non-insulated shielded cable?

[dennyg]

I accidentally ordered bunch of non-insulated, braided shield 22gauge cable.  After going thru my "awe man" moment, got me thinking that other than making sure it gets firmly placed away from any potential voltage contacts, that laying it against the chassis would provide excellent shielding - and without the trouble of soldering in the ground lead for the shield.
I didn't even know this type of shielded cable existed, but sure does look cool.
What say ye veterans of the trade? 

[shooter]

without the trouble of soldering in the ground lead for the shield.

just laying it on the chassis will NOT be a good thing, ground want a really good mechanical bond.

slid some shrink-wrap over n you have insulation.  Are you sure there's not a clear enamel, shellac coating on the braid?

[tubenit]

I am wondering that since you ground the shield only on ONE end that if it was touching the chassis in one or more places also would be problematic and/or create hum.

[sluckey]

Take a look at the reverb cables on an original Fender blackface amp.

[PRR]

I would just use it.

Don't let it touch live wires/lugs, of course.

[kagliostro]

Years ago it was a common type of shielded cable





and it was secured, to avoid movements, soldered in several points of the chassis and mechanics

but this didn't mean it was a good choice, I consider it a practice of the past, like grounding one leg of the heaters

Franco

[dennyg]

Well i bought the stuff and it looks cool so I'm gonna work it into my next build.  Here's my theory on why i think it will serve it's purpose:  the connection to chassis is only for shielding, not for a ground circuit which carries current, so creating a ground loop within the shield shouldn't be an issue as long as it lays against the chassis for much of its length.  What would be problematic is if it only touched the chassis at a couple spots then the resistance between those spots could create a slight noise voltage across it.  But then again I use a star ground with only a single connection to the chassis for the entire amp circuit ground, so in theory there should be minimal ground currents flowing thru the chassis - except i guess between the safety ground and the star point.  But at the end of the day, it will either contribute to a quiet amp or not.  I'll report back in about a month when i plan to finish the next one, and it's an ultra high gainer so it'll definitely expose shielding flaws. 

[DummyLoad]

fender reverb tank cables were made with that type of cable.


--pete

[TIMBO]

Hi guys, These local built Fi Sonic's used miles of the stuff.
There is a main buss wire that runs the length of the amp and the braid is soldered to it, so neither end is actually connected.

These amps are generally quiet at idle.


I have used this method a few times with no problems.

[kagliostro]

Ciao TIMBO

a picture is worth more than a hundred words

That is exactly what I was trying to say (soldered in several points of the chassis and mechanics)

Franco

[Ed_Chambley]

I am wondering that since you ground the shield only on ONE end that if it was touching the chassis in one or more places also would be problematic and/or create hum.

I will cause ground loops.  You may not notice, but they will be there and it will wait until the performance of you life, says Murphy, to squeal like a pig.  You can think about it, but don't do it.

[Ed_Chambley]

Well i bought the stuff and it looks cool so I'm gonna work it into my next build.  Here's my theory on why i think it will serve it's purpose:  the connection to chassis is only for shielding, not for a ground circuit which carries current, so creating a ground loop within the shield shouldn't be an issue as long as it lays against the chassis for much of its length.  What would be problematic is if it only touched the chassis at a couple spots then the resistance between those spots could create a slight noise voltage across it.  But then again I use a star ground with only a single connection to the chassis for the entire amp circuit ground, so in theory there should be minimal ground currents flowing thru the chassis - except i guess between the safety ground and the star point.  But at the end of the day, it will either contribute to a quiet amp or not.  I'll report back in about a month when i plan to finish the next one, and it's an ultra high gainer so it'll definitely expose shielding flaws.

Check our Teflon Tubing on ebay or McMaster-Carr.  It is clear, tough.  Buy enough to cover the wire when you want to use it for more than a ground buss.

[Willabe]

Check our Teflon Tubing on ebay or McMaster-Carr.  It is clear, tough.  Buy enough to cover the wire when you want to use it for more than a ground buss.

Yep, agree.