Magnavox/Rola fullrange 8"

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Hey all! I got two old FM026 radios recently, restored one and used the other as a display case for models ( it was pretty trashed.)

I got a nice amp86 out of the deal though :D It is now restored and in use in my main system.

Now I have these two 8" full range speakers that I don't know what to do with! They have AlNiCo magnets, 3/4" coils and a wizzer cone.

I tried them in my little 2 watt guitar amp and they sound wonderful, but they also sound AWESOME as mid/hi-fi speakers! They have a pretty loose surround, so the bass responce is pretty impressive for such old and small speakers.

The code on the back is 285307. The 285 says their Rola's. I don't know Rola date codes ( it would be nice if someone could point me toward some.)

I really like the sound of them, and they don't take hardly anything to drive them to decent levels. They will take about 10 watts before bottoming out. I want to build some cabinets for these, maybe transmission line loaded?

I wanted some opinions here, because I know that a lot of old console speakers were deisgned for open baffle types. I was thinking that a mid sized ( 3-4 foot tall) transmission line was in order. Maybe there are some fostex drivers that have similar Thiele-small's that I can input to get an approximate cabinet design in winisd?

I have pictures of the speakers if one wants.
 
I am having difficulties calculating the VAS.

I do not have a sealed box to use so I am using the added mass method.

I am using Rod Elliots TSP spreadsheet, however in his article it says there are calculations given in it for calculating vas using mms, there is even a pic on the webpage, however in the spreadsheet no such entries exist.....


Here is as far as I have been able to get...

RE= 3.7 ohms
FS = 61.75 hz
RM= 14.06 ohms
Fh = 54.57 hz
Fl = 66.65 hz
 
ThSpeakerDude88 said:

Here is as far as I have been able to get...

RE= 3.7 ohms
FS = 61.75 hz
RM= 14.06 ohms
Fh = 54.57 hz
Fl = 66.65 hz

Greets!

FYI, Fl, Fh is backwards. ;) Regardless, when I punch these specs into my SS I get the kind of numbers that are a bit high, but more in line for radio drivers than a ~0.35 Qts:

Qms = 9.9646
Qes = 3.5588
Qts = 2.6223

That 90 L box is looking down right tiny now. ;)

Anyway, your numbers are suspect since Fs should be equidistant between Fl,Fh = SQRT(54.57*66.65) = ~60.31 Hz.

GM
 
I am going to recalculate everything today. I need to remeasure the speaker as well.


Does anyone know of any other spreadsheets that are better?

As I said before I am using the added mass method to calculate Vas because I don't have a sealed enclosure.

Planet10, I would have to say that is 1957, because I believe the radio model was made from 1957-1960. It couldnt be 1967 anyways, because its a tube consolette. Had the magnavox amp86 in it, complete with Mullard 6bq5's! I think mine is approx. 1958. Beautiful radio btw, more in the hi-fi range than most. Reminds me of an old Normende or Grommes consolette.

To get my numbers for Fh and Fl it says to run the frequency up and below resonant frequency untill a predetermined voltage ( from the SS) appears across the dropping resistor, which in my case is 10r.

Whe I redo the measurments I will post a pic of the SS with values entered. After I'm done measuring these, I think I am going to move on to my maggie 15 inchers

:D
 
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