beginner44

How many amps for this setup

4 posts in this topic

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

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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,

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@ 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

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