Cabinets, other drivers, XO, pretty packing boxes, labour, management, advertising, rent, insurance, accounting, manufacturer margin, distributor margin, dealer margin, shipping...
And if they are buying any quantity they are paying significanly less for the woofer.
Now you can see why we diy :^)
dave
To make speakers that would beat the stuffing out of any speaker in the same price league, and give ones that you'd pay 4x your project's worth for a decent run for their money?
Vista is the bane of my school life.
Chris
I hate vista too...but my boot time is still under 20 seconds....
Debian Lenny on my ancient laptop - 7.9 seconds from BIOS handoff to login 🙂
Cheers!
Ok, I've finalised notch filter values, and the wood is cut.
R=24.2 ohms
C=3.5uF
L=0.06mH
And the wood has been cut. Went for 1.26m x 0.36m x 0.15m. I chose the height because it was ~20mm MDF, with sheets 1.22m wide. B&Q sold me the sheet (cut) for £10 so no complaints here...
The plan is to screw it together, with foam gaskets to seal it. These will be the test boxes. The final boxes will be glued and screwed, with filler covering the screws. Then it will be sanded etc and finished (not sure how yet, leading towards some kind of vinyl cover.
Chris
R=24.2 ohms
C=3.5uF
L=0.06mH
And the wood has been cut. Went for 1.26m x 0.36m x 0.15m. I chose the height because it was ~20mm MDF, with sheets 1.22m wide. B&Q sold me the sheet (cut) for £10 so no complaints here...
The plan is to screw it together, with foam gaskets to seal it. These will be the test boxes. The final boxes will be glued and screwed, with filler covering the screws. Then it will be sanded etc and finished (not sure how yet, leading towards some kind of vinyl cover.
Chris
Construction began today at 11am, (forced) end at around 6pm.
Lots of drilling (screws), got one speaker nearly done (the TL took the time... all those angles), so one should be finished tomorrow morning some time. The (new) plan is to silicone the joins (aswell as screw) so it will be sealed, with no extra dimensions to take care of when making top and bottom. Too busy to take pics (sorry!), but I'll probably have some tomorrow.
Chris
Lots of drilling (screws), got one speaker nearly done (the TL took the time... all those angles), so one should be finished tomorrow morning some time. The (new) plan is to silicone the joins (aswell as screw) so it will be sealed, with no extra dimensions to take care of when making top and bottom. Too busy to take pics (sorry!), but I'll probably have some tomorrow.
Chris
Careful with squeeze-out when using silicone as adhesive - it's a bitch to clean, clogs sandpaper like crazy and can interfere with your finishing, whether painting or applying an adhesive backed sheet product.
An alternative would be something like white PVA glue (Welbond, etc) - these don't cure as hard as yellow glues or the moisture cured polyurethanes, but are much easier to scrape off when dry than silicone.
Sounds like you've been busy. So you decided to implement the TL in the end. Did you just go for an exact copy of the Tysen TL i.e 10:1 taper and same length? Good luck with the rest of the building and look forward to hearing how they turn out.
Ewan
As it happens, I used the numbers you gave me. Don't panic if they weren't spot on - this is for flattening an impedance spike an octave below XO.
Made the first one, plugged it in. Initial impressions are good, but too much bass, so I shorted the FR resistor. Much better now.
Gotta go - hair cut
Chris
Made the first one, plugged it in. Initial impressions are good, but too much bass, so I shorted the FR resistor. Much better now.
Gotta go - hair cut
Chris
I must admit I am slightly worried that I've given you you less than optimal values as they were generated using this spreadsheet http://www.quarter-wave.com/TLs/Alignment_Tables_Calculator_3_3_09.xls and only as a quick look at what the classical TL alignment tables would give for a FRS8M rather than anything serious 😱. However it sounds like the test box is performing ok, so I'm slightly less worried 🙂. Looking forward to hearing how the rest of the build goes and hopefully some pictures.
Ewan
Ewan
Ok, I have more time now.
Must be said, this speaker pushes out a surprising amount of bass - copes with 50W with no excursion problems, which is a good start.
As I said - no worries about the TL - it was something to have as experience, and it doesn't have to be accurate to the nearest Hz, as it's an octave below the XO point.
I'll begin with construction bits I haven't yet mentioned. I put a vertical brace in (like Dave's), with really helps with sorting cabinet resonances. At 4' of MDF, there'd bound to be something there.
I used 18mm MDF, with means it's a) pretty strong, and b) extremely heavy.
If you want to clone this, I used (per speaker, all in mm):
1220x360 x2
11x1220 x2
146x360 x1 (top)
310x410 x1 (plinth - needed for stability)
The TL piece x1
Any bracing you want to put in x1
Hard to tell on sound yet, as there's only one, but it goes plenty loud. Need to stop dad playing The Clash through it now...
Shame you're at the other end of the country - thought you might want a listen, seeing as you've followed this thread for so long...
Pics will come soon - they all need cropping, compressing etc...
Chris
Must be said, this speaker pushes out a surprising amount of bass - copes with 50W with no excursion problems, which is a good start.
As I said - no worries about the TL - it was something to have as experience, and it doesn't have to be accurate to the nearest Hz, as it's an octave below the XO point.
I'll begin with construction bits I haven't yet mentioned. I put a vertical brace in (like Dave's), with really helps with sorting cabinet resonances. At 4' of MDF, there'd bound to be something there.
I used 18mm MDF, with means it's a) pretty strong, and b) extremely heavy.
If you want to clone this, I used (per speaker, all in mm):
1220x360 x2
11x1220 x2
146x360 x1 (top)
310x410 x1 (plinth - needed for stability)
The TL piece x1
Any bracing you want to put in x1
Hard to tell on sound yet, as there's only one, but it goes plenty loud. Need to stop dad playing The Clash through it now...
Shame you're at the other end of the country - thought you might want a listen, seeing as you've followed this thread for so long...
Pics will come soon - they all need cropping, compressing etc...
Chris
Just put the notch filter in - sounds much smoother, and the treble is more in-line (volume-wise) with the mids.
Quick question - I mounted the port at the bottom, meaning is has to go around 4' before going through the port. When I listen right on top of the speaker, there's bass cancellation. Is there a rule of thumb on how far away you can put a port?
Chris
Quick question - I mounted the port at the bottom, meaning is has to go around 4' before going through the port. When I listen right on top of the speaker, there's bass cancellation. Is there a rule of thumb on how far away you can put a port?
Chris
Do keep in mind that with the aspect ratio of your bass enclosure you have an ML-TL not a bass reflex, so if you developed the sim without the MJK worksheets any results you have will not be predicting what is really happening.
dave
That's strange - it seems to do exactly what the sims show. Steep bass rolloff below 40Hz, then pretty much flat for the rest of the frequency response. You've got me doubting the whole speaker, but it sounds that good that I don't think I could take it apart...
Chris
PS - I suppose I could make a stubby version, 1/2 height, 2x width perhaps?
Chris
PS - I suppose I could make a stubby version, 1/2 height, 2x width perhaps?
You can't measure the FR that the sim shows unless you have a really big anechoic chamber or the speaker stuck on the end of a pole some 30 plus feet up in the air.
If, in room, you measure what the sim says then you know for sure that the box is not doing what the sim says.
dave
If, in room, you measure what the sim says then you know for sure that the box is not doing what the sim says.
dave
I haven't measured anything - I don't have the equipment.
I only listened to the bass end (20Hz upwards), and, while 30Hz is audible, it's quite quiet compared to 40Hz. Chances are that this is partly room gain - 30Hz should be lower (in volume) than it sounds.
I'm considering asking for an SPL meter for Christmas, but even the reasonably expensive ones only go from 35Hz to 8kHz
Chris
I only listened to the bass end (20Hz upwards), and, while 30Hz is audible, it's quite quiet compared to 40Hz. Chances are that this is partly room gain - 30Hz should be lower (in volume) than it sounds.
I'm considering asking for an SPL meter for Christmas, but even the reasonably expensive ones only go from 35Hz to 8kHz
Chris
If you're handy with circuits. Check out this measurement mic.
System Test
Cost is low, range is good, and it's DIY. Use your software of choice to measure frequency response. (see synrta or fuzzmeasure)
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