Bose 501's rebuild, high sentimental value...

[o_rod]

Hey guys,

My uncle, who was a major audiophile, passed away last year and in his wake left me some of his gear. While his higher end stuff was dispersed amongst all the family, in the corner of his living room, buried behind alot of speakers was a set of Bose 501's series I that he had purchased many years ago and haven't been played in ages...

While not alot of guys cup of tea, I'd really like to restore these and have them as a keepsake in his honour.

What I've found so far is the woofers are non existent, the 4 tweeters are all functional and the crossovers need new caps and resistors.

I was thinking of using these as replacement woofers, seems like a good match...

https://www.parts-express.com/goldwood-gw-210-4-10-oem-woofer-4-ohm--290-320

Here's how the crossovers look:

My question here is, can I replace the 6.0 and 3.7 uf capacitors that are in series with a single 2.3uf capacitor? Is there any audible difference between series caps and just a single?

Other than that the cabs and grills are in great shape. Anxious to see how these sound...

 

[MacNoob]

How would you take the tap off the middle of a single cap?

 

[swechsler]

when you say "the woofers are non-existent" do you mean that they've been removed? Or that they just don't produce any sound?

 

[Boozehound]

Gee 4 Ohm...I would think the org.
Test out @ 6

Best-

Boozehound

 

[BobHol]

To follow up on what MacNoob hinted at. You would be messing up the function of that crossover if you only put in one Cap. Best bet usually is to stay as close as you can to the original design. Get a 6 and a 3.7 cap or as close as you can.

 

[o_rod]

I think the original woofer are closer to 4ohm from what I've gathered. I wish I had the originals but there were none in the enclosure.

I went with the closest valued capacitors I could find (3.3 and 5.6) and in series they equate to 2.1 uf where as the originals combined were 2.3 uf, close enough I'd think. I overlooked the fact that the resistor is in parallel with just the 3.7uf cap and not both, so I'll keep the design as original as possible.

 

[Boozehound]

Well I am not sure of the 501 ten in. but the 301 and 601 8in call for 8 ohm and test out at around 6. YMMV

Best-

Boozehound

 

[ragtopolds6]

I would get some 601 drivers and stick them in there ..by the way I think those speakers talk pretty well with a good signal..imo

 

[o_rod]

Well I am not sure of the 501 ten in. but the 301 and 601 8in call for 8 ohm and test out at around 6. YMMV

Best-

Boozehound

http://audiokarma.org/forums/index.php?threads/bose-501-series-1-woofer-help-please.520301/

Interesting... that's the thread I based my 4ohm theory around for the woofers. I just ordered them and they're on their way. I could very well be wrong though... Once I get the parts I'll connect everything and see what the final impedance is...

PS... Turns out they are series II not series I, made a typo. Looks like that link is for series I. Not sure how much they changed them.

I would get some 601 drivers and stick them in there ..by the way I think those speakers talk pretty well with a good signal..imo

It will be my first time hearing them or any Bose speakers, I know they don't carry alot of prestige but I think it's a pretty interesting design and will be a fun listen for sure!
I'm going to power them with my Pioneer SX 1250 so hopefully it'll help push them to sound the way they were intended.

 

[onwardjames]

Hope these sound like you want. Sentimentality is my Achilles Heel as well. Good luck.

 

[greatoldone]

The 501 is IMO the best sounding speaker that Bose made! A superior realization of Amar's direct/reflecting theory than the 901! I first listened to them back in 1975 (driven by a receiver) and liked the sound (Moody Blues - In Search OF The Lost Chord). Very 3-D dimensional! So good luck with this restoration project!

 

[nfafan]

I was thinking Series II and later 501's were 8ohm speakers. Regardless, good luck! When I was a poor youngster in the 70's, 501s (and 901s) were always aspirations. Now that I can afford a used pair - I don't have the room to appreciate them!

 

[dshoaf]

The original 501s were rated at 4 ohms but that's nominal. The fact is the 10" woofers had to push hard down low in such a small cabinet. I'd suggest a standard 8 ohm 10" driver would be quite nice. Unfortunately, Bose did not use that same woofer in much of any other models outside their private label, Interaudio 4000.

I'd be inclined to go with that PE woofer linked above, too. Just get the 8 ohm version if they have it.

I agree, the 501s sounded excellent with them spread out on a long wall with room on either side for the rear-facing tweeters. If you can, the sound field is very nice and full. They need to be up against a wall, however, for full bass to be realized. I sold many of those back in the day. They weren't as popular as the 301s and 601s, though, which were easier on placement.

Cheers,

David

 

[Tim D]

I generally avoid non-original replacement drivers. I’m patient enough to wait until original parts come up on the big auction site. Just saying....

 

[o_rod]

Finally received the parts for the 501 refresher and I'm currently listening to Diana Krall through them... Gotta say I'm pretty damn surprised with how warm and vast the soundstage is. I ramped up the top end by 2.5db at 20k hz to give them a little more sizzle but so far I am REALLY enjoying them, the makeshift stands did wonders as well... I hope my uncle Dan is smiling down seeing these old girls sing again!

 

[nfafan]

Kewl, good for you! I was expecting them to be the floor standers of my memory... And they sound fine in that not-so-long wall arrangement? I may have to re-consider them after giving up on them (and 901s)...

 

[o_rod]

Kewl, good for you! I was expecting them to be the floor standers of my memory... And they sound fine in that not-so-long wall arrangement? I may have to re-consider them after giving up on them (and 901s)...

Definitely not ideal, but I had two sick kids sleeping (finally!) upstairs and didn't want to start dragging the D9's around. I'd want them to be 8-10 ft apart ideally. At lower volumes though they sounded great. The goldwood woofer does a fantastic job of producing lows and mids cleanly and with impact, highs roll off a little early though. The stands for me are a must, made a big difference, especially with my smaller rear wall that's congested with equipment. Once my basement is finished I'll have alot of room to play with.

Here's the manual with some pretty good info on them...
https://mans.io/item/bose/501-series-ii

 

[zebra03]

So were the original woofers missing or were the surrounds gone ?

 

[o_rod]

So were the original woofers missing or were the surrounds gone ?

They were missing... Wish it was just a refoam.

 

[zebra03]

They were missing... Wish it was just a refoam.

Too bad . I'm glad the replacements worked out for you .