I wouldn't recommend adjusting the sizes of the VTL. It would be better to use the solid wood as an extra layer on top of the baffle and work it in as a design feature, with the VTL built as standard. Solid wood is not ideal for speaker cabinets.
Earlier in this thread (see message #8) I described three MLTL designs for the Eikona which vary in internal length (height) of 40, 35, and 30 inches. I also show performance plots for these examples. You don't give up much bass extension with the 30" version (a 28 Hz F3 down point) vs. 24 Hz for the 40" example. Perhaps the 30" version would suit the length of Bob Malsberger's available wood.
Many of my MLTLs use real wood for their side and top panels while the front, back, and bottom panels are MDF. The mixture of materials (MDF and wood) have served me well for years of listening.
Many of my MLTLs use real wood for their side and top panels while the front, back, and bottom panels are MDF. The mixture of materials (MDF and wood) have served me well for years of listening.
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Ted's VTL design uses a wide baffle in part because it supports lower registers better than a narrow-baffle version. We used to use it with BSC in the JX92S version but haven't found it necessary with the Eikona. In fact when Ted and I tested it, we thought it sounded better without the additional components in circuit.
I can't comment on the MLTL designs. The software may take into account the question of BSC without using passive components. Jim is your go-to for answers on his designs.
I can't comment on the MLTL designs. The software may take into account the question of BSC without using passive components. Jim is your go-to for answers on his designs.
There's no magic in a wider baffle unless it approaches several (3 ft or more) wide for reducing need for baffle step correction, or unless the design has substantial bass gain such as a back-loaded horn (BLH), a wall-mounted flat speaker, or something like a Karlsonator. You can almost count on -3dB to -5dB BSC being needed unless placement very close to a back wall or corner is utilized to enhance the bass falloff. For the preferred "audiophile" placement about 5ft away from a back wall to provide the best stereo imaging, the BSC will almost certainly be -5dB. So a 86dB sensitive driver speaker will be about 81dB to 82dB (at 100Hz) in practice if you consider balanced bass a requirement.
For an 8ohm impedance speaker in a typical baffle (under 2ft), usually a circa 0.8mH to 1mH coil paralleld with circa 5ohms to 10ohms will be needed to put a high frequency shelf filter starting circa 700Hz and above.
A sim with driver TS parameters and MLTL plus baffle dimensions and driver placement in Akabak or one of the other packages will show the exact values to use but it won't be very different from what I specified above. Then adjust the resistor to taste depending on placement.
A sim in Akabak will also show where the optimum placement relative to a wall should be to avoid back wall cancellations etc.
For an 8ohm impedance speaker in a typical baffle (under 2ft), usually a circa 0.8mH to 1mH coil paralleld with circa 5ohms to 10ohms will be needed to put a high frequency shelf filter starting circa 700Hz and above.
A sim with driver TS parameters and MLTL plus baffle dimensions and driver placement in Akabak or one of the other packages will show the exact values to use but it won't be very different from what I specified above. Then adjust the resistor to taste depending on placement.
A sim in Akabak will also show where the optimum placement relative to a wall should be to avoid back wall cancellations etc.
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As xrk has said a wide baffle is not a solution nor a baffle step correction. All a wide baffle can do is to lower the baffle step frequency onset.
My MLTL design derivation does not include any BSC as the user's placement of the speaker within the listening room and listening desires will ultimately determine whether BSC is needed.
Speaker and room placement simulation, as suggested, can help with a start to perfecting a BSC circuit. Usually a BSC circuit is an inductor (determined by baffle width) and resistor (determines the amount of attenuation) in parallel and then placed in series with one of the feeds to the driver.
If the user has in-room measurement capability, they can quickly determine the amount of attenuation needed without additional simulation.
My recommendation is to build and listen to your speaker and then decide if you wish to enhance (really balance the bass to mid-treble level) the bass response of your speaker. If you have tone controls or equalization capability within your electronics, then a tweak or two can satisfy your needs.
My MLTL design derivation does not include any BSC as the user's placement of the speaker within the listening room and listening desires will ultimately determine whether BSC is needed.
Speaker and room placement simulation, as suggested, can help with a start to perfecting a BSC circuit. Usually a BSC circuit is an inductor (determined by baffle width) and resistor (determines the amount of attenuation) in parallel and then placed in series with one of the feeds to the driver.
If the user has in-room measurement capability, they can quickly determine the amount of attenuation needed without additional simulation.
My recommendation is to build and listen to your speaker and then decide if you wish to enhance (really balance the bass to mid-treble level) the bass response of your speaker. If you have tone controls or equalization capability within your electronics, then a tweak or two can satisfy your needs.
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Then there's also Jordan's own Eikona DCR http://www.ejjordan.co.uk/PDFs/Jordan_Eikona_DCR.pdf
Parallel connect the two drivers if your amp can handle the nominal 3ohm load, series connect with a single amp if not sure about that, or wire for full-range bi-amping if you've got a 4 channels of identical amps available. For a lot of us, that's not as crazy as it sounds.
Parallel connect the two drivers if your amp can handle the nominal 3ohm load, series connect with a single amp if not sure about that, or wire for full-range bi-amping if you've got a 4 channels of identical amps available. For a lot of us, that's not as crazy as it sounds.
If you are placing two drivers in a MLTL box, then consider a bipolar arrangement as I used in my bipolar MLTL reported in:
Bipolar MLTL Speaker with FR125S/WR125S
You radiate the same power into the forward and rear hemispheres so baffle step compensation is inherent within the design. You double the power handling capability as well so you have additional dynamic range.
The drivers are connected in phase for a bipole arrangement and you can either connect them in parallel or series as you wish.
Caveats include the doubling the CSA and port changes for the enclosure. You do need to move the enclosures away from the wall behind them.
You can also mitigate the 3-4 dB dip between 400-500 Hz that I observed in the bipole frequency response wherein the radiation from the rear driver propagates around the enclosure. Essentially, you can low pass the rear driver (add an inductor in series with the rear driver) so that the rear driver rolls off above the BSC region. Or try planet10's capacitor across the rear driver to effect a low pass filter.
Later planet10's Castle series of speakers essentially work similar to a bipole albeit directing the top mounted driver toward the ceiling versus the rear wall.
Jim
Bipolar MLTL Speaker with FR125S/WR125S
You radiate the same power into the forward and rear hemispheres so baffle step compensation is inherent within the design. You double the power handling capability as well so you have additional dynamic range.
The drivers are connected in phase for a bipole arrangement and you can either connect them in parallel or series as you wish.
Caveats include the doubling the CSA and port changes for the enclosure. You do need to move the enclosures away from the wall behind them.
You can also mitigate the 3-4 dB dip between 400-500 Hz that I observed in the bipole frequency response wherein the radiation from the rear driver propagates around the enclosure. Essentially, you can low pass the rear driver (add an inductor in series with the rear driver) so that the rear driver rolls off above the BSC region. Or try planet10's capacitor across the rear driver to effect a low pass filter.
Later planet10's Castle series of speakers essentially work similar to a bipole albeit directing the top mounted driver toward the ceiling versus the rear wall.
Jim
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Series with a cap will not provide BSC.
http://www.planet10-hifi.com/downloads/Dual-Driver-Wiring.pdf
dave
http://www.planet10-hifi.com/downloads/Dual-Driver-Wiring.pdf
dave
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