Denon 1403 & JBL S38 question

Discussion in 'Archived Threads 2001-2004' started by DuncanM, Feb 11, 2003.

  1. DuncanM

    DuncanM Auditioning

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    I bought the Denon 1403 & JBL S38s as the beginning of a system for both music and HT. Right now I'm using it mainly for music (set to stereo mode, fronts large, no sub), but the bass sounds really flat. Does this receiver have enough power for these speakers without a sub? Any suggestions would be appreciated (i.e., what receiver to move up to, what sub might help fix this problem, etc.). Thanks.
     
  2. Phil Iturralde

    Phil Iturralde Screenwriter

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    JBL S38 MFG. Spec:
    • Frequency Response (–3dB): 45Hz – 20kHz
    • Sensitivity (2.83V @ 1m): 89dB

    Denon AVR-1403
    • 70 watts x 5 into 8 ohms (20-20,000 Hz) at 0.08% THD

    Based on the above specs, you have enough 2-channel stereo power to listen to your Music CD's @ near Concert Levels easily.

    For example - using this quick Watts vs. SPL chart ...

    RULES:
    SPL = To HEAR an Audible Increase in loudness, the SPL source must increase by 3 dB min.
    Watts = To Increase SPL by 3 dB would require Doubling the power output ( Watts x 2 )

    Watts....SPL (dB)
    1 .......... 89 (JBL S38 sensitivity rating)
    2 .......... 92
    4 .......... 95
    8 .......... 98
    16 ........ 101
    32 ........ 104
    64 ........ 107
    128 ...... 110

    So, @ half the watts available (32 watts), 104 dB is loud enough to disturb your neighbors!! [​IMG]

    For a more accurate SPL Calculation, use C.M.Collins. excellent SPL Calculator.

    So, the lack of bass you hear might do with the S38 location in the room, away from the wall boundaries, because according to Sound & Vision, the JBL S38 benched marked:

    FREQUENCY RESPONSE: 80 Hz to 20 kHz ±3.8 dB (averaged over a ±30° window, with double weight given to the most common listening angle, 30°)

    So, until you get a powered-sub (like the $549 SVS 25-31PCi), just use your bass control to increase the falling bass response until it sounds right.

    Phil
     
  3. DuncanM

    DuncanM Auditioning

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    Thanks for doing the math for me. At least I know in theory things should sound good. I'll try moving the speakers around and see what happens. I do obviously need a sub, but it's hard to get my head around paying as much for the sub as I paid for the speakers and receiver combined. Maybe that's the answer though. Thanks again.
     
  4. KyleGS

    KyleGS Second Unit

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    I had to move mine away from the corners to lessen the bass. They definately have the ability to be bass heavy given location. Properly located I really don't need a sub for 95% of my music. If moving them towards a wall doesn't help- you could try spiking them if they are on speaker stands or you may have to get a powered sub. It really depends on your room.
     

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