I'm currently building the following pair for my bedroom. Gluing is slow 'cause I only have a few clamps; short ones too 🙁
The MTM enclosures are vented with hand-routed flares. Disassembled, with drivers and all, each box weighs almost 20kg! I used 18mm MDF. Should've doubled the baffle thickness though
The drivers are:
6.5" ReSponse Kevlar woofers and Vifa D26NC-15-06 (D26NC-55-06) 1" tweeters. At AU$79 a pop, the woofers aren't exactly cheap! But I didn't pay much for the drivers 'cause I casually work at JE in between classes at the University.
I'd be interested to see if anyone has taken measurements of these woofers. The screenshot linked from the woofer's website is only of a BB6 simulation 🙄 The FRD files would help in designing the crossovers. Liberty Instruments is taking an awfully long time to reply with pricing and ordering details about their (Kim Girardin) calibrated microphones 😡
Isaac
The MTM enclosures are vented with hand-routed flares. Disassembled, with drivers and all, each box weighs almost 20kg! I used 18mm MDF. Should've doubled the baffle thickness though
The drivers are:
6.5" ReSponse Kevlar woofers and Vifa D26NC-15-06 (D26NC-55-06) 1" tweeters. At AU$79 a pop, the woofers aren't exactly cheap! But I didn't pay much for the drivers 'cause I casually work at JE in between classes at the University.
I'd be interested to see if anyone has taken measurements of these woofers. The screenshot linked from the woofer's website is only of a BB6 simulation 🙄 The FRD files would help in designing the crossovers. Liberty Instruments is taking an awfully long time to reply with pricing and ordering details about their (Kim Girardin) calibrated microphones 😡
Isaac
Looking good m8.
The Vifa D26 is a great treble unit and the build on the mid/bass looks spot on too.
The only problem that I can see is the fact that the baffle is only a measly 18mm thick. If I were you I'd stick another layer of 18mm on the front and then redo the driver cutouts and recesses. Not what you want to hear but from past experience the difference will be audible in the form of a more 'sorted' sound.
The Vifa D26 is a great treble unit and the build on the mid/bass looks spot on too.
The only problem that I can see is the fact that the baffle is only a measly 18mm thick. If I were you I'd stick another layer of 18mm on the front and then redo the driver cutouts and recesses. Not what you want to hear but from past experience the difference will be audible in the form of a more 'sorted' sound.
You can get around the baffle thickness problem by glueing in 18mmx18mm hardwood strips on the inner seams of the baffle and around all the cutouts. Use PVA or even better 2-part epoxy.
I've actually saw those drivers today at my local Jaycar. The quality looks really nice but you definitely need to get some sort of measurements. Cheapest option for now could be a Tandy SPL meter taking measurements every 3rd octave or so.
Your woodwork looks very professional by the way.
Cheers
David
www.gattiweb.com
I've actually saw those drivers today at my local Jaycar. The quality looks really nice but you definitely need to get some sort of measurements. Cheapest option for now could be a Tandy SPL meter taking measurements every 3rd octave or so.
Your woodwork looks very professional by the way.
Cheers
David
www.gattiweb.com
Thanks for the kind words!
I had decided to double the baffle thickness, but I thought these new sheets of MDF I bought could be used for another project. I've 5 Vifa M22WR-09-06 woofers just waiting to be used 😀 Boy this hobby is really addictive! So I just decided to finish up the whole thing as is.
I managed to glue up one of the pair last night, so I fired up the midbass drivers to see if there were any air leaks. The port is quiet thanks to the flares shown below.
The tweeters aren't connected yet, but vocals come out quite well. I'll wait 'til the other one is glued up, and both are fitted with crossovers, before I make a side-by-side comparison to my B&W 601-III -- my only pair of speakers.
Martinlo, I'll be building a site detailing design and construction. I'll bump this thread up when the site is done.
David, your speakers are impressive (!!) and they must have taken a lot of time to build! These are actually my 2nd pair of DIY speakers. I built the 1st pair, which I gave away, 10 years ago when I first learned of vented-box resonance 🙂
I skimmed through a recent issue of Silicon Chip, and it looks like Altronics has a very good SPL meter, measures very flat right up to about 16kHz if memory serves me well. Not eactly cheap, and I'd rather spend the money on a Girardin mic. Won't be long now 'til I get a response from libinst regarding shipping cost and payment options. I'll just have to do a temp crossover by ear for now
Cheers!
I had decided to double the baffle thickness, but I thought these new sheets of MDF I bought could be used for another project. I've 5 Vifa M22WR-09-06 woofers just waiting to be used 😀 Boy this hobby is really addictive! So I just decided to finish up the whole thing as is.
I managed to glue up one of the pair last night, so I fired up the midbass drivers to see if there were any air leaks. The port is quiet thanks to the flares shown below.
The tweeters aren't connected yet, but vocals come out quite well. I'll wait 'til the other one is glued up, and both are fitted with crossovers, before I make a side-by-side comparison to my B&W 601-III -- my only pair of speakers.
Martinlo, I'll be building a site detailing design and construction. I'll bump this thread up when the site is done.
David, your speakers are impressive (!!) and they must have taken a lot of time to build! These are actually my 2nd pair of DIY speakers. I built the 1st pair, which I gave away, 10 years ago when I first learned of vented-box resonance 🙂
I skimmed through a recent issue of Silicon Chip, and it looks like Altronics has a very good SPL meter, measures very flat right up to about 16kHz if memory serves me well. Not eactly cheap, and I'd rather spend the money on a Girardin mic. Won't be long now 'til I get a response from libinst regarding shipping cost and payment options. I'll just have to do a temp crossover by ear for now
Cheers!
Hey there bowdown. They've been playing for weeks now. The crossovers were adjusted using trial-and-error because my measurement microphone hasn't yet been calibrated. Given this, and the fact that the woofers aren't of the branded type, the resultant sound quality is impressive!
Liberty Instruments didn't reply to my last email so I decided to build my own mic instead. I just gotta find some free time to go to our University's acoustics lab; to have my microphone calibrated against their lab mics. (This is way practical compared to forking out over $200 for a KG mic.)
The MDF enclosures are probably going to stay oh naturale. I bought a long length of Consolidated Edgings-brand walnut veneer, which I had planned to use on this particular project, but I decided to use the veneer on another project in the very near future.
This site already has construction pictures. It will be updated with more pictures and some design/simulation details when my microphone is finally calibrated.
Cheers 🙂
Isaac
Liberty Instruments didn't reply to my last email so I decided to build my own mic instead. I just gotta find some free time to go to our University's acoustics lab; to have my microphone calibrated against their lab mics. (This is way practical compared to forking out over $200 for a KG mic.)
The MDF enclosures are probably going to stay oh naturale. I bought a long length of Consolidated Edgings-brand walnut veneer, which I had planned to use on this particular project, but I decided to use the veneer on another project in the very near future.
This site already has construction pictures. It will be updated with more pictures and some design/simulation details when my microphone is finally calibrated.
Cheers 🙂
Isaac
Looking very nice. Could not seem to find any woofer measurements at Jaycar but looked like nice drivers. I think they were down to $45 each in my local store on sale a few weeks back. Very interested to see your listening impressions.
In the outer west Sydney suburbs, 45min to the CBD by train, +20min. thanks to daily $hittyRail delays. We should all have a DIY Sydney gathering... Like we had planned a couple of years ago 😀
I'm always at the USyd if not at work; I'm always in the city regardless.
I'm always at the USyd if not at work; I'm always in the city regardless.
Too bad the woofers are 4 ohms. Two in parallel gives only 2 ohms. Isn’t that too low for most home amps?
Nice job on the boxes.
Nice job on the boxes.
2-ohms is bad, but I got 'em running in series. This way, the sensitivity, is actually good enough. They're serving as computer speakers in my 4m x 3.5m bedroom. They're really loud for such a small room.
In series you lose 6 dB sensitivity. They'e rated at 87.73 so that brings them down to 81.73. you will need to pad the tweeters by -8.27dB.
sorry, but that's not correct..
when you put a pair of drivers in series, you get a gain of 3dB from having 2 drivers, then loose it again because the amp sees twice the impedance.. net gain/loss is zero !
I guess in a way though, you could say its a 6dB loss relative to wiring them in parallel..
when you put a pair of drivers in series, you get a gain of 3dB from having 2 drivers, then loose it again because the amp sees twice the impedance.. net gain/loss is zero !
I guess in a way though, you could say its a 6dB loss relative to wiring them in parallel..
Member
Joined 2002
I'm aware of the 0dB sensitivity change with series drivers of course 😉 It's not an issue with such a small listening room. With WindowsXP's volume control at 80%, and my elcheapo Pioneer A-102 amp's volume knob positioned at 50%, I'd have to speak out loud to be heard.
Thanks for the kind words jleaman 🙂
Thanks for the kind words jleaman 🙂