Shielded cable

[Darkbluemurder]

Please forgive me that I bring this up again. I did a research for "shielded cable" and found like 50 matches or so - information overload.

I understand from some posts I've read that it is best to go unshielded whereever possible. I never used Belden which I understand is equivocally rated as crap in terms of high capacitance. What do you think of the following cables (if used as a grid wire):

- George L's guitar cable
- the shielded cable Fender used in the Rivera-era amps (there's no label on them)?

Further, does shielded cable have the same effect when used for plate wires? Is there any benefit at all to use shielded wire in plate circuits?

As always many thanks in advance.

[dogears]

Just use some RG58/59 style cable..... Try and keep capacitance under 30pf/ft

Standard video coax works well.

[img:250:39]http://cache.smarthome.com/images/8529a.gif[/img]

[dobbhill]

Does this link help anyone:
http://www.repeater-builder.com/antenna ... cable.html
D

[jaysg]

Canare GS-4 is really meant to be an external cable, but the specs are nice. Just be careful what it can run into. Of course, HAD could have chosen something with more pF per foot on purpose. Sneaky #$%*.

http://www.canare.com/index.cfm?objecti ... 7554228243

[ApexJr.]

I have lot's of different shielded wire in stock...

I have Canare GS 6 in stock that's the 18 Awg version of the GS 4
talked about above, also teflon 1 cond shielded in 24, 22, 20 and 16 AWG.
Teflon 2 and 3 conductor shielded too.

Steve @ Apex Jr.
www.apexjr.com

[glasman]

I have lot's of different shielded wire in stock...

I have Canare GS 6 in stock that's the 18 Awg version of the GS 4
talked about above, also teflon 1 cond shielded in 24, 22, 20 and 16 AWG.
Teflon 2 and 3 conductor shielded too.

Steve @ Apex Jr.
www.apexjr.com

Steve, do you ever see any 95 ohm teflon coax? This would be great in this application. Low cap (!16 pf / ft) and durable.

Gary

BTW, Sorry that I missed you when I was in Beautiful downtown Burbank. I did make it over to the 'Other' Apex with Gil. Holy S&*T. Reminded me of digging around Apache reclaimation here it Phoenix, except Apex had MUCH BETTER s$*t. I could have spend a day looking at the old military surplus radios and such. Awww to have my old BC-348 back again.

[glasman]

Here are a few interesting observations on cable that are based on measurements I made this weekend.

Over the past several months I have been using a video cable made by GEPCO (I am not affliliated with them). And recently I purchased a couple of rolls of the cool white teflon jacket cable that we have seen in so many of the "mans" amps.

I rolled off 9 feet (only had a yard stick handy) of each of the three cables and I thought you might find the measurements interesting.

Gepco - meausred total cap of 160pf over 9 feet = 17.7pf

Roll one of teflon = 445pf over 9 feet = 49.4pf / ft

Roll two teflon = 325pf over 9 feet = 36 pf / ft.

I am not drawing any conclusions as of yet.

Gary

[ApexJr.]

Gary...

I just checked stock and found a small quantity of some Teflon
RG 180A/U 95 ohm say about 75-80ft in stock. .60ft
Also not listed on my website...
I also found some RG 174A/U which I've sold for amps before too.

Steve @ Apex Jr.

[Darkbluemurder]

Guys,

Thanks for the info. Where can you get such wires in reasonable quantities? I am definitely not into buying a 1000 ft roll (as offered by e.g. Mouser).

Cheers DBM

['67_Plexi]

With a decent lead dress, you should only need sheilded cable on the grids of the first two preamp tubes, ala Dumble. Four pieces in total. Use the recommended coax and make them as short as possible and you'll be fine.

[Darkbluemurder]

With a decent lead dress, you should only need sheilded cable on the grids of the first two preamp tubes, ala Dumble. Four pieces in total. Use the recommended coax and make them as short as possible and you'll be fine.

That is what I have in my amp, plus of course

1. the wire from the OD level to the reverb stage/mixing resistor (in both amps)
2. the wiring to the effects loop (in the Concert)
3. the wire from the reverb to the phase inverter coupling cap (in the Concert).

I am not sure whether the 80s era Fender lead dress qualifies as "decent", although the tone caps and the OD coupling caps are close to the pots (short grid wires, long plate wires). Haven't had any problems with the shielded cables so far so I'll probably leave everything as is until the next gig. If it's too dull I can still reduce the snubbers (560p and 500p in the Concert, 390p each in the Deluxe II).

[ayan]

With a decent lead dress, you should only need sheilded cable on the grids of the first two preamp tubes, ala Dumble. Four pieces in total. Use the recommended coax and make them as short as possible and you'll be fine.

For what it's worth, Dumble uses four pieces of shielded wire as described PLUS two more from the output of the LEVEL and RATIO pots to the board, for a grand total of six pieces of shielded wire all together.

Cheers,

Gil

['67_Plexi]

Who's going to argue with a man who's seen one internally first hand

For what it's worth, I actually got away without the extra two cables in my HRM clone, but it required some attention paid to lead dress and routing.
I was working in a Twin Reverb chassis so space was a premium to.

Alan.

[ayan]

Who's going to argue with a man who's seen one internally first hand

Alan.

Well, everyone on this board that downloaded the pictures I posted here a few months ago saw the very same things my eyes saw.

Gil

['67_Plexi]

Yeah...but you actually touched it....

All right...I'm just blind....LOL