I'll be watching this project with interest as I've built an aperiodic box for the FR125 (a little bigger than 7 ltr. total IIRC) and it works fairly well but misses out on the bass. I might drill a port if you have some success. The FR125's long suit is in the imaging. These little drivers throw out a great sound stage. I use them now for surrounds for HT and they do a good job but that's not the better use for them, IMO. Good luck with the build.
I'm in on this late, hope my comments don't send you for a dive....
If you use standard modeling to extract as much bass out of the FR125 as a quick look at the sim graphs indicate you will end up with too much bass instead of trying to extract everything available. Unlike any other driver i've played with, the WRs & FRs require designing to not have too much bass. I expect an FR in a 7 liter box with BSC will be WAY bass heavy. In my experience 7 liters is too small. 12-13 litres is the sweet spot -- turning your design aperiodic may be required, and if it is anywhere near a wall, you'll want to rip out the BSC (in the miniOnkens, even 4 ft out from a wall i prefer them with none)
My personal preference is for the FE127e (modified -- i haven't heard the FX120), but that assumes an amplifier that you can listen to without its flaws getting in your face. With a lessor amp the FRs ability to moosh over an amps deficiencies gives it an edge.
As to the Neo-fone, mine (w Foster ribbons) should be somewhere over the Pacific right now.
dave
If you use standard modeling to extract as much bass out of the FR125 as a quick look at the sim graphs indicate you will end up with too much bass instead of trying to extract everything available. Unlike any other driver i've played with, the WRs & FRs require designing to not have too much bass. I expect an FR in a 7 liter box with BSC will be WAY bass heavy. In my experience 7 liters is too small. 12-13 litres is the sweet spot -- turning your design aperiodic may be required, and if it is anywhere near a wall, you'll want to rip out the BSC (in the miniOnkens, even 4 ft out from a wall i prefer them with none)
My personal preference is for the FE127e (modified -- i haven't heard the FX120), but that assumes an amplifier that you can listen to without its flaws getting in your face. With a lessor amp the FRs ability to moosh over an amps deficiencies gives it an edge.
As to the Neo-fone, mine (w Foster ribbons) should be somewhere over the Pacific right now.
dave
Rocky said:
Not sure... maybe a combo of the XBL & the design drive to see how much bass could be had out of a 5" driver. It really does produce bass.
But like is all to often done with subs, if you design to get the lowest flatest bass in your modeler you end up with too much.
Somewhere at home i have some measures Al Wooley did.
dave
Dave,
Do you think it might be the fall in the response above 10kHz that leads to the perception that it is too bass heavy (i.e. lack of highs)? What I did on it, after calculating the equivalent circuit of the FS125S, I imported the response graph from your webpage to an FTABLE in my Capture CIS, I ran an "Edge" simulation (the baffle step proggie by Svante), divided the results by 2 (3dB baffle step instead of 6dB) and placed these numbers in a FTABLE as well. I ran it in PSpice, composed a zobel and BSC, and while I got it flat up to 10kHz, I got a significant dip at 10kHz and upwards. I didn't get satisfactory simulation results until I added a 6.8uF capacitor in parallel with the BSC.
EDIT: I mean ca. 8kHz.. not 10kHz..
Do you think it might be the fall in the response above 10kHz that leads to the perception that it is too bass heavy (i.e. lack of highs)? What I did on it, after calculating the equivalent circuit of the FS125S, I imported the response graph from your webpage to an FTABLE in my Capture CIS, I ran an "Edge" simulation (the baffle step proggie by Svante), divided the results by 2 (3dB baffle step instead of 6dB) and placed these numbers in a FTABLE as well. I ran it in PSpice, composed a zobel and BSC, and while I got it flat up to 10kHz, I got a significant dip at 10kHz and upwards. I didn't get satisfactory simulation results until I added a 6.8uF capacitor in parallel with the BSC.
EDIT: I mean ca. 8kHz.. not 10kHz..
Rocky said:
Yes... it has been our method of taming unruly FR125 BRs/ML-TLs, even the MiniOnken which is already heavily towards aperiodic benefits in some rooms.
I personally wouldn't bother buying aperiodic vents -- they are too easy to build (sandwich a 2 or 3" piece of fiberglass insulation between 2 pieces of mesh). Getting the tuning right is a bit trickier.
Not quite as effective, but it works is to build the BR and then play with stuffing the port -- in some situations an old sock has done the job.
dave
12-13 litres seems the sweet spot... as close as you can get to that...
I note that in your drawing you are using 3/4 & 1" material. If you use ply 1/2" is suffiicent (just make sure that you have a brace running from the baffle/back of magnet to the back of the box -- if your box is taller than it is wide the brace should run vertically)
dave
I note that in your drawing you are using 3/4 & 1" material. If you use ply 1/2" is suffiicent (just make sure that you have a brace running from the baffle/back of magnet to the back of the box -- if your box is taller than it is wide the brace should run vertically)
dave
With Great Dave around I've prefered to lurk...
just wanted to point out that....
1. if the cabinet walls are bent/curved you can get by with 12mm as the wood is prestressed and hence more inert. The easiest walls to use this on are the side walls (then you might have to relocate your filter)
2. one place to relocate your filter wold be to the top of the cabinet. then on can remove the top and tune at will without disturbing the rest of the speaker.
just wanted to point out that....
1. if the cabinet walls are bent/curved you can get by with 12mm as the wood is prestressed and hence more inert. The easiest walls to use this on are the side walls (then you might have to relocate your filter)
2. one place to relocate your filter wold be to the top of the cabinet. then on can remove the top and tune at will without disturbing the rest of the speaker.
Funny how things work out sometimes, here the other day I got an offer I just couldn't refuse (no, not Don Corleone..) to buy some really good priced drivers from a local speaker manufacturer (seas, norway), so now I have two aluminum basses and aluminum dome tweeters I will have to use. Not what I planned, but I'm really happy with the deal. The aluminum bass if flat except for a 100-300Hz peak that fills up what the baffle step effect doesn't take care of, it all looks pretty good in Pspice. Both the basses and dome tweeters have serious cone breakups though, peaks in the order of +10dB and +12.5dB, so crossover design is going to be a challenge, but again, Pspice rocks in this aspect. My simulated crossover grows quite large, but the response is pretty much flat now except for the tweeter dome breakup that peaks from 25kHz to 28kHz with a +10dB top. I don't know what to do with that one. I've tried a notch filter, but I can't seem to hit the peak down without affecting sub-20kHz response with a premature HF rolloff, so I consider not addressing those resonances at all.. afterall, it's outside the human hearing range, and there's no pets where the speakers will go..
Zaph has a nice design for Seas Aluminium speakers, one with the L15 and the other with the L18.
His L18 design has an aluminium tweeter which sounds very much like the one you have, and he's not touched the ultrasonic resonance at all actually, so it shows up in the finished speaker as well.
www.zaphaudio.com
His L18 design has an aluminium tweeter which sounds very much like the one you have, and he's not touched the ultrasonic resonance at all actually, so it shows up in the finished speaker as well.
www.zaphaudio.com
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