I bought into the "never wire in series" position until not long ago. Then an article appeared in AudioExpress a few months back in which the proposition was tested not by a theoretical thought experiment or even a simulation but by actual experimentation using measurments.
Unfortunately I didn't keep a copy of the issue or I would provide the citation. Anyway, speakers having such a wide range of characteristics I don't think the article was proof to the contrary with regard to ALL speakers, under ALL circumstances, but it was enough to convince me that I cannot contuinue hold the position as an inviolable rule.
Unfortunately I didn't keep a copy of the issue or I would provide the citation. Anyway, speakers having such a wide range of characteristics I don't think the article was proof to the contrary with regard to ALL speakers, under ALL circumstances, but it was enough to convince me that I cannot contuinue hold the position as an inviolable rule.
Bill, about wiring in series, this certainly IS true. When running speakers parallel the differences in resistance e.g. won't affect eachother as much as when you would when run them in series.
I 1st thought that it wouldn't matter, but an article in a german speakerbuild magazine proves it DOES matter.
I 1st thought that it wouldn't matter, but an article in a german speakerbuild magazine proves it DOES matter.
I've heard arguments both pro and con about wiring drivers in series. My feeling is that series is bad, in that the other drivers destroy any damping factor that you might have had, thus control at low frequencies. In a case like this, where you're using drivers "full range" and with drastic EQ, that could be critical. The counter argument involved something about the back EMF from the other drivers making up the difference. It's been a while. The reasoning was actually somewhat logical, but I remember leaving with the feeling that it would take a little bit more to convince me.
Speaking of non sequiturs, I think I've detected one in the statement that dispersion makes up for lack of dynamics. Clearly we have a True Believer on our hands. I find it fascinating that people still fall for the direct/reflecting advertising hoopla--it was debunked years ago. 'Life-like' it isn't. Adding ambience from unpredictable listening room acoustics to those of the original recording doesn't reproduce anything accurately, unless your goal is the acoustic equivalent of a funhouse mirror. Might as well go to a mall and listen to the ceiling speakers. It's the same effect--widely dispersed sound, poor frequency response, and lots and lots of ambience from all those nice, acoustically reflective walls and floors. Unfortunately, it's not in the same ballpark as high fidelity; it's just, for want of a better term, a special effect. The predictable sour grapes sentiment comes in the follow-up post: Oh well, can't have good sound anyway...might as well goof up the sound some more.
I don't know what the max SPL of the 901 was, but there was a black cabinet version sold for several years in the '70s for PA use. I don't remember the nomenclature, but it was nothing more than a standard 901 played 'backwards,' i.e. with the drivers facing the audience rather than the wall, and without the wood veneer. I played in a band once that used them. Always thought they sounded pretty poor. When we got a chance at a larger outdoor gig, we jumped at the chance to play through another band's PA system. What a relief.
Grey
Speaking of non sequiturs, I think I've detected one in the statement that dispersion makes up for lack of dynamics. Clearly we have a True Believer on our hands. I find it fascinating that people still fall for the direct/reflecting advertising hoopla--it was debunked years ago. 'Life-like' it isn't. Adding ambience from unpredictable listening room acoustics to those of the original recording doesn't reproduce anything accurately, unless your goal is the acoustic equivalent of a funhouse mirror. Might as well go to a mall and listen to the ceiling speakers. It's the same effect--widely dispersed sound, poor frequency response, and lots and lots of ambience from all those nice, acoustically reflective walls and floors. Unfortunately, it's not in the same ballpark as high fidelity; it's just, for want of a better term, a special effect. The predictable sour grapes sentiment comes in the follow-up post: Oh well, can't have good sound anyway...might as well goof up the sound some more.
I don't know what the max SPL of the 901 was, but there was a black cabinet version sold for several years in the '70s for PA use. I don't remember the nomenclature, but it was nothing more than a standard 901 played 'backwards,' i.e. with the drivers facing the audience rather than the wall, and without the wood veneer. I played in a band once that used them. Always thought they sounded pretty poor. When we got a chance at a larger outdoor gig, we jumped at the chance to play through another band's PA system. What a relief.
Grey
GRollins said:
You need to brush up on both your reading and your listening skills. I never said dispersion compensates for the loss of dynamics in a recording. Neither did I say that a dispersion speaker is "life-like." What I did say is that the dispersion theory is an attempt to compensate for the dynamic loss by increasing the amount of sound waves in the listening environment, and by doing so be more life-like than a standard speaker arrangement. That it can do so is a fact to those who have adequately explored it. It's only been "debunked" by the tin-eared or those who haven't adequately explored the concept.
One thing you don't need to improve is your arrogance, which it seems grows out of both your ignorance and your acceptance of only one way to appreciate sound. Whatever trips your trigger.
That Bose PA system was the Bose 800, it included 8 Bose drivers and all were in sealed enclsoures. I could only see it being used as a mid-high section for small PA applications.
I can't bring any reflection based speaker names, but I believe I read on tnt-audio a speaker that relies on the wide reflection of sound to provide the listener with the reproduction of the recording. As with all reflection based speakers, proper setup was a crucial fact of getting the right sound from the system.
The reviewer was left as a converted, all sound must be direct and very little, if any reflected believer.
I can't bring any reflection based speaker names, but I believe I read on tnt-audio a speaker that relies on the wide reflection of sound to provide the listener with the reproduction of the recording. As with all reflection based speakers, proper setup was a crucial fact of getting the right sound from the system.
The reviewer was left as a converted, all sound must be direct and very little, if any reflected believer.
While all you guys puss and moan about whether Bose speakers are any good, I'll answer the question.
Figure about 4 hours apiece. But most of it is waiting for glue to dry. I used the rims of glasses to apply pressure to the foam for attachment to the frame. Because of the angles, you can only do four at once, then the other four, and finally the one. This is "work" for in front of the TV on a Sunday afternoon, not real work. This is not brain science or rocket surgery. The only tools might be a sharp piece of flint or sharpened bone... relax.
Ignore the comments about not being able to reproduce the original FR. That's most likely an improvement. In the true DIY spirit, you can tell people that you rebuilt them. If you don't like them, f'em and grab some jing on Ebay.
I might add (although never owning a pair), could the 901 be:
1. the most recognized speaker on the planet?
or...
2. The longest running model currently available for sale?
or...
3. The most popular mid to high end (as in numbers of speakers sold, popular) home audio speaker ever built.
or...
4. The coolest speakers you could have owned in 1974?
1. the most recognized speaker on the planet?
or...
2. The longest running model currently available for sale?
or...
3. The most popular mid to high end (as in numbers of speakers sold, popular) home audio speaker ever built.
or...
4. The coolest speakers you could have owned in 1974?
jmikes,
"I never said dispersion compensates for the loss of dynamics in a recording."
"...dispersion theory is an attempt to compensate for the dynamic loss by increasing the amount of sound waves in the listening environment."
You contradict yourself and lay the blame for your illogic at my feet. How quaint.
For the dynamic loss...? Loss how? By, perhaps, the recording/reproduction process? That dispersion, i.e. spreading sound waves around the listening area, can in any way substitute for dynamics is simply untrue. Might as well say that smearing mustard on your refrigerator will make your neighbor's dog quit barking at night. The two are not related.
(While mustard on the refrigerator won't stop the neighbor's dog from barking, cinnamon oil on a tennis ball will. Here, Buffy...here Buffy...catch!)
I've heard plenty of pairs of 901s under all sorts of conditions, including factory rep. setups back in the '70s and loads of home situations. There's a reason no one takes them seriously. They aren't serious speakers. They're cheap cabinets (do they still use moulded plastic? ugh!), filled with cheap drivers, heavily EQ'ed to bring them anywhere close to flat response, and inflated with preposterous advertising flapdoodle.
They're not so much a speaker as a cult religion.
Clearly you have bought the advertising, hook, line, and sinker. Bose is proud of you.
Bose(o),
The 800! Exactly. Thanks. That was annoying me, because it was on the tip of my tongue and was going to drive me crazy. I couldn't remember whether there was a driver in the "back" or not. You're quite right, they were pretty midrange-ish (as is the home version) and would have sounded better with help on top and bottom.
The band had them when I arrived, so I just kinda fell into a pre-existing situation. There was never enough money to buy anything better. I and the guitar player went on to play together for many years. What happend to the rest of them, I don't know.
kelticwizard,
Like you, I'm concerned about the refoaming question. I've been mulling this one over and the only thing I can think of is the possibility that the spider deteriorates over time as well as the surround. If so, then a complete reconing would be necessary to bring the driver back to life. Even more expense. Alternatively, the adhesive holding the cone, voice coil, and spider together might deteriorate. Just thought of that. Actually, I think that might be more likely than the deteriorating spider idea. Your thoughts?
Grey
"I never said dispersion compensates for the loss of dynamics in a recording."
"...dispersion theory is an attempt to compensate for the dynamic loss by increasing the amount of sound waves in the listening environment."
You contradict yourself and lay the blame for your illogic at my feet. How quaint.
For the dynamic loss...? Loss how? By, perhaps, the recording/reproduction process? That dispersion, i.e. spreading sound waves around the listening area, can in any way substitute for dynamics is simply untrue. Might as well say that smearing mustard on your refrigerator will make your neighbor's dog quit barking at night. The two are not related.
(While mustard on the refrigerator won't stop the neighbor's dog from barking, cinnamon oil on a tennis ball will. Here, Buffy...here Buffy...catch!)
I've heard plenty of pairs of 901s under all sorts of conditions, including factory rep. setups back in the '70s and loads of home situations. There's a reason no one takes them seriously. They aren't serious speakers. They're cheap cabinets (do they still use moulded plastic? ugh!), filled with cheap drivers, heavily EQ'ed to bring them anywhere close to flat response, and inflated with preposterous advertising flapdoodle.
They're not so much a speaker as a cult religion.
Clearly you have bought the advertising, hook, line, and sinker. Bose is proud of you.
Bose(o),
The 800! Exactly. Thanks. That was annoying me, because it was on the tip of my tongue and was going to drive me crazy. I couldn't remember whether there was a driver in the "back" or not. You're quite right, they were pretty midrange-ish (as is the home version) and would have sounded better with help on top and bottom.
The band had them when I arrived, so I just kinda fell into a pre-existing situation. There was never enough money to buy anything better. I and the guitar player went on to play together for many years. What happend to the rest of them, I don't know.
kelticwizard,
Like you, I'm concerned about the refoaming question. I've been mulling this one over and the only thing I can think of is the possibility that the spider deteriorates over time as well as the surround. If so, then a complete reconing would be necessary to bring the driver back to life. Even more expense. Alternatively, the adhesive holding the cone, voice coil, and spider together might deteriorate. Just thought of that. Actually, I think that might be more likely than the deteriorating spider idea. Your thoughts?
Grey
GRollins said:
Well, the website I posted is the first I heard of any refoaming problem with the 901 drivers. I have only the website owner's word for it. By what he said on the website, it seems to be a problem with applying the new foam surrounds, he mentioned nothing else.
The spider and glue might conceivably be the case, but that rarely seems to happen on other old speakers, I see no reason for it to be likely to happen with Bose. Still, I think that msl422 should visually inspect for loose glued surfaces, etc, before he decides to refoam.
I have heard of foam surrounds being difficult to apply to polypropylene cones, because nothing sticks to poly. But Bose cones are paper, so that shouldn't be an issue. I cannot think why Oaktree would find them difficult.
My best guess is that Oaktree is real stickler for getting precise frequency response, and will reject a driver if it varies by more than 1 dB from the original. With any speaker, I would doubt what 1 dB variation would mean in a speaker, but with Bose that doubt would be magnified. I believe that it is well established that the Bose 901 driver does not go up to 20,000 Hz smoothly, there is in fact cone breakup there. If that is the case, bothering with a 1 dB difference for the new surrounds seems rather pointless.
I would go with Chipco's recommendation and do the refoaming himself.
As far as msl422 goes, I would say that he seems to have had his heart set on these Bose for some time, he shouldn't cheat himself of the chance to have them for himself, at least for awhile. But I also think he should build a decent pair of speakers himself, and decide which he likes better. I do believe a good set of 901's get a decent resale price, so he might as well spring for the $40 for a kit.
paul,
It's been quite a while since 901s took up retail space in stereo shops. Keeps 'em from being compared to other speakers. As you've noted, they don't fare well.
I've worked in retail audio twice, once during the '70s and once in the '80s. Beats flipping burgers for a living, but the downside is that your paycheck tends to evaporate--something to do with that new preamp back at the house...
kelticwizard,
I've always been suspicious of meeting original specs after reconing. It's one thing if you're talking a 12" guitar speaker, but hi-fi is another realm entirely. I've got a row of speakers on a shelf that I keep meaning to recone and use in speakers for my shop or something. Never seem to get around to it. (Read: Why refoam when they'll just self-destruct again? It's money down the drain.)
My thinking regarding the adhesive was that if it got dry and brittle it might crack or turn to dust. Something of that nature.
Another option for rehabilitating 901s might be to wait until Parts Express does one of their nifty 99 cent surplus driver specials and load up on cheap parts that way. Who knows, might even sound better. It's for sure that Bose doesn't sink their money into quality parts.
ChesterFuzzin',
Based on the description in the original post, I doubt that the EQ is the problem. The title of the thread uses the term clipping, which is an electronic term, not a speaker term, but clipping doesn't sound like click-a, click-a. That's almost certainly the sound of the voice coil slapping the back plate of the magnet structure. Two possibilities have been mentioned: rotted surrounds and bottoming. They amount to the same thing, really, in that a rotted foam suspension (foam suspensions always crumble with time) will not support the cone properly and it will bottom. A rubbing voice coil results in a scraping sound (not click-a), which is why I'm not inclined towards that line of reasoning.
All this comes with the caveat that trying to diagnose a problem from miles away can be a bear. You do the best you can with the description of the problem that you're given and hope that the person on the spot can piece it all together on their end.
Grey
It's been quite a while since 901s took up retail space in stereo shops. Keeps 'em from being compared to other speakers. As you've noted, they don't fare well.
I've worked in retail audio twice, once during the '70s and once in the '80s. Beats flipping burgers for a living, but the downside is that your paycheck tends to evaporate--something to do with that new preamp back at the house...
kelticwizard,
I've always been suspicious of meeting original specs after reconing. It's one thing if you're talking a 12" guitar speaker, but hi-fi is another realm entirely. I've got a row of speakers on a shelf that I keep meaning to recone and use in speakers for my shop or something. Never seem to get around to it. (Read: Why refoam when they'll just self-destruct again? It's money down the drain.)
My thinking regarding the adhesive was that if it got dry and brittle it might crack or turn to dust. Something of that nature.
Another option for rehabilitating 901s might be to wait until Parts Express does one of their nifty 99 cent surplus driver specials and load up on cheap parts that way. Who knows, might even sound better. It's for sure that Bose doesn't sink their money into quality parts.
ChesterFuzzin',
Based on the description in the original post, I doubt that the EQ is the problem. The title of the thread uses the term clipping, which is an electronic term, not a speaker term, but clipping doesn't sound like click-a, click-a. That's almost certainly the sound of the voice coil slapping the back plate of the magnet structure. Two possibilities have been mentioned: rotted surrounds and bottoming. They amount to the same thing, really, in that a rotted foam suspension (foam suspensions always crumble with time) will not support the cone properly and it will bottom. A rubbing voice coil results in a scraping sound (not click-a), which is why I'm not inclined towards that line of reasoning.
All this comes with the caveat that trying to diagnose a problem from miles away can be a bear. You do the best you can with the description of the problem that you're given and hope that the person on the spot can piece it all together on their end.
Grey
Well I finally got around to tearing the grill off and taking a look, so we can put to rest the debate about what's wrong with the speakers. The Bose debate, of course, can continue...
There is obvious physical damage to the foam/surrounds, I'm not sure what the terminology is here. Anyway, take a look for yourselves and survey the damage. Warning: it's pretty hideous looking.
View the damage
Now that's the "surround" we're talking about that's all messed up around the edge of the cone, right? Is this different from the "foam"?
And this will fix it?
-Mark
There is obvious physical damage to the foam/surrounds, I'm not sure what the terminology is here. Anyway, take a look for yourselves and survey the damage. Warning: it's pretty hideous looking.
View the damage
Now that's the "surround" we're talking about that's all messed up around the edge of the cone, right? Is this different from the "foam"?
And this will fix it?
-Mark
I think it's called "rot".
Will the PE kit fix the problem?
Yes. I love PE but the price is cheaper elsewhere. When you order, please ascertain that the shims are included. The shims are used to align the voice coils whilst the foam is being glued.
Kit with shims for $48.00 (18 speakers)
Mark,
Yes those are the surrounds that have rotten. Foam is one of the materials that surrounds are made of.
Just judging by your questions, are you sure you're up to this? Not to slight you, but it sounds like this will be the first such job you have attempted.
That's 18 of those drivers you have to do.
18 chances to make 1 mistake.
1 mistake = no speakers.
All have to be fully functional in a series set-up.
I guess if you have nothing to lose, then go for it. Just be careful. By the time you're onto the 15th one, you might start to get lazy and...oops
Cal
Yes those are the surrounds that have rotten. Foam is one of the materials that surrounds are made of.
Just judging by your questions, are you sure you're up to this? Not to slight you, but it sounds like this will be the first such job you have attempted.
That's 18 of those drivers you have to do.
18 chances to make 1 mistake.
1 mistake = no speakers.
All have to be fully functional in a series set-up.
I guess if you have nothing to lose, then go for it. Just be careful. By the time you're onto the 15th one, you might start to get lazy and...oops
Cal
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