Crossover component choice


2013-04-12 10:13 pm
Ive been having a nerd online and am confused by the huge variety and cost of audio parts.
There seems no limit as to what I could spend (other than common sense and a limited cash supply), yet there are good value, even cheap parts out there that work well.
Can people suggest lower priced parts that are good ?

Resistors - wirewound cement cased ones start at 12p from Farnell, Are the cheap ones any good ? Do I need "audio" ones ? They all look alike to me.

Capacitors - polyprop - start at a couple of quid, loads at £4-10, then a huge leap into bank robbery territory. Some of the £3 Wima items seem to be highly thought of, for example.

Inductors - coils of wire - plenty to choose from below a fiver. I dont see any need to overspend on them provided resistance is kept within limits -what limits ?

thanks in advance, Geoff
Solen sells 'good' resistors (mills copies?) for 75 cents each. Cement ones may be ok but not enough $ savings to explore that possiblity.
Solens are baseline good capacitors, Wimas are not.
Avoid cheap solid core coils, as few are made well enough to be genuinely good.
Again Solen wire wound air coils have proven to work well. Foil coils even better..smallish gains for significant cost increases involved though.
OR not be pound foolish and simply Buy the Bespoke Tannoy crossovers.. and never needs worry about 'IF only' :).


2013-04-12 10:13 pm
interesting, I'll have a look at solens, especially for the resistors and coils, hopefully a uk supplier will come up with sensible prices
the "genuine" tannoy x/o on ebay are probably well made and correct circuits, but the identifiable parts seem to be the cheapest available, for the dosh I can make much better

first and foremost: component VALUE trumps component TYPE, always!
Obvious as that may sound, what it really means is: don't even THINK about buying exotic parts until your crossover has been checked, double-checked, triple-checked... and you are ABSOLUTELY SURE it is the very best you are capable of designing. Sub-optimal, non-optimized "minimalist" crossovers with premium parts ALWAYS sound FAR WORSE than painstakingly designed and tested crossovers that are built with cheap parts.

Then, with that out of the way...

COILS: this is where you want to start spending, especially for the Woofer. Coils are generally the weakest link in the chain. Fortunately, they are also the easiest (but not the cheapest) to get right. Basically, use air core inductors for the mid and tweeter, trying to keep the DCR reasonably low if possible. For the woofer, keeping the DCR as low as possible (I mean < 0.3 Ohm, and ideally even lower) is instead even more important, which generally means using cored inductors with thick wire. A couple of 2.2mH low-DCR transformer coils may easily end up swallowing up 30 to 50% of your crossover budget.

CAPS: just avoid electrolytics and you´ll be fine. Really. Then, if you really want to get fancy, try to stick to polypropylene ones for the mid and tweeter; polyester is fine for the woofer. Fancier still? Getting to the diminishing returns area, but if you must... "boutique" caps that I quite like are for instance Jantzen Superior (but, really, think twice before investing in these, and DO consider all of the above first)

RESISTORS: ceramic will do just fine, 20W for the woofer and 5 to 10W for the mid and tweeter. Non-inductive MOx may be worthwhile for the tweeter (and they aren't that expensive anyway)

That's it in a nutshell. Hope this helps.

Any suggestions as to makes of coils, or should I just get air cored, thick wired, low resistance from farnell ect for a few quid each ?
Just get those; try to keep DCR < 0.3 Ohm (more or less), the lower the better. If that isn't possible for the coil(s) in series with the Woofer, go to ferrite core inductors. The best are the transformer type.

I have played with many coil types ( including foils that I use in my crossovers now ) - best bang for the buck seems the 1-1.4mm of Janzen audio. Avoid coils with ferrous core, there are some non-ferrous coils by Janzen that might be worth checking ( should be powder with somekind of epoxy resin ) if low DCR is essential.
Caps - you can get Clarity caps from falconacoustics, the PX range is cheap and very good, I wouldn`t spend more on caps no matter how many people claim that some gold-silver NASA technology €299/piece cap sounds. Perhaps the only PP cap I found to sound very different was the Visaton MKP, worse than most others and expensive for what it offers.
Resistors - get Mills, you`ll need 1-2 per speaker anyways. For parallel resistors, MOX or even cement ones should be good. The rest "superior" types seem like a marketing blurb to me.
Its better to do the crossover with very cheap parts until you are satisfied with the tonal balance and overall sound. Then just replace with better quality parts, the other way is expensive :)
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