Keith Kidder's 4eleven

[MIKET]

I am looking at building this project with a few modifications.
Replace the MCM aluminum cone woofers with the Dayton 7" aluminum cone woofer PE part # 295-335
http://www.partsexpress.com/pe/pshow...number=295-335

The Vifa M13 Alnico mid would be replaced with a Davis Acoustics 13MP5G
http://www.partsexpress.com/pe/pshow...=297-562&DID=7

The tweerter would be the TangBand soft dome 25-669B PE part # 264-800 rather than the Vifa XT25
http://www.partsexpress.com/pe/pshow...number=264-800

I would like to here from others before I send Parts Express a check.

[PHilgeman]

Ummmm... Did you e-mail Keith?

I hate to break it to you, but there is simply no way that it will work.

You will end up with a couple hundred bucks worth of junk. Unless you have software to measure and simulate the response of crossover networks etc, and have completed several two-ways, then you are going to have a tough time trying to do what you want to do.

-Paul

[MIKET]

Yes I did e-mail Keith and he didn't seem to feel there would be a problem.
I do have access to an anechoic chamber, B&K dB meter frequency generator etc. weekends when its not in regular use.

This will be my 10th or so speaker building project.

The Dayton 7's look very promissing as they can achive an f3 of 35Hz in a small vented box.

The Davis mid is as flat as a ruler.

The only driver I'm feeling kind of ??? about is the TangBand tweeter.

[MIKET]

The Peerless DT 100 H looks like it might be a good choice as well.
http://www.partsexpress.com/pdf/277-408.pdf

[Zaph]

Originally posted by MIKET
The only driver I'm feeling kind of ??? about is the TangBand tweeter.

IMHO, stay away from the TB 669. It has ferrofluid and dome coating consistency problems. The last 4 samples I tested had a big, honking peak at FS that was made even worse from diffraction effects when mounted on a baffle.

I can't say much about the Davis drivers as I've never tried them. They look overpriced to me, so I probably never will.

The 7" Dayton Aluminums have the exact same response curve as the MCM 55-1860. Probably because the cone and surround are the same thing, produced in the same Asian factory. PE decided to use a different frame, longer voice coil and vented magnet to differentiate their woofer from the popular MCM 55-1860. The vented voice coil likely makes this a better woofer.

Kieth's 411 is a nice design though. the 4 aluminum cone woofers will offer a nice tight slam and impact. The Dayton aluminum woofers are a suitable replacement for the MCMs, but I'd personally make different choices for the mid and tweet.

Note that the TB 669 response shown below was on an infinite baffle. The peak at 1k gets worse when mounted in a box.

[454Casull]

IIRC the aluminum cone drivers distort pretty badly...

[Kilentra]

At what frequencies do these aluminum drivers distort badly?

[Zaph]

Originally posted by 454Casull
IIRC the aluminum cone drivers distort pretty badly...

Only if you cross them over too high. But if you cross over at least 2 octaves below the main breakup node, the harmonic distortion level will almost alway be lower than their paper or poly counterparts.

Below 2Khz, these two Dayton aluminum cones and their MCM counterparts, have lower distortion than many speakers in the 3 digit price range.

[Zaph]

Originally posted by MIKET
The Peerless DT 100 H looks like it might be a good choice as well.
http://www.partsexpress.com/pdf/277-408.pdf

I hate to sit around here and shoot down all your ideas, but that tweeter isn't very good. I've got a pair in my closet right now gathering dust. Actually it's not as bad as the TB 669, but the response is still a bit ragged. If you cross over high and steep enough however, this is a very low distortion tweeter. I recommend 4th order at 3khz.

Of the bargain basement tweeters, I think the Seas 25TFFC is the best bet for $24 ea, and then the 27TDFC for $29 each. These tweeters have well controlled low end rolloffs, which mean simpler crossovers. If I had to pick the best tweeter under $20, it would be the Vifa D27TG05 or 15. The problem really is that all the under $20 tweeters lack rear chambers, which means they all have high Fs and high Qts, which in turn means they require more components to smooth and control the low end. So in summary, there are a lot of sub $20 tweeters but they may not be the best value choice. Open up the budget to $30 tweeters and the doors open to some excellent tweeters. But insist on a sub $20 tweeter, and you will almost always pay more for crossover parts.

[Zaph]

Just for comparison, here's a Seas 27TDFC. Incredible tweeter, and worth every cent of it's $29. Very easy to cross over, with it's controlled low end rolloff and smooth impedence curve.