{"id":4219,"date":"2014-01-03T13:00:51","date_gmt":"2014-01-03T13:00:51","guid":{"rendered":"http:\/\/www.audioexcite.com\/?page_id=4219"},"modified":"2020-11-28T14:45:01","modified_gmt":"2020-11-28T14:45:01","slug":"satori-two-monitor","status":"publish","type":"page","link":"https:\/\/www.audioexcite.com\/?page_id=4219","title":{"rendered":"Satori Two – Monitor"},"content":{"rendered":"

Concept:<\/span><\/h3>\n

 <\/p>\n

\"\"<\/a>\"\"<\/a>\"\"<\/a><\/p>\n

Satori Two \u2013 Monitor<\/strong><\/span> is a large sized 2-way stand-mount loudspeaker for small to medium sized listening rooms. The loudspeaker uses custom built enclosures with a stepped baffle configuration in order to time align the driver units.<\/p>\n

Note!<\/strong> The tweeter grill can be removed if you don\u2019t like the look of it. Removing the grill doesn\u2019t affect the frequency response or the loudspeaker performance in any way.<\/p>\n

Loudspeaker driver units:<\/span><\/h3>\n

 <\/p>\n

Satori Two \u2013 Monitor<\/strong><\/span> uses a 4\u2126 mid-woofer from the SB Acoustics Satori series. The Satori MW16P-4 driver is one of the very best mid-woofers in its size, available to the DIY market today. It has a nice bass performance and a very nice mid-range reproduction, combined with very low distortion.<\/p>\n

The tweeter section consists of a compact sized 4\u2126 driver from ScanSpeak Illuminator Series. The D3004\/602010 tweeter has a small face plate which allows a close center to center spacing between the mid-woofer and tweeter. It has great off-axis dispersion combined with low distortion.<\/p>\n

For further details see:
\nSB Acoustics Satori MW16P-4<\/a>
\nScanSpeak D3004\/602010<\/a><\/p>\n

Cabinet:<\/strong><\/span><\/h3>\n

 <\/p>\n

The<\/span> Satori Two \u2013 Monitor<\/strong><\/span> uses a custom built 20 liter enclosure. The enclosure is made of 19mm MDF and uses internal braces in order to make the enclosure more rigid. The baffle is made of two 19mm MDF pieces in order get a \u201cstepped\u201d baffle design and has an 18mm baffle edge round-over in order to reduce baffle diffraction.<\/p>\n

\"ST-M<\/a><\/p>\n

\"SONY<\/a><\/p>\n

 <\/p>\n

The internal cabinet walls are taped with strings of bitumen pads to reduce resonances. The enclosure is lightly filled with sheep wool. All drivers are flush mount and in order to let the mid-woofer \u201cbreathe\u201d properly, don\u2019t forget to chamfer the baffle.<\/p>\n

 <\/p>\n

Box simulation:<\/span><\/h3>\n

 <\/p>\n

\"ST-M<\/a>
\nThis is the anechoic response when using the custom built 20 liter enclosure. When the volume for the drivers, port and bracing are subtracted we have an effective net volume of about 19 liters.<\/p>\n

19 liter bass-reflex box with Fb = 36Hz (anechoic response)<\/strong>
\n-6db = 34Hz
\n-12db = 27Hz<\/p>\n

19 liter closed box with Qt = 0,6 (anechoic response)<\/strong>
\n-6db = 47Hz
\n-12db = 29Hz<\/p>\n

12 liter closed box with Qt = 0,71 (anechoic response)<\/strong>
\n-6db = 49Hz
\n-12db = 32Hz<\/p>\n

The closed box version is not tested, but could be an option if the loudspeaker is placed very close to the rear wall or actively crossed-over and used together with a sub-woofer.<\/p>\n

Cross-over design:<\/span><\/h3>\n

 <\/p>\n

The Satori Two \u2013 Monitor<\/span><\/strong> uses a true symmetrical second-order Linkwitz-Riley (LR2) filter topology.<\/p>\n

When using a shallow sloped cross-over like the LR2 filter topology, one of the most important design factors for a successful implementation is to time align the loudspeaker drivers. In this case the mid-woofer and the tweeter need to have their \u201crelative acoustic center off-set\u201d adjusted.<\/p>\n

The most common way to address the driver units relative acoustic center off-set is to use asymmetrical cross-over slopes, a sloped baffle or to use an electronic time delay circuit. In this design I use a different approach to time delay the tweeter to adjust the acoustical center off-set. It\u2019s done by using a \u201cStepped Baffle\u201d and where the mid-woofer is mounted 19mm in front of the tweeter.<\/p>\n

\"ST-M<\/a><\/p>\n

 <\/p>\n

The mid-woofer cross-over filter section is very simple and consists of a coil (L1<\/strong>) and a response shaping filter circuit (C1+L2+R1<\/strong>) and impedance equalization circuit (C2+R2<\/strong>) which shapes the cross-over slopes to a LR2 (acoustical) roll-off with a targeted 2.5kHz cross-over point. The inductor (L1<\/strong>) and the response shaping filter circuit (C1+L2+R1<\/strong>), tunes the design with a full \u201cBaffle Step Compensation\u201d (BSC).<\/p>\n

If using a different coil (L2<\/strong>) than shown in the schematics, the sum of the resistance for the coil (L2<\/strong>) and the resistor (R2<\/strong>) should be about 5,75 Ohm.<\/p>\n

\"SAT-M<\/a><\/p>\n

The effect of the response shaping circuit (C1+L2+R1<\/strong>) and the impedance equalization circuit (C2+R2<\/strong>) can be seen in this picture. Without the response shaping circuit (C1+L2+R1<\/strong>) the loudspeaker have too much energy in the mid-range and is too much forward sounding to sound natural.<\/p>\n

The tweeter cross-over filter section consists of a single tweeter padding resistor (R3<\/strong>) and a second-order electrical filter (C3+L3<\/strong>) and a response shaping circuit (C4+L4+R4<\/strong>) that shapes the cross-over slope to a LR2 (acoustical) roll-off with a targeted 2.5kHz cross-over point.<\/p>\n

Note!<\/strong> The tweeter is connected with reverse polarity.<\/p>\n

\"SAT-M<\/a><\/p>\n

As shown in this picture, (C4+L4+R4<\/strong>) flattens out the tweeters frequency response peak around 2kHz, partly caused by the added baffle diffraction of the \u201cstepped baffle\u201d design. This response shaping circuit is necessary to shape the filter to a LR2 filter slope.<\/p>\n

If using a different coil (L4<\/strong>) than shown in the schematics, the sum of the resistance for the coil (L4<\/strong>) and the resistor (R4<\/strong>) should be about 4.5 Ohm.<\/p>\n

Tweeter tuning options:<\/strong><\/p>\n

\"SAT-M<\/a><\/p>\n

The value of (R3<\/strong>) can be changed to adjust the tweeter level to personal preferences. Any resistor padding value between 1.0-2.2 is acceptable, but 1.5 Ohm is what I ended up with as the reference level.<\/p>\n

R3<\/strong> = 1.0Ohm -> +1dB @ 10kHz
\nR3<\/strong> = 1.5Ohm -> Reference tweeter Level
\nR3<\/strong> = 2.2Ohm -> -1dB @ 10kHz<\/p>\n

Cross-over simulation:<\/span><\/h3>\n

 <\/p>\n

\"SAT-M<\/a>
\n\"SAT-M<\/a>\"SAT-M<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Top:<\/strong> Tweeter-axis, 15deg off-axis response.<\/p>\n

Left:<\/strong> Tweeter-axis, 15deg off-axis response, reverse polarity.<\/p>\n

Right:<\/strong> Individual driver unit phase tracking.<\/p>\n

The reverse polarity simulation shows a very deep reverse null at the cross-over frequency, indicating a good phase tracking between the two driver units at the cross-over point.<\/p>\n

Impedance measurements:<\/span><\/h3>\n

 <\/p>\n

\"SAT-M<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Blue:<\/strong> Left loudspeaker<\/p>\n

Green:<\/strong> Right loudspeaker<\/p>\n

3.2 Ohm impedance minimum @ 400Hz. For best performance, a 4 Ohm rated and capable amplifier should be used with this loudspeaker.<\/p>\n

Frequency measurements:<\/span><\/h3>\n

 <\/p>\n

If nothing else is noted in the comments, the following frequency measurements of the finished loudspeaker are made at a 2m distance at tweeter height.<\/p>\n

All frequency response charts are presented in a 50db scale with 1\/24 octave smoothing and the measurements are valid down to 400Hz.<\/p>\n

\"SAT-M<\/a><\/p>\n

Frequency response 15deg off-axis:<\/strong><\/p>\n

Blue:<\/strong> Left Loudspeaker
\nRed:<\/strong> Right Loudspeaker<\/p>\n

Overall a very smooth frequency response. The tweeter response gradually drops from about 15kHz and is down about -3dB @ 20kHz.<\/p>\n

\"SAT-M<\/a>\"SAT-M<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Left:<\/strong> Tweeter-axis @ 2m, 0, 15 and 22.5deg off-axis.
\nRight:<\/strong> Tweeter-axis @ 2m, 30, 45 and 60deg off-axis.<\/p>\n

Between 15-30deg off-axis we have a dip in the frequency response around 5kHz due to the baffle diffraction effect. This smooths out as we go beyond 30deg off-axis.<\/p>\n

 <\/p>\n

Stepped baffle diffraction effect:<\/strong><\/p>\n

\"SAT-M<\/a><\/p>\n

\"SAT-M<\/a>\"SAT-M<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Top:<\/strong> Tweeter-axis, 15deg off-axis response blue = With felt, Red = Without felt.
\nLeft:<\/strong> Without felt 0, 5 and 10deg vertical off-axis response above tweeter-axis.
\nRight:<\/strong> With felt 0, 5 and 10deg vertical off-axis response above tweeter-axis.<\/p>\n

 <\/p>\n

\"\"<\/a>As we can see by the frequency response curves, we can smooth out the diffraction issue around 5kHz by adding some felt below the tweeter at an 45deg angle (see picture). This smooths out the frequency response considerable between 3-15kHz, but introduces another diffraction issue right in the middle of the cross-over region at 2.5kHz.<\/p>\n

Remember that dips are less audible than peaks in the frequency response. The felt tweak is more of a cosmetically frequency response curve nature, than anything else.<\/p>\n

I personally think that the loudspeaker sounds better without the added felt than with it, because the felt introduced diffraction is worse than the dip around 5kHz caused by not using felt. However, the felt tweak is an easy cheap way to test and I do recommend testing it.<\/p>\n

The listening sweet spot is a bit more limited in the vertical plane when taking the diffraction into account and I recommend sitting down and listen to the loudspeaker at tweeter height rather than standing up, which of course would be the normal thing to do anyway.<\/p>\n

Distortion measurement:<\/strong><\/span><\/h3>\n

 <\/p>\n

Measurement setup:<\/strong><\/p>\n