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12" passive radiator replacement?



 
 
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  #11  
Old January 6th 20, 08:05 AM posted to rec.audio.pro
Don Pearce[_3_]
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Posts: 2,329
Default 12" passive radiator replacement?

On Mon, 06 Jan 2020 08:05:27 +0100 (CET), "Mat Nieuwenhoven"
> wrote:

>On Sun, 05 Jan 2020 14:12:19 GMT, Don Pearce wrote:
>
>>On Sat, 4 Jan 2020 18:21:29 -0800 (PST), nickbatz
> wrote:
>>
>>>Happy New Year.
>>>
>>>So I just dumpster-dived a pair of mid-'80s (guessing) RS Sierra tower speakers from a neighbor.
>>>
>>>This is a premature question because I haven't hooked them up yet, but they have 12" rear-firing passive radiators with totally shot foam surrounds.
>>>
>>>Assuming it's worth fixing them - if only to trade someone for something else - is it likely to make any serious difference what round 12" cone-shaped thing I put back there? Serious = commensurate with the quality of these speakers.
>>>
>>>My guess is that these are hyped speakers, because I know Rogersound Labs and other stereo stores used to compare speakers to JBL L100s in those days. But the tweeter, midrange, and woofer are outwardly in good shape. The cabinets are in reasonable shape, but because I've been doing a lot of woodworking* recently I can easily replace some of the walnut veneer if it's necessary.
>>>
>>>TIA
>>>
>>>* By the way, if anyone knows anyone in the market for custom studio furniture, especially a unique composer's desk, let me know and and I'll send you some pictures. This has become a serious side business - I just shipped a desk to Paris, another to Florida - and I'm truly enjoying it.

>>
>>If you have the TS parameters for the main driver, you can probably
>>design a port that will allow you to do away with the stupid passive
>>radiator. They are no more than a spring and a mass, just the same as
>>air in a port tube, but suffer added non-linearity due to the
>>suspension. Any subwoofer design software will let you do this.

>
>A passive radiator is designed to match the main driver and do away
>with the port. A port works fine at low volumes, but if a lot of air
>needs to move it suffers from compression problems, especially if the
>port is longer. Plus mid-range leakage if it is at the front. A
>passive radiator does not have distortion problem any more than the
>matching main driver, and can be the only solution if the port would
>otherwise become too long.
>
>Mat Nieuwenhoven
>
>


None of those "problems" is actually a problem. The passive driver is
just another piece of stuff to introduce its own problems.

d
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  #12  
Old January 6th 20, 03:35 PM posted to rec.audio.pro
Mike Rivers[_2_]
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Default 12" passive radiator replacement?

On 1/5/2020 9:43 PM, nickbatz wrote:
> I have to listen and to get an idea of how much energy these speakers warrant putting into repairing them. It's not like I don't already have a bunch of very good ones.


I really wish I could be more selective and brutal about what I keep. I
have a growing pile of non-working, semi-working, or
works-but-obsolete-and-has-already-been-functionally-replaced stuff -
useful, too nice to throw away, but questionable as to whether it's
worth the bother, time, and money to bring back to life.

I guess they'll go to the landfill along with me after I check out.

--
For a good time, call http://mikeriversaudio.wordpress.com
  #13  
Old January 6th 20, 05:50 PM posted to rec.audio.pro
Scott Dorsey
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Default 12" passive radiator replacement?

In article >, Mike Rivers > wrote:
>On 1/5/2020 9:43 PM, nickbatz wrote:
>> I have to listen and to get an idea of how much energy these speakers warrant putting into repairing them. It's not like I don't already have a bunch of very good ones.

>
>I really wish I could be more selective and brutal about what I keep. I
>have a growing pile of non-working, semi-working, or
>works-but-obsolete-and-has-already-been-functionally-replaced stuff -
>useful, too nice to throw away, but questionable as to whether it's
>worth the bother, time, and money to bring back to life.
>
>I guess they'll go to the landfill along with me after I check out.


They will wind up at the Manassas Hamfest.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #14  
Old January 6th 20, 08:43 PM posted to rec.audio.pro
nickbatz
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Posts: 152
Default 12" passive radiator replacement?

On Monday, January 6, 2020 at 7:35:21 AM UTC-8, Mike Rivers wrote:

> I really wish I could be more selective and brutal about what I keep.


We had rats in the garage two summers ago, which - because they're prolific - meant that everything in there had to be taken out and cleaned before being put back.

It took me and three other big guys a very long day, and I filled an entire construction trailer all the way up - you know, maybe 8' x 15' x 8' high - plus the back of the big pickup truck that hauled it - with 25 years of clutter.

Among my favorite throwings away were broken cassette decks, some old computers, two broken stereo receivers, one broken amp, some old printers, and my absolute favorite: three @#$)(@#$!!! laser printers (two to cannibalize for parts for the first) that invariably ended up with paper thrown away and toner all over the place.

I still have boxes of cables I'll never use. Who knows what's in all the cartons I didn't take the time to go through. Probably a couple of useful things.

But I'll either fix these speakers or get rid of them. They're too big to pile in the garage.
  #15  
Old January 6th 20, 08:58 PM posted to rec.audio.pro
nickbatz
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Default 12" passive radiator replacement?

Speaking of Mike's AR speakers, my theory is that big - with big boxes - ported speakers (including passive radiator designs) are capable of producing a more natural-sounding low end than sealed/acoustic suspension ones.

That's the main thing I like about my UREI monitors, warts and all: the low end just sounds overwhelmingly right. I suspect it has to do with acoustic compression making smaller speakers sound more like the sound is coming from a box.Maybe it's more than just the low end, it could be the lower mids too.

Now, I also have a Blue Sky System One setup - two sealed sats + a sub. They're much better for working on, and the sub goes all the way down. And they're really good, and nice to listen to.

But I can't help thinking that even though the NFM concept has been unquestioned for at least 40 years, there's still something you can only get from big-ass monitors.
  #16  
Old January 6th 20, 09:32 PM posted to rec.audio.pro
Mike Rivers[_2_]
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Posts: 2,135
Default 12" passive radiator replacement?

On 1/6/2020 3:43 PM, nickbatz wrote:
> But I'll either fix these speakers or get rid of them. They're too big to pile in the garage.


That's pretty much the same as what I say to myself when I put something
on the pile of things to fix. Trouble is that there doesn't seem to be a
statute of limitations for broken things to remain broken. It's a
benefit and a curse of living alone.


--
For a good time, call http://mikeriversaudio.wordpress.com
  #17  
Old January 6th 20, 09:42 PM posted to rec.audio.pro
Don Pearce[_3_]
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Default 12" passive radiator replacement?

On Mon, 6 Jan 2020 12:58:46 -0800 (PST), nickbatz
> wrote:

>Speaking of Mike's AR speakers, my theory is that big - with big boxes - ported speakers (including passive radiator designs) are capable of producing a more natural-sounding low end than sealed/acoustic suspension ones.
>
>That's the main thing I like about my UREI monitors, warts and all: the low end just sounds overwhelmingly right. I suspect it has to do with acoustic compression making smaller speakers sound more like the sound is coming from a box.Maybe it's more than just the low end, it could be the lower mids too.
>
>Now, I also have a Blue Sky System One setup - two sealed sats + a sub. They're much better for working on, and the sub goes all the way down. And they're really good, and nice to listen to.
>
>But I can't help thinking that even though the NFM concept has been unquestioned for at least 40 years, there's still something you can only get from big-ass monitors.


I have decent large-ish sonus-faber speakers for mains and a 50 cubic
foot sub with a 15 inch Adire driver in it. That makes for very
relaxed bottom end, particularly as it is all integrated with
Sonarworks, which is so far the only software I know that measures
multiple (37) points in the room so it doesn't try to correct moding
nulls.

d
  #18  
Old January 6th 20, 09:45 PM posted to rec.audio.pro
nickbatz
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Posts: 152
Default 12" passive radiator replacement?

> I have decent large-ish sonus-faber speakers for mains and a 50 cubic
> foot sub with a 15 inch Adire driver in it. That makes for very
> relaxed bottom end, particularly as it is all integrated with
> Sonarworks, which is so far the only software I know that measures
> multiple (37) points in the room so it doesn't try to correct moding
> nulls.



Thinking about it, it may be the size of the box itself that I'm hearing. I've heard quite a few small ported speakers that lack a relaxed sound.
  #19  
Old January 8th 20, 04:05 AM posted to rec.audio.pro
Trevor
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Default 12" passive radiator replacement?

On 6/01/2020 12:53 am, Scott Dorsey wrote:
> In article >, Mike Rivers > wrote:
>> On 1/4/2020 9:21 PM, nickbatz wrote:
>>> Assuming it's worth fixing them - if only to trade someone for something else - is it likely to make any serious > difference what round 12" cone-shaped thing I put back there? Serious = commensurate with the quality of > these speakers.

>>
>> A passive radiator is just a driver without the motor. When you get an
>> "edge kit" you leave the original cone in place, so you don't have to
>> worry about matching the cone mass and stiffness, they thing that should
>> match the original is the stiffness of the suspension.

>
> A lot of passive radiators, though, have the stiffness entirely the result
> of the surround; there is no spider, no other suspension and so consequently
> the surround has to be constructed differently and the surround needs to
> be selected properly for the driver.
>
>> I have some Advent speakers that had foam rot. I'd never worked on a
>> speaker before so I was hesitant to operate on them, but figured that
>> for ten bucks or so I'd give it a try. It worked out just fine. The
>> hardest part is to get all the the old glue off the frame where the
>> suspension is attached.

>
> In the case of speakers, the stiffness is mostly the result of the spider,
> so you can swap out the surround with impunity without affecting the
> driver Fs appreciably.
>
>> I got my kit from Simply Speakers. Their web site gave me enough
>> confidence that I could do the job, and they were helpful with some
>> pre-purchase questions. You might take a look and see if they already
>> know what you need and can supply it.
>>
>> https://www.simplyspeakers.com/ of course.

>
> Passive radiators aren't expensive. The stiffness on them varies. If it
> were me, I'd get one of every kind that Madisound sells, try them in turn,
> and see which one gives most accurate low end. Then I'd buy a second one
> of that model for the other speaker.



A lot of passive radiators are tuned by adding mass to the cone. So if
you can measure the bass response, it will be cheaper to simply adjust
the cone mass. Cheaper still to throw away the PR and tune the box with
a port.


  #20  
Old January 8th 20, 04:32 AM posted to rec.audio.pro
Michael Beacom[_4_]
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Posts: 25
Default 12" passive radiator replacement?

On 2020-01-06 15:35:17 +0000, Mike Rivers said:

> On 1/5/2020 9:43 PM, nickbatz wrote:
>> I have to listen and to get an idea of how much energy these speakers
>> warrant putting into repairing them. It's not like I don't already have
>> a bunch of very good ones.

>
> I really wish I could be more selective and brutal about what I keep. I
> have a growing pile of non-working, semi-working, or
> works-but-obsolete-and-has-already-been-functionally-replaced stuff -
> useful, too nice to throw away, but questionable as to whether it's
> worth the bother, time, and money to bring back to life.
>
> I guess they'll go to the landfill along with me after I check out.


And let the mermaids flirt with you?
(https://weeniecampbell.com/wiki/inde..._Flirt_With_Me)


I'd offer to help with the stuff, but suffer from the same affliction.

Cheers
Mike



 




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