Bestbuy Insignia - moded a la Dennis Murphy

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Hello everyone.

Nothing to special here, but I did notice that no one reported their results with the Dennis Murphy's Insignia mod: http://murphyblaster.com/content.php?f=insignia.html
I received a pair of Bestbuy Insignias for X-mas and decided to mod the x-over according to his design. Here are my findings:

The Insignias are cheaply built. The front panel or the enclosure is made of two pieces joined vertically. You can see it only once you've removed the glossy baffle which probably helps stiffen things up. The damping material used in the enclosure could be easily improved on. I will probably stick a layer of carpet foam with a thick layer of tile adhesive. This adhesive looks like tar and smells like it so I will leave the speakers open to dry for a good week. The tar/glue is so heavy I'm hoping it will help dampen things a little more. Specially on the top and bottom panels where Insignia has put nothing at all. Stock, the speakers sound ok for the price but to me they sound a little boomy, the male voices are recessed and the treble is harsh.

With Dennis Murphy's x-over, the differences are not night and day but it is a nice improvement. For some reason they don't sound boomy to me anymore. Surprising since Dennis says it's something his x-over doesn't address. The male voice are definitely better as the mid range has been filled up. The treble still sounds a little harsh from time to time but it's an improvement. The treble harshness is also very variable. It depends on the track I play and on the recording format. For example lower bit rate MP3 or oven 192kbs that have been encoded a long time ago with an older version of Lame encoder sound terribly harsh. I suggest you do your listening tests with CDs because these tweeters are definitely on the revealing side. I used the latest lame encoder 3.98 beta 6 and encoded at v=2 and it seamed to help quite a bit. You can get it here: http://www.rarewares.org/mp3-lame-bundle.php

If you decide to rebuild the x-over keep in mind that Dennis re-used the 0.70mH ferrite inductor from the Insignia x-over and it was meant to be use on the woofer as L1011. Also the 5ohm resistor R1031 can generate some heat if you like to play your music very loud. I suggest you mount it in a way that allows air to circulate all around it and do not glue any components to it. An even better solution would be to replace it with two 10ohms resistors in parallel, also mounted with room for air to circulate around them. Mine got so hot while I was testing, I was worried it could damage the capacitor it was glued to. For the capacitors I used two electrolytic mounted in parallel because I couldn't find the right values. This could make them a little more robust , I don't know. So for C1031 at 65uF I used 18+47uF. For C1041 at 50 uF I used 22+27uF.

I'm happy with the way they sound over all and they can play very loud before they distort... I was very surprised. I used an old 90w receiver/amp and I was never able to play them louder then half way... Started to sound a little distorted (but no clipping) and my ears were begging me to turn it down. A friend of mine is going to use these for his HT system and I can't imagine a better use for them. For pure music listening, they are very nice for background music or slightly higher level. For medium listening levels or higher they are definitely fatiguing with some tracks. Other tracks are just fine.

Hope this encourages some of you to try this mod. I recommend it fully. I give thanks to Dennis Murphy for his generosity and patience.

Peter
 
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