I have a pair of Infinity Kappa 7 speakers that I have had for about 8 years -- I bought them used. The polydome midranges on the speakers are in need of replacing (probably because my 2 year old likes to poke them). There are small cracks on the driver, which causes distortion when the speakers are moderately loud.
Some used midranges show up on Ebay, but from what I can tell, they often have holes or small cracks, and although the sellers say they work fine, I am skeptical.
So, is there anything I can do to repair the drivers? They don't appear to be too brittle. Maybe a special glue or something?
There are a couple of websites that sell replacement drivers, although they are 8 ohm, not 4 ohm like the Kappa:
(I am new and am not allowed to post linkes, so here goes)
www dot speakerex dot com/D75MX.html
www dot speakerrepair dot com/mm5/merchant.mvc?Screen=PROD&Product_Code=02-239&Category_Code=
This one looks like it is the same thing, but they don't have very good information.
www dot mark1electronics dot com/mid-range_tweeters.htm#MD-75
So, any ideas? Will any quality midrange suffice? Or am I better off moving on to something else.
Thanks,
Richard
You have a quandary. It is clearly not possible to repair your drivers. This seems to be a problem with them as you have discovered.
The speaker offered for sale by Speaker Repair, Orange County and Mark I electronics, is the Vifa/Scanspeak Dome midrange. This is a fair to poor driver. The folks at Madisound are not over impressed with it.
This is the driver in question.
Here is the spec sheet.
Now as you say, your speaker is four to six ohm nominal, but we don't know what the impedance of your midrange driver is. The Vifa over its pass band is 7 ohms. The crossover points of your speakers are 800 Hz and 4500 kHz. The top crossover point is pushing it for the Vifa unit. As you can see the frequency response of that unit is less then optimal, as is the off axis response above 4 kHz.
Now if the impedance of that driver is significantly different from your drivers, the crossover points will change and the crossover of your speakers need modifying.
The other issue is sensitivity. Your speaker have a sensitivity of 88 db 1 watt 1 meter. We don't know how much your mid is padded down by L-pad. However because of the date of your speakers I doubt the sensitivity of the driver is 92 1 watt I meter which is the sensitivity of the Vifa.
So my guess is at a minimum the replacement driver will play too loud and your speakers have a shouty midrange.
Obviously the speakers do not sound the same after replacement, as Orange County say you have to replace both drivers because the speakers sound different.
The cheapest price is Mark 1 at $68 each, next is Madisound at $90 each.
So I suspect with shipping if you gamble on this you will be in for about $150.
If you don't like what you hear then unless you have the skills to revoice and pad the crossovers, your investment will be a total loss, as you can not return installed drivers.
I think that is a lot of money to put in speakers over 20 years old, especially as changing drivers from original is seldom a happy state of affairs. The chances are you won't like what you hear.
So you will have to decide if the gamble is worth it. That driver by the way, is the only possible replacement.
