12in AN driver has a Vas so vast as to make it's use in a cabinet of this nature a little tricky, and we've got a mid-Q too which compounds the issue. I freely confess I had this down to sloppy engineering until GM gently corrected me on this point (cheers as ever Greg), but unfortunately, they're not really ideal for a resonant cabinet. Height isn't a problem -we're mass-loading the line remember (and target Fc /4 = line length as a formula doesn't work anyway): box volume is. It needs to be big.
Right. My prose got a bit wooly there.
It'll work, & it should sound good. Too hugeous for my taste, but could make an interesting focal point to a large room.
Perhaps if we could shape a cabinet with a couple of 18in woofers like the Sphinx to position centrally, and paint the whole shebang yellow...
BTW: bipole 168ESigma Metronome = good plan IMO guys.
It'll work, & it should sound good. Too hugeous for my taste, but could make an interesting focal point to a large room.
Perhaps if we could shape a cabinet with a couple of 18in woofers like the Sphinx to position centrally, and paint the whole shebang yellow... BTW: bipole 168ESigma Metronome = good plan IMO guys.
Driver selection
I'm really taken with this design. This will be my first build, but I'm really torn about driver selection. I have a friend coming over from Japan who will bring me some Fostexs.
My room is largish - 5 by 6 metres, my tastes are rock/pop/electronic/jazz. Amplification will be a Charlize T-Amp. My inclination is the 168sigmas instead of the 207. Iv'e heard the 168s in a BIB and was very impressed - plenty of bass and dynamics, but the BIB cabinet will be a little over powering for this room and corners are limited. Another choice could be the F120A, but not that efficient?
Any thoughts anyone? I'm a bit concerned the 207 will be shouty and harder to live with that the 168.
I'm really taken with this design. This will be my first build, but I'm really torn about driver selection. I have a friend coming over from Japan who will bring me some Fostexs.
My room is largish - 5 by 6 metres, my tastes are rock/pop/electronic/jazz. Amplification will be a Charlize T-Amp. My inclination is the 168sigmas instead of the 207. Iv'e heard the 168s in a BIB and was very impressed - plenty of bass and dynamics, but the BIB cabinet will be a little over powering for this room and corners are limited. Another choice could be the F120A, but not that efficient?
Any thoughts anyone? I'm a bit concerned the 207 will be shouty and harder to live with that the 168.
Re: Driver selection
I've only briely heard 207, and not even seen a 168 yet. I have a set of 207s here (+FT17) for a set of Bruce... your room isn't as large as mine, so unless you like LOUD level with either & your amp should be fine level-wise.
Let me throw you a curve... bipole FE127. Althou -- if i could afford to keep any of the box of 8 207s i just got, i'd be thinking of a bipole with 207s.
dave
NICKEL said:
I've only briely heard 207, and not even seen a 168 yet. I have a set of 207s here (+FT17) for a set of Bruce... your room isn't as large as mine, so unless you like LOUD level with either & your amp should be fine level-wise.
Let me throw you a curve... bipole FE127. Althou -- if i could afford to keep any of the box of 8 207s i just got, i'd be thinking of a bipole with 207s.
dave
Driver Choice
I had thought of the dipole initially, then dismissed it when I read about rear reflections - the speakers will need to be within 3 feet of a large window, with wooden blinds. And the bass seems to roll off around 55Hz?
I take it the 127 dimensions are the same as the 126? - I found this on WAD site
"The inside area of the top is equal to the effective area of the driver cone found from the specs on the Fostex site.
The cabinet then tapers outwards from there to 4X the effective cone area by the time it gets to the base.
The driver itself is placed exactly one third of the way along the pipe.
(I don't know much yet - so I'll ask) ,The inside area of the top is equal to the effective area of the driver cone found from the specs on the Fostex site.
The cabinet then tapers outwards from there to 4X the effective cone area by the time it gets to the base.
The driver itself is placed exactly one third of the way along the pipe. So, why are the dimms for the FE167 the same as for the larger FE207 and Hemp? Is there some other factor at work here? And if I can ask two more - the FE208 mentions a 4 ohm resistor - what is the relevance of this. And ,if I went with a 208 Metronome, any ideas on where to mount the tweeter - in the speaker above the driver, or to one side?
I had thought of the dipole initially, then dismissed it when I read about rear reflections - the speakers will need to be within 3 feet of a large window, with wooden blinds. And the bass seems to roll off around 55Hz?
I take it the 127 dimensions are the same as the 126? - I found this on WAD site
"The inside area of the top is equal to the effective area of the driver cone found from the specs on the Fostex site.
The cabinet then tapers outwards from there to 4X the effective cone area by the time it gets to the base.
The driver itself is placed exactly one third of the way along the pipe.
(I don't know much yet - so I'll ask) ,The inside area of the top is equal to the effective area of the driver cone found from the specs on the Fostex site.
The cabinet then tapers outwards from there to 4X the effective cone area by the time it gets to the base.
The driver itself is placed exactly one third of the way along the pipe. So, why are the dimms for the FE167 the same as for the larger FE207 and Hemp? Is there some other factor at work here? And if I can ask two more - the FE208 mentions a 4 ohm resistor - what is the relevance of this. And ,if I went with a 208 Metronome, any ideas on where to mount the tweeter - in the speaker above the driver, or to one side?
Re: Driver Choice
The 127s won't go as low as the 167 or 168 or 207 for sure... 3 feet is usually more than enuff for a bipole to work (and it is a bipole not a dipole -- the 2 are VERY different beasts). I've attached 127 vrs 207, i don't have a 168eS sim for the Metronome. The 168 is generally considered a good compromise between high end extension, midrange smoothness, and bass extension.
The stuff on the WAD site you quoted is from classical design.. of historical interest only and shouldn't really be applied. For instance, the best placement of the driver is near half-way.
The dimensions for various metronomes are here: http://www.frugal-horn.com/metronome-table.html
The area is the important dimension, the WxD are just suggestions.
dave
NICKEL said:
The 127s won't go as low as the 167 or 168 or 207 for sure... 3 feet is usually more than enuff for a bipole to work (and it is a bipole not a dipole -- the 2 are VERY different beasts). I've attached 127 vrs 207, i don't have a 168eS sim for the Metronome. The 168 is generally considered a good compromise between high end extension, midrange smoothness, and bass extension.
The stuff on the WAD site you quoted is from classical design.. of historical interest only and shouldn't really be applied. For instance, the best placement of the driver is near half-way.
The dimensions for various metronomes are here: http://www.frugal-horn.com/metronome-table.html
The area is the important dimension, the WxD are just suggestions.
dave
Attachments
Thanks Dave
Sorry my previous reply was a bit messed up.
I think the 168 is what I'm looking for. More I read about FR, the more I realise its about making compromises around budget, woodworking skills and limitations of the driver, but good design is paramount and sometimes the hardest to get my mind around. You, Scott and et al provide fantastic advice for a beginner such as myself.
Cheers
Nick
Re: Re: Driver Choice
Yes it was I who was guilty of that.
It was done simply because the Metronome concept was still developing in my mind and I:
A - didn't know any better
B - Did not know about Scott or Dave.
After posting on this site Scott and Dave soon put me right. Scott worked out the correct mass loading to make my fledgling design work correctly and together with Dave they came up with all the variations in the Metronome tables. These of course are done properly.
Scott made such a good job on my originals, which flawed though they were in the first instance are still doing the business in my own system a year on.
Steve .
planet10 said:
Yes it was I who was guilty of that.
It was done simply because the Metronome concept was still developing in my mind and I:
A - didn't know any better
B - Did not know about Scott or Dave.
After posting on this site Scott and Dave soon put me right. Scott worked out the correct mass loading to make my fledgling design work correctly and together with Dave they came up with all the variations in the Metronome tables. These of course are done properly.
Scott made such a good job on my originals, which flawed though they were in the first instance are still doing the business in my own system a year on.
Steve .
Re: Re: Re: Driver Choice
Personally, I think the original Metronome was a great design. OK, so it benefited from some tweaking, but most cabinets need that to varying extents, and the concept is spot on. I like. Looking forward to hearing them again at the next Eggfest -they image like crazy.
Personally, I think the original Metronome was a great design. OK, so it benefited from some tweaking, but most cabinets need that to varying extents, and the concept is spot on. I like. Looking forward to hearing them again at the next Eggfest -they image like crazy.
Re: Re: Re: Re: Driver Choice
Steve had the conceptual breakthru that puts this design on the map, Scott & i just helped polidh it sonically. (and took the opportunity to propagate the concept across many drivers)
I hope to see these in many homes where the exceptional WAF will give us diyers the chance to get our creations into the living room.
dave
Scottmoose said:
Steve had the conceptual breakthru that puts this design on the map, Scott & i just helped polidh it sonically. (and took the opportunity to propagate the concept across many drivers)
I hope to see these in many homes where the exceptional WAF will give us diyers the chance to get our creations into the living room.
dave