There was some technical discussions of frequency responses and such in the thread by various members. The main details of the actual project are here written up by BillD and some additional notes by me:
"BillD has been updating his blog since Friday, when he arrived at my place outside Santa Fe -- I'll not try to upstage him nor pretend to be able to describe technically what we (actually HE) did during the 3 1/2 days here doing delicate surgery on my system.
He left this morning on his next leg of the road trip, then he'll return to Santa Fe in about a week and we'll see what still is in place and working in the Carver/Sunfire stack and the Amazing Originals upgraded to Plats (without internal crossovers now).
It's been educational and very stressful and tiring being involved in the revisions, amputations, testing, sound level measurements, frequency responses, equipment quirks (both the testing and the various components like the Rane crossover, the PE15 equalizers, starts and stops when the speakers acted up for reasons to be determined (but luckily survived whatever momentary electronic hic-cups were going on).
Yes, the Amazings are now bi-amped with Silver 7t's on the woofers, and Silver 9ts on the ribbons; two sets of fused binding posts on each Amazing, duplicate speaker cable runs now for woofers and ribbons. Photos to follow.
The most frustrating phase was probably removing and then putting all the various pieces of equipment back into the Chinese cabinet (or putting it there for the first time), dealing with very cramped space (would the 19" Sunfire tube pre actually fit in the lower space allotted or not? Could we turn it up at an angle to get it inside the doorframe, then flat down? How to protect it from nicks and bangs while we struggled? Numerous cursings and sweaty foreheads dealing with all the wiring and hookups for the many, many pieces of equipment in that system, re-routing, drilling new holes in the wooden cabinet to fish the wires and cables through; mysterious speed bumps along the way, all resolved by Bill as they came up ---- I would be weeks doing this alone, trying to be talked through it by emails or by phone! I doubt I actually could have or ever could have figured out the technical side of this project.....
Bill will be posting here with the complete story -- and with some humor, I know! By the way, the end result is STUNNING!
Bill and Reese's Excellent Adventure is not over yet --- I may slip the C-19 into the mix to give me more options (more source connections, more AC plugs behind it, and make it another source for the Sunfire ! BWAHAHAHAHAHA!
Reese (poster boy for OCCD, I think) "
I arrived at Reese’s on Friday, and we had a great get together chat and listened to his plats until about 8 PM when we went out for some dinner at a local al fresco restaurant. The next day (Saturday) was devoted to my performing surgery on his Rane AC-22 to transplant the delay circuit from the low end to the high end and re-wiring the plats for dual binding posts after the passive crossover removal. The goal was to have the speakers play before bedtime, which was accomplished with several missteps along the way.
The metal used in the four-way binding post plate proved a little tougher than anticipated. We needed to drill two ½" holes in each plate for fuse holders, and the plate got away from me while drilling and caused minor injuries. We decided to screw the plate down to a board before drilling, and that made the job more manageable.
We rewired the ribbons and the woofers to the binding posts. Interestingly, Reese had one speaker with 4 original woofers and one with 4 Dynavox woofers (the difference being that one set had the Carver part number stamped on it and one set had the Dynavox part numbers). Also the woofers were wired in a parallel,/series setup (versus vice versa), which means there were two parallel pairs (2 W) in series yielding 4 W, rather than two series pairs (8 W) in parallel yielding 4 W. The Parts Express plate that Reese had bought fit over the hole in the woofer back cover without further carpentry, thank goodness. We put the speaker panels back on (which is a chore) and had a light lunch. After lunch, on to connections.
When trying to hook up the Rane stack (two PE-15s and the AC-22) we discovered an interesting problem with the Sunfire Classic Vacuum Tube Controls Center (hereinafter referred to as simply the Sunfire). It seems that one of its XLR outputs has a plug blocking insertion of the XLR female plug into it (the other one was fine). After some consternation, we decided to use the RCA jacks through one of my unbalanced to balanced converter boxes I'd brought along to the PE-15s XLR balanced inputs. We hooked everything up, bypassing the PE-15s. Using test tones we set the crossover point on the AC-22 to 200 Hz for both speakers, and usng the delay transplant circuitry, aligned the woofers with the ribbon, and violà, music. With that, we started fiddling with the parametric equalizers. We noted that the PE-15s were noisy, but decided to defer investigating that until later. We managed to lose all bass for awhile due to cockpit errors with the PE-15s. Then we blew a fuse in one of the speakers and lost all of its bass. We decided we were getting tired and needed to have a little supper and some sleep, and tackle the problem anew on Sunday. We went to bed not knowing whether or not we’d blown the woofers in one of the plats or if it was something else entirely.
The next morning (Sunday) we took the panels off the failing speaker (again), and I found one that was shorted. As it turns out, we had used a piece of aluminum foil to protect the woofer cones when soldering, and we had pushed the wires to the voice coil together on the bottom woofer (where the binding posts connect). Separating the wires and we had bass again. We decided not to put the covers back on lest we have to take them back off again. We then disassembled the Rane stack so I could look at the noisy PE-15s. I discovered one bridged solder junction in one and one ungrounded leg in the other, which I fixed. We then sprayed all the pots and switches with Deoxit, and reassembled everything. Music once again, and the noise was gone.
After many attempts to get rational readings on the ribbons using a variety of tools (SPL meter, tone generator, spectrum analyzer, we decided to use previously known data plus our ears to equalize the response. We put a one octave maximum boost at 20kHz due to rapidly falling response at the high end. We put in the resonant cut at 6,500 Hz and a sharper one at 2,500 Hz. We also put in a sharp cut at 850 Hz. Not knowing anything about the bass, we left that alone for listening tests. What we found was a little cut necessary for Reese’s room around 80 Hz due to reduce some boom. We needed to adjust the depth of the cuts slightly but, other than that, Reese was pleased with the overall tonal balance on some of his favorite classical pieces. I found the speakers showed remarkable cohesiveness. There was no evidence of crossover transitioning, even with tone sweeps. We used the tone generator on my laptop through my USB DAC and ran tone tests and sweeps to get a feel of the balance at the sweet spot, which was good. Then, we just played a variety of music much to both of our satisfaction. We ended a very successful day over a nice dinner at a local spot.
We devoted Monday to relaxing and listening to music, as well as cleaning up the enormous mess we had made. Reese got the Rane stack into his media cabinet after drilling a couple of holes for wire access and removing a spare C-4000t.. We also played with his Oppo BDP-83 and listened to some SACDs I’d brought along. After lunch, we attempted to get the Sunfire into his media cabinet. Unlike the Carvers, that only have handles that stick out in front, the Sunfire is 19" wide front to back, making it difficult to wiggle into a cabinet with only an 18" opening in front and only 20" inside. Because of this and some previous issues with wiring access, it was necessary to dismantle Reese’s entire wiring setup and start over. Mind you, this is not an easy job in that Reese has a ton of components in there. In fact, he has more components than can be serviced by the Sunfire. Anyway, it was a long and tedious (and strenuous at times) process, but we managed to get it all back together around 8:30 PM only to find that we had lost the right speaker (the opposite one from the one where the voice coil wires were touching. I jumped to the conclusion that the stereo/mono switch on the AC-22 had failed and took it apart to see if I could short the appropriate contacts together, but that made no difference. Then Reese noticed that the balance control on the Sunfire had been turned all the left. Whew! That fixed that and we were in business. We finished the evening listening to harpsichord music. Reese showed me how much better it sounds on the plats versus the two pair of Maggies he has hooked up elsewhere in his house. We both think something is the matter with the Maggies, but he says they both sound the same and I find that for all four to go bad the same way unlikely.
I left today and am finishing this up in a hotel room in Shamrock, TX, on the way to visit my sister in Edwardsville, IL, just across the border from St. Louis, MO. I left Reese this morning with a challenge to piggyback his C-19 into the Sunfire so he’ll have enough inputs to connect all the sources he has in that stereo cabinet. I will be back through there in about a week to check his progress and report back.
Update from Joplin, MO. The Internet connection at the hotel in Shamrock was down, but I have one tonight. I've got some pictures to post but need to resize them, so I'll post those later. For now, here's the update. "
"I called Rita's yesterday morning to inquire about the odd male balanced connection on the Sunfire -- I talked with "Bill" at Rita's and explained what we'd run into -- sort of like a disk or the bottom of the socket halfway or more up the pins in the socket, leaving just some pin length exposed (which looked normal at a quick glance from above), which prevented inserting the female balanced connector sufficiently onto the pins to make and hold connection. The other plug was fully connectable. He could only say, "That's not right, they should be the same".....
So someday (not too soon, after struggling to get that Sunfire preamp into place and all wired up!) this could be a little electronic project to replace the balanced blocked plug and insert a new one that accepts the female connector.
I did hook up the C-19 yesterday into the chain -- making it an "AUX" source on the Sunfire's source dial - -- and plugged in the DAT deck, a CD 5 disk changer/burner, a dual well cassette deck for the occasional desire to play tapes again, and some mystery cable that I still have to figure out what it goes to or from!
A bad hum in the turntable connection despite firm grounding to the Sunfire is an issue -- I'm sure it's an obvious fix and will tackle that soon. Otherwise, everything is working fine and a joy to play with!
Quite a light show when everything's powered up! lolol "
"The Amazings' speaker performance itself was always excellent, and I was using the Sunfire Tube Preamp anyway. I think the major improvements have been in the equalization for the room's acoustics, flattening out the dips and peaks on ribbons, keeping the bass supportive and realistic, not boomy, not shy, and making small adjustments as we listened carefully to the sound coming out (and what the spectrum analyzer and other software on Bill's laptop showed) ....it is all there in heavy classical orchestral music, baroque, opera, in jazz, in pop, in vocals, whatever. The beautiful sound stage is there in spades -- and the loafing along with four Silver t's meters not even moving much off the left end even at full room listening volume.
That isn't too scientific, just subjective impressions so far. I may even be altering the furniture arrangement more or less to fully expose the lower half of the left speaker as heard from the listening chair/sweet spot position. But as always with reflected and di-polar sound, there's plenty moving around the room and that makes up much for the partial reception of the full sound from the left speaker. However - this is a compromise situation as always -- life intrudes, not much is perfect, and this still is a mightily impressive and enjoyable set of audio equipment! "
"A couple of points. The Plats are definintely 4 ohm, either with the honeycomb or with the normal 16 ohm woofers. The honeycombs even say 4 ohm on the back of them. Reese, I thought we'd gotten rid of the turntable hum when we tried it last. Could it have anything to do with the C-19?"
"I can't imagine the C-19 is related to the phono hum, but what do I know? The turntable isn't connected to the C-19, it's hooked into the Sunfire. And the ground seems firmly secured. We'll discover something eventually, I know."
"BTW, what do you think the difference would be if we rewired the woofers so that they were two series pairs in parallel versus the way they are. What we noticed is that one pair of the speakers (bottom) appear to have more movement than the top pair."
"Probably best if you try it both ways and see; to the amp it's the equivalent impedance, but to the drivers you're putting some in series and some in parallel, the series drivers will be affected by the series inductance of the coils preceding, so there'll be not only damping effect but phase shift.
I don't know what would work best
two drivers in series, and then each bank paralleled should give you a more balanced phase shift across the array (IOW from top to bottom you'd have top two in series, bottom two in series, then top and bottom banks in parallel) that config would give you the middle two affected by the phase shift of the outer two.
If you put the top two in parallel, bottom two in parallel, then each bank in series, the inductance of the top bank is going to mess with the phase of the bottom bank....that seems not optimum to me, but again, you'd probably be better served trying it both ways."
"I think the optimum thing would be to change woofers to the non-honeycomb ones that are 16 ohm and put them all in parallel."
"I've been wondering about that, too, Bill. If I already have 60" ribbons and Plat upgraded crossovers, why not simply use the non-honeycomb woofs as long as I replace them wholesale if the Dynavox woofs are an exact match? My sense is the upgrade kit was more cost effective by leaving the honeycombs in place, otherwise the only thing left original would be the baffle."
"I think the optimum thing would be to change woofers to the non-honeycomb ones that are 16 ohm and put them all in parallel.
yes, that would be the preferred configuration; no phase shift or damping reduction"
"The effective mounting of both woofer type is slightly different, Also, besides the impedance difference and the need to change the wiring sequence, the crossovers are also different, so changing woofer types is not really economically feasible, nor might it be desirable. If you have to change the ribbons, the woofers, the wiring, crossovers AND the baffles to upgrade to true Plats, all you are left with are the grilles and floor stands from your originals. Might as well just buy a set of Plats if that is exactly what you want.
I do have a question for you guys. What exactly is it about the flat woofers that makes someone want to replace them with the cone types? I always thought that the flat honeycomb woofers were what made Originals so desirable to most people."
"From what I remember, you're really only worried about the Sd (cross sectional surface area) so ideally the driver should be a flat piston; the cone shaped drivers would flex if they were flat (unless they were made of a much higher mass material). The honeycomb driver CAN be flat and low mass because they are mostly empty space, the honeycomb internal structure increases rigidity.
Shouldn't be a preference one way or the other as far as shape (they both have the same Sd) BUT, the original design (square drivers) would have had a higher Sd. The problem being the same as with that airplane that had square windows (the connie?) if you drive a round voice coil into a square driver, stress points eventually cause the corners to fail, so they scrapped the idea."
/quote Robert R/
"Obi - I 'd want to convert to cone-types when convenient, simply because I suspect they are likely to be repairable/replaceable for a longer reach of time into the future. Maybe. As far as I've ever heard, the bass performance is about the same, given enough quality power. Another point to ask Bob about - I'm making a list."
"This is all fascinating! I think I'll keep the honeycomb woofers in place -- I seem to really like the idea of planar speakers pushing big areas of air! lol And no thanks to potentially having to rig up some way to suspend new cone woofers in already existing slightly larger cutouts! (Of course, many years from now -- if it must be done, it must)
Yes, Rich -- we removed the Plat upgrade internal crossovers altogether, using external active Rane crossover and parametric equalizers now -- ultimately tweakable, I'd say."
There may be a quote or two missing of short comment or questions not directly related to the Amazing Plats and the bi-amping. If so, my apologies. Also, photos will be coming later when BillD gets back from his trip.
Sunfire Classic Tube Preamp; 2 Carver Silver 7ts, 2 Silver 9ts; bi-amped ALS (Originals upgraded to Platinum), Rane PE15's eq's and Rane AC22 xcrossover; Carver c-19 tube pre;
Carver 390t CD carousel; Carver 490t CD player; BBE 362 Sonic Maximizer; C-9 SH; Sony ES tuner and DAT deck; Sony CD copier/burner; Sony dual cassette deck; TEAC 2340R 4 ch r to r tape deck; Dual CS5000 tt, Shure V15 Type V-MR cartridge