strider75 said:
We are playing with the Silver Flutes as a lower cost option... i have 4 of the W14s in process.
I also have a few of the 7" Easttech left... i'm going to need 4 for the TLs, but any in excess of that will go out the door for $40/pr. A pair go into a 28 litre vented box.
I even have the FonkenWoof variation for these already drawn up.
dave
Re: Re: Re: Re: Cabinet design
I'll take your CAD derived figure over my cocktail napkin sketch/calculator method any day.....
Ignoring aesthetics, is there a reason to stick with the Fonken's chamfer edged front profile in the bass cabinets? Would a rectangular lower cabinet be enough to negatively affect the defraction of the sound wave from the Fonken driver?
planet10 said:
I'll take your CAD derived figure over my cocktail napkin sketch/calculator method any day.....
Ignoring aesthetics, is there a reason to stick with the Fonken's chamfer edged front profile in the bass cabinets? Would a rectangular lower cabinet be enough to negatively affect the defraction of the sound wave from the Fonken driver?
Re: Re: Re: Re: Re: Cabinet design
Except maybe for those 2 corners right up top, the reason for maintaining the front profile is aeshetic. A retangular box would be an easier build, and you can realize a bit more volume.
I must say thou, that the job Chris nade of my efforts to design in aesthtics and get the box to be as large inside as possible, as non-resonant as possible, is really a work of art. It is actually "prettier" from a design point on the inside than on the out. A lot of excersixe for the hole saw thou.
dave
strider75 said:
Except maybe for those 2 corners right up top, the reason for maintaining the front profile is aeshetic. A retangular box would be an easier build, and you can realize a bit more volume.
I must say thou, that the job Chris nade of my efforts to design in aesthtics and get the box to be as large inside as possible, as non-resonant as possible, is really a work of art. It is actually "prettier" from a design point on the inside than on the out. A lot of excersixe for the hole saw thou.
dave
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strider75 said:
I have no experience with GR Research drivers but the price is nice. I'll have a good look at the spec. but I'm no inclined to go with a ported box unless it some kind of Onken-style ports can be rigged to keep the driver well-loaded at those low frequencies. I suspect it's not worth the construction effort and a sealed box is where I'm heading.
Dave is the expert here, but wondering if he will reveal his secret mods for the SDX-7
I don't mind if you use the term Fonken (it is after all, a Fostex Onken style box)... just add a prefix or suffix that makes it your own...
Your effort has also egged me on to do do some internediate sizes that have been floating around in my head for sometime, so a claim the names cFonken (centiFonen) and dFonken (deciFonken), in keeping with the metrix nomenclarture of my smaller Fonkens? (i can hear Chris screaming from here
)I'll probably do wallFonken vesions of all of these too... i've been meaning to add surrounds to my HT that fit on the wall, but the Audax based DIVAs i had intended are just too big to be convienient, a micro or deci versionshould be a nice size.
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planet10 said:
Your effort has also egged me on to do do some internediate sizes that have been floating around in my head for sometime, so a claim the names cFonken (centiFonen) and dFonken (deciFonken), in keeping with the metrix nomenclarture of my smaller Fonkens? (i can hear Chris screaming from here
I'll probably do wallFonken vesions of all of these too... i've been meaning to add surrounds to my HT that fit on the wall, but the Audax based DIVAs i had intended are just too big to be convienient, a micro or deci versionshould be a nice size.
dave
I'm glad to hear, I've no aspirations to try and earn a living from my efforts in this direction and if I were still playing with DIY in a couple of years it would be thanks to your help.
I think you will do very well with an intermediate size. I picked 6L (actually 6.25L) as it corresponds nicely with the 80Hz cut off that matches with my HT plans. I think this is a good cut-off because it corresponds to where our ears lose directionality.
The base response is good and it's not overly sensitive to the port design (from simulations). For home use it's a much more convenient size and weight.
I was pretty excited about building a Fonken-style speaker and the idea of building the miliFonken just didn't excite me with the simple slot port instead. The Fonken appears to be such a classic that I just had to build one to this style.
I think it's possible to scale the full Fonken design down to well below 6L with some careful design and construction (i.e. I was able to design a miliFonken with the Onken ports). Part of this design included the use of a router to cut out ports on two faces of plywood that would then sandwich together without any spacer strips. And those funny holes in my boxes you noticed also saved me volume.
Another thing that I did was to narrow the ports with thinner spacers. I think that the smaller boxes do better with shorter ports or they get too deep and to avoid losing the port resistance you have to narrow the openings. Mine went down to 0.635cm, about 2/3 that of the Fonkenprime. I had suggested folded ports, but these eat up a lot of volume in a small box.
My 6L design scales nicely (it was planned from the start to do so). I can add an extra pair of ports of same size and shape with a corresponding increase in box height to achieve a nice 8L. Another pair of ports (8 total) gets a nice box at 10L. The front aspect of the 8L version is the most pleasing of these three.
With the 6L box you have something that isn't too tall to accommodate a nice woofer-in-a-speaker-stand without the total assembly being too high. It's shallow enough for wall mounting (in my opinion). The wall Fonken was tempting, but I was disuaded by two factors, i) box being shallow enough to impact sound, ii) requiring folded ports to achieve good port length or having to put the ports out the sides at the back (loses the Fonken aesthetic), iii) box having to be wider than I wanted from my aesthetics.
But there's a big market for HT and I'd suggest you introduce a full range of HT_Onken's (I'll give you that name) which may or may not be based on the FE127E driver.
Afterall that, I may not build the 8L for my front speakers, as I have some new thoughts on the Onken aesthetic for improved WAF which I need to think about further. I'll be sending more questions your way though
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We need to pull this thread back on track
So, simply, the idea for LF support to a Fonken is a box designed as a stand for the Fonken, same shape only taller. The internal volume could be in the range 15L to 30L+ depending on the specific Fonken and the height.
We put an SDX-7 in one of the sides (or two in opposite sides) to make a sealed box sub. To the first order I think the performance of this sealed box is fairly insensitive to the internal volume over a reasonable range. There doesn't seem to be much argument in favour of using the larger SDX-10 ?
Is this the best approach ?
Any deviation from this simple approach means more complexity or cost or some other tradeoff so is there much more to talk about or am I missing something
So, simply, the idea for LF support to a Fonken is a box designed as a stand for the Fonken, same shape only taller. The internal volume could be in the range 15L to 30L+ depending on the specific Fonken and the height.
We put an SDX-7 in one of the sides (or two in opposite sides) to make a sealed box sub. To the first order I think the performance of this sealed box is fairly insensitive to the internal volume over a reasonable range. There doesn't seem to be much argument in favour of using the larger SDX-10 ?
Is this the best approach ?
Any deviation from this simple approach means more complexity or cost or some other tradeoff so is there much more to talk about or am I missing something
AdamThorne said:
I'm XOing mine at 100 Hz and i'd recommend taking the load off the bottom of the Fonken with at least a 1st order HP. This is most easily accomplished by an appropriately sized cap on the input of the HF amplifier such that the RC formed with the amps input impedance turns over at the frequency of choice,
Sneakier but more invasive is to reduce the size of a coupling cap in your amplifier to accomplish the same thing.
dave
Bigun said:
Due to the (at least minimally treated) SDX7's smooth & extended response, XO options are considerably widened. A true subwoofer like the SDX10 has more limited HF capability and needs a fairly fast turnover.
Using a low order XO on the SDX7 means it is there to help fill in where baffle-step has reduced the respnse of the front facing driver.
dave
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