snip
chrisb: as usual, right on top of all things construction (and sound-wise too). Question: what's your experience using splines in a 45° joint and BB ply?
Being a lazy hacker with no occupational training and over 40yrs of bad habits, I don't bother with splines, biscuits or glue-lock joint on mitres - just rabbets or dadoes when looking for reinforcement or extra glue surface area on butt joints, or screwed glue block/cleats on inside of exposed mitered joint (such as the bamboo PAWO)
We call them “keft cut”, but I’m easy ~ “rabbit” is fine. They may seem like extra work, however they make clamping easier, especially when gluing more than one side and/or angled pieces. They don’t have to be very “wide” just enough to hold the adjoining piece (top/bottom/side).
Don’t forget to add the extra material when calculating the panel sizes.
*A kerf is the distance of material a saw blade takes out as it cuts. For most home projects, a kerf is too insignificant to measure it out, but some projects that need to ... http://www.doityourself.com/stry/kerf explanation
The 50% - 50% water to glue: you can coat everything, but be on standby for a few minutes, so it can soak in. It does seem to give the MDF a hard outside shell.
Don’t forget to add the extra material when calculating the panel sizes.
*A kerf is the distance of material a saw blade takes out as it cuts. For most home projects, a kerf is too insignificant to measure it out, but some projects that need to ... http://www.doityourself.com/stry/kerf explanation
The 50% - 50% water to glue: you can coat everything, but be on standby for a few minutes, so it can soak in. It does seem to give the MDF a hard outside shell.
Chris,
May I ask what is a factory recommended DBR? Double bass reflex? I did finish up the double tall boxes, but when I started to test them, the top half/top box was sounding really nice (may not use bottom section).
For this set I used Fostex plans; medex wood and lead lined the top chamber; they do have very nice bass, again just the tops sections. I did flip the “L” port for the small chamber, which gave me a little extra room for dampening.
I can always cut away the bottom sections, if I don’t end up using them, or they can be extra tall stands.
IMO, it’s a good driver, amazing sound for only 4”.
May I ask what is a factory recommended DBR? Double bass reflex? I did finish up the double tall boxes, but when I started to test them, the top half/top box was sounding really nice (may not use bottom section).
For this set I used Fostex plans; medex wood and lead lined the top chamber; they do have very nice bass, again just the tops sections. I did flip the “L” port for the small chamber, which gave me a little extra room for dampening.
I can always cut away the bottom sections, if I don’t end up using them, or they can be extra tall stands.
IMO, it’s a good driver, amazing sound for only 4”.
Attachments
ODougbo - yes by DBR, I was referring to the Double (chamber) Bass Reflex. The Fostex sketch that accompanied your FX120 is not a unique occurrence of such a design. To be honest, I haven't heard them, but after participating or listening to several (at least 4?) builds of various of their "recommended" designs, I've pretty much closed my mind on that subject - there are far too many much better sounding enclosure designs for their drivers.
Yup, the FX120 is a great driver, but at approx the same size and 1/3 the cost, the bang for the buck from the FF125W is even more amazing.
If you venture into another smallish FR driver project, might I suggest you try the opposite approach of materials / damping? - i.e. light and stiff plywood (or solids if you're that confident), well braced, but absent the mass loading for "resonance control" . Since you happen to have 4 pieces of a very good driver that can work well in smaller less complicated boxes than your existing, if you really want to be adventuresome, try building identical pairs with both techniques - it might be an eye / ear - opener.
Yup, the FX120 is a great driver, but at approx the same size and 1/3 the cost, the bang for the buck from the FF125W is even more amazing.
If you venture into another smallish FR driver project, might I suggest you try the opposite approach of materials / damping? - i.e. light and stiff plywood (or solids if you're that confident), well braced, but absent the mass loading for "resonance control" . Since you happen to have 4 pieces of a very good driver that can work well in smaller less complicated boxes than your existing, if you really want to be adventuresome, try building identical pairs with both techniques - it might be an eye / ear - opener.
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AKA "tempered" hardboard, Masonite etc (well, actually not all pegboard is tempered - most specifically the 1/4" generally isn't, but let's not get too pedantic)
by HDF I mean High Density Fibreboard other types of wood fibres, different resin and more pressure applied.
"Product: High Density Fibreboard [HDF], Wood Species: Mixed Tropical Hardwood, Resin Used: Urea Formaldehyde (UF), Density kg/m3 900+/-20"
Density of Wood
so, Nanook of the North...
tell me about that plan
"Product: High Density Fibreboard [HDF], Wood Species: Mixed Tropical Hardwood, Resin Used: Urea Formaldehyde (UF), Density kg/m3 900+/-20"
Density of Wood
so, Nanook of the North...
tell me about that plan
with two pairs of speakers I saw this interesting design (in my modest opinion since, unfortunately, I don't have the mathematical knowledge to understand it)
http://homepage.mac.com/tlinespeakers/FAL/box-plans/BD-pipes-drawing.gif
BD-Pipes
I just think that maybe the upper driver should be proportionately smaller since it's upper in the "tube", but then again that wouldn't be a single full-range speaker; maybe it should be two proportionally drivers with the same colouration (same brand and model class)...
:s
http://homepage.mac.com/tlinespeakers/FAL/box-plans/BD-pipes-drawing.gif
BD-Pipes
I just think that maybe the upper driver should be proportionately smaller since it's upper in the "tube", but then again that wouldn't be a single full-range speaker; maybe it should be two proportionally drivers with the same colouration (same brand and model class)...
:s
All very fascinating ~ an all new experience for me. I got off to a really bad start; the amplifier was set all wrong, the DIP switches were very hard to see, and the bass filters were set “on”.
The DBR really has nice bass extension; I did make a couple of modifications. If I was going to do it again, some bracing in the larger cabinet might be good.
I’m looking forward to a new build with the FX120 (I have a couple more) what box would you suggest?
I did see the T-line project on a DIY page, the author said the bass was not impressive, so that got me worried that this might be a big box, that didn’t work.
*The tall micro towers: I can always hook up the second lower pair to an on-off switch; it would only change the ohms from 8ohm to 4ohm.
Thanks for your help and clarification.
The DBR really has nice bass extension; I did make a couple of modifications. If I was going to do it again, some bracing in the larger cabinet might be good.
I’m looking forward to a new build with the FX120 (I have a couple more) what box would you suggest?
I did see the T-line project on a DIY page, the author said the bass was not impressive, so that got me worried that this might be a big box, that didn’t work.
*The tall micro towers: I can always hook up the second lower pair to an on-off switch; it would only change the ohms from 8ohm to 4ohm.
Thanks for your help and clarification.
Dave, basically "chip board" then
at least based on the images I can find. Standard stuff uses formaldehyde, Meditell is formaldehyde free. Something like OSB, but at much lower pressures. Most images I could find showed some lengths of fibres, not sawdust. Are we talking the same language?
If we are, it could definitely be a material to consider. Perhaps OSB could be too, as it off-gases almost no formaldehyde.
ODougdo which DIY page for the speaker plans ? DIY AUDIO PROJECTS - Do-It-Yourself Hi-Fi for Audiophiles,
if so then "The Fostex FX120 speaker is well balanced, with a relaxed sound, detailed midrange and good highs (also very well assembled). The TQWT enclosure gets good low end from this little driver. Of course the bass doesn't blow you away, but 50 Hz is there and it fills my room with music. Small group and acoustic music sounds wonderful. When the recording is good (for example 'Songs from the last century' by George Michael and the recordings from Norah Jones) the artists seem to be standing in front of you. I was surprised with the performance of this driver. I have no measurement equipment, but what I hear seems to correspond with the simulation. In my opinion the FX120 is worth every cent you pay for it."
I don't think that 50Hz is bass shy, just not bass heavy. I'd take accuracy over deeper bass anyday, a sin of ommission rather than of commision. If deeper bass is required accurately, a woofer (or sub) could be added per channel as per the FAST systems. There is a limit to the amount of bass imact available from a 4" cone.
at least based on the images I can find. Standard stuff uses formaldehyde, Meditell is formaldehyde free. Something like OSB, but at much lower pressures. Most images I could find showed some lengths of fibres, not sawdust. Are we talking the same language?
If we are, it could definitely be a material to consider. Perhaps OSB could be too, as it off-gases almost no formaldehyde.
ODougdo which DIY page for the speaker plans ? DIY AUDIO PROJECTS - Do-It-Yourself Hi-Fi for Audiophiles,
if so then "The Fostex FX120 speaker is well balanced, with a relaxed sound, detailed midrange and good highs (also very well assembled). The TQWT enclosure gets good low end from this little driver. Of course the bass doesn't blow you away, but 50 Hz is there and it fills my room with music. Small group and acoustic music sounds wonderful. When the recording is good (for example 'Songs from the last century' by George Michael and the recordings from Norah Jones) the artists seem to be standing in front of you. I was surprised with the performance of this driver. I have no measurement equipment, but what I hear seems to correspond with the simulation. In my opinion the FX120 is worth every cent you pay for it."
I don't think that 50Hz is bass shy, just not bass heavy. I'd take accuracy over deeper bass anyday, a sin of ommission rather than of commision. If deeper bass is required accurately, a woofer (or sub) could be added per channel as per the FAST systems. There is a limit to the amount of bass imact available from a 4" cone.
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Yes that is that article.
*
I would have to agree with this statement, “the artists seem to be standing in front of you”. The sound stage is very precise, and they do fill the room with sound.
*
The double bass reflex cabinet goes way lower than 50hz, maybe the author was referring to flat response. I would say, the bass is quite warm/nice; no testing equipment here, but I could borrow a pink noise, spectrum analyzer from a buddy and see what kind of results I can acquire.* I do hear bass down to 25hz – 30hz; sweeping with a generator.
*
The Fostex double bass reflex build is pretty easy, e.g. 6” rips of wood and the side panels.* Here’s the recipe I came up with for the top chamber: (1) line it with lead (2) cut a snug piece of 1” foam; cut a 2” hole in that (3) add standard wool, the foam keeps the wool from blocking the vent.* Again, I used Medex, a grade up from MDF.
*
I made to 2 small modifications; I flipped over the top “L” for the top chamber and moved the large chamber’s front port to the back.
*
Just to be clear, I referring to the top sections only – when all 4 are playing, they have an 8” - 10” woofer sound (but it is somewhat muddy). *I’m going to add a simple switch, a bass boost, 2 speakers or all 4. *
*
I would have to agree with this statement, “the artists seem to be standing in front of you”. The sound stage is very precise, and they do fill the room with sound.
*
The double bass reflex cabinet goes way lower than 50hz, maybe the author was referring to flat response. I would say, the bass is quite warm/nice; no testing equipment here, but I could borrow a pink noise, spectrum analyzer from a buddy and see what kind of results I can acquire.* I do hear bass down to 25hz – 30hz; sweeping with a generator.
*
The Fostex double bass reflex build is pretty easy, e.g. 6” rips of wood and the side panels.* Here’s the recipe I came up with for the top chamber: (1) line it with lead (2) cut a snug piece of 1” foam; cut a 2” hole in that (3) add standard wool, the foam keeps the wool from blocking the vent.* Again, I used Medex, a grade up from MDF.
*
I made to 2 small modifications; I flipped over the top “L” for the top chamber and moved the large chamber’s front port to the back.
*
Just to be clear, I referring to the top sections only – when all 4 are playing, they have an 8” - 10” woofer sound (but it is somewhat muddy). *I’m going to add a simple switch, a bass boost, 2 speakers or all 4. *
ODougbo - if you're still uncertain about Martin Paul's ML TQWT project some suggestions for FX120:
BIB - I'm fairly certain that these have been executed - a relatively simple build
Metronomes - The Metronome
Jeff (vinylkid) can attest to this driver's performance in a slightly retuned version of this one:
Meet the Fonkens
Ultimately the FX120 or any driver of this size will have some limitations in ultimate SPL and weight/impact in the lowest couple octaves, regardless of available power, EQ etc. This might not really be a problem in a HT system for modest sized room, as powered woofer(s) are part of the mix. Another viable option for 2 channel music only could be an OB project such as:
Project 9 : Eminence Alpha 15A Experimental Open Baffle Design
over the past several years, a variety of DIYers have been very happy with this approach - keep in mind that even the smallest OB may not work for every room
please do yourself a favor and invest the extra few dollars in high quality multi-ply ( Baltic Birch, Murphy multi-ply, Europly, etc) on at least one project with a driver of this quality - then you'll know for sure if it's worth it to you
.
BIB - I'm fairly certain that these have been executed - a relatively simple build
Metronomes - The Metronome
Jeff (vinylkid) can attest to this driver's performance in a slightly retuned version of this one:
Meet the Fonkens
Ultimately the FX120 or any driver of this size will have some limitations in ultimate SPL and weight/impact in the lowest couple octaves, regardless of available power, EQ etc. This might not really be a problem in a HT system for modest sized room, as powered woofer(s) are part of the mix. Another viable option for 2 channel music only could be an OB project such as:
Project 9 : Eminence Alpha 15A Experimental Open Baffle Design
over the past several years, a variety of DIYers have been very happy with this approach - keep in mind that even the smallest OB may not work for every room
please do yourself a favor and invest the extra few dollars in high quality multi-ply ( Baltic Birch, Murphy multi-ply, Europly, etc) on at least one project with a driver of this quality - then you'll know for sure if it's worth it to you
.
The Fonken Design, now that’s a very nice looking speaker project. How was it retuned for the FX120?
The BB plywood; that’s really going keep me up at night – as mentioned, I’ve been using density board(s) with lead lining, my speakers are more like cannonballs. A strategy that I picked up from a small speaker company that was here in the area.
The BB plywood; that’s really going keep me up at night – as mentioned, I’ve been using density board(s) with lead lining, my speakers are more like cannonballs. A strategy that I picked up from a small speaker company that was here in the area.
No retuning, a completely independent design based on the p10 miniOnken principals.
Add mass without adding stiffness, lower Q resonance + more likely to have audiable resonances.
dave
P10/chrisb do not pander, but here's another of my "plugs"
First a disclaimer: Please take my comments with a grain of salt: I consider Dave and Chris to be friends. There is no personal financial gain to be had commenting about my experiences about them and their products (hey guys, maybe I should become the P10 "press agent " ). I like good, honest, generous folks to be successful in their endeavours. If I always seem to be "high" regarding the P10 designs and products, it is because I am. I believe their products/designs/ideas to be significant. End of disclaimer.
As I stated, although their "design library" is open to all, I cannot state enough the significant upgrade to the stock units that happens in the wilderness that is the "Finlayson Audio Laboratory" (or is it FALL?).. Enjoy the Music has also commented on the modifications and resultant benefits here . I am convinced that even the least expensive option (CHR70eN, which I have a pair of and absolutely love in "Onken" style enclosures as designed by Dave) are incredible. Planet10 hi-fi also supports the forums.
If the drivers are not in the realm of possibilities (financially), I think they and others have DIY eN "kits" that allow you to treat your drivers yourself, whatever those drivers might be. To me though, the real bargain is purchasing the modified drivers directly from planet10-hifi: each lot shipped from a manufacturer or supplier is hand measured, and paired with the closet driver within the shipment, as measured after the modifications. Where else do you get hand matching and modifications for under $200 a pair (currently listed as sold out, but I think CAD$160-170 per pair, correct Dave?)
Now regarding the sound of the CHR70eN drivers in "Onken" style enclosures and I am sure that vinylkid58 (is that right Jeff?) can add specifically to this regarding the FX120 drivers in the "Fonken" enclosures:
If after the above disclaimer you question the impartiality of my opinion, please read the linked article. I have had experience with the "Monolith" series (Demetri-8" Hemp Audio drivers w/phase plugs and basket modifications and Mileva- using Fe127eN), Fonkens (using Fostex FE127eN drivers), and Onkens (designed for the CHR70eN drivers, but given a plethora of names. Mine are the "prime" sized versions for the CHR-70eN drivers). In each case I am always floored at how good each sound. Different characteristics, but each very good. End of praising all things Planet10-hifi (for a while). Just when you consider the cost of even the modified drivers and the cost of a good DIY enclosure, you simply cannot beat the value presented.
The OB design: done by another very generous loudspeaker guy via the Internet (Marin J King). His modeling of loudspeakers has opened up a universe of DIY loudspeaker designs via Mathcad that would otherwise be beyond the scope of even "gifted" diy'ers. His personal projects are very well documented as well. All would do well to follow both mjk and P10...
First a disclaimer: Please take my comments with a grain of salt: I consider Dave and Chris to be friends. There is no personal financial gain to be had commenting about my experiences about them and their products (hey guys, maybe I should become the P10 "press agent "
). I like good, honest, generous folks to be successful in their endeavours. If I always seem to be "high" regarding the P10 designs and products, it is because I am. I believe their products/designs/ideas to be significant. End of disclaimer.As I stated, although their "design library" is open to all, I cannot state enough the significant upgrade to the stock units that happens in the wilderness that is the "Finlayson Audio Laboratory" (or is it FALL?).
. Enjoy the Music has also commented on the modifications and resultant benefits here . I am convinced that even the least expensive option (CHR70eN, which I have a pair of and absolutely love in "Onken" style enclosures as designed by Dave) are incredible. Planet10 hi-fi also supports the forums. If the drivers are not in the realm of possibilities (financially), I think they and others have DIY eN "kits" that allow you to treat your drivers yourself, whatever those drivers might be. To me though, the real bargain is purchasing the modified drivers directly from planet10-hifi: each lot shipped from a manufacturer or supplier is hand measured, and paired with the closet driver within the shipment, as measured after the modifications. Where else do you get hand matching and modifications for under $200 a pair (currently listed as sold out, but I think CAD$160-170 per pair, correct Dave?)
Now regarding the sound of the CHR70eN drivers in "Onken" style enclosures and I am sure that vinylkid58 (is that right Jeff?) can add specifically to this regarding the FX120 drivers in the "Fonken" enclosures:
- bass: subjectively much deeper than one would expect. I listen to these in a 11.5' X 19' room and have had no issues regarding the bass. The bass impact is not significant (as it cannot be), but the depth of bass is remarkable. Having no measurement tools available, I can only say that they go much deeper than my old Castle Acoustics Durham 900s which I love, and are apparently good to 50ish Hz (-3dB)
- treble: top end is very well balanced and is not "honky" in any way. No fullrange driver "cupping" apparent. Very open and smooth, Well balanced with the bottom end.
- midrange: the "meat" of the music. Stellar. At first listen tonally lean, but upon extended listening and acclamation to their sound (fullrangers in general), you realize that it isn't lean, it is very precise and articulate.
If after the above disclaimer you question the impartiality of my opinion, please read the linked article. I have had experience with the "Monolith" series (Demetri-8" Hemp Audio drivers w/phase plugs and basket modifications and Mileva- using Fe127eN), Fonkens (using Fostex FE127eN drivers), and Onkens (designed for the CHR70eN drivers, but given a plethora of names. Mine are the "prime" sized versions for the CHR-70eN drivers). In each case I am always floored at how good each sound. Different characteristics, but each very good. End of praising all things Planet10-hifi (for a while). Just when you consider the cost of even the modified drivers and the cost of a good DIY enclosure, you simply cannot beat the value presented.
The OB design: done by another very generous loudspeaker guy via the Internet (Marin J King). His modeling of loudspeakers has opened up a universe of DIY loudspeaker designs via Mathcad that would otherwise be beyond the scope of even "gifted" diy'ers. His personal projects are very well documented as well. All would do well to follow both mjk and P10...
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Thanx Stew. Good thing they can't see my face turning red...
Finlayson Arm Loudspeaker Laboratory
... 20 minutes or so from downtown Victoria (as long as timing is such that you don't hit the Trans Canada "parking lot"
dave
Finlayson Arm Loudspeaker Laboratory
... 20 minutes or so from downtown Victoria (as long as timing is such that you don't hit the Trans Canada "parking lot"
dave
Maybe it's time to step out of your "comfort zone"? - as has been mentioned elsewhere, I've been working for over 18yrs in a commercial millwork/cabinet shop and if patient enough to pick through the off cut bins, could build over 90% of my smaller speaker projects from free scraps of MDF - and did so for at least the first 5-6yrs. Then thanks to some inspiration I can't even recall anymore, decided to try Baltic Birch - and even went so far as to build 2 pairs of a "reference" design - one pair each with MDF and the ply.
AFAIC, it's worth every penny of the extra cost - and is an important part of a design philosophy of light / stiff / well braced enclosure construction, as opposed to the brute force / mass attempts to "control" resonance.
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