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skudra
09-28-2009, 11:27 AM
Hi-I have a hybrid amp (tubed input stage with mosfet output stage) Moscode 402Au that has an output impedance of 0.22 across the entire audioband, with the amp's frequency response modification as it interacts with how a loudspeaker's impedance varies with frequency being +/- 0.15db.
I have a custom horn speaker system with 803B multicells, unobtanium compression driver and JBL 2235's in a modified Altec A-7 box.
The specs for the JBL are as follows:
THIELE - SMALL PARAMETERS:
fs: 20 Hz
Re: 6.0 ohms
Qts: 0.25
Qms: 2.5
Qes: 0.28
Vas: 460 L ( 16.2 ft3)
Sd: 0.089 m2 ( 138 in2)
Xmax: 8.5 mm (0.33 in)
Vd: 757 cm3 (46 in3)
Le: 1.2 mH no (Half space)2: 1.3%


I'm wondering how you think the amp's output impedance will affect the control of the bass driver?
I am getting quite impressive, thumping bass, but have yet to fully realize if it's controlled enough.
Thanks in advance for any comments you might have.

jcrobso
09-28-2009, 12:17 PM
Hi-I have a hybrid amp (tubed input stage with mosfet output stage) Moscode 402Au that has an output impedance of 0.22 across the entire audioband, with the amp's frequency response modification as it interacts with how a loudspeaker's impedance varies with frequency being +/- 0.15db.
I have a custom horn speaker system with 803B multicells, unobtanium compression driver and JBL 2235's in a modified Altec A-7 box.
The specs for the JBL are as follows:
THIELE - SMALL PARAMETERS:
fs: 20 Hz
Re: 6.0 ohms
Qts: 0.25
Qms: 2.5
Qes: 0.28
Vas: 460 L ( 16.2 ft3)
Sd: 0.089 m2 ( 138 in2)
Xmax: 8.5 mm (0.33 in)
Vd: 757 cm3 (46 in3)
Le: 1.2 mH no (Half space)2: 1.3%


I'm wondering how you think the amp's output impedance will affect the control of the bass driver?
I am getting quite impressive, thumping bass, but have yet to fully realize if it's controlled enough.
Thanks in advance for any comments you might have.

I assume that you are using a crossover network, which one as it will also affect what happens.

frank23
09-28-2009, 12:35 PM
I wouldn't worry too much. Placement and the tube input probably have more impact on how the low end sounds than the output impedance which is not very low, but not too high either. The 0.15dB is peanuts compared to room effects which can run up to 10dB or more I think.