DCAudioDIY.com

DC Area Audio DIYer's Community
It is currently October 26th, 2020, 8:10 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 19 posts ]  Go to page Previous  1, 2
Author Message
PostPosted: December 19th, 2019, 1:20 pm 
Offline

Joined: July 8th, 2016, 4:34 pm
Posts: 401
You might be interested in the Carver woofer design -

http://www.integracoustics.com/MUG/MUG/ ... er-ALS.htm


Top
 Profile  
 
PostPosted: December 21st, 2019, 3:54 pm 
Offline

Joined: June 22nd, 2013, 11:00 am
Posts: 818
Anybody have an old, matching pair of two-way passive crossovers?


Top
 Profile  
 
PostPosted: December 29th, 2019, 3:32 pm 
Offline

Joined: June 22nd, 2013, 11:00 am
Posts: 818
mix4fix wrote:
Looking for free. These speakers are not worth putting money into but are kept around.

On a side note, are those woofers or subwoofers?


How deep are they?


Top
 Profile  
 
PostPosted: January 2nd, 2020, 2:14 am 
Offline

Joined: June 22nd, 2013, 11:00 am
Posts: 818
David McGown wrote:
That is a complex question, and depends on the speaker impedance (nominal), sensitivity, enclosure size and alignment you are putting the driver into. You need different types of drivers depending on whether it is a sealed box or vented box. It is relatively easy to fit a replacement woofer to sealed enclosure, but much more difficult with an vented box enclosure, since the port size and length (tuning) becomes a big factor speaker.

You want to look at the Thiele-Small parameters of the driver as a rough guide.

Typically, a sealed box woofer is going to have a Qts between 0.4 to 1.0
A vented box woofer typically will have a Qts below 0.4.

The higher the Qt parameter, the weaker the motor, and ability to control the driver at resonance (Fs). The driver will have a peaking low frequency response (boomy).

I would tend to avoid drivers with a high Qts (above 1.0), but unfortunately, that eliminates many of the cheapest drivers listed such as the GRS or Golldwoods

If you are looking for a cheap sealed box 12" driver, the GRS 125FPC-B (Square frame) or Goldwood GW-1244 (4 ohm) or GW-1248 (8 ohm) might fit the bill for inexpensive replacement drivers. They both have Qts around 0.7, which indicates moderate LF peaking (loss of control) which will give the impression of more extended bass.

For a vented box, difficult to advise. The Dayton DC300-8 might work, but have to know more about the enclosure and port size and length to see how it could be made to work. It is not easy to try to match and requires calculation. It might be better to convert the vented box into a sealed box enclosure to make things simpler.

The unfortunate fact of life is to get better or have more choices will cost more money, and is probably not worth it for a cheap pair of speakers. Close enough may be all that is affordable.

David



Why are there square framed woofers?


Top
 Profile  
 
PostPosted: January 2nd, 2020, 6:55 am 
Offline

Joined: February 28th, 2013, 1:19 pm
Posts: 484
Just a different mounting ring that allows you to use a slightly larger driver on a baffle with limited width and to allow closer driver spacing. It is more difficult to flush mount on a baffle because it needs a special routing template (pain for a DIYer, not so much for a production shop), so many square mounting rings are shaped and filleted on the edges so they can be more attractively mounted on a baffle without any rebate.

David


Top
 Profile  
 
PostPosted: January 2nd, 2020, 4:26 pm 
Offline

Joined: June 22nd, 2013, 11:00 am
Posts: 818
Any difference in the woofers themselves? Are they interchangeable?


Top
 Profile  
 
PostPosted: January 2nd, 2020, 5:56 pm 
Offline

Joined: February 28th, 2013, 1:19 pm
Posts: 484
The mounting flange by itself, i.e., all other things about the woofer being the same, identical design parameters, power rating, response, etc., should not make a difference. But if you are comparing different drivers, one of which have a square flange and the other a round flange, are most likely to be different in subtle (if lucky), or in very significant ways, just like the difference between two different round flange woofers. That being said, I have the following observations about a square flange woofer vs a round flange.

1. A square flange woofer only has 4 mounting screws versus 8 for a round flange woofer, and therefore more difficult to get even compression and sealing of the flange gasket.

2. Many square flange woofers baskets are stamped from a thinner gauge steel than round flange baskets, which is therefore more likely to flex or distort when mounting (particularly given only 4 mounting screws), causing the problem with uneven gasket compression noted above. The thinner gauge basket is not as stiff and therefore could be prone to ringing or misalignment of the voice coil in the gap, particularily if the driver is mishandled. There is a reason why good drivers use a cast frame.

David


Top
 Profile  
 
PostPosted: February 19th, 2020, 4:43 pm 
Offline

Joined: June 22nd, 2013, 11:00 am
Posts: 818
mix4fix wrote:
Anybody have an old pair of matching, functional 8 ohm 12 inch woofers (not subwoofers) laying around they can part with?


Bump.


Top
 Profile  
 
PostPosted: April 18th, 2020, 12:44 am 
Offline

Joined: June 22nd, 2013, 11:00 am
Posts: 818
Stuart Polansky wrote:
Are you looking for freebies, or are you paying?

If you are paying, I have a pair of new, in the original box, custom Eminence 12" woofers.

Here are the T-S parameters, if they work for you.

They sound excellent in the right enclosures.

$100 each.

RE OHMS 6.31
FS HZ 26.59
LE MH 1.49
MS GMS 71.80
QM 9.70
CMS mm/N .4990
QE .440
RMS NS/M 1.2367
QT .420
VAS LTRS 189.11
XMAX MM 4.80
SD SCM 519.45
BL TM 13.13
EBP 60.5
EFF % .78
SPL dB 90.9


How deep are they?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 19 posts ]  Go to page Previous  1, 2

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 4 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group