Bose 601 series 2 rebuild questions

onwardjames

Hoardimus Maximus
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After much deliberation, I picked up some Bose 601 series 2's at a yard sale for 50 bucks. Of course a refoam, and very dirty. Been sitting awhile, screw heads rusty, and may have to rewire, as front left and rear tweeter on both speakers don't work (put leads directly to them, they do. Like I said, been somewhere relatively humid)

I noticed one of those glass thermistor things was blown. I contacted Bose, they are trying to sell me a fuse kit with holder. I don't think this is the part I need, got tired of arguing with them.

Anyone know what this thing is? Digikey/Parts express have something that would work?

And should I recap? These have mexican poly's, and wasn't sure of life cycle of those. Resistors are unglued from the body of the crossover, so I'll need to reattach, but should these be replaced?

I planned to fix up and sell, but after the ugly refoam I'm not sure anyone would buy. I made the mistake of gluing on the edge of the foam topside per instructions, and I know it's a good thing to do, but glue came out a little clumpy and to a potential buyer, they might find it a little unprofessional. Not too ugly, more like some of the drivers I see on older vintage stuff.

Missing a foot as well. Anyone have one laying about?

Any advice on this rebuild would be appreciated. If I keep, they'll probably end up on the porch where I can hear it while I garden in the summer. With that wide sweet spot, figure they'd be perfect.
 
Resistors are a piece of cake to test, but I've never "needed" to replace any.

Glue mess? If passes movement test and sounds good, a potential buyer would have to be either stupid or "cosmetically" obsessed not to be interested.

Missing foot can't help with.

The Glass thermistor I'm betting is a "lamp". These are pretty common with many brands, but most often mentioned by Mach Two owners (like myself). Basically it protects the driver inline by raising the impedance as signal is increased, sparing damage to the driver. The drawback is that the drivers typically need more power before they open up. My Mach Two speakers don't seem to really come alive till the volume is up there. People who have removed or bypassed the lamp have said the speakers liven up (brighten up?), mids and highs improve. But the downside is the drivers are unprotected at this point. I've yet to perform a "scientific" test, but I believe these lamps increase in value (so to speak) with age, use and abuse, and therefore should be replaced. If I'm correct, this will liven up the speakers naturally, rather than the risk of bypassing. I'm sure that Bose support is likely right, the "fuse" kit is likely a functional substitute for the built in lamp.

If you have the meter to test the caps I'd check to play it safe. But if they are Poly, pretty good bet they should be good still, unless abused but that may not be apparent visually.
 
Thank you, copa!

When I refoam, I'm so paranoid I typically overdo the glue. I re-read Rick Cobb's writeup (excellent) and realized I wasn't putting a final bead where surround meets cone on top. Never been a problem, but I see where it would guarantee a seal. I'll post pics, it isn't bad, just not military perfect like my buddy. I pay him to do the important refoams, such as my yamaha ns 690 III's. He is amazing.

I'll order those from bose. Thanks for the info. Resistors I'll measure and glue back down. Actually, I've already measured. They were fine.

Watch me end up liking these and keeping. Jesus, I suck at flipping, lol.
 
Thank you, copa!

When I refoam, I'm so paranoid I typically overdo the glue. I re-read Rick Cobb's writeup (excellent) and realized I wasn't putting a final bead where surround meets cone on top. Never been a problem, but I see where it would guarantee a seal. I'll post pics, it isn't bad, just not military perfect like my buddy. I pay him to do the important refoams, such as my yamaha ns 690 III's. He is amazing.

I'll order those from bose. Thanks for the info. Resistors I'll measure and glue back down. Actually, I've already measured. They were fine.

Watch me end up liking these and keeping. Jesus, I suck at flipping, lol.
Look forward to more posts.
 
Here's a couple shots of the woofers ready to be glued to the basket. Oh, and a before pic, not very good at that.

The two dusty ones were on top. I got too much glue around where the inner ring overlaps the cone. The ones that aren't dusty were originally on bottom, and I made sure to have plenty of glue under the inside lip so I wouldn't need to apply around the top edge. More of a clean refoam that way. Can't see them pulling loose.
 

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The fuse is a functional substitute for the lamp without the coloration compromises. The lamps value changes over time and alters the tweeter output, the fuse is a consistent form of protection.

No need to buy a kit from Bose, your local auto parts store should have an assortment of fuse holders to choose from.

I know there is a math equation that I can't think of right now that will give you the correct rating for the fuse but I would go with 1.25 to 1.5 amps off the cuff.

If it were me, I'd keep them and let the neighbors enjoy them too.
 
wmgwizard, so what you're telling me is, I could just wire in a normal fuse, say 1.5 amps (I don't play anything above 10 watts) and it'd be just fine??

Hell, I can do this. I thought it was something that was essential to the design of the crossover. They kept saying on the phone that it was a fuse and fuse holder. I kept telling them "No, there's no holder, just a bulb wired up."

If it is that easy, I'll be rocking in a couple days!
 
And I may just keep them. Wife will have a fit, as I SWORE i'd sell.

I have read many threads on AK about these. Seems the series III were prettier, in that they used real wood veneer, but that different angle wasn't as good. Always heard the series 2 (mine) sounded best.
 
What you have is a small incandescent bulb in line with the tweeters. Original 601s didn't have them and Bose came out with a retrofit kit with instructions for all warranty tweeter repairs to have them installed at Bose expense.

The folks you spoke with at Bose would have been young kids - at best! - when this happened so they would not know that history. All you need to do is replace the bulbs with a like kind rating of bulb and you're good to go. I also think you should be impressed that Bose would even support 601s that are heading for 40 years of age.

If the bulbs were blown - as opposed to the filament just failing from fatigue - then suspect a tweeter or 2 that may also have a problem. Blown bulbs usually indicated excessive drive which usually meant too much partying without paying attention to the speakers.

Warranty repair of a 601 called for replacement a the driver and then a cabinet resonance test involving running a frequency generator into an amplifier and then sweeping the audio range listening for vibrations or resonances, too. That was standard practice for all Bose products - something I applied to all repairs I did back then.

Hope that helps.

Cheers,

David
 
dshoaf, yes, thanks, very helpful.

One of the bulbs is clearly blown, however, I connected a live lead to each tweeter, with no problems apparent. One sounded slightly different, but the wires are so corroded, I could not ascertain if it was blown, or just not getting a good connection.

Do you happen to know what the rating of that bulb might be? I've no idea. And would a straight fuse be better in the long run?
 
New 8 inch woofers can be had from
Bose.

Looks like the top 6 inches of the cab.
Has been cut off in your pic.

Bose sold a outside of the cab.fuse
Kit ,for the org. 601. Back in the day.
 
boozehound,

The pic shows the plastic sides and grills removed. They were filthy, and needed a soak. There is nothing else wrong. I tried removing the top housing, but got stymied. Not necessary anyway, I can reach the crossover just fine.

I think the outside of the cab fuse kit is what they are trying to sell me. Only 18 bucks, so I may go that route, if only to be legit for flipping, if I decide to.

Gotta finish them up and listen.
 
I hope you get them up and running. IMO the 601's are the best sounding speakers Bose ever made.
 
All very cool, am really excited to see how it all comes out. I want a pair of those to play with too!

Biggles
 
New 8 inch woofers can be had from Bose, because that's the same part number for most 301 series 'till this date. ;)

If the specs are exactly the same is another story (I really don't know), but here's what I do know:

- I also had a pair of these on mint conditions except for the woofers, so I fitted 4 brand new original woofers;

- I checked the crossover following the original Bose schematics, to make sure that the previous owner didn't messed with it (it didn't);

- With all things checked and new 4 woofers installed, I still felt that this was a very unbalanced loudspeaker, with lots of high mids and with a bass response below what I would expect from 2 x 8 inch woofers per loudspeaker;

- I knew a few more cases where the woofers were replaced by new ones (Bose originals), and the end result was always the same (soundwise).


Now, bear in mind that I don't know how these speakers sounded brand new, so I can't tell if they always sounded like that.

Instinctively, I would say that they had to sound better, because any 301 IV/V will sound way better (I do know how most Bose speakers sound), and I was tempted to rebuild the crossover using new components.

I ended up selling them and trying out other things, which means that my doubt around them remains... :)
 
boozehound,

The pic shows the plastic sides and grills removed. They were filthy, and needed a soak. There is nothing else wrong. I tried removing the top housing, but got stymied. Not necessary anyway, I can reach the crossover just fine.

I think the outside of the cab fuse kit is what they are trying to sell me. Only 18 bucks, so I may go that route, if only to be legit for flipping, if I decide to.

Gotta finish them up and listen.

Onwardjames: Sorry my bad I missed that they were series 11
I listened to the two's when they first came out and was very impressed.

Hope you get them up and running I noticed you have a SX rec.
Ready to make them sing.
 
All very cool, am really excited to see how it all comes out. I want a pair of those to play with too!

Biggles

Unfortunately, there is no water damage, Biggles. :D
Thanks for the encouragement. I'm always afraid to go tearing into stuff, although I restored some DCM TF-350's that were as gone as possible, and they turned out okay. Same for those Epicure Model 20's, which I need to pm you and send photos of the swelled backs, see what you'd suggest.

I hope you get them up and running. IMO the 601's are the best sounding speakers Bose ever made.

I've heard that too, and remember selling them back when I had a p/t job at a hifi store back in the day. They were always my faves of the lineup.


The woofers are all good, and I'll be finishing up gluing to the basket (the critical part of a refoam) and then on to detail work....

gotta cut some new foam seals. i have leftover floor backing from a recent remodel of the listening room...seems to be the same stuff as the original seals, so i'll be trimming new ones from that.

Then it's retest all tweets (one was fishy) and figure out what to do with the fuse dilemma (leaning towards the kit from bose) and then buttoning it all up.

Still missing one foot, should anyone have a spare or ideas towards a fix. No biggie.
 
Unfortunately, there is no water damage, Biggles. :D
Thanks for the encouragement. I'm always afraid to go tearing into stuff, although I restored some DCM TF-350's that were as gone as possible, and they turned out okay. Same for those Epicure Model 20's, which I need to pm you and send photos of the swelled backs, see what you'd suggest.

The thing to really be afraid of is to not tear in to stuff and let the good times pass you by. Where I run in to problems is when I get antsy and impatient. That's where naps and fudgsicles come in to play, ya know?

Biggles
 
Ahh, naps and fudgesicles.

So I'll be utilizing another AK trick of rolling cardboard into a shape to press down the edges of the surround after the 30hz centers the vc.

Hope to have them drying soon.
 
New 8 inch woofers can be had from Bose, because that's the same part number for most 301 series 'till this date. ;)

If the specs are exactly the same is another story (I really don't know), but here's what I do know:

- I also had a pair of these on mint conditions except for the woofers, so I fitted 4 brand new original woofers;

- I checked the crossover following the original Bose schematics, to make sure that the previous owner didn't messed with it (it didn't);

- With all things checked and new 4 woofers installed, I still felt that this was a very unbalanced loudspeaker, with lots of high mids and with a bass response below what I would expect from 2 x 8 inch woofers per loudspeaker;

- I knew a few more cases where the woofers were replaced by new ones (Bose originals), and the end result was always the same (soundwise).


Now, bear in mind that I don't know how these speakers sounded brand new, so I can't tell if they always sounded like that.

Instinctively, I would say that they had to sound better, because any 301 IV/V will sound way better (I do know how most Bose speakers sound), and I was tempted to rebuild the crossover using new components.

I ended up selling them and trying out other things, which means that my doubt around them remains... :)
In researching 601 speakers they seemed to very a lot from series to series. So much so that there are people who have owned them that single out (usually) the Series II as the best overall. Looking at them "physically" they were distinctly different.

That said, do you recall if the 601 you were familiar with were Series II?
 
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