Crossover questions

Trelja, e-mail me and we can discuss speaker design sometime, if you like.

My opinion is that series crossovers aren't a "forgotten technology", it's just that they are difficult to design, and are very unpredictable (very difficult to model with computer programs). I believe Joseph Audio's legendary x-overs are series, and his are supposed to be the steepest in the industry. The Stereophile review measurements confirm it, too. You can bet he hasn't "forgotten the technology".

I have two suggestions for you to check out:

First, if you like connecting speakers directly with no crossover, consider building a system with Fostex full-range drivers from Madisound (similar to Lowther, but much cheaper). At least visit their site and take a look at the drivers, and their flat frequency response. I've never heard them myself, but I bet they're worth the money, wheras the Lowthers are insanely expensive!!

Or second: Consider the Bottlehead.com speaker kit. They connect a bunch of aluminum coned midwoofers in series-parallel, use a high sensitivity tweeter (looks like a Focal clone), and the sensitivity is around 95 dB. It's an easy load to drive.

If I didn't already have several speaker projects going, I'd have bought the Bottlehead one immediately. I'm actually trying a project of parallel midwoofers. it will be a more difficult load to drive, but with these particular ones, it might work. I hope to use two tweeters in parallel per channel, and the sensitivity should be around 96 1w/1m. The catch is that the cabinet will be quasi-dipolar, and I'll augment with whatever powered subwoofers I have on hand...currently the Sunfire.

I just bought some Infinity Emit ribbon tweeters from Speakercity.com for only 40 bucks a piece, and they're simply incredible! I bet they're 99% of the performance of the Raven R-1's, at least until you get closer to their thermal limit.

I doubt it's much lower. To my ears, it's about 93 dB, wheras the R-1 is supposed to be 95. Speakercity also have the Hi-Vi Research RT-2 Ribbons close-out priced for only $31 a piece...I bought a pair of those too. They aren't flat though, and will need a gradual rolloff below 10kHz to bring the top octave up. By contrast, the Infinity Emit seems to have nearly the same dispersion as a one inch dome, and even more surface area. A pair of the Infinitys in parallel might be a better approach than a single R-1, at least where money is concerned (i.e., more surface area and higher efficiency). To my ears, it's as good as the circular ribbon Genesis uses, and that's saying a lot!

If you're wanting several midwoofers in series-parallel, then of course your cost will go WAY up. I still would like to suggest the Bottlehead kit. You could even modify it by using a different tweeter, like a Focal dome (or that pricey new one Kharma uses), a Raven, a Fostex, an Eton, or whatever. As is, though, I bet it would more than suit your needs.

If you have more money than sense, you might want to buy a pair of the new Accuton DIAMOND DOME tweeters, for $2500 a piece!! I bet they are just killer! Supposed to be pistonic to 100 kHz!!

Actually, the 8 AWG North Creek air coils have the absolute lowest DCR of any inductor on Earth, and DCR is always a direct function of the cross sectional area of any conductor. The main advantage that Solo's or Alpha Core's foil-coils have, is in reduced skin effect, since the entire conductor is a ribbon, so it conducts electricity entirely on its "skin". However, their largest ones are only 12 AWG, so their DCR is radically higher than that of North Creek's 10 or 8 AWG air core coils. Solen even makes 10 and 12 AWG heptalizt coils that are supposed to be magnificent.

In one of my projects, I went from a 14 AWG Solo CFAC inductor (identical to, and predating, Alpha Core), to a 10 AWG North Creek, and every aspect of performance improved (that driver is a Dynaudio 15W75-04).

Well, good luck in your project. I'll check out that iprimus site.

I never said Accuton was new; I said the Diamond dome was new. It will be interesting to see which manufacturer uses it first.

The sensitivity for the Emit-B seems higher than 90dB to me. The sound is fantastic imo; far more detailed and dynamic than I was expecting. It's a modern unit, with Neodymium magnets, so it's bound to ouperform those Infinity units you heard in the 80's.

Also, the published sensitvity for the new Raven R-1 is only 95 dB, the higher sensitivity is for the previous models (now discontinued). I think a pair of the Emit-B's in parallel would equal or exceed that sensitivity. Keep in mind that neither of these small tweeters will work below 3kHz.

As I've said before, if you absolutely want to run a midrange driver "flat out" you should consider a fullrange speaker like a Lowther or a Fostex. I've not heard the Fostex drivers, but their specs look more than adequate for their price, even a match for the Lowthers. The 8 inch model has nearly 100 dB sensitivity!! A series crossover isn't quite the same thing as running a fullrange driver with no crossover at all, imo.

Have you looked at Madisound's site, under Fostex drivers? Also, their ribbon tweeter looks about as good as the Raven R-1, and the Fostex one is only around $100...half the price.

I had thought that your goal was to throw something together for your secondary system, and to experiment; I didn't realize you wanted it to be a "statement" project. Those can be difficult and time-consuming...and let's face it, neither of us is a world class designer.

I, too, am no fan of Focal tweeters. Problem is, if you want to use only one tweeter, and decide you'd rather have a dome than a ribbon, the Focals are the only ones with high sensitivity, without horn loading.

The problem with using compression drivers and horns, is that you wind up padding them way down to match the lesser sensitivity of the midwoofers, so a lot of power gets wasted in the crossover, and I'm not sure it's even possible/ideal to use series crossovers in such an application.

I think you'll find, that unless your living room exceeds perhaps 7000 cubic feet, you won't need a speaker higher than 100 dB sensitivity (even with only a 3 watt amp)...and in any case, without the proper room treatment and placement, you'll hear more of the room's echo than you realize, imo.

You are quite welcome. I've always felt that the problem with "highend audio", is that there aren't more folks like us. I have to laugh, when I think of all those consumers that take loudspeakers and room acoustics for granted, and instead pay more attention to "tweaks", like gold-plated titanium rollerballs, etc.

I look forward to hearing from you in the future.

Did you happen to hear that Alon Statement speaker? it's the only one I'm aware of that uses the Ravens, they're the smaller R-1, and it uses 6 per channel I believe.

The speaker I'd like to hear, is that Impact "Airfoil" bending wave model...supposed to be a new take on bending wave drivers, uses them in a line array, fullrange down to about 100 Hz.

Does the Coincident speaker model you have not use the Seas Excel magnesium coned midwofers? I thought they all used those magnesium cones...the thing with them, is that you can never get rid of that ringing, even with an infinite slope crossover. It's just that it's essentially inconsequencial in the final speaker, since the ringing still is mostly focused on-axis.

Metal cones do have an efforteless controlled snap to the sound, I have to admit. I own an aluminum-coned Seas, for yet another project. The corresponding magnesium model rings somehwat louder than the aluminum, though...but that solid copper phase plug in the Excel versions sure looks awesome.

In my opinion, the 8 AWG North Creek coils get very close to the performance of not having a coil at all. However, they aren't exactly the same, obviously.

No, I've not heard any of the Fostex line. I'm curious if the driver you heard was mounted on a baffle in a finished design, and if so, which model was it? Was it any of the current ones in production, as listed on the Madisound website? Did it use a rear-loaded horn, a front-loaded horn, or both?

I'm trying to decide which 4 inch midwoofers to get, for the tiny "monitor" project with the Emit tweeters I bought. There is an older Vifa 4 inch polypropylene cone that has an EXTREMELY smooth rolloff, and might work with no crossover: the P11WG-00-08.

I may try using this one myself, but according to the Solen catalog, it will only yield an F3 of 60Hz, and I was hoping for a tad lower.

If I can't find a treated paper 4 inch cone with a low enough Fs, I may try and use that poly-coned model I mention above. It's just that I'm getting tired of the sound of poly cones. They have the advantage one you go bigger than 6 inches diameter, but not for 4 inches diameter, imo.

All would be fine, if Audax's new "polymer chassis" line, didn't feature back plates WITHOUT vent holes for the pole piece. Why anyone would ever buy midwoofers without vented pole pieces is beyond me. And they even charge as much for this new polymer line, as they did for the premium zinc-chassied line. That just seems outrageous to me.

I own 6 of those too (they're spectacular imo), it's the treated paper version of those found in the Pipedreams. They're discontinued now, so they only sell the carbon fiber model, again as found in the Pipedreams.