good? Most of the strippers are $14-$18...kind of expensive for the limited application I would use it for. ]

This ties in with the above question on soldering too: you need to practice on cheapo cable and RCA plugs first, if you have never soldered. I would recommend at least a pair of needle nose pliers, and a pair of medium size cutting diagonals or dykes, and get some el-cheapo coaxial cable and some el cheapo RCS plugs from RS to practice on. Get a small quantity of regular 60/40 electrical solder, and practice making joints with that. You can also practice taking apart the cheap coax with an xacto knife, and get the hang of it, be sure to practice over a surface that you do not mind marring or cutting, burning or scorching! You will be stripping the center core completely out of the cable jacket and shield braid, so you could cut through the jacket, and then slip the braid off, and cut the foil loose, or just cut everything, as a small penetration of the center core is not a big deal. It is very difficult to cut through everything, a good sharp box knife actually works better than an xacto knife will.

Once you get the hang of it, instead of ruining the first set of cable,s and having cold solder joints, and ruined RCA plugs, you have half a chance to do OK. If you learn how to solder with the 60/40, then switch to Ersin 62, you should have no problems when it comes time to do the actual good stuff. I realize that you may use the set screws on the RCA, but this is only for the center pin, you will still have to solder the ground connections. See the Tweaks section for comments on solder, and soldering, or use the AA search engine to seek posts about how to solder, I posted specific instructions somewhere here.

Jon Risch

 

Whoa! Hold on there, Sparky!, posted on July 10, 1999 at 12:32:26
Robert


 
Rob,

First, if you don't have a soldering iron or solder you need to slow down! (I know you're excited!) Rat Shack sells a 35 watt iron for about $10, it'll work for your purposes (get an extra tip for $1.29). For the solder, Kester Rosin Flux Silver Solder worked well for me, but can be a bit tough to find locally. If you want to try Multicore, I've included a link to their contact page. Fill out the form asking for the nearest retailer to you for buying Rosin Flux Leadfree Silver Solver, and they'll send you the name of the closest dealer. That form is good for anywhere in the world, you pick the division of Multicore nearest you from the dropdown list on the form.

I have a cheap ($5.99) Radio Shack co-ax cutter, but more times than not I use my trusty X-acto knife. I use a small pair of wire cutters a lot too.

I mentioned all the soldering supplies first because you're going to be soldering. I've not used the SF plugs, but generally those screws are for strain relief (after you've made your solders you screw in the screw to hold the cables in place). Even with the screws it's still a wise idea to buy ½" adhesive-lined heatshrink (most electronics stores carry 4" length bags) cut a 4" length in half, you now have two 2" lengths, one for each end of your IC. Place the shrink so ½" of it covers the bottom part of the plug barrel and the rest is on the cable, then heat (don't forget to put that screw in before you put the shrink on!). This will provide additional strain relief. But before you apply the HS you want to make sure that your solders are up to snuff...

When you get the soldering iron buy several feet of cheap coax cable and some cheap Rat Shack® RCA plugs . When you get the solder you plan to use, sit down and make about 15 practice solders, some with the plugs, some with just two wires. You'll think you've got the hang of it by the 5th solder, but you're wrong. Even 15 times soldering is not very much, but you'll be wanting to do the real thing before that. The more you practice the better your "real" solders will be. The job you do soldering is key, I think it's more important than Kester vs. Ersin, because if the joint is poor the best solder on earth is not gonna help. Your focus needs to be on the job *you* do. Take your time. Focus.

Best of luck,

Robert

 

Fools rush in..., posted on July 10, 1999 at 19:28:50
Robert


 
I need to cool my own jets and read the posts a more carefully before typing. I screwed up on my comments on the screw! Jon is correct (as usual!)...

Robert

 

Re: 89259/89248 questions: Thanks Jon & Robert...., posted on July 10, 1999 at 21:39:51
Rob


 
Ok...thanks first of all for your replies....

I know I came across as very eager, but really - I've already waited a month planning on this project. Since I knew I didn't have all the parts necessary I wanted to figure out what was left. Rest assured I intend on doing the practice runs on cheap stuff first as you both have suggested...

Now, your replies have raised some other questions for me....the shielding is apparantly the way to go. Do I then attach both the 89259 *and* 89248 to the positive, with the shield then soldered to the ground? I remember seeing something in Jon's notes about grounding the shield to only one end - I believe it was to be at the source end if I'm correct.

Concerning the set screws....let clarify my original description .....there are actually *2* set screws....one is for strain relief and would be cranked down on the entire cable assembly. The other set screw is on the 1/4" positive "nubbin" that I would insert the bare wire thru. I have a set of jeweler's screwdrivers. Will this provide adequate torque on the screws? I really want this to be a top-notch job, so if soldering this connection is the better way to go I can remove the set screw and just solder the joint instead.

Shield - Jon, I don't recall seeing much in the way of final outer coating of the cable in your notes - I think I recall your recommendation to another post of using dippable or paintable pvc to cover the spaced copper braid. Is this correct? Or would I just leave the copper braid bare?

BTW - the rotary coax stripper I saw allows for adjustable depth of cut so that you can just strip off as deep as you want....it is not your typical wire cutter (scissors type)

Thank you both again for your help.

 

Re: 89259/89248 questions: Thanks Jon & Robert...., posted on July 10, 1999 at 22:39:39
Robert


 
Rob,

Here's a very basic rundown of what you'll be doing...

First, remove the outer jacket AND copper braid from 2 equal lengths of 89259 and 2 more of 89248, this will leave you with 4 lengths of wire surrounded (insulated) in Teflon. Make sure the lengths are longer than you want the final wire to be, twisting the pair will result in a shorter length than what you've started with. Use electrical tape to temporarily tape the end of one of the 89259 wires together with one end of an 89248 wire, this is to hold the wires together while you twist. Twist the pairs tightly as Jon suggests. When you reach the other end, tape the two wires with electrical tape to hold the twists in place temporarily. I suggest you get some Teflon plummer's tape (97¢ ea. @ Home Depot) and wrap it around the two wires to make sure they are as as tight together as possible. Also add Teflon tubing as Jon suggests in his post, so when you add the shield the braid will be distanced away from the field generated by the twisted pair of wires. Remove the electrical tape from one end and strip the Teflon 1/8" from the end. Push both wires into the RCA plug. You can solder the 89259 (stranded/multiple wires and smaller diameter Teflon) to the center pin of the RCA plug and solder the 89248 (solid wire and larger diameter Teflon) to the body of the RCA (or you solder the 89248 to the center and 89259 to the body-- this is what Jon is saying in his post in this thread, some people ask which is best...). Done with one end! Solder the other end the same way. Next take the large diameter copper braid you'll use for your shield (as per Jon's notes) cut to length, and solder to one end (you could just solder one end of a small piece of extra copper wire to the body and then solder the other end of the small wire to the braid shield. Make sure the copper braid doesn't touch the RCA barrel at the other end. Add heatshrink and you're done with one cable, do the other one.

As for whether to use the tiny screw on the center pin or solder, Jon can say. I misunderstood, and wrote about the bottom screw in my other post. My point was that the bottom screw is only going to do so much good, and in my opinion I wouldn't rely only on that to provide the strain relief.

Again, best of luck.

Robert


 

Re: 89259/89248 questions: Thanks Jon & Robert...., posted on July 11, 1999 at 11:42:40
Rob,

Robert is correct, and his post saves me the trouble of typing it. He even realizes the set screw situation in the later post.

Good luck on your DIY cables, and as suggested, if you take your time, practice, and keep it all together as much as possible then your results will be quite positive.

Jon Risch

 

Re: 89259/89248 questions: Solder and Teflon tubing, posted on July 13, 1999 at 07:05:36
Rob


 
Jon....checked out the McMaster Carr per your post and also contacted the company. The solder is ersin multicore. I'm planning on placing an order soon....will also pick up some 60/40 ratio to practice with.

Concerning the teflon tubing - spacer....the largest diameter of teflon tubing they carry is .130".......according to my belden product guide the inner core diameter of the 89248 is .170" and the 89259 is .135"
Is the goal of the spacing to "round" out the cable as much as possible? I would conclude then that I would want the largest diameter possible tubing. Is this correct? I realize that you have recommended using cut cores of other cable, but the 89248 and 89259 were both fairly expensive (I bought by the foot) and to buy more of them just to use the cores doesnt seem practical to me.

I contacted the company I ordered belden from and they quoted belden 9259
cable for 20 cents/ ft.....you have suggested this as a source for the shield braid....if I were to order the largest size teflon tubing - would the braid still fit? Should I use the inner core of the 9259 instead? - I realize that the inner core is foam polyethylene and is not high on the list of dialectrics - but as cheap as the 9259 is I could knock out two birds with one stone....getting the braid and the spacer together.

Thanks

Rob


 

Re: 89259/89248 questions: Solder and Teflon tubing, posted on July 16, 1999 at 08:02:23
The purpose of the extra insulation is to space the shield away from the twisted pair wires, so that the EM field has plenty of space to develop and travel without getting shorted out by the shield. The .130 diameter is actually too big, something 2/3 to 1/2 that size will do the job, you mainly want to keep the braid out of the twisted pairs crease, that is the worst thing to do.

The 9259 insulation is foamed PE, and this is not as good as the teflon, or foamed teflon. If included as a spaced element, it becomes part of the dielectric system, and will influence the sound to a degree. That is why I suggest a quality insulation be used as the spacer.

Jon Risch

 

Thanks Jon!, posted on July 16, 1999 at 10:07:03
Rob


 
I will order the tubing soon. Since I am moving in 2 weeks, I probably won't have an opportunity to start the project for a while. I will post my results and experience as I'm finishing. I also plan on taking some pictures of the process - I don't know if there is any place to post them, or if you would object....just let me know. Thanks again Robert, Jon, and all for your patience with all of my questions!

- Rob


 

Re: DIY 89259/89248 interconnect questions: Jon & all, posted on July 18, 1999 at 16:20:57
Jon,

In many of your recent posts regarding the performance of both loudspeaker and interconnect cables, you have made numerous comments that have led me to believe you rely almost entirely on A/B listening comparisons to identify differences in performance. Indeed, you appear to have little or no regard for measurements of the electrical properties of cables and what they might reveal about a cables "potential" to accurately "transport" complex, wideband signals between system components.

Some of your comments call into question your academic credentials, relevant technical experience, and whether or not you possess suitable facilities and test equipment to measure and quantify the many electrical properties that might determine a cable's audible accuracy when carrying complex, wideband signals between different system components having either low impedance or high impedance input/output circuits.

Since my C.V., containing complete info regarding my technical background, can be found on DAL's WEB Site at WWW.DUNLAVY AUDIO.COM, perhaps you might wish to provide readers with at least a "thumb nail" sketch of your own technical background, experience, etc. It might make a lot of us feel more comfortable about what you say and propose. (Of course, some may say that this is irrelevant and that you should be judged only by what you post. However, I suspect that relatively few readers have the technical and academic underpinnings to determine the accuracy and relevance of much that you post.)

Best Regards,
John Dunlavy


 

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