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gaust said:
Jon,
My apologies for not responding. Since finishing the speakers I've been trying to learn about amplifiers, pretty much starting from nothing as I did with the speakers.
1/ I didn't use an Onken calculator. I'll give you a long answer first (forgive me if you know all of this already!) and then the short one. There are some Onken calculators about but I found them next to useless. Actually, I don't really subscribe to the constraints that some people ascribe to the design if it is to be called an 'Onken'. There are no real black and white rules and there are so many variations. I first 'discovered' the design idea via planet10's web site. I then found many different approaches on the internet stretching back years but in terms of modern design and support - planet10 are the guys.
My opinion is that the Onken design is a kind of blend between two other methods sometimes quoted.
One of them is the Base Reflex design, a vented box in which the air inside expands and contracts through the port and there is a natural frequency that this resonates at. This resonance reinforces the frequency response of the speaker to improve the bass response. The tradeoff is that once it runs out of steam, i.e. at even lower frequencies than the resonance, the speaker performance drops like a stone.
The other method is called aperiodic. It's basically a box where the air can move in and out through a vent that is so restricted that it finds it hard to 'breath'. This can't resonate like a bass reflex but it dampens out the natural resonant frequency of the driver/box so that a smaller enclosure can be used without a nasty peak in the bass response.
The Onken approach I used is simply a bass reflex design. By making the ports long and thin you get some resistance to the air flow like an aperiodic design. This is supposed to dampen slightly the bass reflex resonance to improve the performance. I can't say that this is the case but I do like the sound of the speakers.
Short answer: I just used a Bass Reflex design approach to calculating the total port area and port length for the box size and drivers. I don't know if Dave would agree but when I apply this approach to his Fonkens I find the numbers match his designs perfectly. So with that I felt that I was on safe ground.
2/ YES, just make sure you design it with the right volume and port specifications for your driver. If you don't know exactly but have a rough idea, you can always 'tune' the port if you design the speaker so that it can be modified.
3/ Other than mentioned by Dave and what I said above the other advantage is that it is fun to build, is unusual (wait til your friends see it) and looks darn cool
but it is more complicated than a straight base reflex design and in my humble opinion the BR approach has a lot to recommend it.
G.
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OK, so it's been a few weeks now and this has given me enough time to reflect less emotionally on the performance of these Moon Onken speakers. Mostly the 'sound' is a feature of this Fostex driver. The bass response is determined by the box. This maybe over-simplifying but unless the box is poorly executed I would argue that this is a fair summary.
Bass: Without the Altair Sub the bass extension is fine but you know when the sub is off. So my comments apply more to the driver than the box design.
Switching back to my PMC FB1's does mean accepting the limitations of a two-way with passive cross-over. But it's a cross-over that has been very well designed and constructed with very high quality components. And I paid for it !
The PMC's are clearly superior in listening satisfaction. Subjectively, they are a lot smoother, have wider dynamic range and a much flatter response. My initial impressions were more in favour of the Onkens because of their very clear and open vocals when not drowned with a lot of background. But this represents a fairly narrow range of music. The order of the Universe is restored. Expensive and professionally designed and constructed speakers such as the PMC's can and do sound simply excellent.
The DIY speakers can't be easily compared if cost is taken into account but for the money they are leagues ahead of what I've heard at the local 'box stores'; they will do very nicely for my HT set-up when I get to finish it.
Some time in the future I must return to taming the high-end freq. response to maximize the performance of the Fostex drivers; they are too peaky. I may be able to implement some active roll-off in the amplifier now that I'm building my own [http://www.diyaudio.com/forums/showthread.php?s=&threadid=140461&pagenumber=1] and maybe some cone treatments...
But for my next project (near-field monitors) are there better full-range drivers out there if my top priority is a smooth flat spectrum rather than deep bass or extensive high freq ? or do I need to build a two-way
Bass: Without the Altair Sub the bass extension is fine but you know when the sub is off. So my comments apply more to the driver than the box design.
Switching back to my PMC FB1's does mean accepting the limitations of a two-way with passive cross-over. But it's a cross-over that has been very well designed and constructed with very high quality components. And I paid for it !
The PMC's are clearly superior in listening satisfaction. Subjectively, they are a lot smoother, have wider dynamic range and a much flatter response. My initial impressions were more in favour of the Onkens because of their very clear and open vocals when not drowned with a lot of background. But this represents a fairly narrow range of music. The order of the Universe is restored. Expensive and professionally designed and constructed speakers such as the PMC's can and do sound simply excellent.
The DIY speakers can't be easily compared if cost is taken into account but for the money they are leagues ahead of what I've heard at the local 'box stores'; they will do very nicely for my HT set-up when I get to finish it.
Some time in the future I must return to taming the high-end freq. response to maximize the performance of the Fostex drivers; they are too peaky. I may be able to implement some active roll-off in the amplifier now that I'm building my own [http://www.diyaudio.com/forums/showthread.php?s=&threadid=140461&pagenumber=1] and maybe some cone treatments...
But for my next project (near-field monitors) are there better full-range drivers out there if my top priority is a smooth flat spectrum rather than deep bass or extensive high freq ? or do I need to build a two-way
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Gareth, there is no "best', and even "better" is subjective to the application.
There's no arguing there are some folks/systems for whom any of the Fostex aren't a comfortable fit. I'll admit that it's hard for me to avoid an almost evangelical zeal for the improvements that the P-10/ EnABL treatment can elicit in the FE126 and FE127 - I've been living with them for almost 2 years - stock drivers sound "confused"
If you're looking for a neutral, smooth and musical driver for a small nearfield monitor that is tolerant of a wide range of amplifiers, you might want to take a look at the new Mark Audio drivers. So far I've played with both the Alpair 5 and CHR70; the latter could be well suited to your task, and the little MLTL box is a vastly simpler build than the Fonkens.
There's no arguing there are some folks/systems for whom any of the Fostex aren't a comfortable fit. I'll admit that it's hard for me to avoid an almost evangelical zeal for the improvements that the P-10/ EnABL treatment can elicit in the FE126 and FE127 - I've been living with them for almost 2 years - stock drivers sound "confused"
If you're looking for a neutral, smooth and musical driver for a small nearfield monitor that is tolerant of a wide range of amplifiers, you might want to take a look at the new Mark Audio drivers. So far I've played with both the Alpair 5 and CHR70; the latter could be well suited to your task, and the little MLTL box is a vastly simpler build than the Fonkens.
Bigun said:But for my next project (near-field monitors) are there better full-range drivers out there if my top priority is a smooth flat spectrum rather than deep bass or extensive high freq ? or do I need to build a two-way
How near is near? I'm still really enjoying my FX120's, which have permanently replaced the FE127's in my Fonken-like boxes. The FX's are much smoother thru the mid-band, but lack the top end sparkle of the FE's. You can feel the bass coming from the FX's, where as with the FE's you just heard it.
I don't get "the look" from the wife anymore when I turn up the volume using the FX120's. She almost always complained when I was listening to the FE127's.
IMHO as always.
Jeff
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I can see its hard to make clear distinctions in favour of one driver over another.
For near fields I will try something other than FE127 just because it's a change and this will be interesting.
My existing HT speakers already hold some investment in FE127s that I would like to keep. The issue is mostly the 'brightness' at the top end. I have no baffle step correction - perhaps this is something I need and this will 'fix' my subjective concerns ???
It could also be the nasty 7kHz spike in the driver response that is hurting the subjective sound quality. I could try to lower this with a more aggressive baffle step correction, but I wonder if the cone treatments can help with this particular issue ??? (I thought I remember something about painting the cone for this, not the full eNable)
For near fields I will try something other than FE127 just because it's a change and this will be interesting.
My existing HT speakers already hold some investment in FE127s that I would like to keep. The issue is mostly the 'brightness' at the top end. I have no baffle step correction - perhaps this is something I need and this will 'fix' my subjective concerns ???
It could also be the nasty 7kHz spike in the driver response that is hurting the subjective sound quality. I could try to lower this with a more aggressive baffle step correction, but I wonder if the cone treatments can help with this particular issue ??? (I thought I remember something about painting the cone for this, not the full eNable)
Gareth, contact Dave offline for the full history on mods for the FE126/7 - he had already spent a lot of time playing with them before our discovery of EnABL.
I think you'd find that the upper midrange issues you're experiencing can be mitigated without the full polka-dot regimen; but the full-zoot treatment definitely takes these drivers to another place.
At the risk of public flogging, I'll state that in almost 4 years, I've yet to try a BSC on any of my Fostex systems, but I rather doubt that one would resolve the measured narrow bandwidth resonances that are at the root of the "shout".
Definitely consider the CHR70s for a mini monitor - dead stock from the box even our little 6 litre sealed driver break in enclosure sound quite nice. Lots of detail, and definitely a different character than the Fostex - not too difficult to notice the distinction, but perhaps a mistake to quickly judge one over the other.
I think you'd find that the upper midrange issues you're experiencing can be mitigated without the full polka-dot regimen; but the full-zoot treatment definitely takes these drivers to another place.
At the risk of public flogging, I'll state that in almost 4 years, I've yet to try a BSC on any of my Fostex systems, but I rather doubt that one would resolve the measured narrow bandwidth resonances that are at the root of the "shout".
Definitely consider the CHR70s for a mini monitor - dead stock from the box even our little 6 litre sealed driver break in enclosure sound quite nice. Lots of detail, and definitely a different character than the Fostex - not too difficult to notice the distinction, but perhaps a mistake to quickly judge one over the other.
Hi
These Moon Onkens look just like what I am after for my FX120eN drivers. Congratulations.
I will be using a pair of subs, so low end issues are not too important. My main criteria are small size and wall mountable ability. Oh, and getting the best midrange available.
Could I use the plans off Post 2, or should I be looking to redesign for the slightly different perameters of the FX120 over the FE127E?
FX120: http://www.fostexinternational.com/docs/speaker_comp/pdf/fx120.pdf
FE127E: http://www.fostexinternational.com/docs/speaker_comp/pdf/fe127erev2.pdf
These Moon Onkens look just like what I am after for my FX120eN drivers. Congratulations.
I will be using a pair of subs, so low end issues are not too important. My main criteria are small size and wall mountable ability. Oh, and getting the best midrange available.
Could I use the plans off Post 2, or should I be looking to redesign for the slightly different perameters of the FX120 over the FE127E?
FX120: http://www.fostexinternational.com/docs/speaker_comp/pdf/fx120.pdf
FE127E: http://www.fostexinternational.com/docs/speaker_comp/pdf/fe127erev2.pdf
Hi Dave
My subs have a built in XO at 120hz, but I may decide not to use the FX120eNs via the High Level Sat output of the plate amps and feed them direct from the main amp.
I suppose that a realisitic target is anywhere between 80 and 120 Hz.
A small enclosure is still appealing.
Do you need to use a holely brace the inside the cabinets with the FX120s? They have a cast alloy frame that is very sturdy.
My subs have a built in XO at 120hz, but I may decide not to use the FX120eNs via the High Level Sat output of the plate amps and feed them direct from the main amp.
I suppose that a realisitic target is anywhere between 80 and 120 Hz.
A small enclosure is still appealing.
Do you need to use a holely brace the inside the cabinets with the FX120s? They have a cast alloy frame that is very sturdy.
dublin78 said:
Good plan - without some serious part or circuitry upgrades, the hi-pass filters for most plate amps are definitely worth avoiding. However, if your listening levels exceed the FX120's comfort zone, then PLLXO and bi-amping may be desirable.
The brace is really intended to couple the driver and top/bottom/back panels of the cabinet as tightly as possible - we even used them on the F120A "Fonkensteens"
With the sandwiched assembly that forms the walls and port slots, the side panels of the smaller Fonken cabinets are fairly inert, but it wouldn't hurt to add another layer or two on the top/bottom - it allows enough meat for a chamfer to those edges as well.
Dave probably has some archived photos of a pair of beater FE127 Fonkens recently tweaked this way.
In the case of the larger floorstander FE167 (and if we ever do a 207 version
), there are a pair of smaller vertically oriented "bow-tie" braces between the two internal slot panels and the driver brace.
Gareth - I haven't seen new posts from you for a while, if you're still interested, the new Mark Audio drivers (particularly the CHR70) are a helluva bargain; they sound quite decent dead stock from the box, and abso-bloody-lutely respond well to the EnABL process.
Based on experience with 3 models of Mark Audio drivers to date, (Alpair 6 & 10, CHR70) the only caveats I'd declare would be that the sensitivity and impedance could create an issue for flea power amps of any stripe.
We're only starting to play with enclosure configurations on these, and it's perhaps premature to speculate on "best"
Based on experience with 3 models of Mark Audio drivers to date, (Alpair 6 & 10, CHR70) the only caveats I'd declare would be that the sensitivity and impedance could create an issue for flea power amps of any stripe.
We're only starting to play with enclosure configurations on these, and it's perhaps premature to speculate on "best"
P10 - Those fonkens with the four bevelled edges and the grilles look stunning. Well done.
Great.
They could be wall mounted, but this will limit the ability to toe in if needed. I have some nice and chunky brackets that leave the rear of the cabinets 10cm off the wall and allow a good deal of movement. Using these or similar would be my preference.
OK. Thanks for the education.
Great.
They could be wall mounted, but this will limit the ability to toe in if needed. I have some nice and chunky brackets that leave the rear of the cabinets 10cm off the wall and allow a good deal of movement. Using these or similar would be my preference.
OK. Thanks for the education.
dublin78 said:
You could always "butterfly" the ports of the fonken putting them on the back, yielding a wide and shallow version suitable for hanging. You could orient the ports vertically for better aesthetics. The ports could also be interlaced for narrower and taller configuration if you believe you have to have them exiting out the sides.
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