Thanks all.  I have a few homework assignments.

If what you say is true, then Core32's suggestion of the 50 ohm resistor could help??

I can give the 50 ohm a try.

Also attaching the test lead between the two amp chassis might help.  Attaching to the Crown is easy.  Not sure where to attach to the Torii??

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Center rear of amp is the power receptical. Center receptical prong is the Earth Ground. Ohm meter should test 0 resistance between power receptical Earth Ground prong and: RCA outer jackets, Top plate, Top plate screws & probably toggle switches. So a lead between the two amp chassis can be attached anywhere on the chassis that is common with the power receptical Earth Ground prong on each amp.

Check for continuity from power receptical Earth Ground prong to negative speaker post. If there is no continuity then speaker negative is floating separately from the AC power receptical Earth Ground.

Best to have speaker wires and interconnects removed when testing for the above.

If it works you could also just use a single RCA cable and connect an unused RCA INPUT on the Crown to an unused RCA INPUT on the Torii if they are available.
No harm in connecting two INPUTS together between amps.
This would have the same effect (but neater) as the wire between amp grounds.

If there is an RCA output on the Crown it could still be connected to the RCA INPUT on the Torii, as long as it's some standard signal out.
Just a thought.
Obviously no OUTPUT-to-OUTPUT connections are recommended....  

So the Crown inputs are grounded (=0) and the Torii speaker outputs are floating.
Definitely a ground loop situation feeding back to the speaker.
Can you lift the ground connections ONLY of the magic cables going back to the speaker (-) ?
So the series resistor part of the magic cable is the only connection between Crown and speaker?
Start with the volume low, just in case removing the ground reference causes the buzz to be louder in stead of quieter.

You leave the signal path intact. Just remove the ground wire from the magic cable.
The magic cable consists of two wires. One that has the series resistor in it (signal) and the other just goes from the outer connection to the speaker (-).
You remove the outer connection only.

Leaving the ground wire off is like adding a really REALLY large value resistor......    ;)

Pal,

Have you tried searching on amazon for "Female Spade", they have quite a few options. Available widths include: 6.3 mm = 0.25", 4.8 mm = 0.20", 2.8 mm = 0.11" I could only find 6.3 mm at Parts Express which seems strange?

The tabs on my Alpha 15A are 4.8 mm. I use the non-insulated Female Spade with shrink wrap and they look nice.

http://www.amazon.com/100Pcs-Pluggable-Terminals-Female-Connector/dp/B016WZM3S8/...

So how did you cure the BUZZ ???

Makes some sense. Mixing Floating Ground of Decware and Earth Ground of Crown and the two together are not happy. Great News.

Solving Grounding issues are often a lot of trial and error.

Glad to hear it Pal.
With the Torii's floating outputs and removing the magic cable ground connection to the Crown, the "return path" is now through the common earth ground of both amps power supplies. (The AC power cable ground.)
That is still not ideal but what it has done is removed the majority of the ground loop and thus the buzz.
I do not think there is a passive way to reduce it further and any "active" way may just color the sound to the Crown.
Maybe make sure the Torii and Crown are powered from the exact same AC circuit.

Did you say you had an AC line isolation transformer or similar that your Torii and Crown are being powered from?
If so if that has a ground lug I would do it there.
Proper grounding is such a pain in the ass for critical audio listening.
Adding a ground is just as likely to exacerbate the problem as fix it....

The DACs external power supply, what type connection does it have to the power plant?
If it is just two prong or just a wall wart/brick that could again be a source of ground loop.

Rob stopped over yesterday afternoon for a mini CDApS.  We only had an hour.  We demo’d the OBs on the Torii using some of my music and some that he brought.  Then we played with the crossover point and finally, we put the Zen UFO in to see how it did.

I hope Rob will get some time to weigh in with his thoughts.  He was impressed with the speed and transparency of the Tang Bands.  He also commented that the highs were good.   He thought the bottom end was good, but felt that the Crown did not better his dual Rythmik plate amps he runs the 4 Augies in his Trios with.

We threw some pretty heavy stuff (at least heavy for me) at the OBs and all but a couple of songs, I think the Tang Bands held up and produced enjoyable music.  One song we couldn’t finish was an Alabama Shakes song.  I may give that one another try under a different gain mix as it’s a pretty hot recording.  

I think these speakers are widening my musical horizons.  Not sure I am going to become a metal head, but I dig some of the progressive rock Rob has on his playlist and even some of his metal.  I think one of Rob’s parting comments was that these speakers were very good for the kind of music I listen to.  Lots of jazz and lighter rock with some alternative rock tossed in.  He preferred the meat of the larger 15” coax driver in his Trios for more of the music he listens to.

We experimented with the crossover and both felt that the higher crossover of around 105Hz sounded better with the Torii.  I had it set at around 50hz when we started.  I punched it up to 250hz and we both agreed it sounded horrible.  I may still try high passing the Tang Bands at 250hz (like Pure Audio) rather than low passing the Augies at 250hz.

We tossed in the Zen but unfortunately, we did not get the quality of results we got with the Torii.  We did adjust the crossover up to try to give it more weight, but still the results were not as satisfying.  I got similar results with Rachael, but hoped that maybe the UFOs would come to the rescue.  Overall, my conclusion is that the Tang Bands need more juice.

Eric is next up.  We've just had difficulty connecting with our schedules lately.

After Rob left, my son came home from college.  We ate some Chinese food and had a couple glasses of wine.  I always ask him to listen to my system when he comes home and he kind of grudgingly does so.  So the agreement was he would listen to one song.  

He likes that Daft Punk Random Access Memories album so I put on a track.  Head started bobbing, foot tapping.  So we listened to another, then another and after about 30 minutes he said, “can we hook up my Macbook?”  

We listened to all kinds of stuff and had a little bonding time. We played hip hop, progressive, electronic, alternative etc.  A couple hours later, his Macbook ran out of juice so only then, we quit.  My point being that I believe these speakers to be engaging across a wide variety of music.  

BTW, it was interesting what a hit the performance took when we switched to his Macbook.  Rather than download the USB drivers, we just ran optical.   I felt pretty good about the investment in the upgrades to my Mac mini.  And for sure felt better about USB vs optical.

One thing I discovered during my build is that Randy's design is deceptively simple.  The man has experience and that OB design of his is no accident.

I just wanted at least 22" because Darrell Hawthorne said his  production baffles are that wide and Randy also suggested the wider you go the better the bass on an OB.

There are guys on that gravity of the dark Star thread that experimented with crazy widths.  

I think my next build will be thinner just to see what I lose in the bass department.   I can't have something this big in a second system.  Back a few years ago pre decware I did some with the piano hinge.  You could fold them when you were not using them.  It was a short term experiment because I could never integrate the bass properly.

Bet those don't come with "FREE SHIPPING!!!!"   lol
Maybe a small fork-lift!

My new favorite (and recurring) phrase on the forum: "An Error Has Occurred".

It appears that my admittedly rudimentary computer skills are worse than I had feared.

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Similar experience with my 15" Lo Frequency Open Baffles. I run them full range, big open sound. I tried a couple of Eminence passive crossovers and it just sucked the life out of the low end (a night & day difference).

Thanks for the vote of confidence, Pal.

I already have my next project in mind, if my ship comes in. Or more correctly I should say if I can ever reinflate myself after the squashing that I took when the real estate market tanked. Anyway, if Steve is still making the FRX2 drivers, I'd like to pair those in an open baffle with a Tori Jr straight from a source. No preamp, no ZStage, no ZBit, no nuthin'. I have been finding that I'm happiest with the music when my system is the simplest. (OK, well, I do have my Regen with Curious Cables before and after in my system, so there's that). I'd also like to 3D print the baffle - but not before I do a few mockups in cheapo plywood. Never any shortage of ideas around here (just $$).

Randy

Hey Randy do you hear benefit of the curious cable before and after the regen?

Randy…I really like the idea of 3D printing the baffles.  What printing material are you planning to use and will it be anti-resonant?  

I have also been eyeing the FRX2 drivers due to treble frequency response.  I don't have a treble control on my amp to tame the high frequency increase typically present on most single driver systems.

I wonder how the FRX2 would sound in combination with an AMT driver as a super tweeter?

It really matters what kind of 3D printer you have in regards of what kind of material you can use.
Most small "Maker Bots" are just melting what amounts to ABS plastic.
Some of the high end stuff have many different materials from hard plastic to a pliable plastic that feels like rubber.
This week I watched a printer print metal. It was slow and glitchy, but it is the future.
I've seen sand, ceramic, wax, plastic and metal printed.
I'm going to print up logo's for my new OB speakers this week, just because I can.