Speaker Asylum

Posted by nocoastjazz@gmail.com (A) on May 27, 2012 at 15:38:23

This project started nearly two years ago. I do not move fast!

I found a pair of Knight KN-800A 12" co-axial speakers in a Craigslist ad. I was initially drawn to the quality of the cabinets and had never heard of Knight speakers. A little research and I found they were common in their day and a part of the Allied Radio catalog. Date codes on the speaker frames (220113 and 220108) all but confirm they are identical manufacture to Jensens of the same type.

I did not think much of them until I got them home and hooked them up - wow! Very natural, decent bass, decent mids - these speakers LOVE to play guitar and bass. Didn't trust my judgment until another audio friend came over and remarked how nicely they sounded and immediately offered to buy them!

I knew I needed to recap the speakers but could not figure out how to get the speaker covers off. I was reluctant to scrape off the sticker decal on the covers which have the model number and other information. I ended up letting them sit forever as I moved on to other projects.

Just this week I decided I was tired of looking at them collecting dust and started hacking at the back of the speaker covers. Quickly found two phillips screws for each cover, located at 2 and 7 o'clock approximately. Once inside, I saw an ancient, huge 4.0 mfd 50v capacitor made by Chicago Industrial. I had a pair of Kimber Kaps 4.7 / 250v I thought would work nicely. 20 minutes of soldering and that was done!

I noticed the backs of the original L-pads were covered in a kind of corrosion or chalky film. I had new L-pads on hand and thought it would be best to swap them out! I just followed the original wiring layout for the L-pads.

The sound was easily improved! The highs which had been missing or muddy had opened up, and was very responsive to L-pad adjustment. Everything else I had already liked about the speakers was there - but more of it. Better, deeper bass, warm yet tight midrange and just enough air around everything.

Next up was recovering the speaker with new grill cloth. I had purchased some new cloth (retro style!) from Parts Express (I think) over a year ago. I couldn't stop now and so I forged ahead installing the new cloth and it looks pretty good.

These cabinets are built very well inside and out and the front speaker board is ingeniously screwed in so that I could remove it which allowed me to wrap and staple the board to get a tight fit. It was a pain in the butt though!!

In all, I spent $100 for the original pair of speakers and cabinets, another $50 to $75 in grill cloth, L-pads, and new caps. Before doing this work I was tempted to post the speakers for sale on Craigslist for the same $100 I had spent. Now I don't plan on selling them and if I changed my mind I will be asking a lot more!

A very decent vintage speaker and plays nicely with tube gear and vinyl!

I decided not to open up the speakers or explore a recap until I heard them perform. The cabinets you see in the pics were originally cut for 15" drivers. I fabricated an MDF panel (grey), bolted the drivers to the panel, and screwed the MDF panel to the existing front panel from the inside. Binding posts to follow but for now I just ran speaker wire directly from the drivers to my amp!

Tonight is the first night I have hooked up both drivers in some other cabinets I found (yes, another Craigslist ad). They sound open, warm, and have my feet tappin'. I just wanted to shout out a thank you to WB!



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