EODevan,
From memory, the Alpair 12P in small BR boxes did give a nice, smooth sound. The Alpair 10P also. Btw, IMHO the both the Alpairs pair well with single ended tube amps - probably the higher output impedance and lower damping factor of these amps gel with the drivers. Having said that, they also work fine with solid state amps too. And just to make it clear, these drivers in BR boxes will not dig in deep as the Carreras.
No experience with the Fostex FF225WK.
From memory, the Alpair 12P in small BR boxes did give a nice, smooth sound. The Alpair 10P also. Btw, IMHO the both the Alpairs pair well with single ended tube amps - probably the higher output impedance and lower damping factor of these amps gel with the drivers. Having said that, they also work fine with solid state amps too. And just to make it clear, these drivers in BR boxes will not dig in deep as the Carreras.
No experience with the Fostex FF225WK.
Looks like you have found yourself a winner - Bob Brines is a well respected designer. He's also on diyA.
Remarkable. I own both, and that's close to my experience. The Lowther
should have the overhung 16 ohm silver voice coil, though.
Technically, the Feastrex is 9 inch.
Hi Nelson!
Have you compared either of those two drivers vs the Voxativ AC-4X with the wooden cone and paper whizzer? Just curious...
I'm listening to: A Place For Me by Margot Roi
Thetubeguy1954 (Tom Scata)
There is no best, but this one is well loved by many who have built it. It's not as hard as it looks. Best value is the PA-130 version in 0.53x. Great huge sound and nice full bass.
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds.html
More compact is 0.40x with Faital Pro 3FE25.
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds.html
More compact is 0.40x with Faital Pro 3FE25.
I like FE206EN for its cheerful midrange - less :dark than AN Super 8 ferrite. FE206EN has a high Q narrow band peak centered around 3.16KHz. I've had it in 4 sizes of Karlson coupler from factory K8 to "SK8" tp 0.62 scale K15 to the 1955 K12
0.62 scale Karlson
1960's factory Karlson Eight (about 1/2 cubic foot back chamber, fb 95Hz)
0.62 scale Karlson
1960's factory Karlson Eight (about 1/2 cubic foot back chamber, fb 95Hz)
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a better term would be: A wide band mid range
Because there is really no such thing as a full range unit. Please allow me to add in a quote here:
It is practically impossible for a single radiator to cover the 20 Hz to 20 kHz audio frequency range at adequate sound pressure levels (SPL) and with wide dispersion off-axis. At a 50 Hz bass frequency, for example, it takes an air volume displacement of 214 cm3 to generate 90 dB SPL at 1 m distance from the source in free space. Take a typical 6.5 inch (132 mm effective) diameter driver and its cone would have to move 14 mm peak-to-peak linearly, which by far exceeds its excursion capability (Ref. 4).
At 1000 Hz, though, the same driver would have to vibrate only with (50/1000)2 = 1/400th of this excursion for the same 90 dB SPL, but now the cone is in its breakup region and no longer acts as a rigid piston, causing energy storage and deteriorating off-axis radiation. Thus, this driver will have to be complemented with a larger one for low frequencies, and a smaller one to extend the highs, in order to obtain full frequency range coverage. The electrical audio signal then needs to be divided between three drivers.
Crossovers
Because there is really no such thing as a full range unit. Please allow me to add in a quote here:
It is practically impossible for a single radiator to cover the 20 Hz to 20 kHz audio frequency range at adequate sound pressure levels (SPL) and with wide dispersion off-axis. At a 50 Hz bass frequency, for example, it takes an air volume displacement of 214 cm3 to generate 90 dB SPL at 1 m distance from the source in free space. Take a typical 6.5 inch (132 mm effective) diameter driver and its cone would have to move 14 mm peak-to-peak linearly, which by far exceeds its excursion capability (Ref. 4).
At 1000 Hz, though, the same driver would have to vibrate only with (50/1000)2 = 1/400th of this excursion for the same 90 dB SPL, but now the cone is in its breakup region and no longer acts as a rigid piston, causing energy storage and deteriorating off-axis radiation. Thus, this driver will have to be complemented with a larger one for low frequencies, and a smaller one to extend the highs, in order to obtain full frequency range coverage. The electrical audio signal then needs to be divided between three drivers.
Crossovers
Yep, the merest hint of a tweeter tickled in at over 10khz, a nice vintage german fullrange 8 inch on an open baffle, and an actively crossed over sub at below 400hz to take care of the baffle step correction. The tweeter and main driver can be crossed with a simple cap (and padding resistor if necessary) and driven by a low powered valve amp (5watts is more than necessary) and the bass driver can be driven by a 30-50 watt chip amp or digital amp.
I messed around with a lot of fullrange setups to get to this conclusion. The problem with most of the voight type solutions is comb effect in the bass. Mass loading the bass off a voight can work - but you lose a hell of a lot of power doing it that way and the bass tends to sound weedy.
Shoog
I heard both.
The 225 in its bass reflex factory enclosure (heard it in japan in the ready made cabinet that fostex sells there for minimal diy) is beautifully warm and full with decent bass regarding the relatively compact cabinet. You wouldn't guess there is a resonance peak in the fr plot because it is truly smooth. However, it also sounded as dark as a very old radio. To my taste, I could not live with it without a supertweeter.
Considering the pleasant sound of the ff225wk, I would run it full range without any filter components, and would add a high crossing tweeter.
The a12p. I heard it in the superpensil. Truly fullrange and smooth. I could compare it with a lowther dx? Variant in a lowther corner enclosure. Actually the a12p was almost as good.
I bought a pair, but unfortunately since I am still in hong kong in an apartment (was not originally planned), I couldn't make the speakers yet.
Between the 2, the a12p is the exquisite true fr unit, however don't discount the 225, I bet it will sound great with a tweeter, and it will have fuller bass in reasonable sized enclosures. Probably a safer bet if you also like tock music.
Talaerts-
Thank you for the very informative post! I just wish it made the choice easier, haha! I definitely think that if I was going for a single speaker solution the 12p would be a no brainer. But right now I have Carmody Carreras for those times I want to rock and Sennheiser HD-800 for detail and sizzle. Now I want liquid gold for those times I want to be lulled into a catatonic state by listening to Sinatra being pushed by one or two SET watts. I just don't want liquid gold to turn into molasses sludge. I'm real close to trying the Fostex sans tweeter, knowing I have alternatives. I have to walk the WAF line as far as speaker builds go, so buying both to compare is a stretch.
It would surprise me if you'd truly like the fostex without a tweeter. It is lovely but truly lacks sparkle. Hence make sure it is easy for you to add a tweeter. Because you will!
Fyi I heard the ff225wk in this box, you could quickly slap it together before trying bigger builds:
http://www.fostex.jp/products/bk225wk/
http://www.fostex.jp/products/bk225wk/
That would be an easy one to build. I can always go for the 12p too, it's a great driver. I was just hoping to find a bigger version of the CHP-70. But even the CHP will strike me as bright at times. I love the imaging, soundstage, and direct connection to the amplifier that a single driver offers, but I just can't seem to find one that is easy on the ears. I've only heard small full rangers and was hoping a larger driver would be more mellow. All the replies have been great so far.
