This is, in fact, the standard technique for bi-amping: eliminate the woofer portion of the crossover (inductor) and continue to use the remaining two-thirds of the three-way crossover (midrange and tweeter portions). A big advantage arises by removing the DCR of the inductor, though low for a low-gauge coil, improves the damping factor and eliminates any losses from ohmic heating. Moving to three amplifiers eliminates any phase shifts in the midrange band, a decided advantage as animal hearing is typically superior in the midrange band compared to the other, higher and lower, bands.
The load presented to the amplifier depends upon the impedance of the individual drivers. Impedance is consequently unaltered when bi-amping is performed, provided each group of drivers is separately driven as a unit.
Now, if one were to hypothetically alter, say, a Symphony with dual 16 Ω woofers wired in parallel to yield 8 Ω impedance to instead use a separate amplifier chanel for each individually, then the impedance seen by the amplifier would obviously change since the speakers were no longer in parallel (8 Ω) and were now individually driven (16 Ω). But you are not making such a change so the impedance would remain its nominal value.
The N-106 was likely connected to whatever stereo was being used. Did you check to see if this was also available? Bozak owners back in the day had high incomes, as the speakers were very expensive compared to the average hourly wage. It would be nice to pick up a vintage McIntosh amplifier originally mated with the speakers. Not sayin', just sayin'. Always pays to ask.
Yeah, these came from a VERY wealthy Owner, in one of the ritziest cities in the country.
He said the amps were already gone. He is selling the home, and only the Speakers remained. Like I said, they’d been “re-veneered” in Black Formica, and new black grille cloth was installed, just like the Klipsch Heritage speakers use, to match his Giant 90s entertainment center.
He did use Macs initially, though he was “persuaded” to “trade up” to some Pioneer Elite amps in the 90s, by a not so honest Stereo shop, imo.
The home was mostly empty, and I was only allowed to “look quickly” as he was in a hurry.
I spotted them and luckily saw just a quick glimmer/flash from the aluminum,on the always peeling latex on the mid. Though it’s 95% there. That and the shape made me think....”whoa!! No way!? Symphonies in disguise??!!”
I wasn’t even allowed to listen to them. As the owner had a “dinner date”. So I had to act fast, wasn’t aware of the N-106, and the price was too cheap to think twice and miss. He doesn’t seem to remember the N106 when I called back later and asked, but he didn’t ever hook any of it up,he paid installers. All other Stereo Equiptment was gone. He had some Satellite receivers and VHS re-winders etc, all nineties looking black box electronics in the corner. I’m hoping the N-106 is still in that pile, as he said he has “that junk” still. Fingers crossed.
I had to lug them up from his giant finished “basement”, (nicer than my home) a spiral staircase with 23 steps. Lol no help, just my trusty Hand Truck.
That was fun as it was 100 degrees that day and humid as could be, and the owner didn’t have the air on, as he didn’t live there anymore. There were painters, painting said staircase. Lol and the owner followed me up watching that I didn’t mar his precious paint. Which I didn’t, I respected his home.
Then I somehow loaded both, by myself in my Dodge Journey. They barely fit, this is when a small piece of the ugly black veneer popped off. Revealing the gorgeous original Bozak walnut veneer.
I’ll be removing the rest of the Formica, stripping the glue and refinishing to original. They are the Moderns, so I’d like to find similar grille cloth. Though the black “klipsch style” grille looks good.
I’d love to find another cheap Mac, and I was thinking the same thing. Anyone who ponies up for Symphonies, probably had a Mac Tube amp runnin then, or a Fisher 800 atleast. Lol
I did the conversion, and Symphonies purchased at $2k in 1967, equates to over $14k today, according to google....so yeah, owners of these had some cash.
I plan to run them with my 2 Mc240’s and MC-110z, all restored! A perfect mate for Bozaks. I’ve read Rudy voiced these with Macs. Though I’ve read conflicting reports he used SS and Tube.
If I use the Tobin 104t lll run each strapped as a mono amp. When I get the N106, or other active, I’ll run one for the Hi’s and One for the Lo’s in normal stereo mode.
I also have a MC2105, and believe me, I’ve though about throwing all the Bozak Crossovers out of the equation, and Tri-Amping with the SS 2105 on the Woofers. I think a 2105 would handle those babies well. I’ll do this at some point.
But I’d like to keep the 2105 open for my B302a’s for now.
In the end, I want all 3 options.
1. Tobin 104t modded x-over
2. Original N-106/N-107 combo
3. Custom Tri-Amp setup. Though I’m not sure which Crossover to use. I’ve read a lot of Bozak owners use the Pioneer 850, which is nice. But kinda pricey, I think I could do better, tho keeping the “vintage” look would be nice.
I’ve heard my Friends Concert Grands, I set them up for him, Tri-Amped with 3 Carver M1.5t’s. I know, way too much power. It’s what he wanted, I couldn’t convince him otherwise. No way tweeters need 350 wpc. The gain is barely above 1.5 on the tweeter leg of the active crossover.
Anyway, once they’re hooked up, I’ll add some pics.
