You will likely need to actually test any replacement drivers with the same kit to get numbers that can be compared.
The manufacturers data is (almost universally) done using LEAP or LMS at much higher driver levels -- which, unless the driver has flat T/S curves, means a different set of numbers, sometimes dramatically so.
dave
As Planet10 (Dave) says, the Chester is a paper cone. 
Review | Carbon fibre Castle | Page172 - November1996 - Gramophone Archive
I stand corrected. Crossover suggests about 0.9mH inductance (Le) to me at a wild guess.
Review | Carbon fibre Castle | Page172 - November1996 - Gramophone Archive
I stand corrected. Crossover suggests about 0.9mH inductance (Le) to me at a wild guess.
I've picked up a pair of these Seas Prestige H1217-08 CA18RLY
I've measured them with the Dayton Audio DATS and these are the paramters for each:
* Manufacturer: Seas
* Model: H1217-08 CA18RLY
* Piston Diameter = 125.0 mm
* f(s)= 44.41 Hz
* R(e)= 6.04 Ohms
* Z(max)= 28.37 Ohms
* Q(ms)= 2.647
* Q(es)= 0.717
* Q(ts)= 0.564
* V(as)= 24.860 liters (0.878 cubic feet)
* L(e)= 0.92 mH
* n(0)= 0.29 %
* SPL= 86.72 1W/1m
* M(ms)= 10.93 grams
* C(ms)= 1.18 mm/N
* BL= 5.07
* Manufacturer: Seas
* Model: H1217-08 CA18RLY
* Piston Diameter = 125.0 mm
* f(s)= 44.41 Hz
* R(e)= 5.99 Ohms
* Z(max)= 29.82 Ohms
* Q(ms)= 2.526
* Q(es)= 0.634
* Q(ts)= 0.507
* V(as)= 24.860 liters (0.878 cubic feet)
* L(e)= 0.90 mH
* n(0)= 0.33 %
* SPL= 87.25 1W/1m
* M(ms)= 10.93 grams
* C(ms)= 1.18 mm/N
* BL= 5.37
Original Castle mid/bass drivers:
* Manufacturer: Castle
* Model: Chester
* Piston Diameter = 125.0 mm
* f(s)= 71.33 Hz
* R(e)= 5.49 Ohms
* Z(max)= 59.38 Ohms
* Q(ms)= 6.439
* Q(es)= 0.656
* Q(ts)= 0.595
* V(as)= 10.250 liters (0.362 cubic feet)
* L(e)= 1.00 mH
* n(0)= 0.54 %
* SPL= 89.43 1W/1m
* M(ms)= 10.27 grams
* C(ms)= 0.48 mm/N
* BL= 6.21
* Manufacturer: Castle
* Model: Chester
* Piston Diameter = 125.0 mm
* f(s)= 66.62 Hz
* R(e)= 5.55 Ohms
* Z(max)= 63.98 Ohms
* Q(ms)= 5.847
* Q(es)= 0.555
* Q(ts)= 0.507
* V(as)= 11.420 liters (0.403 cubic feet)
* L(e)= 0.85 mH
* n(0)= 0.58 %
* SPL= 89.74 1W/1m
* M(ms)= 10.57 grams
* C(ms)= 0.54 mm/N
* BL= 6.65
Measured a little different to the published data, but as some have said may be due to the levels used to test. I'll get the cabinets modified to fit them, be interesting to see how they measure with the existing crossovers.
I've measured them with the Dayton Audio DATS and these are the paramters for each:
* Manufacturer: Seas
* Model: H1217-08 CA18RLY
* Piston Diameter = 125.0 mm
* f(s)= 44.41 Hz
* R(e)= 6.04 Ohms
* Z(max)= 28.37 Ohms
* Q(ms)= 2.647
* Q(es)= 0.717
* Q(ts)= 0.564
* V(as)= 24.860 liters (0.878 cubic feet)
* L(e)= 0.92 mH
* n(0)= 0.29 %
* SPL= 86.72 1W/1m
* M(ms)= 10.93 grams
* C(ms)= 1.18 mm/N
* BL= 5.07
* Manufacturer: Seas
* Model: H1217-08 CA18RLY
* Piston Diameter = 125.0 mm
* f(s)= 44.41 Hz
* R(e)= 5.99 Ohms
* Z(max)= 29.82 Ohms
* Q(ms)= 2.526
* Q(es)= 0.634
* Q(ts)= 0.507
* V(as)= 24.860 liters (0.878 cubic feet)
* L(e)= 0.90 mH
* n(0)= 0.33 %
* SPL= 87.25 1W/1m
* M(ms)= 10.93 grams
* C(ms)= 1.18 mm/N
* BL= 5.37
Original Castle mid/bass drivers:
* Manufacturer: Castle
* Model: Chester
* Piston Diameter = 125.0 mm
* f(s)= 71.33 Hz
* R(e)= 5.49 Ohms
* Z(max)= 59.38 Ohms
* Q(ms)= 6.439
* Q(es)= 0.656
* Q(ts)= 0.595
* V(as)= 10.250 liters (0.362 cubic feet)
* L(e)= 1.00 mH
* n(0)= 0.54 %
* SPL= 89.43 1W/1m
* M(ms)= 10.27 grams
* C(ms)= 0.48 mm/N
* BL= 6.21
* Manufacturer: Castle
* Model: Chester
* Piston Diameter = 125.0 mm
* f(s)= 66.62 Hz
* R(e)= 5.55 Ohms
* Z(max)= 63.98 Ohms
* Q(ms)= 5.847
* Q(es)= 0.555
* Q(ts)= 0.507
* V(as)= 11.420 liters (0.403 cubic feet)
* L(e)= 0.85 mH
* n(0)= 0.58 %
* SPL= 89.74 1W/1m
* M(ms)= 10.57 grams
* C(ms)= 0.54 mm/N
* BL= 6.65
Measured a little different to the published data, but as some have said may be due to the levels used to test. I'll get the cabinets modified to fit them, be interesting to see how they measure with the existing crossovers.
Hi,
Note that the cone masses are similar, so the differences in Vas and Fs
are very mutual. Also the lower BL of the Seas driver probably indicates
more excursion, but with lower sensitivity.
The x/o looks fairly standard and may work well with treble L-pad adjusted.
My limited experience of putting higher Vas and lower Fs drivers into tuned
1/4 wave boxes is not good, a serious case of one note bass resulted.
But I guess you'll have to suck it and see.
rgds, sreten.
Note that the cone masses are similar, so the differences in Vas and Fs
are very mutual. Also the lower BL of the Seas driver probably indicates
more excursion, but with lower sensitivity.
The x/o looks fairly standard and may work well with treble L-pad adjusted.
My limited experience of putting higher Vas and lower Fs drivers into tuned
1/4 wave boxes is not good, a serious case of one note bass resulted.
But I guess you'll have to suck it and see.
rgds, sreten.
Sreten what was your choice of stuffing material that resulted in one note bass?
Many claim good results with fiberglass. Many old articles in books and magazines of it being to reactive compared to wool and low density polyurethane foam.
I would suggest using low density polyurethane foam for the damping material.
Approximately 60% in the first third of the line length. Reducing the foam to 40% in the middle and about 15-20% in the last section of the line. Place the foam in the line between the cabinet walls and not up against them.
A free flow of air must occur in the line.
I would be more than happy to send you an email of the many examples I have.
Fiberglass is very reactive and does act as a no pass filter in T-lines if heavily stuffed.
Many commercial designs do use the foam.
They look like older Focal carbon fibre drivers. i had a pair with papercone that had nearly exactly the same shape basket. i saw some on ebay USA last year if your lucky.
Finally got round to fitting the replacement drivers I picked up last year!
Just a bit of routing of the recess and the enlarging the mounting hole a little, the new Seas CA18RLY fits fine.
Also cleaned off the original dark stain from the cabinets and just used a clear danish oil to finish them, an improvement I think.
Haven't wired up the crossovers yet of run them yet, I'll get that done and compare the response with standard drivers later this week.
Just a bit of routing of the recess and the enlarging the mounting hole a little, the new Seas CA18RLY fits fine.
Also cleaned off the original dark stain from the cabinets and just used a clear danish oil to finish them, an improvement I think.
Haven't wired up the crossovers yet of run them yet, I'll get that done and compare the response with standard drivers later this week.
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