[HAM] DC filtering to the heater filament voltage of the AO28

[Kon Zissis]

Hi Keith and everyone.
The locally built Lorantz C386T/PA/16 bass speaker in my Leslie 122 is
the 16 ohms version of the C386T/PA/8 speaker, and the Thiele / Small
parameter specs are shown below. I do not know what  these Thiele /
Small specs mean as far as the actual sound quality is concerned and I
do not know how these compare with the specs of the Jensen FC15Ll or the
P15LL or the  black Utah bass speaker with the square magnet  that was
originally in my 1971 Leslie , but hopefully these specs may help you to
give you an indication of the sound quality.

Can you please  tell me if these specs do indicate the sound quality to
you ?

Lorantz C386T/PA/8  8 ohms 15 inch bass speaker Thiele/small parameter
Specs:

Maximum program power      = 400 watt.
Thermal power rating       =  200 watt RMS
Rated nominal impedance    =  8 ohms ( 16 ohms for the C386T/PA/16 in my
Leslie 122)
Rated frequency range      =  30 Hz to 5 kHz
Piston sensitivity level   =  97 dB SPL
Octave band SPL pink noise =  100 dB SPL
Resonant frequency         =  40 Hz
Mechanical Q            QM =  4.1
Electrical Q            QE =  0.54
Total speaker Q        Qts =  0.482
Moving mass           Mms  =  67 gms
Effective diaphragm diameter  D = 33.5 cm
Peak linear vol. displacement  Vd =264 ccm
Vol. equiv to speaker compliance Vas  = 260 litres
Mechanical compliance   Cms  = 2.36E-4M/N
BL product               BI  =  13.6 T.M
Voice coil diameter       d  =  63.5 mm
Voice coil material          =  copper
Voice coil DC resistance Re  =  6 ohms ( possibly 12 ohms in the
C386/T/PA/ 16 in my Leslie 122 )
Voice coil inductance   Lvc  =  0.88 mH
Voice coil height            =  14 mm
Height of air gap        Hg  =  8 mm
Peak linear displacement Xpk  =  3 mm
Reference efficiency          =  3%
Speaker total mass            =  5.7 kilograms

The infinite baffle frequency response curve which was recorded at one
metre is as follows:
20 Hz = 84 dB
30 Hz = 89 dB
40 Hz = 91.5 dB
50 Hz = 93 dB 
60 Hz = 94 dB
70 Hz = 94.5 dB
80 Hz = 95 dB 
90 Hz = 95.5 dB
100 Hz = 95.8 dB
150 Hz = 96.5 dB
200 Hz = 96.5 dB
300 Hz = 97.9 dB
400 Hz = 96.2 dB
500 Hz = 97.5 dB
600 Hz = 98 dB
700 Hz = 97.7 dB
800 Hz = 97.2 dB
900 Hz = 99 dB
1 kHz = 99.8 dB
1.5 kHz = 102.5 dB
2 kHz = 100.5 dB
3 kHz = 100dB followed by a steep roll off with the following kHz
frequencies with 5 kHz being 88.5 dB

The recommended  vented enclosures are 90 to 350 litre capacity  and
sealed enclosures are 60 to 90 litres

I hope that that all of these specs and frequency response dB levels
will give you a reasonably accurate indication of the sound quality of
the Lorantz  C386T/PA speaker.

Merry Christmas.
All the best.
Kon

  
Keith H Clark wrote:
Definitely better but the Leslie cabinet will never replace a good
acoustically designed cabinet for low frequencies. The good point is it
doesn't emphasize bass problems.
    What is the efficiency spec of that driver and it's -3 db down
point?
Anyway, Merry Christmas....Keith