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Old 4th November 2011, 06:56 PM   #121
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Quote:
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Wow, I didn't know the price was up that much, makes my little speakers more valuable
I invested in them before they went up. I have 22 of them.

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Old 5th November 2011, 01:19 AM   #122
Bigun is offline Bigun  Canada
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Will they be getting the polka dot treatment ?
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Old 5th November 2011, 01:45 AM   #123
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At some point likely. We were considering doing them up as a fill-in for the old FF85, but the price jump and the new FF85 killed that idea.

We are likey going to build an experimental array

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Old 21st April 2012, 11:24 AM   #124
Bigun is offline Bigun  Canada
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Well it looks as if prices are reasonable on these drivers (e.g. Madisound $39.90). I may build another pair.

I thought I'd update this thread with some more data.

First image are the calculations I used for the horn-shaped slot port.

Second image shows the simulated impedance curves for a straight bass-reflex design. Note the two peaks, typical of a BR design the interaction of the driver and box, they are roughly the same height. The simulated resonance peaks are at 50Hz and 140Hz.

Third image shows the measured impedance curves. I used my DIY TGM3 amplifier (solid state) with a resistor in series with the ground wire and a DMM across it to measure the rms voltage and used this to calcite the current and along with the signal amplitude the impedance of the speaker. I used a sine wave generator signal source. The vertical axis is not calibrated in Ohms but it is linear. The measured resonance peaks are at 50Hz and 140Hz, matching the BR simulation. BUT note that the left hand peak is much smaller - a result of the damping provided by the Onken style ports.
Attached Images
File Type: jpg IMG_0420Z.jpg (136.3 KB, 538 views)
File Type: jpg MartelloZcalc.jpg (123.1 KB, 497 views)
File Type: jpg MartelloImpedance.jpg (31.4 KB, 481 views)
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Old 19th May 2012, 07:56 PM   #125
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I realised now that tomorrow will be a boring day with nothing to do. Why not use some of the scraps of 12mm and 22mm particle board in my garage and build a pair of Martellos? This time I will focus on making them look as good as possible and if they turn out well I'll buy drivers, binding posts and damping material
Should be able to build a pair in just a few hours
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Old 19th May 2012, 11:38 PM   #126
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Must be nice not to have an infinite list of honeydos. Make hay while the sun shines. You're time is coming:-)
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Old 20th May 2012, 01:45 PM   #127
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Most pieces cut
Took more time than expected because my dad had "stolen" all the tools so all I had was a handsaw... And when I came to the point of putting the pieces together I found out that I had no glue and no wooden plugs :S
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Old 20th May 2012, 07:51 PM   #128
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by Rullknufs View Post
I realised now that tomorrow will be a boring day with nothing to do. Why not use some of the scraps of 12mm and 22mm particle board in my garage and build a pair of Martellos?
over here it's a long weekend, we get Monday off - the country celebrates Queen Victoria's birthday and we do that with horizon-to-horizon blue skies, 30 deg.C and a cold beer or two

Good luck with the build - but it's handy having the drivers to hand in order to size the opening / clearance whilst still keeping enough wood for the mounting screws to bite into - it's a bit of a balancing act so be careful with that.

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Must be nice not to have an infinite list of honeydos. Make hay while the sun shines. You're time is coming:-)
and that's the other balancing act !
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Last edited by Bigun; 20th May 2012 at 07:53 PM.
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Old 20th May 2012, 07:55 PM   #129
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So should we, back in the old country. However, we do have Her Majesty's Diamond Jubilee celebrations in a couple of weeks.
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Old 20th May 2012, 08:02 PM   #130
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Quote:
Originally Posted by Bigun View Post
over here it's a long weekend, we get Monday off - the country celebrates Queen Victoria's birthday and we do that with horizon-to-horizon blue skies, 30 deg.C and a cold beer or two

Good luck with the build - but it's handy having the drivers to hand in order to size the opening / clearance whilst still keeping enough wood for the mounting screws to bite into - it's a bit of a balancing act so be careful with that.
We also had long weekend, but last thursday and friday was "free" for me. Unfortunately I had to help dad clear some huge (yes, huge!) fallen trees at our summer house. About +10c and rain those two days...
I'll be careful when doing the baffles, to make sure I got enough wood for the screws. Wont be easy but with some precision work it should work
Was +5c and rain today... Will be warmer tomorrow it seems.
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