Hi,
I jumped in and built a pair. They are almost fully assembled with the baffle clamped and sealed with opencell foam for tune-up. So far, the sound is quite good (20h of break-in) when at hear level with a simple BSC filter (2.7ohms/0.39mH for 3dB at 1100Hz). I still have to find something not too ugly to raise them by about 8" because lowering my head as I do presently is not very confortable.
The only problem I have is a nasty resonance around 150Hz (WAG based on tests with Foobar equalizer) when installed on my desk. I tried to raise them a bit (about 2") on some polystyrene blocks I had laying around to lower the reflections on the desk but with no help. I also listened to my desk with a screwdriver and it's not a resonance from the desk.
So I was wondering if it could come from the lining I used since I had no flet:1" dense polyester batting, probably half the density of cotton felt, on all side except brace and baffle... or can it be simply the box liking at the baffle?
I jumped in and built a pair. They are almost fully assembled with the baffle clamped and sealed with opencell foam for tune-up. So far, the sound is quite good (20h of break-in) when at hear level with a simple BSC filter (2.7ohms/0.39mH for 3dB at 1100Hz). I still have to find something not too ugly to raise them by about 8" because lowering my head as I do presently is not very confortable.
The only problem I have is a nasty resonance around 150Hz (WAG based on tests with Foobar equalizer) when installed on my desk. I tried to raise them a bit (about 2") on some polystyrene blocks I had laying around to lower the reflections on the desk but with no help. I also listened to my desk with a screwdriver and it's not a resonance from the desk.
So I was wondering if it could come from the lining I used since I had no flet:1" dense polyester batting, probably half the density of cotton felt, on all side except brace and baffle... or can it be simply the box liking at the baffle?
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I'd suggest the felt lining is most important for the treble (> 5kHz) - preventing sound bouncing around inside the box and back out through the driver. I can't see it affecting frequencies down at 150Hz.
I've no real ideas what could produce a resonance there unless something is off-base in terms of the construction or that clamping of the baffle isn't cutting it somehow. You said it occurs when installed on your desk - does it happen when it's not on your desk but, say, on a hard surface like the kitchen floor ?
I've no real ideas what could produce a resonance there unless something is off-base in terms of the construction or that clamping of the baffle isn't cutting it somehow. You said it occurs when installed on your desk - does it happen when it's not on your desk but, say, on a hard surface like the kitchen floor ?
why is the filter even needed, my speakers have great response at all frequencies as far as i can tell
what's with the new FR89EX? he has a paint coated Cone that calms the peaks?
bigger Xmax and big Magnet! 😀
https://www.madisound.com/store/product_info.php?products_id=8824
bigger Xmax and big Magnet! 😀
https://www.madisound.com/store/product_info.php?products_id=8824
It needs a tweet according to the DIYMA crowd, quite a few on there say the same thing after using them.. ie the cheap coating seems to reduce treble performance unlike the cheaper untreated version.
My father-in-law built and stained a pair for me. Lined it with open cell foam. These really do sound great!
That is nice!
I added the notch filter, per an earlier post, and have really come around on it. Originally, it really took some of the sparkle out of acoustic steel string guitar, but has come back with about 100h of burn in. These are now being used with a small tube amp, which is making a great small apartment combo for a friend.
I added the notch filter, per an earlier post, and have really come around on it. Originally, it really took some of the sparkle out of acoustic steel string guitar, but has come back with about 100h of burn in. These are now being used with a small tube amp, which is making a great small apartment combo for a friend.
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I was contacted by a person from Indonesia who was not able to obtain this driver, but did have it's brother, the FR89.
These are my thoughts on the suitability of this driver for the Martello enclosure:
First off, I've not tried it of course so I took a quick look at the datasheets for both drivers.
The frequency response curves of both drivers look very similar, no problem there.
Next I took a look at the specifications
fs 95Hz vs 97Hz - close enough so no problem there
VAS 1.269L vs 1.111L - here the's a bit of a difference. I don't think it's critical, the FR89 has a smaller VAS but the driver also has a larger magnet and eats into the enclosure volume slightly
Qts 0.472 vs 0.468 - close enough so no problem there
Lastly I took a look at the physical size:
magnet depth: 38mm vs (46.9mm-4.3mm=) 43.6mm - a noticeable difference, but all this means is that the holey brace behind the driver will need to be shorter to accommodate the deeper driver, just cut it size as you build
hole cut out diameter: 73mm vs 73mm - same, no problem
Overall I'd say yes, that this driver would be suitable. It won't sound exactly the same though. Of course, it might sound better 🙂
These are my thoughts on the suitability of this driver for the Martello enclosure:
First off, I've not tried it of course so I took a quick look at the datasheets for both drivers.
The frequency response curves of both drivers look very similar, no problem there.
Next I took a look at the specifications
fs 95Hz vs 97Hz - close enough so no problem there
VAS 1.269L vs 1.111L - here the's a bit of a difference. I don't think it's critical, the FR89 has a smaller VAS but the driver also has a larger magnet and eats into the enclosure volume slightly
Qts 0.472 vs 0.468 - close enough so no problem there
Lastly I took a look at the physical size:
magnet depth: 38mm vs (46.9mm-4.3mm=) 43.6mm - a noticeable difference, but all this means is that the holey brace behind the driver will need to be shorter to accommodate the deeper driver, just cut it size as you build
hole cut out diameter: 73mm vs 73mm - same, no problem
Overall I'd say yes, that this driver would be suitable. It won't sound exactly the same though. Of course, it might sound better 🙂
What would be best if building these?
22mm particle board or 12mm particle board? I have some scrap pieces lying around at home and the drives are quite cheap. A pair of martellos would make a nice gift or just a desktop speaker.
22mm particle board or 12mm particle board? I have some scrap pieces lying around at home and the drives are quite cheap. A pair of martellos would make a nice gift or just a desktop speaker.
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I would suggest the 12mm because it will be a challenge to scale the design for the thicker board. I'm not much of an expert on particle board - don't know how suitable it is for this project. But it's DIY - give it a go and let us know if you like the sound !
Go with the 12mm. For a box this small, it should be enough. If course, particle board would not be my first or second choice.
Okay, as i thought the 12mm would be better. I still have some left from my Mar-Kel70 build. I found the FR88EX in sweden for ~$45/each which seems to be a quite ok price.
That is not bad. They are up around $50 now after Neo inflation. I paid a little over half that for mine.
dave
dave
Yes i was actually a little "shocked" about the good price. Only ~$5 higher than at madisound, and that's across the ocean where things usually are a lot cheaper than here.
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I paid $22.75 each back in February. Now they are listed for $39.90. That is a huge increase. I probably would not have built my Martello's if the drivers had cost that much. Glad I got them when I did.