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How many amps for this setup


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#1 beginner44

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Posted 19 June 2012 - 02:17 PM

Hi there,

this is my first post here. I really need your help, as I'm a beginner in the audio gear worl !

I'm building my hometheater.

The speakers are :

LCR : JBL 3678 (so 3 pieces)

Frequency range (-10 dB): 30 Hz to 20 kHz
Frequency response ( 3 dB): 45 Hz to 12 kHz
Power capacity1
(passive): 300 W
Power capacity (bi-amp): HF:  50 W
LF: 600 W
Sensitivity: 98 dB
Nominal impedance: 8 ohms
Crossover Frequency: 1 kHz
Nominal coverage: 90 horizontal, 90 vertical
alf-space reference ef?ciency: 3.3%
ximum acoustic power output
(sine wave input) 8 acoustic watts


Surround : JBL 8330A (4 pieces)

Frequency Range (-10 dB): 40 Hz - 20 kHz
Frequency Response (3 dB): 70 Hz - 14 kHz
Power Rating1
: 100 watts continuous pink noise, 400 watts peak
Sensitivity2
: 91 dB SPL, 1W @ 1m (3.3 ft)
Nominal Impedance: 8 ohms
Hor. Coverage Angle (-6 dB): 110 averaged 400 Hz to 12 kHz
Vert. Coverage Angle (-6 dB): 105 averaged 400 Hz to 12 kHz
Directivity Factor (Q): 4.5 averaged 400 Hz to 12 kHz
Directivity Index (DI): 6.5 dB averaged 400 Hz to 12 kHz
Crossover Frequencies: 650 Hz, 3.1 kHz


Subwoofer : JBL 4641 (1 piece)
Rated Impedance: 8 ohms
Minimum Impedance: 6.3 ohms
NDLING CAPABILITY:
ntinuous Pink Noise1
: 600 Watts
Continuous Program2
: 1200 Watts
Peak Power3
: 2400 Watts
OUTPUT CAPABILITY:
Axial Sensitivity4
: 50 Hz to 500 Hz; 98 dB, 1W @ 1m
40 Hz to 100 Hz; 97 dB, 1W @ 1m
Power Compression5
:
10 dB power (60 W): 0.8 dB
3 dB power (300 W): 2.6 dB
ated power (600 W): 4.3 dB
Single Two Four Eight
Module Modules Modules Modules
Reference Ef?ciency6
: 2.9% 5.8% 8.7% 11.6%
ontinuous Acoustical
Power Output: 17 W 70 W 209 W 557 W
uous SPL @ 1 meter7
: 125 dB 131 dB 136 dB 140 dB
Peak SPL @ 1 meter7
: 131 dB 137 dB 142 dB 146 dB
QUENCY RESPONSE8
: Lower Frequency Limits (no EQ):
-10 dB: 25 Hz
-3 dB: 35 Hz
Lower Frequency Limits (with EQ):
-10 dB: 22 Hz
-3 dB: 25 Hz
ossover Frequencies: High-pass: 20 Hz, 24 dB/octave or greater
Low-pass: 80 Hz to 150 Hz, 12 dB/octave or greater



Now the questions :

1 - I found the specs and users' feedback very positive on the CTs series, so I plan to use a bunch of them. Has anyone experience of these in such a context ? (my room is around 6300 pi3, 560 pi2)

2 - for the sub, I would use CTs2000 (2 * 1000 W) ; for Left & Right, CTs600. What about Center ? Can I use the spare channel on the CTs2000 ?

3 - for the surround, JBL documentation (JBL Cinema Sound Systemrecommends CTs1200 ; I do not undestand why CTs600 would not be appropriate (despite the lower sensitivity (91 db) of these speakers) ?

4 - can I plug the 4 surrounds on the same CTs1200 / CTs600 ? (I know I would not be able to define a different delay for each surround in that case) ? Or shoud I use 2 amps (1 per pair) ?

I thank you very much in advance for your help,

Best regards,

B44




#2 dakos

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Posted 25 June 2012 - 06:00 PM

In a cinema surround system every speaker has its own signal which slightly differs from the other speakers so every channel needs its own dedicated amplification.
Using one channel of the amp for the sub and the other channel for the center is perfecrly fine.
Your setup will sound great.
CTs1200 fits better then the CTs600 for the surround speakers but the 600 will do a great job as well,

#3 beginner44

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Posted 03 July 2012 - 01:57 PM

@ dakos :

many thanks for your answer.

I have an opportunity to buy a used CTs4200, I guess it would fit perfectly for my 4 surround speakers.

Take care,

BG44

#4 dakos

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Posted 08 July 2012 - 01:25 PM

most definitely :)