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My New Crown XTi 1000s Are Here!!


BEC

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Without being able to measure things in a precise way, I may never know exactly what accounts for the following.

All of the parts for my passives showed up Wednesday, and I finished building them early this morning. With the D45 still in the box, I let some music repeat through the networks with an XTi for a few hours while I caught up on some other things around the rest of the house -- and I went upstairs after lunch to have a go at things. There's a pretty big difference in sound between the XTi/active and XTi/passive, and I much prefer the latter. I'm a little surprised by this because with my last set of passives I preferred the XTi/active. OTOH, the parts investment in this new set of passives is almost double to what I put into the first set, so maybe I shouldn't be so surprised. Overall, the signature is warmer, more rounded out and relaxed sounding, while the active method sounds very thin and flat in comparison. The imaging is a lot better too with the passives -- it now goes wall to wall instead of just hanging between the speakers. After I went through a few CD's I really felt the XTi was getting an undue bad rap. It may not put out the most refined sound an amplifier is capable of, but it's very listenable. O.K, well, that's what I thought until I dropped the D45 into the system. I guess the XTi/active setup was an improvement over my Super-T and previous passives, but it doesn't hang very well with these new passives and the D45. The word "etched" kept coming to mind while doing the comparisons, and right now I think it's still the best word for describing the signature of the XTi in comparison to the D45. On the whole, which means just about anything about the sound one would care to describe -- the passives and D45 are far and away much more pleasing to listen to.

Damn, I was really hoping I could be one of those "liberated audiophiles".

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Without being able to measure things in a precise way, I may never know exactly what accounts for the following.

All of the parts for my passives showed up Wednesday, and I finished building them early this morning. With the D45 still in the box, I let some music repeat through the networks with an XTi for a few hours while I caught up on some other things around the rest of the house -- and I went upstairs after lunch to have a go at things. There's a pretty big difference in sound between the XTi/active and XTi/passive, and I much prefer the latter. I'm a little surprised by this because with my last set of passives I preferred the XTi/active. OTOH, the parts investment in this new set of passives is almost double to what I put into the first set, so maybe I shouldn't be so surprised. Overall, the signature is warmer, more rounded out and relaxed sounding, while the active method sounds very thin and flat in comparison. The imaging is a lot better too with the passives -- it now goes wall to wall instead of just hanging between the speakers. After I went through a few CD's I really felt the XTi was getting an undue bad rap. It may not put out the most refined sound an amplifier is capable of, but it's very listenable. O.K, well, that's what I thought until I dropped the D45 into the system. I guess the XTi/active setup was an improvement over my Super-T and previous passives, but it doesn't hang very well with these new passives and the D45. The word "etched" kept coming to mind while doing the comparisons, and right now I think it's still the best word for describing the signature of the XTi in comparison to the D45. On the whole, which means just about anything about the sound one would care to describe -- the passives and D45 are far and away much more pleasing to listen to.

***, I was really hoping I could be one of those "liberated audiophiles".

Dude those look amazing. Great work...WOW

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Mark:

I think I remember reading about that in the past. The Black Gates are nice electrolyitics, the torpedo-sized 100uf power supply version pretty expensive, but good. I used Black Gates in cathode bias resistor bypass positions. I also remember being scolded by someone years ago because I even dared to use 220uf in an input stage bypass, but it was actually very good sounding. I took the bypass caps out of my Moth amp to see what it would sound like, and it was horrible, no sparkle at all. I'm using 470uf. Anyway, thanks for the clarification.

Regarding Dean's networks: I would honestly and genuinely be interested in what the same network would be like using an autoformer. I'm not sure of the order of slope used in the midrange (is this two-way or three driver jubilee?), and obviously, one can't simply switch out L-pad resistor/s for an autoformer without compensating for the change in load impedance, but does anyone know if experiments were done with this? Maybe it would be worth a try. Al's ES networks are very high order passive networks, but, if I'm not mistaken, still incorporate the autoformer for squawker attenuation.

Erik

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Nice words guys, thanks.

More of a form follows function layout -- I just dropped a coil in each corner to get them as far apart as possible and went from there. Board sizes were dicated by my shelf size -- I wanted to get them in my rack. I decided that on top of the bass bins is a bad place to put them -- you have the big woofer magnets right below and the large magnet from the compression driver right above.

L-pads might be better than what I did -- per the schematic, I just used series resistors for attenuation. The schematic calls for zero to 4 ohms (a choice), and I set two of the values up between the two terminal blocks ( 2 ohms and 4 ohms) so I could change the attenuation by just moving my postive tweeter lead. No attenuation works best for very low volume listening, with 4 ohms being the best for movies and concert DVD's when the volume is cranked up a bit. I have autoformers, and I may insert them at some point -- I set that middle area of the board up with the two terminal blocks for that very reason -- once I remove the resistors I have a place to put the autoformer. I decided to build per the schematic to begin with because I wanted to do as close to apples to apples as possible. My other networks used Auricaps, Dayton resistors and Erse steel laminates -- these use Sonicaps, Mills, and Jantzen air cores -- and I wanted to evaluate that change first.

As for the autoformers -- I've started the process of rebuilding the Jubilee networks that were used at the Pilgramage last June. I'm going to reuse all of the coils and the polypropylene caps with their lead integrity still intact -- and replacing others that look like they've seen better days (along with a couple of Mylars). I'm starting with one network, I'll set it up so I can easily go back and forth between the series resistor and an autoformer -- after a day or two of playing with that I'll make a call on which I prefer. With the autoformer, the output of the amplifier will be wired directly to the input tap, and the entire HF leg will hang off the output tap (those change depending on attenuation level). By doing it this way, none of the part values in the network have to be changed (for the same reason that tweeter network values don't have to rescaled when you move down the taps on the Heritage networks). However, impedance seen by the amp will go up as I attenuate, and the downside here is that it might make the D45 the five watt amp PWK always wanted.:) There will also be 90 degrees of phase rotation with the autoformer, and I have no idea what the audible effect of that might be. Anyways, it will be a week or two before I do any of this.

Mike -- no zobels. Don't need them, so they didn't go in. I can always add them later if need be.

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Here is the layout.

My layouts look goofy sometimes because I don't like to add wire, and always shoot for shortest path and the least amount of connection points possible. I eschew standoffs and parts are always directly connected to parts -- I normally take advantage of a coil's heavier guage wire to support the lead of a cap. Still, after I got done I immediately found two things I'd wished I'd done differently. Layouts tend to get cleaner and more sensical looking after you build a set or two.

The circled areas are the traps (EQ).

Coils on the HF boards are Janzten air cores, coils on the LF boards are Jantzen powder cores. The latter are secured by scuffing the bottoms and surface of the board with 100 grit and mounting with hot melt. I also use hot melt for the air cores -- filling the hole with about a 1/4" of glue, and after it solidifies I pass a brass screw through the middle and into the board. Coils and terminal blocks are from PartsExpress. Blue caps on the LF board are Clarity Caps from Madisound. White caps are Sonicaps from Soniccraft. Resistors are 12w Mills -- also from Soniccraft. Next level up would be Litz air cores from Solen and PPT Thetas -- too rich for my blood -- maybe next year.:)

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Three boards actually -- I put the LF circuit for each bass bin on one board. I was going to the do the HF sections the same way, but the single board ended up being too small because of all the extra parts in the HF section. So another eight inches was added and the board split in two. I split the board so I could pull them apart a bit on the rack to increase distance between some of the coils.

Yes, I'm biwired. I'm thinking down the road I might buy a preamp and vertically biamp -- I wanted to keep that option open without having to muck around with the layouts.

I'm surprised no one said anything about the cockeyed blue Clarity Caps.:) Kind of have to do the big ovals that way with those zip ties -- if you don't you can't the screwdriver to the screw without rubbing against the cap with the screwdriver.

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Dean:

Setting that up to compare would be interesting, and at the same time I understand about the time involvement to do that -- not to mention extra cost for parts. And in the end, might not be worth the hassle if what you've got is sounding good as it is.

Monster coils in there! They sort of caught me by surprise this early a.m.

Erik

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Nice looking nets Dean. You found out the same thing as I did. Passives sound better than the XTI active solution by a good margin........and I'm using totally different passives than you are.



For the ALK guys........I'm using a set of ALK ES nets without any autoformer. The Jub bass cabinet and top section play at very close levels. The top does not need to be attentuated very much......less than 1 db. I just ran it direct to the network and raise the bass bin levels by about 1 db.....which is how it is done in the active setup. The K69 is 8 ohms and I just ran an 8 ohm swamping resistor across it to bring it down to the 4 ohms of the network. This is not one of Al's standard ES networks.

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