Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Who's Online (4)

Please review the site Rules, Terms of Service, and Privacy Policy at your convenience. Rules, TOS, Privacy
Get familiar with the reaction system: Introducing the Reaction System

Woofers from Sony MB-350H

These are 8" woofers from the same family as the midwoofers found here: https://diy.midwestaudio.club/discussion/704/midwoofers-from-sony-mb-150h/p1

Similar construction and overall cosmetic appearance - but these have a truncated frame.

The small motor gave me some concern, but as can be seen in the measurements it wasn't well-founded concern.





A plastic frame emulating some higher end cast frame drivers. These are very lightweight drivers, which means they are high on my list of drivers to use for a project to ship to InDIYana. 

Here are measurements taken post-break-in. 

Loudspeaker parameters:

Fs  = 29.48 Hz
Re  = 7.13 ohms[dc]
Le  = 598.58 uH
L2  = 1288.34 uH
R2  = 41.23 ohms
Qt  = 0.45
Qes = 0.50
Qms = 4.57
Mms = 33.93 grams
Rms = 1.375012 kg/s
Cms = 0.000859 m/N
Vas = 62.16 liters
Sd= 226.98 cm^2
Bl  = 9.424753 Tm
ETA = 0.30 %
Lp(2.83V/1m) = 87.42 dB

Added Mass Method:
Added mass = 40.00 grams
Diameter= 17.00 cm

As can be seen by the Le numbers, probably limited to a 3-way. The wrinkles in the impedance would also seem to indicate a 3-way, as well:



On the other hand, the Ts parameters are a pleasant surprise. When I saw the small motor, I was anticipating a Qt in the 1+ range along with a much higher Fs. These are actually workable beyond building a fun little high Q boombox. The wrinkle at 900Hz is of concern, as there is probably a cliff in the response. In a typical 3-way, though, that is probably going to be worked into the low-pass slope etc. It looks like the cone breakup is in the 2800 range - so a 2-way is likely not easy regardless.

I recently decided to take advantage of my paid subscription to Office ($100/yr for access to MS Office and over a TB of cloud space) but that means WBCD no longer works. To my surprise, Unibox works just fine. So I will be using that going forward. 

For modeling, I used 5mm of Xmax. Probably close to reality.

Here it is in a sealed, 30L enclosure. This models really well in a sealed enclosure, could even go smaller. 



20W excursion sealed:



Now lets put a port in the same box:



That 2db peak is, in my experience, not at all offensive - although it remains to be seen if the extra few Hz of excursion is worth it. My guess is no, not in a typical environment. 

So, again I am surprised at some of the drivers the lower echelon OEM guys are using. These exceeded my expectations considerably, and they were about $40 shipped via Ebay. I won an auction. They also showed up with the corresponding TM module, but those both look to be pretty much junk, so I may put them back on the Bay to recover a few bucks of my investment. 

Given they weigh almost nothing, and building a good enclosure out of 1/2" plywood will also end up being fairly lightweight, I might be able to swing shipping a pair of standmount 8" 3-way to InDIYana.
I have a signature.

Comments

  • edited January 2019
    re: WBCD - yeah, most or all Jeff's excel programs need "fft.dll", so no cloud use.
    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • Office doesn't run on the cloud in this case, it is locally installed. It is a VBA limitation.
    I have a signature.
Sign In or Register to comment.