Found 8 inch woofer replacement for AR7

[Guest ginshin99]

I have a pair of AR7. I sent them in for repair around 20 years ago. The shop replaced the woofers with two no-brand paper woofers. They just never sounded right afterwards. Since then I moved to DIY speakers and did not use them. Nonetheless, I checked every few years to see what I can do with them.

A few years ago, I found one of the tweeter was shot and replaced it with a genuine AR tweeter. To my dismay, the new tweeter looks the same but is much louder than the original one. I also coated the paper cone with puzzle coat and did not hear any difference. Finally, I gave them to my son to use in his dorm. A few weeks ago, he blew one of the woofer so I was out looking for replacement woofer again.

As these speakers are not in top shape and are used in a dorm, I do not want to pay top dollars to buy "replacement" woofers. I decided to find generic 8 inch woofers from Parts Express and MCM Electronics.

AR7 is a very small speaker. It is difficult to find woofers that will work. Finally, I found MCM 55-1940 that should do well. I used a box calculation tool on the Internet to check the frequency response. F3 should be around 75 Hz with Q at 0.96. Not low but OK. The most important part is that they cost only 15.95 each and are 8 ohm.

I received them a week ago. They look very well built. The paper cones are stiff with foamed EVA surround. The basket is a little bit too big to fit. I have to file down the woofer hole a bit to put them in. After a few hours of beak-in. They sound awesome. The bass is tight and deep enough. When I play drum music, I can once again "feel" the drum. Since I do not have original AR7 to compare, I don't know how authentic they sound.

These woofers are not perfect yet. Some minor adjustment of the crossover cap may be needed to have a smoother transition for the new tweeter. The original tweeter may be too weak to match with the new woofer. But overall, they sound amazingly good. I strongly recommend it for AR7 owners.

I have also put them into my RA Lab speakers. The size of the RA Lab speaker is very similar to AR-4x. The woofers are supposed to be Roy Allison design. The MCM woofers sounds much better than the original 8 inch woofer with a bit loss in low end extension.