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-   -   12" passive radiator replacement? (http://www.audiobanter.com/showthread.php?t=141860)

nickbatz January 5th 20 02:21 AM

12" passive radiator replacement?
 
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.

nickbatz January 5th 20 02:24 AM

12" passive radiator replacement?
 
https://www.amazon.com/ESS-Speaker-P.../dp/B009DNMZ6M

For example

nickbatz January 5th 20 02:26 AM

12" passive radiator replacement?
 
I'm thinking $3 foam surrounds from ebay would probably do the job, right? No need for the Italian silk ones with solid gold mounting hardware?

Mike Rivers[_2_] January 5th 20 01:42 PM

12" passive radiator replacement?
 
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.

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.

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.



--
For a good time, call http://mikeriversaudio.wordpress.com

Scott Dorsey January 5th 20 01:53 PM

12" passive radiator replacement?
 
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.

Somebody who actually knows those speakers can likely do better, and it's
possible some place like Simply Speakers or the Speaker Factory in
Gathersburg, MD might know them.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Don Pearce[_3_] January 5th 20 02:12 PM

12" passive radiator replacement?
 
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.

d

Les Cargill[_4_] January 5th 20 07:24 PM

12" passive radiator replacement?
 
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.
>
> d
>


Would WinISD be a good choice for this, Don? That's where I'd go first.

--
Les Cargill

Don Pearce[_3_] January 5th 20 07:41 PM

12" passive radiator replacement?
 
On Sun, 5 Jan 2020 13:24:36 -0600, Les Cargill
> wrote:

>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.
>>
>> d
>>

>
>Would WinISD be a good choice for this, Don? That's where I'd go first.


WinISD is fine. You can put in the dimensions of your box, and let it
design the port.

d

nickbatz January 6th 20 02:43 AM

12" passive radiator replacement?
 
Okay, thanks very much everyone.

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.

Mike, I'm definitely not afraid to work on drivers - I even have a heat gun and glue, etc. :) But I'll have to see whether it's possible to salvage the cones. I only looked at them briefly and have been out all day.

My sense is that replacing the foam with similar foam will be close enough, same with the cones if necessary.

Mat Nieuwenhoven January 6th 20 07:05 AM

12" passive radiator replacement?
 
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





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