|2nd January 2013, 10:16 PM||#1|
Join Date: Jun 2005
Here I present my RefSpeaker, I have just finished them and I'm very pleased with the result
I wanted to make a speaker that ended my quest and lust for something better so it should be something very very good.
When visiting some audio shows there were some speakers that I liked a lot, most of them had an Accuton as midrange.
What I really like about those Accutons is their ability to create a holographic view into the music.
Problem with those speakers that I liked at the audio shows is the price, they were in the way too high range of 20000-50000€
So as a DIY guy I thought I can do this for 1/10th of the price
The most important design goals that I tried to accomplish are:
1) completely transparent and natural sounding
2) very detailed over the whole spectrum without sounding thin or harsh.
3) relative high sensitivity, 93db or more so I can use my great F5 (Thx Mr Pass!)
4) should be able to do 30-20000 with good deep bass
5) low distortion, also at high output levels.
6) moveable, so I don't need a forklift when I want to put them in another room.
7) passive crossover
8) good looks
I started working around the Accuton C173-6-090 mid driver,
this is a beautiful mid with very low distortion, high sensitivity and no nasty breakups, I've been able to buy them at 400€ before the Neodymium prices skyrocketed, now they cost almost double.
As tweeter I've often seen the Raal ribbons in conjunction with Accutons, so I took the Raal 140-15D amorphous core, also because I like the relaxed sound of ribbons.
Now for bass I needed something that it is also detailed as the Accuton mid so it would blend nicely with it, that means also hard cones.
If cost was totally no object I would have bought some 11" Accuton bass drivers, they have the matching performance and looks.
But I found a nice substitute(much cheaper) in the Alcone AC10HE, a 10" woofer with an extremely rigid anodized aluminum cone, they're 90db so two of them should match the Accuton mid. A nice bonus is their silver-white color.
Once the drivers arrived I started working on the cabinets, the bass and the mid/high are separated, mainly for easily moving them around, but this way they're also acoustically decoupled.
The cabinets are made of 18mm birch multiplex, the bass cabinet is about 80 liters with plenty of bracing on the inside and a front-panel made of 18mm birch + 30mm MDF, bass-reflex pipe is at the bottom.
The dimensions of the cabinets are calculated according to the golden ratio to avoid standing waves with the help of boxnotes
The mid/tweeter cabinet is shaped with some wings, inspiration comes from the starfighters in Battlestar Galactica
the compartment for the Accuton mid has an irregular shaped backside, is only 3.5 liters and is aperiodic vented, the rest of the cabinet is room for the crossover.
The crossover is fairly simple: third order electrical on the woofers to suppress the breakup of the cones. 2nd order on the mid, no need for notches.
3rd order on the Raal.
It took me 30+ versions before I finally arrived at a version that sounded and measured good.
Crossover points at 220Hz and 3000Hz.
Minimal impedance: 3ohm
The quality of the crossover components is very important for these drivers, give it crap and you will hear it.
For the woofer I used transformer coils with the lowest possible resistance: two 5.6mh coils in parallel for 2.8mH 0.075ohm and two 2.2mh coils in parallel for 1.1mH 0.050ohm
The Accuton mid has Jantzen wax coil and Siemens MKV caps in series.
For the Raal ribbon I used Audyn reference caps bypassed with Audyn true copper caps + 10nF silver mica and as resistor a Duelund graphite (makes big difference compared to standard sand cast)
Now that they're finished I just listen to the music that flows over me, it has become very easy to completely immerse into the music
Last edited by danny_66; 26th July 2014 at 06:33 PM.
|3rd January 2013, 09:40 AM||#9|
Join Date: Sep 2007
Congratulations! Nice build.
Author of the "AudioExcite Loudspeaker Design" website
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