Hi all! I've built a couple of sets of speakers before, and was curious to try out a full range Transmission Line design. I have a pair of the "NSB" speakers from Parts Express about 15 years ago (!), and thought I might give them a shot in a TL.
I was looking at similar designs and came across the Woden BabyLabs designs. In particular, the "Shrike", which is designed for the 4" Fostex FE103-SOL.
I plugged in the TS parameters for the NSBs into the Leonard Audio TL design program, and attempted to enter the design parameters for the "Shrike" cabinets:
- Start area: 26.25" (5" x 5 1/4")
- End area: 8.53" (1 5/8" x 5 1/4")
- Length: 33" (11" + 11" + 11", the internal height of the cabinet)
First time using the software. Did I do that right?
The output isn't so bad. +/- 1.5db down to 59hz, F3 of 57hz but -10db by 51.5hz. The box is about 10L/.35cu.ft. Using WinISD the driver looks better in a ported box tuned to 55hz (2" port 6.5" long), with an f3 of 44hz and f10 of 39hz. But I thought I'd give the TL a try.
I know the NSB drivers aren't great. I'll probably try treating the paper cones by spraying them with a few light coats of lacquer as others suggested back in the archives. Plus side is that I should be able to build these cabinets with a handy panel of 1/2" ply and an afternoon at the table saw.
Any thoughts?
I was looking at similar designs and came across the Woden BabyLabs designs. In particular, the "Shrike", which is designed for the 4" Fostex FE103-SOL.
I plugged in the TS parameters for the NSBs into the Leonard Audio TL design program, and attempted to enter the design parameters for the "Shrike" cabinets:
- Start area: 26.25" (5" x 5 1/4")
- End area: 8.53" (1 5/8" x 5 1/4")
- Length: 33" (11" + 11" + 11", the internal height of the cabinet)
First time using the software. Did I do that right?
The output isn't so bad. +/- 1.5db down to 59hz, F3 of 57hz but -10db by 51.5hz. The box is about 10L/.35cu.ft. Using WinISD the driver looks better in a ported box tuned to 55hz (2" port 6.5" long), with an f3 of 44hz and f10 of 39hz. But I thought I'd give the TL a try.
I know the NSB drivers aren't great. I'll probably try treating the paper cones by spraying them with a few light coats of lacquer as others suggested back in the archives. Plus side is that I should be able to build these cabinets with a handy panel of 1/2" ply and an afternoon at the table saw.
Any thoughts?
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I found about 40 of these drivers recently myself. I have not simmed them in a bit, but i think that the xmax was a serious limitation. Can you see excursion in winISD? I suspect that the low end plot will look very different with the xmax limit set. I can whip this up in hornresp later tonight as I am curious now. I seem to remember not getting much below 75 or so hz but maybe my memory is from trying to fit that in a reasonable sized line array.
Thanks for the replies. I agree that xmax might be a problem, with these things only rated for 1.0mm of xmax. I'm missing the mms parameter for these speakers, but estimated 3g based on other similar speakers. In WinISD it looks like it'll take less than 1 watt to push them beyond 1mm below 50hz. The picture has the ported speaker modeled with 1 watt and 7 watts.
I remember making a boom box with 2 of these in a ported box (maybe 20L?) over a decade ago. I don't remember a lot of troubling distortion from them but it wasn't exactly critical listening.
I think I'll go ahead with these in the next couple of weeks and share how they turned out.
I remember making a boom box with 2 of these in a ported box (maybe 20L?) over a decade ago. I don't remember a lot of troubling distortion from them but it wasn't exactly critical listening.
I think I'll go ahead with these in the next couple of weeks and share how they turned out.
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Hornresp gives 3.4 for Mmd, so pretty close to your estimate.
I am not sure how to unwrap the model you found to compare in hornresp. I do find xmax to be a serious issue though with a single watt input. This is for a single driver, not 4.
I am not sure how to unwrap the model you found to compare in hornresp. I do find xmax to be a serious issue though with a single watt input. This is for a single driver, not 4.
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I got around to building the TL box for the NSBs so I thought I'd share the results in case others are interested.
I did a frequency response test just using my phone and AudioTool, and the results are pretty consistent with what others have said about the NSBs. There's a massive peak around 7k, and a big dip at 15khz. On the low end it rolls off in the 50s, and there's a peak around the FS of 100hz, as well as ~300hz (3rd harmonic?).
I tried the cone treatment mods that others had mentioned. I applied about 6 light coats of Livos oil, which is linseed oil-based. Others have used lacquer. I tested the speaker beforehand and between coats and did not measure any difference in frequency response, for better or worse. (the difference, noted on the white lines on the plot, could be due to positioning changes).
I've played around with dampening a bit, including adding a moderate amount of poly stuffing to the front half of the enclosure. The wall dampening is only 1/8" denim padding (moving blanket), so a few more layers may help smooth things out on the low end, perhaps?
XMAX does not seem to be a problem, at all. I didn't hear any mechanical noise, even with test tones at higher than normal listening levels.
Overall... I've heard worse. They'll be going in a small workspace, and they sound better than most of the bluetooth speakers out there. The baffles are also removable in case I want to put some Fostex speakers in the cabinets some day.
I attached a few pics of the speakers, which look the same as other builds. Nothing fancy here!
Jared
I did a frequency response test just using my phone and AudioTool, and the results are pretty consistent with what others have said about the NSBs. There's a massive peak around 7k, and a big dip at 15khz. On the low end it rolls off in the 50s, and there's a peak around the FS of 100hz, as well as ~300hz (3rd harmonic?).
I tried the cone treatment mods that others had mentioned. I applied about 6 light coats of Livos oil, which is linseed oil-based. Others have used lacquer. I tested the speaker beforehand and between coats and did not measure any difference in frequency response, for better or worse. (the difference, noted on the white lines on the plot, could be due to positioning changes).
I've played around with dampening a bit, including adding a moderate amount of poly stuffing to the front half of the enclosure. The wall dampening is only 1/8" denim padding (moving blanket), so a few more layers may help smooth things out on the low end, perhaps?
XMAX does not seem to be a problem, at all. I didn't hear any mechanical noise, even with test tones at higher than normal listening levels.
Overall... I've heard worse
. They'll be going in a small workspace, and they sound better than most of the bluetooth speakers out there. The baffles are also removable in case I want to put some Fostex speakers in the cabinets some day.I attached a few pics of the speakers, which look the same as other builds. Nothing fancy here!
Jared
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