Sorry, somehow misread that as 2.27m cuz I was a little under the weather with flu yesterday. Oops. Brain fever is my excuse... 😱
Looked at the sims in your original post and they look good to me.
For some reason the sims that Mayuri did in Leonard audio look like they are peaking near the cutoff, and sag a bit from 100-200hz. In a large room combined with baffle loss, this will lead to the sound described above. Has anyone compared the Leonard TL simulator to MJK's?
This does bring up the subject of room interaction and TL's. In my experience (22 years btw), the room is especially critical with TL's, and they should be ideally designed with a gain profile that matches. A big room in house with floppy timber and sheet rock walls is going to have much less room gain than a small room in a brick house/flat.
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Mayuri hasn't used the same damping quantities which is why the response profile is different. I believe the software uses different damping models -Martin from his own testing, not sure what the Leonard is based on.
Same applies to any vented box, be it a reflex, TL, bandpass variation or whatever; gain profile should match that of the room. TLs have the advantage of having some flexibility in this sense, but in the absence of being able to measure the room & test construction, it's generally good practice to design assuming reasonably solid construction and a lightly damped LF profile, which can be quite easily adjusted to increase LF gain via reducing the damping without severely impacting on attenuation of unwanted harmonics.
Same applies to any vented box, be it a reflex, TL, bandpass variation or whatever; gain profile should match that of the room. TLs have the advantage of having some flexibility in this sense, but in the absence of being able to measure the room & test construction, it's generally good practice to design assuming reasonably solid construction and a lightly damped LF profile, which can be quite easily adjusted to increase LF gain via reducing the damping without severely impacting on attenuation of unwanted harmonics.
I purposly design my FASTs to support 1st order.
Keep the drivers wired the same polarity, close together, the XO greater than that defined by a 1/4 wavelength of the C-C distance, and use a 1st order XO and you are almost guaranteed that you have phase alignment.
When xrk talks about woofer alignment he is talking about the LF end, but you will be XOing at the other end of the band so it makes little difference.
dave
QWERTY was invented for not making the leverage crash against each other, in old typewriters.
FYI
+1 on the 1st order. There's no point in going to the trouble of building a TL and using a wideband/fullrange mid/tweeter if you are going to screw it up with 2nd order slopes. (I bet I'll get some backlash on that...😱😀 )
I would go for a short stuffed TL for the TC9FD also. It will drastically smooth the impedance curve. Also, to my ears the coolest thing about TL loading is the open sounding mids, not the bass.
I would go for a short stuffed TL for the TC9FD also. It will drastically smooth the impedance curve. Also, to my ears the coolest thing about TL loading is the open sounding mids, not the bass.
Yep, having been smitten by the life-like transients of compression horns, IBs and OBs at a young age, low tuned [ML]TLs are the obvious alternative when a relatively smaller, more compact cab is desired.
GM
GM
Thanks for the input to everyone. I'm pretty much settled on the 50in TL for the bass and shorter TL for full range, lenght depending on XO freq. 3 more questions:
1) How should I account for baffle step? I was thinking of rounding the front baffle edges with router, but what more should I do? Would placing second similar driver on backside of enclosure help? Would adjusting the XO do the trick? If I recall correctly, the normal baffle step loss is about 4db.
2) Should I leave the full ranges TL enclosure narrow end open or closed?
3) I was thinking of installing the full range behind the front baffle, the woofer on surface to avoid bezel diffractions on the full range driver (also don't really fancy the looks of the TC9FDs rectangular bezel. I'd route some kind of rounding for the full range drivers installation hole, maybe a similar rounding as with the baffle edges. Any problems with this?
The reason for all this is that I want to design this speaker as ready as possible before making it. I live in a small apartment and haven't got the needed power tools/space/materials to build many different demo enclosures. I'll just make the plans and have a carpenter cut me the needed pieces of plywood, then assemble it here. Before xrk suggests foam core, it's sadly crazy expensive in here, otherwise I would have my apartment filled with prototype speakers 😀
1) How should I account for baffle step? I was thinking of rounding the front baffle edges with router, but what more should I do? Would placing second similar driver on backside of enclosure help? Would adjusting the XO do the trick? If I recall correctly, the normal baffle step loss is about 4db.
2) Should I leave the full ranges TL enclosure narrow end open or closed?
3) I was thinking of installing the full range behind the front baffle, the woofer on surface to avoid bezel diffractions on the full range driver (also don't really fancy the looks of the TC9FDs rectangular bezel. I'd route some kind of rounding for the full range drivers installation hole, maybe a similar rounding as with the baffle edges. Any problems with this?
The reason for all this is that I want to design this speaker as ready as possible before making it. I live in a small apartment and haven't got the needed power tools/space/materials to build many different demo enclosures. I'll just make the plans and have a carpenter cut me the needed pieces of plywood, then assemble it here. Before xrk suggests foam core, it's sadly crazy expensive in here, otherwise I would have my apartment filled with prototype speakers 😀
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Mayuri, to have full flexibility to correct a designs up and downs where first prototype design is frozen to be the final live box, as xrk971 suggested miniDSP would be a wonder tool and by that you can toggle between different XO frequencies, XO symmetric/asymmetric, various XO slopes, use delay to correct drivers acoustic center, use EQ for both correcting drivers acoustic smoothness, BSC, and correct for room modes/placement.
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Byrtt has good advice. MiniDSP will be really handy to let you test various XO's until you make them in passive.
To answer your questions:
1. Yes, you can add second driver on back and it will eliminate need for baffle step correction and give 6dB boost in sensitivity for parallel wiring. However you cannot use speaker near a wall (at least 4 ft away) as you will get a big cancellation dip. You can also use passive baffle step correction with ahout 0.8mH and 8 to 10ohm resistor. This will drop sensitivity of the TC9FD to about 80dB though.
2. Either closed or open will work but use stuffing in either case - open may have least reflections and best sound.
3. Rounding helps a little but radius needed is quite large. Better off to offset driver laterally so it reduces diffraction effects. Rebating baffle to be flush with driver helps but bezel is very thin already - you won't buy much in reduction of diffraction effects.
To answer your questions:
1. Yes, you can add second driver on back and it will eliminate need for baffle step correction and give 6dB boost in sensitivity for parallel wiring. However you cannot use speaker near a wall (at least 4 ft away) as you will get a big cancellation dip. You can also use passive baffle step correction with ahout 0.8mH and 8 to 10ohm resistor. This will drop sensitivity of the TC9FD to about 80dB though.
2. Either closed or open will work but use stuffing in either case - open may have least reflections and best sound.
3. Rounding helps a little but radius needed is quite large. Better off to offset driver laterally so it reduces diffraction effects. Rebating baffle to be flush with driver helps but bezel is very thin already - you won't buy much in reduction of diffraction effects.
Hmm... Need to seriously consider ordering a miniDSP.
1. Then this route is a no-go. These speakers will have their backs right against the wall. Small room... I will need to look into passive baffle step correction. It will be for the woofer though, as I am worried about it's response rising due to baffle step near XO. The TC9 will only benefit from response dropping afaik. The woofer is more sensitive than the full range so I might need to attentuate it in line level.
2. Alright, open it is then.
3. Makes sense. I might just go for drivers sitting right next to each other and mounted on front as I have no idea how to flush mount a rectangular frame smoothly.
1. Then this route is a no-go. These speakers will have their backs right against the wall. Small room... I will need to look into passive baffle step correction. It will be for the woofer though, as I am worried about it's response rising due to baffle step near XO. The TC9 will only benefit from response dropping afaik. The woofer is more sensitive than the full range so I might need to attentuate it in line level.
2. Alright, open it is then.
3. Makes sense. I might just go for drivers sitting right next to each other and mounted on front as I have no idea how to flush mount a rectangular frame smoothly.
If you will be pursuing DIY speakers farther along and plan to do more FAST then a miniDSP is definitely something that you will use over and over and it will improve the sound quality of your projects immensely. One of the single most important pieces of equipment for Diy. A game changer.
It costs less than expensive passive coils and caps once you make more than 2 or 3 sets. Think of it as infinite number of XO's. EQ built in for baffle step and applying Linkwitz transform for bass is a bonus.
If you have it, 4th order XO's have good phase linearity when done correctly and have nice separation to prevent bleed through of 1st or 2nd order. With miniDSP you have every order up 8th order and in Butterworth or Linkwitz Riley.
It costs less than expensive passive coils and caps once you make more than 2 or 3 sets. Think of it as infinite number of XO's. EQ built in for baffle step and applying Linkwitz transform for bass is a bonus.
If you have it, 4th order XO's have good phase linearity when done correctly and have nice separation to prevent bleed through of 1st or 2nd order. With miniDSP you have every order up 8th order and in Butterworth or Linkwitz Riley.
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Uh, no baffle step is required and to maximize boundary loading HF BW, make the speaker as wide/shallow as practical, i.e. driver depth and get creative with folding the vent if need be, though often damping a too short vent works best overall in such ~near-field apps.
FWIW, making a false baffle from decorative cork sheet/squares was once common. Depending on the thickness used, either an Xacto knife or fine tooth finish hole saw will make quick work of the cutouts.
GM
1) My preference for speakers like this is to cross over at the baffle step. Depending on the width of the cabinet, this might be around 500hz or so. This allows enough overlap for first order. If you cross over lower, you will need both higher order high pass, and some BSC.
Since these speakers will be against the wall, you won't need anywhere near a full 6db of BSC. IME, unless the cabinets are very shallow and fairly wide, typically they will still need some. I'd guess around 2-3db - perhaps none, but it really depends on the room, cabinet dimensions, etc.
Rounding the baffle edges is a good idea, but it addresses edge diffraction not the baffle step. Totally different issue.
2) Try it both ways, but probably open. If it is stuffed near the terminus and open, it will have a very smooth impedance curve, making a passive level high pass an option.
MiniDSP sounds like a great option for testing for the best crossover point and slope, even if you end up making a passive one eventually.
3) You will get the best imaging and open sound if you flush mount to the surface. I second GM's suggestion of cork sheet if you don't have a router. I still use cork sheet, even with a router. In my view, the front baffle should not be overly reflective, and the cork helps with panel damping.
Hmm, why do you need any BSC when up against the wall unless there's no room gain in the speaker's pass band, which is unlikely in most rooms and especially in a small one, so curious what room conditions, bass alignments you've found the need?
GM
GM
Very interesting ideas with the cork baffle. I found some pictures of cork baffle with plywood sides, looks quite pretty.
I was wondering what kind of finishing would fit the cork baffle since I haven't got any experience working with it. I was thinking of making the speakers of BB ply, staining them dark and laquering them. What kind of finish would you recommend to cork, does staining them work?
I was wondering what kind of finishing would fit the cork baffle since I haven't got any experience working with it. I was thinking of making the speakers of BB ply, staining them dark and laquering them. What kind of finish would you recommend to cork, does staining them work?
I have no idea about the room gain. If I recall correctly it was about 3m wide and 5m long with 2,6m high ceiling. Speakers will be about 2m from eachother on both sides of TV stand on the shorter edge of room. Listening place is about 3m from speakers.
Never did anything with them as its particular shade of semi-mat brown seemed to go with any decor. I know they will fade to nice tan if left in direct sunlight for a long time though, so may need some UV protection.
I imagine that a latex stain thinned with Floetrol would work, but no clue if an enamel or similar stain will damage it over time.
Your room will have a rising LF response below ~344/2/5 = ~34.4 Hz + any boundary gain of ~3 dB rom 2pi loading, so ignoring any shelf it may be on, a speaker design program's 2pi space sim is what to expect + a bit more if you put the speakers at an odd harmonic of the 3 m side walls, so instead of 0.5 m from each side wall, place them at 3 m/5 = 0.6 m and ideally up the wall at 2.6 m/5 = 0.52 m or some multiple of it.
Ditto for the listening position at an odd harmonic of 5 m, so you're good with your ears at 3 m and again, ideally at an odd harmonic of the vertical.
Obviously, this is all based on an ideal room, but is accurate enough if off a bit, though I would use measured specs. Of course you can use 3rds, 7ths instead if need be. 5ths just seem to work best overall, be it a full size room or a driver, vent location on a speaker cab [tiny room].
Few folks have the option to get this detailed a room set-up, but for those of us who can, it's a worthwhile tweak and best of all it's a cheap one unless you have to build a riser to the get the ideal ear height, though it can do double duty as a near-field sub if tall enough to get at least 6" drivers to fit.
GM
I imagine that a latex stain thinned with Floetrol would work, but no clue if an enamel or similar stain will damage it over time.
Your room will have a rising LF response below ~344/2/5 = ~34.4 Hz + any boundary gain of ~3 dB rom 2pi loading, so ignoring any shelf it may be on, a speaker design program's 2pi space sim is what to expect + a bit more if you put the speakers at an odd harmonic of the 3 m side walls, so instead of 0.5 m from each side wall, place them at 3 m/5 = 0.6 m and ideally up the wall at 2.6 m/5 = 0.52 m or some multiple of it.
Ditto for the listening position at an odd harmonic of 5 m, so you're good with your ears at 3 m and again, ideally at an odd harmonic of the vertical.
Obviously, this is all based on an ideal room, but is accurate enough if off a bit, though I would use measured specs. Of course you can use 3rds, 7ths instead if need be. 5ths just seem to work best overall, be it a full size room or a driver, vent location on a speaker cab [tiny room].
Few folks have the option to get this detailed a room set-up, but for those of us who can, it's a worthwhile tweak and best of all it's a cheap one unless you have to build a riser to the get the ideal ear height, though it can do double duty as a near-field sub if tall enough to get at least 6" drivers to fit.
GM
If you're considering cork:
Yes, you can stain. I used water-based stain on my cork floor, diluted and sprayed. Worked very well.
Yes, you can use water-based urethane on the finish. I used "Deft" UV blocking clear finish. The color still fades. A lot.
Yes, you can stain. I used water-based stain on my cork floor, diluted and sprayed. Worked very well.
Yes, you can use water-based urethane on the finish. I used "Deft" UV blocking clear finish. The color still fades. A lot.
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