{"id":6225,"date":"2016-12-30T13:46:03","date_gmt":"2016-12-30T13:46:03","guid":{"rendered":"http:\/\/www.audioexcite.com\/?page_id=6225"},"modified":"2019-01-07T15:32:03","modified_gmt":"2019-01-07T15:32:03","slug":"bowers-wilkins-685-review-part-4","status":"publish","type":"page","link":"https:\/\/www.audioexcite.com\/?page_id=6225","title":{"rendered":"Bowers & Wilkins 685 review part 4"},"content":{"rendered":"

Disclaimer!<\/span><\/h3>\n

 <\/p>\n

In this final review part I suggest some modifications to the B&W 685 loudspeaker cross-over. Even though I think these mods improve the sound of this loudspeaker I can\u2019t guarantee that everyone likes it better than the original cross-over.<\/p>\n

If you had this loudspeaker for a long time, you might have got used to the sonic profile of it and might not like the mods. I suggest listening to the chosen mod for a longer period of time before making final judgement. If you swap back and forth between the original cross-over and the mod you might be influenced by the \u201cloudness\u201d character of the original cross-over compared to the more neutral and balanced mods.<\/p>\n

If you haven\u2019t owned this loudspeaker before and like DIY experimenting, go find a pair second hand for a good price, test the mods and explore the world of DIY loudspeakers. The B&W uses high quality drivers and is a good speaker even though if you in the end keep the original cross-over.<\/p>\n

Choose your mod level and have fun!<\/p>\n

Cross-over Mod 0<\/span><\/h3>\n

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

This is the simplest modification suggestion, hence the name Mod 0. Actually it\u2019s only a tweeter level adjustment. Thanks to the bi-wiring capabilities of the binding post you don\u2019t even need to open the enclosure. Connect a high quality MOX resistor of 1.0-2.2 ohms between + terminals as shown in the below picture \u2013 that\u2019s it!<\/p>\n

<\/a>
\nMake sure you connect your loudspeaker cable to the lower terminal when using the above Mod.<\/p>\n

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

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

Left:<\/strong> On-axis, 2.2 ohm resistor
\nRight:<\/strong> On-axis, 2.2 ohm resistor, reverse tweeter polarity.<\/p>\n

The 1.0 ohm resistor dampens the tweeter 1.5-2dB between 8-20kHz and the 2.2 ohm about 2.5-3.5dB. You can use any resistor value between 1.0-2.2 ohm in order to fine tune the tweeter level to your own liking. The frequency plot shows a slightly deeper notch at the cross-over point for the reverse polarity check, indicating that the phase behavior is unaffected by the mod.<\/p>\n

Cross-over Mod 1<\/span><\/h3>\n

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

This mod is a bit more complex and requires you to open the enclosure and remove the original cross-over. This mod suggests that you keep the coil in the mid-woofer section from the original cross-over, in order to reduce the cost for the new cross-over. If you want to keep the original cross-over intact and don\u2019t want to unsolder the coil from the cross-over board \u2013 Go to the mod 1.5 instead.<\/p>\n

If you can\u2019t find an 18uF cap, use a 10+8.2uF cap connected in parallel instead.<\/p>\n

Note!<\/strong> For a perfect phase behavior and driver time alignment, it\u2019s required to tilt the enclosure backwards about 5 degrees. Listening height is slightly below tweeter level (10-20mm).<\/p>\n

 <\/p>\n

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

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

Upper left:<\/strong> On-axis frequency response.
\nUpper right:<\/strong> On-axis frequency response vs. original cross-over.
\nLower left:<\/strong>\u00a0 On-axis frequency response, reverse tweeter polarity.
\nLower right:<\/strong> Individual driver unit phase tracking.<\/p>\n

Mod 1 uses a third-order Bessel topology (acoustical) and the cross-over point is at 2.7kHz. This cross-over is a bit \u201chotter\u201d in the 0.5-2kHz region, but flatter and more linear from 2kHz and upwards compared to the original cross-over.<\/p>\n

The tweeter reverse polarity check show a deep notch at 2.7kHz and the individual driver unit phase response show a close phase tracking, indicating a good phase behavior at, below and above the cross-over frequency.<\/p>\n

Cross-over Mod 1.5<\/span><\/h3>\n

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

Choose the mod 1.5 if you don\u2019t want to reuse the 1.35mH coil from the original cross-over or\/and don\u2019t want the \u201chotter\u201d frequency response between 0.5-2kHz compared to the original cross-over and mod 1.<\/p>\n

The 1.35mH (17AWG) coil is replaced by a 1.50mH (15AWG) coil.<\/p>\n

If you can\u2019t find an 18uF cap, use a 10+8.2uF cap connected in parallel instead.<\/p>\n

Note!<\/strong> For a perfect phase behavior and driver time alignment, it\u2019s required to tilt the enclosure backwards about 5 degrees. Listening height is slightly below tweeter level (10-20mm).<\/p>\n

 <\/p>\n

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

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

Upper left:<\/strong> On-axis frequency response.
\nUpper right:<\/strong> On-axis frequency response vs. original cross-over.
\nLower left:<\/strong>\u00a0 On-axis frequency response, reverse tweeter polarity.
\nLower right:<\/strong> Individual driver unit phase tracking.<\/p>\n

Mod 1.5 uses a third-order Bessel topology (acoustical) and the cross-over point is at 2.5kHz. This cross-over is flatter and more linear from 2kHz and upwards compared to the original cross-over.<\/p>\n

The tweeter reverse polarity check show a deep notch at 2.5kHz and the individual driver unit phase response show a close phase tracking, indicating a good phase behavior at, below and above the cross-over frequency.<\/p>\n

Cross-over Mod 2<\/span><\/h3>\n

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

Mod 2 is the full mod and gives you the flattest frequency response as well as the most balanced sound.<\/p>\n

If you can\u2019t find an 18uF cap, use a 10+8.2uF cap connected in parallel instead.<\/p>\n

Note!<\/strong> For a perfect phase behavior and driver time alignment, it\u2019s required to tilt the enclosure backwards about 5 degrees. Listening height is slightly below tweeter level (10-20mm).<\/p>\n

 <\/p>\n

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

Mod 2 uses a third-order Bessel topology (acoustical) and the cross-over point is at 2.7kHz. C3+L3+R2 notch out the slightly “hot” frequency response between 0.5-1kHz and reduces the level about 2-2.5dB in that region. Its frequency response is flatter and more linear compared to the original cross-over.<\/p>\n

The tweeter reverse polarity check show a deep notch at 2.7kHz and the individual driver unit phase response show a close phase tracking, indicating a good phase behavior at, below and above the cross-over frequency.<\/p>\n

Happy DIY!<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Disclaimer!   In this final review part I suggest some modifications to the B&W 685 loudspeaker cross-over. Even though I think these mods improve the sound of this loudspeaker I can\u2019t guarantee that everyone likes it better than the original cross-over. If you had this loudspeaker for a long time, you might have got used […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-6225","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.audioexcite.com\/index.php?rest_route=\/wp\/v2\/pages\/6225","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.audioexcite.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.audioexcite.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.audioexcite.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.audioexcite.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6225"}],"version-history":[{"count":20,"href":"https:\/\/www.audioexcite.com\/index.php?rest_route=\/wp\/v2\/pages\/6225\/revisions"}],"predecessor-version":[{"id":7199,"href":"https:\/\/www.audioexcite.com\/index.php?rest_route=\/wp\/v2\/pages\/6225\/revisions\/7199"}],"wp:attachment":[{"href":"https:\/\/www.audioexcite.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6225"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}