Jim, I've been doing something similar to what you proposed. There is a good post on the fullrange forum just this weekend on this subject. You didn't say if you want to use one amp for both the FR and the woofer, but based on your question about relative sensitivity, it sounds like that is your plan. Personally I went for the bi-amp route and use a pro sound amp on the woofer. That way I get an inexpensive way to drive it, I have a L&R volume adjustment on the bass amp, and I have plenty of power to drive. It also opens the door for lots of experimentation and the ability to have woofers that don't match the FR. It also leaves the top end free to use some nice tube equipment. Right now I'm using Fostex FF85Ks in an open baffle on top and crossing to a woofer at about 200hz. I've used both a Shiva sub in a 60L sealed cabinet, and also tried an old Utah 12" woofer I had in the same cabinet (which modeled well for it). Both integrate very nicely. I have also tried a similar setup with FE166Es in sealed cabinets on top, similar results, though I like the OB better for depth of sound stage and imaging.
smbrown said:
By far & away the best route.... even if you just use some plate amps (gainclones are pretty appealing too)
I could never get my Shivas (Mk 1s mind you) to go hi-enuff to make me happy. Even with a 4th order XO at 125 Hz i could still hear them getting rough at the top of their passband.
Due to my frugal-phile(tm) situation/temperment, i have been mostly using old extended range 10s & 12s from speakers i recycle... i've a set of 4 12" Fosters in the queue at the moment. If my experiments with subtractive XO on another project turn out well, i'll use that.
dave
I am using it in what would more accurately equate to an open back box. Since I had on hand Dick Olsher's Basszilla plans, I used the same crossover he suggests for the Fostex version (platinum?). I think those points are about 220 rolloff for the full ranger and 190 roll in for the bass. My thought here was that if it worked for a Fostex with a much lower Qt, and same impedance, the crossover as designed might just work for the FF85K. So far, I'm very pleased with the sound. I have measured the response in my listening room with my trusty RS SPL meter and I get a pretty flat (+/- 2db) response from the 80's through the top end, with a bit of a dip (-4db?) around 200. The open box they are in is about 8.5" wide and 11" deep. I did have to add some stuffing along the walls to keep down some resonance. I have also tried the FF85K in a more traditional OB - 14" wide with 2 or 3" side wings. Similar results. I just like the looks of the box better and I think they image better, too. Given some time I will probably go to an OB with angled sides and see how that does.
I am using one FF85K per side. My room is 18' x 30' with 14' vaulted celings. It is for hi-fi listening only, not HT. I use a very unique amp at this time. Is was based on a design by Gary Pimm and is a direct coupled (no caps in it anywhere) EL34 PP amp putting out about 6 class A watts. I don't know what the damping factor is, but I'd guess it's about the same as a SE amp because I'm running the EL34s in pentode. I'd measure SPL for you, but it's 6:00 AM here and wife would not appreciate that. I will say I generally listen (seat is about 9' from speakers and speakes are about 4' from back wall), around 70 to 90 db, but certianly crank it from there, once in a while. I do not hear audible distortion, but I certianly have from other speakers. I will add that without the high pass on the FF85k, I did get plenty of distortion from them at higher volumes, but the filter cleaned that up very nicely. The amp for the bass speakers is a Crown pro amp that is rated for 200 wpc.
Let me know if you have any other questions.
Steve
Let me know if you have any other questions.
Steve
Fe127 with Eminence Alpha10
Hi,
Just realised that I still have a pair of Eminence Alpha10's.
According to some simulation I can get 40Hz and an overall sensitivity of 94dB. Could this be correct ?
That leaves 91dB when I include baffle step, right ?
So the Fe127 could be a good choice then ?
Thanks,
Jim
Hi,
Just realised that I still have a pair of Eminence Alpha10's.
According to some simulation I can get 40Hz and an overall sensitivity of 94dB. Could this be correct ?
That leaves 91dB when I include baffle step, right ?
So the Fe127 could be a good choice then ?
Thanks,
Jim
Oh i have lot of questions.smbrown said:
your room is huge...3.5 times mine in volume. but your listening levels are about 5-6db less than what i require (95db/2m). so i guess that evens things.
Q1. your XO is electronic so what is the slope? is it a very steep slope. I was looking at a 6db slope (passive or Passive line level) to keep things simple and retain transient response.
Q2. have you tried using multiple FF85Ks. I was looking at maybe using 4. however i dread the lobing effects. another alternate i was looking at is a forward facing 85k and a FF125k firing upwards running fullrange to lend support to the low end.
Q3. My amp will be a EL84 PPP that i expect puts out 20-24W. Hence i figured 4 x FF85K would make sense. there are 3 options.
a) 4 in line (here OB can be an option).
b) push push - 2 in the front, 2 in the rear
c) diffuse field - 1 in the front, 3 facing the rear at 45 deg 9a la Bose 901).
Opinions and Ideas are welcome.
I have not tied multiple FF85K's, I figured that would take away from the point of a single driver. I have seriously thought about a larger, higher quality driver like the FX200, but cash shy at the moment. My crossover is (currently) a simple passive, as I said eariler, I used the components specified by Olsher for the Basszilla using the Fostex driver. These are both 2nd order filters, so the slope is steeper. Given some more time I will put it into a line level passive instead so I can go directly from the amp to speaker.
My plan on the LL passive is to make both the low pass and high pass variable so I can continue to experiment with a variety of drivers. In fact, it should allow me to experiment even easier.
I remeasured SPL last night that I typically listen to - yep around 80 - 85db. But when I crank it a bit I'm into your 92 - 95 db range no problem. But given the music I listen to, most of the peaks that hit that mid 90's mark are bass notes, and those are handled by the high excursion Shiva with much more drive behind it. I think that's why the FF85k's continue to sound so good, they're still not being over driven. As for amp power, sounds like you're on track with that.
I have thought about trying the Jordan, it seems like a great unit. I do like the idea of a smaller driver, so maybe I'd give that a shot instead of the bigger Fostex.
My plan on the LL passive is to make both the low pass and high pass variable so I can continue to experiment with a variety of drivers. In fact, it should allow me to experiment even easier.
I remeasured SPL last night that I typically listen to - yep around 80 - 85db. But when I crank it a bit I'm into your 92 - 95 db range no problem. But given the music I listen to, most of the peaks that hit that mid 90's mark are bass notes, and those are handled by the high excursion Shiva with much more drive behind it. I think that's why the FF85k's continue to sound so good, they're still not being over driven. As for amp power, sounds like you're on track with that.
I have thought about trying the Jordan, it seems like a great unit. I do like the idea of a smaller driver, so maybe I'd give that a shot instead of the bigger Fostex.
i hear the FF85K within it's limitations which is 5W (300Hz+) might be a better driver than the JX92 or JX53.
I am notone to judge a driver based on its price although being a frugal phile I do question a higher priced driver. I feel that a higher priced driver must offer a significant advantage over a lower priced driver.
eg: TB W3 871 v/s FF85K v/s JX53 (I did not compare the JX92 here because it does offer better bass performance over these 3).
The 871 is about $10, the FF85K about $30 and the JX53 about $120.
I am notone to judge a driver based on its price although being a frugal phile I do question a higher priced driver. I feel that a higher priced driver must offer a significant advantage over a lower priced driver.
eg: TB W3 871 v/s FF85K v/s JX53 (I did not compare the JX92 here because it does offer better bass performance over these 3).
The 871 is about $10, the FF85K about $30 and the JX53 about $120.
smbrown said:
my fear of the FX200 is it's large size that might lead to beaming. i'd take the JX92 over the FX200 unless someone else has a rational argument to counter my above aphrehension.
one option i did not mention before is to go push push and wire 4 FF85ks so that i can use either 2 or 4. 2 would feed of the 4 or 16 ohm taps and 4 would feed of the 8 ohm taps (EL84PPP amp). so when i am listening to music i use 2 and when i need more power for HT I use 4. Having 2 drivers will also allow me to have a 1st order filter at 200Hz instead of 2nd order. will it?
BTW what music u listen to? I usualy listen to what is called "classic rock" and also some jazz, blues and classical.
Navin, have you checked out this site?
http://de.geocities.com/peter_rehkop/system.html
Kind on topic for this discussion and mentions a variety of full range drivers in this application. As for my music, I listen to mostly jazz, but also classical and classic rock.
http://de.geocities.com/peter_rehkop/system.html
Kind on topic for this discussion and mentions a variety of full range drivers in this application. As for my music, I listen to mostly jazz, but also classical and classic rock.
that system is bigger than my living room. i guess u want my wife to throw me out 
just kidding.
this link was interesting tooo
http://de.geocities.com/peter_rehkop/ff85k2.jpg
just kidding.this link was interesting tooo
http://de.geocities.com/peter_rehkop/ff85k2.jpg
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