Low input signal strength into amp

nebborjk
nebborjk Posts: 425
edited November 2007 in Electronics
It seems I can only get my amps (AudioSource AMP100) to power up when the volume is really high, as I back the volume down the the amps seems to lose the signal and the sound drops out. Is this caused by the avr sending a weak signal or does the problem lie with the amp.

Thanks in adavance.
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Post edited by nebborjk on

Comments

  • nebborjk
    nebborjk Posts: 425
    edited November 2007
    Bump

    Anyone have an opinion on what is causing this?
    Proud SOPA Member since 2005!
  • zombie boy 2000
    zombie boy 2000 Posts: 6,641
    edited November 2007
    Does your AVR use a passive (or low gain) preamp stage? If so, what is the amp's sensitivity?
    I never had it like this where I grew up. But I send my kids here because the fact is you go to one of the best schools in the country: Rushmore. Now, for some of you it doesn't matter. You were born rich and you're going to stay rich. But here's my advice to the rest of you: Take dead aim on the rich boys. Get them in the crosshairs and take them down. Just remember, they can buy anything but they can't buy backbone. Don't let them forget it. Thank you.Herman Blume - Rushmore
  • Gaara
    Gaara Posts: 2,415
    edited November 2007
    Clarify a little more, do you mean turn down the volumes on the amps or the rcvr?

    The amps sensitivity is good at 1.4v. I got a feeling that it is a combo of the low power and dual attenuation.
  • zombie boy 2000
    zombie boy 2000 Posts: 6,641
    edited November 2007
    Plus... what are you using as a source? I'm assuming at least 2.0v from a CDP are in order. But you never know.
    I never had it like this where I grew up. But I send my kids here because the fact is you go to one of the best schools in the country: Rushmore. Now, for some of you it doesn't matter. You were born rich and you're going to stay rich. But here's my advice to the rest of you: Take dead aim on the rich boys. Get them in the crosshairs and take them down. Just remember, they can buy anything but they can't buy backbone. Don't let them forget it. Thank you.Herman Blume - Rushmore
  • nebborjk
    nebborjk Posts: 425
    edited November 2007
    Okay here's where I'm at. The AVR (Kenwood VR-7070) spec reads Pre-Out...1V / 500Ω. The Amp specs read 8Ω input sensitivity: 1.4V RMS, 4Ω input sensitivity: 1.2V RMS. As for the source it doesn't seem to matter. It will behave the same on the DVR, HD-DVD and CD-DVD Player. The connection type doesn't seem to matter either; toslink, 2-channel analog or 6-channel MC analog from DVD-A all act the same way. Is my problem the difference between the AVR outout,1V and the amp's input 1.4V? If so which one isn't "normal"?

    Thanks for your responses.
    Proud SOPA Member since 2005!
  • hypertone
    hypertone Posts: 150
    edited November 2007
    8 ohms input?? Amplifier input impedences are usually in the Kohms. An 8 ohm input wouldn't get any power as there is no way any line level source could drive a load like that.
  • nebborjk
    nebborjk Posts: 425
    edited November 2007
    I think it was refering to the speaker being an 8 ohm load.
    Proud SOPA Member since 2005!
  • Gaara
    Gaara Posts: 2,415
    edited November 2007
    nebborjk wrote: »
    Okay here's where I'm at. The AVR (Kenwood VR-7070) spec reads Pre-Out...1V / 500Ω. The Amp specs read 8Ω input sensitivity: 1.4V RMS, 4Ω input sensitivity: 1.2V RMS. As for the source it doesn't seem to matter. It will behave the same on the DVR, HD-DVD and CD-DVD Player. The connection type doesn't seem to matter either; toslink, 2-channel analog or 6-channel MC analog from DVD-A all act the same way. Is my problem the difference between the AVR outout,1V and the amp's input 1.4V? If so which one isn't "normal"?

    Thanks for your responses.

    The differences in sensitivity isn't that much, it just means that the amp won't be able to get to full power. You might lose a few db of available volume, which will equate to around 15wpc or so in this situation. This could be a problem though if the unit is sent to auto sense the signal.

    Is there a way to bypass the signal sensing feature? This could definitely be what is causing the problem. If it is set to on and the avr volume is to low it thinks there is no signal and shuts off.

    Again, how do you set your volume? Are the amps set to max and then you control with the avr or do you use the volume controls on both?
  • nebborjk
    nebborjk Posts: 425
    edited November 2007
    Gaara,

    I have the amps volume set to max and use the avr volume control. Should I try to lower the amp volume level and increase the volume at the avr. In theory I should be able to get the same spl during playback once calibrated.
    Proud SOPA Member since 2005!
  • Gaara
    Gaara Posts: 2,415
    edited November 2007
    First things first, is there a way to turn off the signal-sensing feature, and do you need it to be on? It sounds like this is the problem, and if you set it to not to this it wouldn't shut off.

    Decreasing the volume on the amp and increasing it on the AVR should work also, as you will have the same spl (as long as you calibrate after the change) but the signal being sent from the AVR will be stronger.
  • jakelm
    jakelm Posts: 4,081
    edited November 2007
    I'm having the same issue with both my subs, I dont like it, but I just have to leave them on (all the time). Watching a movie at low volume or first turning on the system and never having the volume loud enough to turn the subs on, was unavoidable other than leaving the sub amps on.
    Monitor 7b's front
    Monitor 4's surround
    Frankinpolk Center (2 mw6503's with peerless tweeter)
    M10's back surround
    Hafler-200 driving patio Daytons
    Tempest-X 15" DIY sub w/ Rythmik 350A plate amp
    Dayton 12" DVC w/ Rythmik 350a plate amp
    Harman/Kardon AVR-635
    Oppo 981hd
    Denon upconvert DVD player
    Jennings Research (vintage and rare)
    Mit RPTV WS-55513
    Tosh HD-XA1
    B&K AV5000


    Dont BAN me Bro!!!!:eek:
  • Gaara
    Gaara Posts: 2,415
    edited November 2007
    jakelm wrote: »
    I'm having the same issue with both my subs, I dont like it, but I just have to leave them on (all the time). Watching a movie at low volume or first turning on the system and never having the volume loud enough to turn the subs on, was unavoidable other than leaving the sub amps on.

    I had the opposite problem with my sub, it was getting to much of a signal. I had the thing dialed in just below off and if I turned the volume knob any lower it would be off. I ended up adding a attenuator to fix the problem.

    Can you possibly up the signal from the HK, perhaps through speaker level settings? If you could pump it up say 6db and then adjust the volume knob down accordingly it should help alleviate the problem.
  • jakelm
    jakelm Posts: 4,081
    edited November 2007
    Gaara wrote: »
    Can you possibly up the signal from the HK, perhaps through speaker level settings? If you could pump it up say 6db and then adjust the volume knob down accordingly it should help alleviate the problem.

    Raising the AVR level and lowering the subs volume level was counter productive. Cancelled each other out. Raising one and not the other, effected callibration. The only thing I found was leaving the amp on.

    The only way I can see to fix this issue, is to change the sinsetivity on the plate amp. But without having to change resistor/cap values, it would be unchievable.
    Monitor 7b's front
    Monitor 4's surround
    Frankinpolk Center (2 mw6503's with peerless tweeter)
    M10's back surround
    Hafler-200 driving patio Daytons
    Tempest-X 15" DIY sub w/ Rythmik 350A plate amp
    Dayton 12" DVC w/ Rythmik 350a plate amp
    Harman/Kardon AVR-635
    Oppo 981hd
    Denon upconvert DVD player
    Jennings Research (vintage and rare)
    Mit RPTV WS-55513
    Tosh HD-XA1
    B&K AV5000


    Dont BAN me Bro!!!!:eek: