| don't need to sim it [message #40068 is a reply to message #40059] |
Tue, 28 January 2003 06:37   |
Sam P.
Messages: 307
Registered: May 2009
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Grand Master |
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to build it, as I believe Wayne has already done the sims for a Pi-type version or two.
I am still investigating what my final filter topology will be, but 2nd order Bessel LP with a subsonic HP (20Hz or 30Hz.), taking into account the input Z of the following power amp, is looking good so far. HP will be 2nd order also, might add a 3rd pole after the CF like on the Glass-ware site schematic. 800Hz., so it can be compared against the XM9L I use now.
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Much more trouble than parts chasing is the need to fabricate a chassis from scratch. That is the "kit" advantage, and everyday(week?) my tube active crossover project drags on I think, "why didn't I just build another XM9L?!"
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ONE 19/32 hole for the 6X4 socket, Six 3/8's holes for the jacks, a 7/16 for the CRAP fuse holder that I need to find another of as it is so cheap(pe 070-630) it is already broken before being installed, the rectangle cutout for the power cord socket, etc... :(
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The $$$ you may save going DIY over kit are considerable, if you figure this is a hobby and your time is "free", the parts costs for something like the Bench circuit, "done right" at the hobbyist level will run maybe $300? Will it perform better than the XM9L in any measureable or meaningfull manner? I can't say yet:)
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I'm thinking this active tube xover project is essentially NO HARDER than building a tube preamp, or SET amplifier.
In fact, I think a stand alone tube based RIAA phono stage will be my next beattheheadagainstthewalloohthatfeelsgoodwhenIstop form of relaxation.
Either kit or diy, the builder will need to pay attention, and strive for a zero defects build quality, as troubleshooting something like the marchand tube kit will be a nightmare compared to fault locating in a single triode gain stage per channel, especially if you don't need the steeper filter slopes of the kit.
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What speakers/amps are part of your "plan". That could be a BIG factor about what you should look for. Keep working at the pspice, I think you need all the downloads in the same folder. Also, wayne's tube model download needs to go into the spice "library" folder, IIRC, but I am as clueless about this as you are. Once I got it working, I simmed a bunch of changes, then "figured out" it was auto saving, and my original file was GONE, mutated, and had to be reinstalled! Then the wife says, just save the original file, but with a new name. So you muck that one up, and Wayne's model stays INTACT for comparison purposes.
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YES, I must force myself to put in the "book time" and learn how to use pspice, but for my immediate needs, Wayne's model works great. Phono stage? Norman Crowhurst already did those SIMS back in 97 or 99, and they ARE INCLUDED with the pspice library from Cadence. Don't give up. Sam
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