teknofossil

I would offer the theory that the grill cloth was changed and/or they are very late production. Your woofers look like the drivers that came from my AR-2aX's and the set in my AR-5's. I believe the standard grill cloth that were shipped was the off-white/beige color.

I am testing some Allison drivers, made in 1984. I noticed the Q measured with a DATS v2 is considerably different. I know the ferro fluid gets gummy with age and /or heavy use. Any thoughts on this? Thanks, Tom

Hello all. I just completed replacing some surrounds that were incorrect types installed by a previous owner (5/8" roll, over sized surround used, by cutting out a section). My question is about the replaced dust cap(s). These are of the felted (porous) type that allows air passage. Since the AR voice coil formers are the vented type, should the the dust caps be sealed? It has been my experience they should. Thoughts? -Tom

I only listened to them briefly. They sounded decent. Not like an AR, more like a JBL of the late 70's.

Thank you for the schematic. Will help a lot. Also, my comment "nice job modifying these" stems from the fact the changes are minor, the were done neatly and he obviously either knew something about speaker design or he had assistance from someone who did. In any event restoring them to their original condition should be without issues.

Hello again. I have acquired some AR-2 speakers that were highly modified. Well, I just happen to have AR-2 original drivers so I will be restoring them back to original condition. Anyone have the schematic for the original AR-2, that is the one with the dual angled mid-tweeter array module? I removed some of the solid brown stain on the cabinets and it appears these have the mahogany veneer. Also, the previouus owner did a nice job modifying these, apparently knew what he was doing or had good advice. Modifications to the cabinet appear minor (vent hole in the driver baffle and grill frame, , widening of the woofer cut out to accept a non circular woofer) Stay tuned. -T

Thank you. Obviously something is off with this woofer compared what KK's figures are. -Tom

Hello all. Does anyone know what the T/S specs on the AR 12" woofers should be? I have been going through my shop cleaning things up and found a pair of woofers that I had bought from a guy in NH years ago. I completely forgot I had these. Surrounds were replaced with what I am guessing were generic 15" woofer surrounds cut down. I ran one across my DATS and measured a free air of 19.5hz and a Qts of .25 (QMS= 2.399, Qes= .2817). Typically drivers intended for sealed enclosures is more like a Qts of.45-.5. I also found with the woofers a AR woofer surround kit from John McPeak at Msound which have the proper 5/8" width roll. Boy have my memories been dropping off the table.... Thoughts ? (no, not about my memory, the woofers) -T

Just because one has power tools, that doesn't mean they should use them...

I'm located in Springfield which is in western Massachusetts. -T

Hello all, I apologize up front if this is posted in the wrong location, moderators please move it to an appropriate page. Due to the health issues of my spouse and my plans to relocate after the situation concludes I intend to skinny down my audio projects. I have Carl's (Carlspeak) AR3a test bed systems that I planned on returning to stock condition, AR5's and drivers for the AR2A. I also have the restored set of early Bose 901 series 1 systems featured in my restoration postings in the Bose section. I also have my remaining inventory of NOS vacuum tubes from my old web shop along with unbuilt tube preamp projects (from the Tube Cad website) and many other devices and preamps. If interested please contact me through the forum. Thx, Tom H

After the Watco stain is applied the manufacturer recommends a 72 hr drying period before applying a poly type finish. I am probably next going to replicate the grill cloth frames. I have all of the parts including new transistors for the equalizer. I am hoping to not replace to funky water tower shaped transistors, but if I have to I have 20 fresh stock, all from from Mouser. I am going to try polishing the RCA's and treating them with Cramolin contact cleaner and preservative. -Tom

Cool!

Happy New Year all! I finally got to start to apply the finishes. After trying various stains I have around here I settled on a blend of Watco oil stain. I used about 2/3 black walnut and 1/3 mahogany. Watco suggests flooding the surface with the stain using a brush, letting it soak the wood for a while and then rub off the stain until the wood appears dry. Then apply another coat and doing the same. Below is the "real" 901 cabinet with "wet" Watco. Next is both cabinets and finally the equalizer cover. Not sure what the final finish will be. Either wiping poly or oil. Both have their pluses and minuses.

I understand your point about the burlap. I am keeping an eye on the web for something more suitable. I bought a couple yards of the burlap since it is dirt cheap. I am thinking about doing a test on one of the 901 drivers with my Omnimic, without any grill, with the original grill and then trying different types of grill material. Just curious. about the result.

Update on the 901 project. Cabinet veneer work is complete except for finish sanding, staining of the walnut and whatever I decide upon for a finish. I read somewhere Watco Danish oil was used. Can anyone confirm that? All of the 901 original and series 2 seemed to have a dark stain applied. Almost a mahogany like color to the walnut. Later 901s seemed to have only a dull clear finish resembling the natural unfinished color of the walnut veneer I purchased from Woodcraft. Also, the equalizer, which has a walnut veneered cabinet had deep scaring and water stains on it so it gets the Full Monty treatment as well. In case anyone hasn't noticed, I took artistic license here and mirror imaged the front baffle of the clone speaker cabinet. Grill cloth. No luck finding any "official" grill cloth. Closest thing is beige burlap. Bose put a fine black mesh between the (outer) grill cloth and the Masonite frames. Not sure what the logic there was. -T

Below is an image of two of the 901 drivers I have. On the left is from the one "authentic" 901 (so called series 1) and the series 2 is on the right. I have recently seen some images of different series 2 drivers. Cabinets were marked series 2. Drivers had round magnets but the diaphragms were black (like the series 1). As you can see my drivers have the Bose logo printed on the cones. I have also seen the same CTS looking drivers sporting blue cones with out the Bose logo printing. These drivers had dust caps embossed with Bose in the dust caps. No idea if this was decorative or there were performance enhancements.

Does anyone have any idea who supplied the grille cloth for the original 901 systems. I know this is a "stretch" for someone to recall something trivial like this. I have the original grilles but to help match something but I'm looking to narrow my search.

I had a set of Ohm Model G used from a strange fellow who had a used audio shop in Northampton MA. Had a lot of bass with the upper ranges tilted downward, balance wise. I had the equalizer which actually compensated for this sonic effect, decreasing the bass and increasing the upper ranges using a 3 position slide switch. A friend in Wilbraham MA bought them from me in the early 80's. I recently asked him about them. Apparently the foam surround rotted and they made rattling sounds. He jokingly said I can have them back if I want to dig down through 20 feet of trash in the local land fill.... As my wife's English nurse says: "Bugger"

Ok, I am a fan of long gone original New England audio manufacturers. After all, I'm a New Englander so there is some "home team pride" that has it's hooks into me .(FYI I am a techno geek of sorts and have little interest in Red Sox, Patriots, Celtics, the Big E and so on...only audio / historical cool stuff like Springfield made Indian motorcycles, Gee Bee race planes, Rolls Royce cars, one of the first commercial radio stations, WBZ in the US, all those computer and electronic companies). I have been a fan of the Bose 901 (along with 3 way AR's and Allisons) for a long time. No, I don't believe it is "the best" as some early adverts from Bose would suggest but they were a cool concept, still are actually and despite the nay sayers when set up as recommended, when operated within the power capabilities of the amplifier and the equalizer is operating properly and in spec they sound impressively good. A few years back while poking about on Ebay I spied an original Bose 901 equalizer. Bid low and won it, thinking I'd maybe do something with it and a pile of series 2 drivers I had siting in my storage room. But all of it ended up collecting dust as other projects came up. Moving on a few years this past October I saw a single original 901 with a few dead drivers for 50 bucks. So, I have decided to copy the cabinet, utilize the series 2 drivers, restore the equalizer and then perhaps give the completed system to my brothers son who is somewhat of a retro tech guy. Below is the original system with the drivers removed. With a set of verniers and gauge blocks I determined the original 901 cabinet side walls were 1/2" plywood. Angled rear panels are also 1/2" plywood. Front panel is 3/4" ply. Top and bottom panels are 3/4" total thickness, veneered particle board, both sides of each panel. Linen covers the front and rear of the fiberglass filling inside the cabinet. Turns out the equalizer is very early production. Some indications of this are Philips head screws to hold the RCA jack assemblies to the chassis, date codes on some of the caps appear to show 1967 mfg dates and the transistors are the early 2N3393 types (later were 2N5088). There were 2 versions of the original 901 circuit board according to the Rainy City Audio website. Below is the initial production board per their info. More later...

Congrats on your purchase. Ben H. Tongue was my uncle. My brother and I wanted to make the trip to West Orange to try and buy a few of his things, but could not due to situations surrounding sick family members. I remember that he had a nice condition AR1W with the Janzen array sitting in his livingroom when I visited him some years ago. It had the mahogany ribbon stripe veneer with a nice luster. The photo you posted didn't look like that one. If anyone wants to look at all the electronic related items offered go to this link: http://www.estatesales.net/NJ/West-Orange/07052/948981 He was great man, friendly and helpful, keenly interested in audio from all era's, fascinated by anything Edison. His main audio playback system for LP's was the Hafler DH-101, DH-200, Lenco turntable played through a pair of JR-149 and the companion cylinder shaped "Super Woofer" with a dedicated amp-crossover. He is missed, really missed.

I remember hearing various ADS systems at an audio shop called "Sound Company" in the city where I live. This was around 1979. The impression I still have was that the system had a unique clarity and smoothness that the other offerings were seriously lacking. I think it may have been the model 610. What happened to ADS? I know they are still around as a corporate entity but they seem to be largely peddling auto sound related products. Did they go down the same path as AR, Advent and so on being bought up by companies that sell video tape head cleaners and such? -T