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  1. #1
    Join Date
    Jun 2008
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    Northern California
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    186

    Default Sub Plate Amp Use High AND Low Level inputs?

    Hi Gang
    The question is can You connect both high level and low level inputs to the PE 300-793 Plate Amp at the same time?

    Here's why. I'm using a PE 300-793 240W Plate AMP in my 12inch project sub. My A/V Receiver is a Pioneer VSX45THX. When I connect LFE out to the low level Sub inputs it works great with 5.1 DVD, DVd-Audio, SACD or Movie with lots of LFE effects but nothing with 2 channel music sources no matter what settings I use in the A/V x-over and speaker/sub setup. I've tried all setup combinations- all small speakers with sub, all all large with sub PLUS etc but I can't trust the Pioneer processing. It's vague

    On the other hand if I split the speaker outputs driving the mains and send to the high level Sub inputs and change A/V settings to no sub it's great for 2 channel music but I'm missing the LFE channel special effects for DVD-Audio, SACD and movies. Also using the high level inputs I'm not keeping lows out of the mains and I'm not sure if I'm getting the advantages of my 5dB boost mod in the sub.

    So if I connect it both ways I'll always get the best of both worlds. Right? Has anyone tried this?
    Any ideas?

    Thanks
    Chris

  2. #2
    Join Date
    May 2008
    Location
    manassas, va
    Posts
    1,388

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    On my Yamaha, I have to set the receiver to 'both'. This is bass to both the fronts & the sub.
    If dynamite was dangerous, do you think they'd sell it to an idiot like me?

  3. #3
    Join Date
    Jun 2008
    Location
    Northern California
    Posts
    186

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    Hi Kid
    Thanks for the reply. In the Pioneer setup it's a similar thing called PLUS which will send low frequencies to both Sub and the Mains even if the mains are set to Large. Still no matter what I try it just doesn't cut it it on 2 channel material. Have you ever tried or heard of anyone trying connecting to both low and high level Sub inputs at the same time?
    Thanks
    Chris

  4. #4
    Join Date
    Nov 2006
    Location
    Austin, TX
    Posts
    718

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    Hi Chris,

    On my Yamaha (RX-V2400) I have diffrent DSPs for this. If I have the receiver set to DIRECT, then only the front mains are running (no sub). If I have it set to 2-CHANNEL STEREO then the sub is added to the fronts.

    This is with my sub conneced only through the line level/LFE.
    Do you have different DSPs in your receiver for this?

    Best regards, Andy.

  5. #5
    Join Date
    Jun 2008
    Location
    Northern California
    Posts
    186

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    Hi Andy
    Thanks for the reply. In the Pioneer I have the same option to run STEREO or DIRECT(bypass all preamp and processor) which just sends signal to the front mains. That's the setting I usually listen to for music CD or Vinyl or Dish 2 channel music programs like Sirius(yuk) or stereo concerts etc. I also listen to 2 channel SACD but through the direct Analog inputs from the Disc player.
    Chris

  6. #6
    Join Date
    May 2008
    Location
    manassas, va
    Posts
    1,388

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    Try standard 2 channel. Maybe even using analog inputs for the experiment. This should tell you if the Direct really bypasses everything. Another possibility, though improbable, is your unit may not run 2.1 in digital. As long as you have things pulled out for connecting, try every combo and see what happens. And, without any disrespect, read the instructions. I think sometimes they make something hard just to force us into the instruction manuel.
    If dynamite was dangerous, do you think they'd sell it to an idiot like me?

  7. #7
    Join Date
    Jun 2008
    Location
    Northern California
    Posts
    186

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    Hi Kid
    I'm ripping into it again tomorrow. No disrespect taken. I've just about memorized the damn Pioneer manual over the past 3 years that I've had it. It's frustrating because it's so dumbed-down and vague. Like Sub PLUS gives you " Stronger more powerful bass...than Sub YES" What the hell does that mean? Why not just give power and frequency or show a response curve? I contacted Pioneer support when I first got it explained that I was an Electrical Engineer and asked for technical descriptions and a signal flow matrix of the different modes. Not available. I have the same issue with a Panasonic Digital camera I have. There are a zillion preset modes with pictures instead of real names like a"camera" means NORMAL, a "flower" means MACRO why not just say macro? I told them I had been a photographer for many years and asked for a description of all the modes in terms like f-stop, shutter speed, etc. Not available. It's just the way marketing is done. Don't give too many numbers or too much technical detail.

    Aaah I feel better now. Sorry for the rant!

    The bottom line is tomorrow I'll trust my SPL meter, test disc and my ears and use some good old fashioned trial and error!

    Still toying with the idea of getting both LFE and Main signals into the Sub somehow. Maybe one channel of Main Pre-out and running that along with the LFE out into the low level Sub inputs? I wish I had a schematic of the Amp to see where and how they sum the inputs.

    I'll keep you posted.

    Chris

  8. #8
    Join Date
    May 2008
    Location
    manassas, va
    Posts
    1,388

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    I am not usually thrilled with the picture buttons either - I also have the flower button on my cannon. I had issue with bass from my mains. After reading the manuel to the end, I discovered the bass control is at 50hz and the treble is at 20k hz. NOT MY FAVORITES...but why that should have even been an issue prior to buying, I never would have figured.

    I think you need to keep trying every combo of connections & settings on your Pioneer. There should be some magical setting to make things work. Then you can memorize the picture for that setting!
    If dynamite was dangerous, do you think they'd sell it to an idiot like me?

  9. #9
    Join Date
    Jun 2008
    Location
    Northern California
    Posts
    186

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    OK So here's the final result!.

    My original quest was to have a Sub setup that was performing well in both Stereo and Surround modes. My Elite VSX-45TX Speaker management settings SAID I should be getting Sub out in Stereo but I wasn't...or so I thought. That's why I was thinking of connecting both high level in Stereo modes and Low level to LFE for surround.

    I've now discovered the real problem. There IS Bass output from the LFE port in Stereo mode! It's there but it's 25dB down from the LFE level in Surround mode! So this modifies the original question of using High and Low level inputs. The real question beacame How do I get higher LF levels to the Sub in Stereo mode whlie preserving the LFE signal for Surround modes.

    Here was my simple solution: The first concern was isolation. I didn't think it wise to tie the LFE pre-out to a Main Pre-out due to possible crosstalk or worse, destruction of the pre output stages in the Elite! But if you look at the Sub Amp input it is a summing stage which provides isolation channel to channel so I felt OK about my experiment. The second concern was loading one mains channel with the input impedance of the Sub Amp. Would this reduce the signal level significantly? I didn't have the inputZ spec for the sub but figured it to be fairly Hi-Z so hoped for minimal load and maybe I would need to compensate with balance settings. So here's the hook-up.

    For Stereo LF I split one pre-out channel which feeds my external Mains amp and sent that to one low level input of the Sub Amp.This samples the exact signal and level being sent to one mains channel. It's the full Frequency spectrum but the Sub LP filter takes care of that. Also the bass content is effectively the same for both channels Since most LF info is mixed mono (panned center) anyway.

    For Surround I simply ran the mono LFE output of the receiver directly to the other low level Sub input.

    The result is exactly what I hoped. No smoke or destruction! Also no level attenuation on the split mains channel. I use a test disc with Sine waves from 10 Hz to 400Hz in 5Hz steps and an RS SPL Meter and published cal corrections. In Stereo modes I was now getting Sub output levels within 1 dB of the LFE levels. There were some new peaks in room response due to overlap of the Mains and Sub even with the Sub LPF set to 40Hz. I then ran the Auto cal/EQ leaving the sub active during the setup. This allowed the system EQ to notch out the most offensive room modes at the listening position. I took 2 days of measurements and listened to a variety of sources.

    Phono-
    Telarc 1812 Overture with Real Cannon Holy ---- YES!
    Dave Brubeck Time Out- Smooth even Bass walking up and down, Great Kick Drum Finally deep bass with my Vinyl! Yes!

    CD- Sine Test Disc, Steely Dan, Sarah McCaughlin Accurate great punch no boom. Finally nice LF extension with Stereo CD's!

    DVD Audio- Sting's Sacred Love is a great demo- Fantastic mix great low bass as before.
    SACD- Dark side of the Moon Wow!

    Video- Diana Krall live in Paris DVD w/DTS Audio. What a great production!
    All movies- Great stuff! LFE effects with all the SwishBangZoom you would expect

    So now I see why newer A/V Receivers and Subs are allowing multiple input/output options with Low level AND LFE connections and seperate control of each. The speaker setup in some A/V receivers doesn't always do the job.

    Thanks for all the input and interest!

    CC
    .
    Last edited by cpcarter; 04-02-2009 at 03:16 PM.

  10. #10
    Join Date
    Oct 2005
    Location
    Homestead, FL
    Posts
    1,242

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    I'm pretty sure the line level inputs don't run through the crossover. I'm 95% sure they don't on my SA-240 at least. You might want to try listening to your sub once without the mains.

    bb

    Since we cannot know all that there is to be known about anything, we ought to know a little about everything.
    - Blaise Pascal (1623 - 1662)

  11. #11
    Join Date
    Jun 2008
    Location
    Northern California
    Posts
    186

    Default Re: Sub Plate Amp Use High AND Low Level inputs?

    Hi Bob
    I have measured the sub alone nearfield and room response at the listening position. The roll-off is about 12 dB/octave. I'm only measuring in 5Hz steps so it's not exact but the variable LPF response is in the spec ballpark.

    I'm not sure which crossover you mean but It's my understanding that both high and low level input are shaped by the adjustable Low pass filter and there is also a "rumble filter" ~18-23Hz combination High pass and EQ. This is the filter that you can change Q and Fc and get up to 5dB of Boost by changing 2 resistor values.

    The low level outputs are direct pass through of the original input signal.

    The speaker level outputs pass the original powered signal through a fixed 125Hz 6dB/octave Low Pass Filter to Satellite speakers.

    Here is the description from the 300-793 manual. Your 240 might be different.
    "... Crossover Frequency Control: Continuously variable from 40Hz to 170Hz at 12dB/octave
    Line-in: These are line level RCA inputs. Use to connect pre-out or preamplifier outputs directly to subwoofer amplifier’s internal crossover. These inputs are summed to mono. If preamplifier outputs are not available, use the High-level inputs.
    Line-out: This line level RCA output provides a full range (20-20kHz) output and is used to connect “daisy chain” the line level signal to other amplifiers. Note: Line out is only active when a signal is present at the line-in input.

    High-level In: Speaker level input. Input connects directly to receiver via speaker cables.
    High-level Out: Speaker level output. Used to connect satellite speakers. Note: Signal only presentwhen hi-level input is used. Features 6dB/octave
    high pass circuit (125Hz @ 8ohm).

    Hope this answers your question.
    Thanks
    CC

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