Amp power cord

miner49er11 · #1 06-07-2009, 05:29 PM

Probably shouldn't post here, but got no response over at the amp forum. I figure you guys are more "electrically oriented" anyway. I have to replace the power cord on my '79 Seymour Duncan Bass 400 amp (getting hot at the strain relief, many broken strands) and it's the old style hardwired pigtail type. It appears to be an 18/3 unshielded cord. Is there any advantage at all to going to a 16/3 or 14/3, or just assume that Seymour knew what he was doing when he built it with an 18/3? How about shielded vs unshielded cord? Thanks for your help.
~Pete

walterw · #2 06-07-2009, 06:38 PM

bigger is technically better, as long as it (and its strain relief) will still fit through the hole in the chassis. 16/3 is plenty big. and no, there's no shielding involved.

better still might be to have it removed entirely and install an IEC power jack (like new amps and computers have).

bongomania · #3 06-07-2009, 06:40 PM

+1
Also is the original a 3-prong? If not, make it so.

Jim Campbell · #4 06-07-2009, 07:01 PM

Quote:

Originally Posted by walterw

bigger is technically better, as long as it (and its strain relief) will still fit through the hole in the chassis. 16/3 is plenty big. and no, there's no shielding involved.

better still might be to have it removed entirely and install an IEC power jack (like new amps and computers have).

14/2 is whats code for 110v 15 amp ciircuits.......14/3 would have an extra hot.........18 is thin even for speakers

Rick Auricchio · #5 06-07-2009, 11:22 PM

But you aren't running 15a through the power cord, so 14/3 is way overkill.

Use 18/3 and you're as good as the original. It should already have a 3-prong plug if it's got three conductors. But +1 to bongo's advice.

It's easy to cut the old wire around the strain-relief to remove and reuse the relief if you don't have a new one. The hardest part is squeezing it around the new cable! But it can be done.

Hint: I did the same repair on a friend's Walter Woods amp. There was no room for an IEC connector in the chassis, so I installed a 1-foot female IEC cable and got him a 10-foot standard IEC cord. So now he has a detachable cable.

I cut the female IEC cable from one of those computer-to-monitor power cables. You can get 10-foot IEC power cords from mouser.com.

miner49er11 · #6 06-08-2009, 02:41 AM

Thanks for the info. I've been thinking about how much larger cable I can fit in the strain relief. Probably stuck with 18 ga cable because the reliefs for 16/3 SJT require a larger hole. I'm leaning towards the Rick's solution. Hardwire a short IEC female. For that matter I can hardwire a real short 18 ga cable & plug and use a 16 ga extension cord. Anyway... Thx again.
~Pete

walterw · #7 06-08-2009, 02:40 PM

the problem with a stubby little cable hanging out the back is that you'll always have the connection hanging in the air, constantly being pulled by gravity and whatnot. if there's no room for an IEC jack on the amp itself, it's better just replace with a fresh cable that's still long enough to at least reach the ground when the amp is on say, an svt cab.

Rick Auricchio · #8 06-08-2009, 09:28 PM

True, but in my case the owner always carries the amp in a case, and he's been happy with it. His jazz gigs aren't rough on the amp.

Miner, you still won't need 16ga cable, though there's nothing wrong with it except weight. Larger wire gauges are necessary to prevent heat buildup. You'll not get enough heating even with 18ga to bother today's modern insulation.