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Bose 601 II journey...

Copa1934

Copa1934

My ears are bleeding
Really began here http://www.audiokarma.org/forums/showthread.php?t=403503 where deep in that post I found my first set of 601 speakers.

Over the last couple weeks I've mostly been tinkering with them. Not too long ago I received some 301 II woofers, hoping of course that they would remedy my immediate issue. I had one woofer that was replaced with an aftermarket, so not wanting to take chances bought a pair of 301 woofers so that I had a matched set.

Well turns out there was more to this picture than first thought. I got a good deal, far as I'm concerned, on the speakers. And I would soon figure out why. The one different woofer I knew about, that was communicated along with images in the CL listing.

I was glad I didn't "test drive" them as the lower woofers were disconnected in both cabinets, two tweeters in one had broken wires and of course bad surrounds all around, well accept the newer replacement woofer.

So, today I began refoam, starting with one each of the woofers (301 and 601). That went fine. I tested both and they are close, but NOT an ideal match. The 601 being 4-ohm and the 301 being 8-ohm. Frequency sweeps were different too with the 301 having a more peaky response, with the impedance changing much more rapidly. I believe the 301 woofer will be better at the top position. The Fs was extremely close, 36.34 for the 601 and 37.01 for the 301.

The tweeters were non functional, after reconnecting the wires. WTF! Working speakers my a.....OK, wait. I check the lamps and both are good. I then check the resistors. Bam! Turns out both had broken leads. Good news? I have the correct rated resistors, pulled from Mach One speakers (unnecessarily at that). Both of which tested just fine. How did I figure this out? I connected to the terminals and got nothing. Bypassing the network, on the inside, all four tweeters came to life. So even more good news.

Since I had it apart I tested the caps as well and they were in spec so I'm not going to fuss with them for now.

Nutshell. The guy likely unloaded them cheap "knowing" they weren't fully functional. Even told me when I picked them up they just needed new foams. His ignorance paid off for me. So all is good for now.
 
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Getting more interesting...

We often read about "surface area" or "piston size" when talking about woofers and bass response. But I've never read, yet, a discussion on the T/S changes when speakers are in Series, Parallel or both (like early 901). Well I'll be posting more later, but was wondering if yet another separate post is in order to discuss this. The ramifications, or benefits depending on how one looks at it, are eye opening AND can open many new doors for DIY builders.

Teaser? What happens when you combine several drivers, in my case 4 tweeters as used in the 601? You go from a Fs of 6k down to 1.2k (and some change). That can make building networks either less complicated or more complicated when combining multiples of the same driver. If you just "do the math", i.e. adding numbers, subtracting numbers, dividing/multiplying, etc., you may never discover where problems lie due to the fact the T/S parameters have shifted dramatically.

Like I said, I'll post more, but it's getting very interesting. If you are like me (and many other people) you've wondered about how the heck these tweeters can be crossed around 3k. You may have wondered the same thing with other speakers as well. I personally didn't anticipate a shift in T/S specs. But I knew something had to be at play here.

I'm going to do some more tests with the woofers, which also are in series.
 
Ciopa,I'll be following this closely,I'm hoping you post info on your testing proceedures and equipment used.I'm pretty sure my drivers are orig.I'll be refoaming soon,but I want these refurbed top notch.
No Whips!
 
scoville said:
Ciopa,I'll be following this closely,I'm hoping you post info on your testing proceedures and equipment used.I'm pretty sure my drivers are orig.I'll be refoaming soon,but I want these refurbed top notch.
No Whips!
Click to expand...
LOL. First check the dust caps, should be cloth. Pretty sure they intended them to be "vented" as they say. Also, they should read just under 4-ohms since they are wired in series, resulting in a "nominal" 8-ohms. I've got to run more tests with the tweeters, I just hate dealing with the wire wrap. I'm tempted to change that.
 
Finally, working speakers! Gads what a long journey. I'll post images later, but I've been interrupted due to needing resistors. I hate driving to RS, especially ours since they don't ever know what I'm looking for. Mention Cell Phone and they're all over you. I was going to order online, but finding close enough values became a challenge and the prices were all over the place. Locally a friend dug up some resistors that were correct, and installed, and working.

Right now I'm taking them in. So far so good. I need to take them home and set them up properly. In the less than suitable environment I have them in now, they sound very good. Their strength clearly is in mids and highs. I'm not sure, but I'm thinking the mid bass is the only weak area, but they're in a large room at the moment. Dimensions are 20'x20' with 10' ceiling.

I've listened to Pink "Missundaztood" and now listening to Tears for Fears. One thing is for sure, really good vocals. Listening to "Sewing the Seeds of Love" and the opening drum was very natural sounding. Bass sounds good, but I'm thinking I'm spoiled by harder hitting speakers (AR3a, Mach One/Two, Pioneer S-710/910 and even Bose 901). But, again, the room likely is on the large side for these speakers.

As already mentioned, main issues were a working "pair" of woofers. I've kept the odd 601 woofer in case I should find a mate. For now the 301 woofers are working well. Wiring and replacing the resistors were the other challenges. Bloody wire wrap, even with the correct tool (which took me forever to find).
 
Hey Copa,

Glad you finally got them working. You think the bass would improve with a correct pair of 601 woofers? I know how easy it is to be spoiled by the AR's, Mack 1's, KLH's, etc... with that lovely addictive bass.

Glenn
 
Images

These are the day I picked them up. I have to download the recent images from my iPhone later. Forgot to do this on the weekend, but with the Superbowl (don't get me started) the day was pretty drawn out.

Listening to Josh Turner at the moment and the bass seems to be better, maybe just needed some time with those new surrounds.

Can't wait to post the after images. I think you're all in for a treat.
 

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Copa, mine were that bad as well.

Those resistors and basically all the wire inside those speakers is VERY brittle. I ended up having a couple resistor leads snap off on mine as well.

I didn't replace the little bulb fuse - I never get above 10 or so watts.

As for bass to 20 hz? I cannot attest to that, tho these things get very low considering their size. Very happy with mine.
 
Have a pair of 601 series 2 here as well. I hope that perhaps your new woofer surrounds just need to break in. Mine go quite deep and tight. Had some "Christmas Pipe Organ" on last mth with them, and they will get down there:music:
 
DaveElton said:
Have a pair of 601 series 2 here as well. I hope that perhaps your new woofer surrounds just need to break in. Mine go quite deep and tight. Had some "Christmas Pipe Organ" on last mth with them, and they will get down there:music:
Click to expand...
I'm finding that at low volumes my 7b speakers walk all over these speakers (in bass) AND they are in an adjacent room of similar size. However, the 7b speakers are 6' up on shelves near (not in) the corners. Also, I feel that the larger (10") woofer may deliver more bass at low volumes. Now, when I'm talking low volume, I'm talking less than 1w. At higher volumes the 601 start to come to life. Listening to Pink "True Love" now and bass is good. One issue with the 7bs is I have to hold back on the volume or the woofers bottom out. This was NOT a pleasant experience. Can't recall what I was listening to prior, but when the player (5-disk) switched to Pink "Misundaztood" I had to race to the receiver and turn down the volume. I just tested the 601 with the same tune and no issues other than the receiver couldn't deliver. At least the 601's were tripping all over themselves.

I don't have space at home to hook these up and run with one of my bigger receivers. I really need to unload some stuff, too crowded in the Man Cave.
 
My 601's do open up in the bass with a little more juice running to them I have noticed...if I am running Mach 2's, or one of my pair of Advents, my "volume-knob-setting" is lower than it is with the 601's. That being said, in my room, the twin 8" ers of the 601's really start to move some air at roughly between 1-5 watts.
 
More images...

Still need to download from the iPhone, but found these already on the puter.

The first image is the cone being "treated" with a, you're going to hate me for this, permanent marker. When I post the "final" images you won't be able to tell.
 

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Copa1934 said:
Still need to download from the iPhone, but found these already on the puter.

The first image is the cone being "treated" with a, you're going to hate me for this, permanent marker. When I post the "final" images you won't be able to tell.
Click to expand...
I hit enter too quickly. The second set of images is the network. They obviously used some kind of double sided foam tape. I installed the zip tie blocks, which work so much nicer. Look cooler too.
 
I love the zip tie blocks.

As for the magic marker, that's a fine idea. I swapped my very dusty and ugly top woofers with the non-filthy/sun faded bottom woofers. I may need to go back and get a sharpie and go to work.
 
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