Home > 3-way, 5-8, 60-90lbs, Active/Passive Combination, Bass Reflex, Tower/Floor Standing > Odyssey Speaker System by Brad Korstange

Odyssey Speaker System by Brad Korstange


My speakers

General Overview:

I wanted to build a pair of tower speakers that would work well will my home theater system that i am in the process of making. I chose tower speakers because with a tower speaker you don’t have to find or make speaker stands and they end up at about the right height while sitting on a normal couch.

Design Goals:
My goals for these speakers were tower speakers! that  was the first and most important thing i wanted. after that the goals get more technical, I wanted them to be able to have a frequency range from 20-40 Hz to 20 kHz. I wanted them to be able to handle both low SPLs as well as high SPLs. Since they will mainly be used in small apartments the drivers don’t need to have the greatest sensitivity.
Design objectives:
• Tower Speaker (I didn’t want to have to build/find speaker stands)
• Capable of handling low SPLs
• Little to no fatigue while listening for extended periods of time
• Good low frequency response for watching movies
Key Features:
• 3 way design
• Active/passive combination
• Vented sub woofer enclosure for extended low frequency response
• Active subwoofer for easy balancing
Technical Specifications:
• Bandwidth 35 Hz-20+ Hz +- 4 dB
• Max SPL 85 dB with 20 dB headroom
• f3 38 Hz
• f10 25 kHz
Cabinet Construction:
My cabinets are made out of 3/4 inch 13 ply baltic birch plywood and 1/2 inch MDF, this was done to keep the boxes resonance down. Plywood because of its construction with alternating grain plys and the glue is know to have acoustical deadening properties and the MDF is dense and helps with the deadening of the cabinet.
First lets look at the subwoofer box, it is composed of a front baffle that is 2 layers of 3/4 inch 13 ply baltic birch plywood and 1 layer of 1/2 inch MDF. the reason for this is because when i got my 10 inch subwoofer I realized how massive it was and i wanted to flush mount it so i needed more support than 1 layer of plywood and 1 layer of MDF. the rest of the cabinet is composed of 1 layer of plywood and 1 layer of MDF glued together.
Second lets look at the mid/tweeter box, it is composed of 1 layer of plywood, because my speakers were originally designed to be dipole so i only had a layer of plywood but as i went through testing of my speakers I discovered that it would be beneficial to enclose the mid/tweeter, so I added a back and top to the mid/tweeter box.
Tweeter:
I chose the Eton 25 SD-1 which is a 1 inch soft dome tweeter, which has an excellent frequency response about 800 Hz to 30kHz. Which gives me a wide range to place my crossover in order to create a smooth frequency response.
Midrange:
The mid range driver I picked is a Creative Sound Solutions FR125SR it is a 4.5 inch driver that is a full range driver and has been incorporated into several open baffle designs previously, which is part of the reason I picked it. how ever for this I liked that it was a full range driver allowing me the option of selecting a crossover point that would work the best. Its frequency response is about 100 Hz to about 6 kHz before it goes a bit wonky.
Subwoofer:
For the subwoofer I went with a Creative Sound Solutions SDX10 which is a 10 inch woofer that is specifically designed for smaller ported cabinets.
Cross-over:
I decided pretty early on that I wanted a 3 way system, how ever our current equipment is some what limited so actually being able to test multiple crossovers for a 3 way system would be pretty difficult. So my solution to this problem presented it self when I was offered a power to test/try out so I decided to go with it and go partially active. I figured that since the crossover components for the subwoofer would be fairly expensive any way why not just spend a bit of money and make the subwoofer active. It would give me easy access to change the crossover frequency as well as the level.
For the mid and tweeter I ended up crossing them over at around 2kHz after experimenting a bit with higher crossover points I decided that 2 kHz worked the best for my drivers. I also ended up adding a 9 dB pad to the tweeter and a 9 dB baffle step compensation circuit to it as well, to tone down the brightness of them.
Documentation:
Testing:

Overall Speaker Performance:

Frequency Response

Full range Frequency response

Harmonic distortion

Please note the scale, y axis only goes to 10

Step Response

Not entirely sure what this graph shows but it is required

Minimum Phase

looks fairly flat to me

Off Axis Response

Blue is on axis, Green is 15 degrees off axis, Red is 30 degrees off axis, and Maroon is 456 degrees off axis

Cross Over Filter Response:

Blue is the subwoofer filter, Red is the midrange filter, and Green is the tweeter filter

Frequency response with individual drivers overlayed

Maroon is the overall response, Green is the subwoofer, Red is the midrange and Yellow is the tweeter

Tweeter Performance:
Frequency Response

Tweeter

Distortion

I'm impressed

Step Response

Looks a bit weird to me

Minimum Phase

It works for me

Off Axis
Red is on axis, Green is 15 degrees off axis, Blue is 30 degrees off axis, and Yellow is 45 degrees off axis
Midrange Performance
Frequency

Yep looks kind of bad in the 300 to 500 Hz range

Distortion

not to bad

Step Response

nice shape

Minimum Phase

pretty flat

Off Axis Response
Yellow is on axis, Blue is 15 degrees off axis, Green is 30 degrees off axis, and Red is 45 degrees off axis
Subwoofer Performance
Off Axis Response

I can't really remember what color is what but as you can see not much happens as you move off axis

Minimum Phase

keep in mind that the sub cross over is at around 100 Hz so everything above that is kind of useless data

Distortion

for the frequency range it is used it looks pretty good

Creative Commons License
Odyssey Speaker System by Brad Korstange is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

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  1. September 14, 2010 at 10:13 pm

    These enclosures are probably viewed only by their creator as attractive.
    Despite a good deal of measured test results, there is no info about listening tests which after all is what this is all about.
    Speaker enclosures need to satisfy simple requirements:
    Perform well in most listening situations with a wide variety of music/voice sources.
    Be cost effective in achieving the desired performance.
    Meet minimum standards of aesthetics, bearing in mind they will be on display “front & centre” in most homes.
    Do these speakers meet this expectation?

  2. Alex
    May 28, 2011 at 5:51 pm

    Loved the look and shape of the speakers. They are somewhat rustic and definitely original.

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