What Do You Guys Think Of This?

[mlucitt]

Randy Sloan is describing a different setup in his article evidently.

Phase Linear did it pretty textbook and well in their establishment of the single point ground as that copper bus between the caps. It does not get much better than that....the single point ground in a PL amp should be this bus bar connection. Thicker is better as always for that bus bar but they did it right.

I tend to agree, my Hafler DH220 Amp was the same, Star ground between the caps. And David Hafler was no slouch when it came to building amps.

 

[wattsabundant]

...but I don't like one end of the shield floating. Joe may be able to shed some light on it if it is vexing you.

The generally accepted practice for terminating the drain wire in a shielded cable is it only gets done at one end. Doing so at both ends introduces a ground loop. It's been 40 years since I've wired racks, but I seem to recall XLR's only had the drain wire terminated at the signal processor input. RCA (Switchcraft 3502) and 1/4" plugs (Switchcraft 280) had the drain and ground tied together at one end. We used Belden 8451 which is 2 conductor plus a foil shield and drain wire. It still seems to be the standard cable. That is what is used for the level controls on 700's.

Here's one link Drain wire that discusses it. Of course there is no universal agreement.

As for RCA input jacks, P/L used Switchcraft 3501's. I generally prefer 1/4" jacks when possible. Most of my amps have them. It doesn't hurt that I was given a 100 or so Switchcraft 111's.

 

[WOPL Sniffer]

The generally accepted practice for terminating the drain wire in a shielded cable is it only gets done at one end. Doing so at both ends introduces a ground loop. It's been 40 years since I've wired racks, but I seem to recall XLR's only had the drain wire terminated at the signal processor input. RCA (Switchcraft 3502) and 1/4" plugs (Switchcraft 280) had the drain and ground tied together at one end. We used Belden 8451 which is 2 conductor plus a foil shield and drain wire. It still seems to be the standard cable. That is what is used for the level controls on 700's.

Here's one link Drain wire that discusses it. Of course there is no universal agreement.

As for RCA input jacks, P/L used Switchcraft 3501's. I generally prefer 1/4" jacks when possible. Most of my amps have them. It doesn't hurt that I was given a 100 or so Switchcraft 111's.

I don't think tying the shields together constitutes a ground loop. The rca's are not grounded, they are on insulators and floating. besides, when you plug in the preamp into the rca's it's probably getting a ground from there. Now THAT may constitute a ground loop. And you are correct, no universal agreement. I think a ground loop would introduce distortion/noise into the system and I have seen no evidence of that. As far as the 3501's and 111's go, the ones that PL used and they are cheap junk. The bean counters probably forced them to use them as a cost savings when there are better rca's available that outperform the $2.00 wonders. When I build a new amp, and have all new stuff, they advertise cheap just by the looks. If I was given 100 pieces of stuff doesn't mean I have to use them to save $10. The Cardas RCA's are quality items and I don't mind spending the money on them and they LOOK good too. I have a couple hundred of those switchcraft RCA's I stripped out of all the amps I've done, maybe Santa will dump them down your chimney for X-mas.

P.S. 1/4" jacks are for guitars and headphones and I have or had buckets of them too I stripped out.....

 

[wattsabundant]

I

I don't think tying the shields together constitutes a ground loop. The rca's are not grounded, they are on insulators and floating. besides, when you plug in the preamp into the rca's it's probably getting a ground from there. Now THAT may constitute a ground loop. And you are correct, no universal agreement. I think a ground loop would introduce distortion/noise into the system and I have seen no evidence of that. As far as the 3501's and 111's go, the ones that PL used and they are cheap junk. The bean counters probably forced them to use them as a cost savings when there are better rca's available that outperform the $2.00 wonders. When I build a new amp, and have all new stuff, they advertise cheap just by the looks. If I was given 100 pieces of stuff doesn't mean I have to use them to save $10. The Cardas RCA's are quality items and I don't mind spending the money on them and they LOOK good too. I have a couple hundred of those switchcraft RCA's I stripped out of all the amps I've done, maybe Santa will dump them down your chimney for X-mas.

P.S. 1/4" jacks are for guitars and headphones and I have or had buckets of them too I stripped out.....

It's my contention that on shielded cable the drain wire has a different function then the ground wire and tying both ends together defeats the purpose. I also don't think it's worth getting worked up over it.

 

[Gepetto]

I


It's my contention that on shielded cable the drain wire has a different function then the ground wire and tying both ends together defeats the purpose. I also don't think it's worth getting worked up over it.

May also depend on if you are using shielded twisted pair or coaxial. With shielded twisted pair you have the option of tying the shield to ground at only one end since the signal and ground are being carried by the twisted pair within. When using coax, which is my go to wire, the shield is used as a conductor and shield for the signal within and must be connected at both ends.

So it depends on what you are using.

 

[Michael F]

I have been trying to find decent RCA Phono Jacks to fit in the 1/2" holes of our PL and WOA chassis. Most of the 'good' RCA jacks (Cardas, Kimber, Neutrik) are 3/8" hole size. There are "audiophile" 1/2" jacks that cost $98.00-$125.00 each and there are Chineeeese imitation jacks that cost $2.00-$20.00 each. I try to avoid anything Chineeeese in these wonderful amps.
Anyway, I stumbled across these last night. They are manufactured in a small Pro-audio (recording equipment) shop in Chino, CA called Manley. Run by EveAnna Manley, she is the daughter of Albert J. Dauray, the owner of Ampeg (sadly sold to Magnavox in 1972), and she is a pistol. The website www.manley.com has some nice images and videos, and their equipment line looks good.
https://www.ebay.com/itm/142339553194

I bought some of the RCA jacks to check them out, and from first Ebay glance they seem to fit the Bob Carver paradigm - rugged, attractive, purposeful. And the price is good for a Made in the USA product.
Thoughts?

Those look very nice. Manley is a very well regarded company, if it`s good enough for their amps, I would trust them on mine. Be sure to post your opinion once you get them.

 

[mlucitt]

I just received the Manley RCA jacks from Ebay. These are now my favorite RCA jacks, the Teflon shouldered washers fit the cutouts in the WOA chassis perfectly (they hold themselves in the hole, the interference fit is as if the same company made both items).
These RCA jacks complement the WOA chassis because they look strong and purposeful. One of the technical advantages is that you can solder the ground/common wire to anywhere on the raised round shoulder. But the best feature of the Manley RCA jacks is that they are made in the USA, just like our WOA components.
Also, I exchanged several emails with EveAnna Manley, she is very friendly and easy to work with. I suggested to her that they ship each jack with one red and one white shouldered washer instead of having each customer specify if they want two red or two white washers with each jack. This way the customer can put a red or a white washer on the outside of the chassis. She thought that was a good idea (I repurposed the idea from Cardas).

I am not affiliated with Manley, Inc. But I wish I was...
Maybe Joe could get a wholesale quantity buy and sell them through WOA. I looked to buy a quantity, the the unit price ($5.00) stayed the same at any quantity.