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Old 30th December 2007, 02:46 PM   #151
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Thank you for very good explanation.

Altough I have used PLL BSC for a long time,the attenuation hasn't been enough with equal size R1 and R2.Thanks to you,now I know to try changing the R2 to a smaller value.

I have found the PLL BSC to have more dynamic and clearer sound than with filters at speaker end.
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Old 12th January 2008, 04:20 PM   #152
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Going there
www.e-speakers.com . Scroll a little down to "Vadim Horn Project".
not only the beloved Hemp but also a Visaton B200 is to be found.
Anybody dos know some facts about this driver ??
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Old 12th January 2008, 05:10 PM   #153
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What, the B200? One of the best known FR drivers around: http://www.visaton.de/en/chassis_zub...nd/b200_6.html

Superb for OB use -can be used in other cabinets with a bit of creative thinking.
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Old 12th January 2008, 05:23 PM   #154
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Ok was a bit shy on this idea as the Vadimis are a rather smalish horn isn't it
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Old 3rd May 2009, 10:25 PM   #155
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Old 3rd May 2015, 04:22 PM   #156
oltos is offline oltos  United States
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Default Omega 2-way Alnico driver in sealed box?

Quote:
Originally Posted by Jim G View Post
Bill I feel that coating the whizzer made a real difference for the good. I also have open cell foam between the whizzer and cone ( 98 cent tweak) I didn't hesitate to try dammar because the whizzer is paper and not the hemp material that the main cone is. Some people have made negative comments about the whizzer. To my ears it works quite well.
Quote:
Originally Posted by lousymusician View Post
Omega uses a version of the FR8 that is tweaked to their spec's. I don't know how much they differ from the DIY version. I suspect that the difference is significant. Dan has posted his pair for sale after losing a listening room, so apparently despite his enthusiasm they never took over the #1 spot in his home.

Another DIY member, Nodiak, posted about trying to add phase plugs to his pair (the whizzers came off with the dust caps), but hasn't posted on them since.

I have my pair in simple BR cabinets, 82 liters volume, 4" dia x 4" long flared ports, and I sit relatively close to them in a smallish room (11 x 14'). So far, I have found them to sound like the FR graph on Hemps Acoustics' spec sheet - the highs are too hot. This didn't smooth out as much as I had hoped during break in, and toe in is not enough to bring the treble in line. The 'turn-'em-up-and-listen-from-the-next-room' test confirmed that the basic balance is tipped up too much for my taste. I put them into the living room HT system for a while, and while the highs were smoother when listening from a greater distance, the balance was still too tipped up.

To try to tame the highs I'm using a treble shelf network inspired by the Visaton open baffle thread on The Audio Circles board, currently a 0.1 mH coil + 13 Ohm resistor in parallel (no Zobel). A pretty aggressive filter, but 8 Ohms were not enough. There is also a little wool fluff tucked in between the cone and the whizzer, which makes a small but audible difference. I've probably lost too much sparkle at the very top end, but the overall balance is much better, voices are more natural, and I don't miss the extreme highs much.

My mono-buttocked network falls short of full baffle step correction. The midrange balance is best with the boxes against the back wall, but this gives a lumpier bass response in my room. I keep moving them around searching for the best compromise location. I'm sure the FR can be improved with a better network, but I don't have good measurement tools and there's not even a published impedance curve for the FR8 so I'm pretty much flying blind for now.

I'm not done working with them yet. At their best the FR8's do a lot of good things. The bass can be strong and well defined, dynamics are good, there's plenty of detail. If phase plugs can be successfully fitted I think they'd help. I wouldn't be surprised if a little cone or whizzer damping (dammar or Mod Podge) would help too, but again I don't really know enough about what I'm doing to want to make drastic irreversible mods to the drivers.

According to the Hemp Acoustics website, a new version of the FR8 with an improved cone is coming. They say, "In the analyses of our full range FR8DIY the peak exhibited in the midband at around 3-4K was significantly reduced as well the lower treble area around 7-10K is now far more linear, not to mention the high frequencies are more perceivable without being shrill or fatiguing." The graph they show of the difference still shows a significant HF rise, but I'd guess the new version would be worth waiting for.

Quote:
Originally Posted by nodiak View Post
After removing the whizzers from the Hemp 8's I played them on ob a couple weeks with the Hawthorne Augie for bass, as of course they have basically none on their own (on ob). Very rich full output. Didn't really catch on they lacked highs until compared to FE108ez.
Quote:
Originally Posted by nodiak View Post
Then rotated CSS125's and FE108ez's each in 10L sealed (cabs were available) to mate with Vifa M22 in 40L vented (ala Dickinson in LCB). The variety has helped me get a better idea what each offers.
Last 2 nights it's Hemp's with M22 bass, they like each other. (GM kindly worked up a mltl for M22, anxious to get that built, should be deeper and a little dryer which sounds good to me).
At this time I don't have a tube amp or even tube pre to go with LM3875 gc integrated, my main amp now. So that isn't fair for the Fostex, barely ok for the Hemp's, but the FR125 seems pretty at home. That's the order I'd put them in for "brightness" and clarity factors vs. "warmth".
But I agree the Hemps have midrange tone and some sweetness. Without the whizzers (I guess?) the highest treble is gone and I've been tempted to go with that and work in a tweeter like the BG Neo 3. But I need to learn what replacing the whizzer would do. Been thinking of Dammaring the whizzer first, think I'll take Jim G's lead and do that. The phase plugs are made for the FE167's and are a bit small. Maybe with pp's and without whiz I'm getting a decent midwoofer. Going to get some Redwood whizzers made by a friend (Dude! Hemp and Redwood, oh yah!) Got some honk, even on ob, but I hear stories of up to 300 hours of break in needed. I'll put them in a 40 L cab (what's immed. available) for awhile to hear their fullrange. Jim G, can you recommend bib cab design? I'm game for that.
The 108's are extraordinarily clear and open and I need to get them in bib or metronone or? to hear some low end from them, to fill things out. And, their designed for tube gear right? I mean they must because with the gc it's too clinical.
FR125's are kinda freaky with so much bass, can't hear the rest as well. Going to xo out the bass and mate with M22 this week so can get a better feel for their mids and highs. At this point they seem the least satisfying -too dark, but I'm sure there's a remedy, open to ideas. The low spl's are a problem for matching to bass drivers. The dipole version must be great tho. BIB's for these huh, have a link?
The new Hemps sound like an improvement, tho these have alot to offer. Just need to try things, bsc sounds like a wise move too. Will try the 98 cent tweak.
BTW, room is ~ 300 ft2, but narrow - 11.5 x 26.5 .
Don

Long before I decided to build and bi-amp a pair of hybrid Sound Lab ESL tweeters/sealed GPA Altec 416-8B midwoofers/Rythmik sealed servo subs, I thought about Louis Chochos’ two-way Alnico drivers. Even now, I am wondering what a pair of these drivers SUPER ALNICO MONITOR would sound like if they were in a sealed box and if my First Watt B4 crossover’s 2 pole Linkwitz-Reilly filter cut their low end off at around 800Hz, to blend with my Altec Alnico 416s. http://www.greatplainsaudio.com/down...ec%20Sheet.pdf

Btw, Gary Dahl, who truly realized their virtues when used in a sealed cabinet, and John Sheerin
Beyond the Ariel confirmed that the
416s really can do a bit above 1kHz, without becoming directional.

The reviews at 6moons and elsewhere rave about their midrange, but what is the quality of the highs through those
whizzers? How would they compare to, say, the SEAS T35 https://www.madisoundspeakerstore.co...alnico-magnet/ ?

OR might there now even be another better performing Alnico MF/HF driver?
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Old 3rd May 2015, 07:53 PM   #157
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Quote:
Originally Posted by oltos View Post
The reviews at 6moons of Omega Alnico drivers and elsewhere rave about their midrange, but what is the quality of the highs through those whizzers?
How would they compare to this HF/MF Alnico driver
https://www.madisoundspeakerstore.com/approx-5-fullrange/fostex-f120a-5-full-range-with-alnico-magnet/

?
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