High Quality 100 uF midrange cap.

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Currently using the 10 of the North Creek 225V 10 uF metallized polypropylene for the midrange series highpass. They sounded a little colored, differently, depending on the way they were oriented; in conversation I learned that this was intentional. By wiring 5 each way in the parallel stack, the colorations canceled, and the resulting performance was excellent for the price.

North Creek is shutting down part of their business, and I'm not sure the caps will be available in the future.

The midrange is the small ATI (Skaaning) C-Quenze, the best mid I've ever heard, with remarkable transparency. As we've steadily improved the system, the question arises, can this capacitor, arguably the most important xo cap, be improved without a second mortgage? We've had good luck with aluminum foil/polyprop, better luck with tin foil/polyprop, and best with tin foil/polystyrene. $500/100 uF is more than we can afford, but $2-300 would be considered (carefully).

We're not very well acquainted with the European brands; here's hoping someone knows of a bargain gem...
 
We thought about that; the amp being used now is $2K used; so costs increase substantially, and you move the problem back to the active crossover. The active crossover passives would indeed be excellent, and could be polystyrene or teflon. However, there is the matter of the active stages, and to some degree inductors or their equivalents.

To our considerable surprise, moving the crossover back to the amplifier and tri-wiring worked out very well. For one thing, it allows light gauge silver cable on the tweeter, for a considerable cost savings over heavier gauge silver. And it got rid of the upper freq grain/hash that we could not seem to avoid with our home made Cu cables.
 
You might want to check out the Duelund brand (http://www.duelundaudio.com/index.htm). Also see http://forum.audiogon.com/cgi-bin/fr.pl?rspkr&1164387495&read&3&zzlJadem6 for a review. I am currently designing a 3 way (my dream speakers) using (per enclosure) 2 AudioTechnology 6" Flex units woofers, an ATC SM75-150S midrange dome and a ScanSpeak R2904/7000 tweeter. I was planning to use North Creek's 8 AWG coils and Duelund's capacitors & resistors. They look excellent though expensive. I don't know who carries them in the US by the Parts Connexion (http://www.partsconnexion.com) has them in Canada. North Creek does have some items still available so you may want to check with them. Emails are generally quite quickly responded to. I contacted George regarding this and I have been able to buy their Cabinet Guide and Wiring Guide as well as the 8 gauge coils.
 
moving the xover back allows for biwiring is all and avoids the voltage drops from the 2 or more sections not to interfere so much with one another. I took the same approach in revamping a pair of JBL 2800 2-way bookshelfs that had a blown tweeter. I thought what the hey, I'll have fun. So, I replaced the tweeters with one of the SEAS metal domed jobs referred to on Zaph's website and did away with the cheap speaker connection, instead drilling holes and installing aluminum threaded spacers in a press fit at both the top and bottom for the woofer and tweeter. This enabled me to run 2 speaker cables from the amp, 1 to the woofer and 1 to the tweeter. of course, the xover inside was made to fit. I just use it for my home theater setup but I can tell you this JBL now sounds much better than it has a right to, but then of course it's not really a JBL anymore.
 
Hi Retro;

What's the difference between tri-wiring from the amp / using a passive XO in the speaker and having the XO near the amp / triwiring to the speaker? The only reason I ask is that I was planning to tri-wire from the amp and having 3 pairs binding posts on the speakers - each connected to their respective XO and driver. If I were not to tri-wire I would need a set of jumpers between the binding posts. Does it matter where the XO's are? Ie: near the amp or inside the speaker?

Thanks,
John
 
Having a xover by the amp allows the wiring (and the respective lossiness) to become part of the equation and that is what you would like to avoid to begin with, so a xover in the speaker would be preferable I'd think. Doing it like I did is what I'd prefer which is why I did what I did. Either way there will be power loss in the wires but I'd rather keep it on the amp side as opposed to the driver side which might influence xover behavior a bit more. I did endeavor to keep the xover parts away from the speaker magnets as much as possible however.
 
We did it for a different reason. For some reason (we must be missing something) we have never had copper sound as clean and neutral as silver in the upper midrange-tweeter bands. (Commercial wires sound fine, I'm using a Cardas Golden Cross IC which is excellent. )

Initial try at DIY speaker cables was Cu, and was not clean. I was wishing I could afford such a cable in Ag, when henchman suggested moving the XO to the amp end, and using smaller sillver for the tweeter only. Great idea! Quick -- to the checkbook!

So using the Cardas 9.5 ga Cu for the woofer, and 5 X 11.5 ga Cu (-+-+- "ribbon") for the mid was fine. And the 5 X 21 Ag "ribbon" was what the tweeter needed. To some extent, the woofer "liked" larger wire, and the mid really did better with heavier wire. The amp is in the next room, so the longer of the speaker cables is 16 feet iirc.

So the reason for our approach was empirical and economically driven, and allowed us to tailor each driver's cable according to perceived need.

The silver is Cardas bare, sleeved (tediously) with teflon tubing. I'm using the fancy Cardas lugs, Rhodium plated, and the Cardas patented "clamp". I'd suggest considering having one end pendant. (I did not, but the cost of the terminations is significant.)
 
The amazing Nocap.

Looking at the exotic caps that would be needed for a significant improvement was economically ummm.... discouraging.

Shorting the mid series cap, and using the mid sealed cabinet for the midrange low end rolloff seems the best answer. First pass listening test with mid cap shorted, and no compensating changes on the woofer demonstrated an improved midrange. Revised woofer lowpass will need a 15 mH low DCR choke; anyone know who stocks small C (cut) cores?
 
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