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Multi-Way Conventional loudspeakers with crossovers

spica tc-60
spica tc-60
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Old 19th May 2006, 06:38 AM   #11
tc-60guy is offline tc-60guy  United States
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Greetings all, You guys are right. John Bau's speakers with their wide baffles,kinky crossovers and thick felt blankets went against the grain at a time when the trend was narrow baffles,minimalist crossovers and wide dispersion. And they sounded great! The audio industry needs cool,oddball designers like him who have a diferent way of seeing things. Think about the weird and wonderful MBL speakers and you know what I mean. It's a shame John Bau got fed up with all the audio industry nonsense and droped out. I checked out the Quicksilver website and their amps look tasty! KT-88s, El-34s,I'm in!!!
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Old 19th May 2006, 11:00 AM   #12
tc-60guy is offline tc-60guy  United States
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Thanks again Inertial, I tried the nearfield setup you mentioned years ago and it did indeed sound just dandy(still rolled off above 10kh tho). The only problem with this setup was the fact that it placed my speakers smack dab in the middle of my room, turning every trip to the bathroom or sink into a high precision slalom course! One time I even ran into the left speaker like it was a tackleing dummy and sent it crashing to the floor! As you can see,this configuration is not viable as a permanent setup. Believe me when I tell you that I've tried every option but duct taping them to my head and useing them as headphones(Bad for the finish and a mite heavy)!
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Old 19th May 2006, 11:44 AM   #13
inertial is offline inertial  Italy
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Hi Bob,
I believe your words.

maybe you can open the spica , extract the x-overs, report us the scheme, and then.... we'll see.

good experimentations
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Old 19th May 2006, 12:24 PM   #14
tc-60guy is offline tc-60guy  United States
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You've read my mind! I'd like to clone the x-over using premium parts, mount it outside the cabinet and beef up the cabinet to make it more non resonant,
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Old 19th May 2006, 03:35 PM   #15
inertial is offline inertial  Italy
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very well, Bob.
I'm curios about the high/pass filter expecially.....
If there is only a capacitor we can do nothing, but if there is also
a resistor.....

cheers,
Inertial
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Old 19th May 2006, 04:16 PM   #16
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Default Re: spica tc-60

Quote:
Originally posted by tc-60guy
You've read my mind! I'd like to clone the x-over using premium parts, mount it outside the cabinet and beef up the cabinet to make it more non resonant,


excerpt from September 2002 interview with John Bau in Enjoy the Music:



OM: Any recommendations for upgrades or modifications for any one of your designs?

JB: For TC-50 and Angelus; replacement of the electrolytic caps with film types will help (they start going south after a decade or so anyway). Exact design values should be used (not the values printed on the parts; we batched all our components to better than 0.1% groups, and paralleled them to achieve exact values). I'd have to dig up the schematics to find the target values. Conversion to bi-wiring would help as well. That requires some ground trace mods to the xover, though. Maybe some additional bracing between back and baffle would help too.
I don't recommend replacing the inductors, as aircore types would have to be humongous to achieve the same high Q of ours, and the resistor values in the circuit are all dependent on the residual resistance of the coils. Besides, all the coils and resistors are non-ferrous and quite linear within the speakers' power ratings.


(emphasis mine)


The box is small enough that a couple of 3/4" x 2" ply braces between the front baffle and rear panel would stiffen it up significantly. Of course, the truly adventuresome would just build a new pair of boxes with extra bracing, including from magnet to rear panel.


Any further modifications to the crossover other than upgrading quality of caps, or changing or adding drivers would result in a completely different speaker system - one that might have more notable performance in some areas, but possibly not the holograhpic coherence for which these little babies were renowned.

Ever have the opportunity to try different electronics ( i.e tubed gear?)



Read the entire interview, John's ennui is our loss


http://www.enjoythemusic.com/Magazin...spicafever.htm
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Old 19th May 2006, 04:29 PM   #17
BHD is offline BHD  United States
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The stereophile review of the TC-60 includes information about the crossover slopes and frequencies, so it should be easy to use a Marchand outboard crossover and actively bi-amp. If it doesn't work, I can always put the crossovers back in.

TC-60 guy - Quicksilver amps are great, but since they're not well known, they go for a song used. I've heard several of their amps, but I still feel the best sounding was the little GLA. They come up on Audiogon from time to time, but keep your eyes open as they get snapped up pretty quick. One thing I really like about them is that you can use many different types of output tubes, so tube rolling can change the sound of the amps.
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Old 19th May 2006, 07:44 PM   #18
tc-60guy is offline tc-60guy  United States
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Thanks a lot guys, The idea of bi-amping the spicas with an active crossover really appeals to me! Alas, droping another 4-5000 bucks into my system is not an option fo a audio bottom feeder like me and might be overkill for an eight year old pair of speakers I only spent five hundred dollars for in the first place. I am however willing to spend five or six hundred dollars to build an upgraded external passive crossover for my babies! Externalizing the crossovers would allow me to better shield them, isolate them from the drivers magnetic fields and allow me to brace the inside of the cabinets without giving up too much internal volume.
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Old 19th May 2006, 07:53 PM   #19
noah katz is offline noah katz  United States
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"The idea of bi-amping the spicas with an active crossover really appeals to me! "

It seems you're missing the point that it would be a different speaker system, not an improved version of the same one.

Active XO's (at least stock ones) are standard XO types/orders, and Spica's are not.
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Old 19th May 2006, 08:42 PM   #20
tc-60guy is offline tc-60guy  United States
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Hi Noah, I have no plans to biamp my speakers due to cost and space considerations. However, putting on my devils advocate hat for a minute, it would seem to me that any passive x-over could be modeled accurately with an active crossover especially if it's done within the digital domain. I'm applying sort of a defacto hippocratic oath to this project (First, do no harm).
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