Amp Choices: Pro vs. Plate - Need your insight

Discussion in 'Archived Threads 2001-2004' started by Jeff Elliott, Feb 23, 2003.

  1. Jeff Elliott

    Jeff Elliott Stunt Coordinator

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    I have recently ordered an AV-15 and may wind up with two sooner or later. Now, I need some amplification. I have always wanted to have a rack with a pro amp neatly bolted in so I'm a bit prejudiced toward the pro stuff.

    The amps I'm considering are as follows:

    -QSC RMX850: 300 watts @ 4ohm, 430 watts @ 2ohm, $300
    -PE 300-794: 272 watts @ 4ohm, $120
    -Any other amp you guys suggest

    I have a few questions:

    1) If I go pro, how do I crossover and rumble filter? Can this be accomplished with the BFD? My receiver has a low-pass out but the freq. is set at 80hz.

    2) Since the AV-15's are supposed to arrive with 2 2ohm vc's, if I go pro could I not send 430 watts to each of the AV-15's coils? Maybe with this much power one AV-15 would be enough?

    3) Besides the cool factor of having a nice rack with pro amps in it, which options offer the most cost effective solution per watt? I know the pro amp yields a bit more flexibility in terms of driving different impedance loads, but does it come at the cost of several other costly components (crossover, etc.)?

    Any suggestions, experience or insight is greatly appreciated!

    Jeff
     
  2. JimPeitersen

    JimPeitersen Second Unit

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    Either of your solutions would work. I would recommend using as much power as you could afford for the AV15. Generally, with plate amps you get some flexibility (crossover, filters, etc.) that you don't get with most pro amps. You should also consider these two plate amps (Stryke 350, and Rythmik Audio plate amp), both will give you more power than the PE for just a little more money. The one advantage of the pro amp is that if you decide to get two AV15's, you can run them off of a seperate channel of the amp (at 4 ohms.) I am sure that others will weigh in with ideas I haven't mentioned.
    JP
     
  3. Bryan Michael

    Bryan Michael Supporting Actor

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    i ordered a samson s1000 from svs the b stock and also got the bass box too. if you decide to add a seccond get a beter amp. also the pro amps need more gain to drive them.
     
  4. Allen Ross

    Allen Ross Supporting Actor

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    sort of of topic but why do you guys call an equilizer BFD?
     
  5. Geoff L

    Geoff L Screenwriter

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    Is that correct that the AV-15 will be 2-ohm coils only for sure???

    I thought I heard/read that some would made available sporting dual 4-ohm coils on the 12 & 15.....

    Would this be correct or not????

    Geoff
     
  6. Martice

    Martice Screenwriter

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    Hey guys. If you read the below thread I'm sure that you'll find all of the answers that you're looking for.

    Good thread

    Enjoy
     
  7. Geoff L

    Geoff L Screenwriter

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    From John J post:

    Tumult, upcoming revisions of the AV drivers and the HE15 all being dual 2-ohm coils...

    So thats where I heard it, must be they started out being dual 4-ohm and John revised them and went to the dual 2-ohm coils on the AV drivers.

    Thanks
    Geoff
     
  8. Seth_L

    Seth_L Screenwriter

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    A BFD is a Behringer Feedback Destroyer. It is a dual (stereo) 12 "band" digital parametric equalizer. For $120 you can't beat it. It doesn't have the limitations of convention EQs (ie: fixed bands, limited filter width, etc). You can put all 12 "bands" or more accurately filters between 20Hz and where every you want to stop. With a test tone CD or program on your PC and a Radio Shack SPL meter you can get a flat in room bass response without too much effort or expense.

    Seth
     
  9. bruin

    bruin Second Unit

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  10. Robert_Gaither

    Robert_Gaither Screenwriter

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    The advantages of a plate amp: integrated x-over (most are useless when applied to ht due to being bypassed and music due too high of x-over for most part)/phase (some variable some just the 0/180 switch)/remote (some)/gain (volume control)/hi-level inputs, cheap (quite a selection for under $200), takes up little space (assuming building into the sub, otherwise maybe not so great), and high/speaker level inputs for those that don't have a sub pre-out on their system.

    The disadvantages of a plate amp: boost which can affect a flat response, subsonic filter which might be set higher than what the home drivers in the diy field are capable of in a sealed cabinet, reuseability (most likely built into the sub cabinet therefore most likely sold with sub and not used for the next project), non-bypassable x-over which might have an interaction possibility with the system, and also most likely placement options if built-into the sub based on convience of outlets and cord reach.

    The advantages of a pro-amp: power for more than one sub (usually a plate amp goes for slightly more than half a pro-amp for comparative quality/power), durability (after all pro use and usually built to a higher standard imho, assuming we're not talking pyramid or gemini), clear signal topology (usually there is no boost), and can easily be used on the next project which includes non-subs.

    The disadvantages of a pro-amp: fan noise, extra channel wasted not doing anything/having already paid for it (of course if you're AVR has a center pre-out...), upfront cost if only doing one sub project or budget strapped, gain stage not sensitive enough (might have to buy a line driver), high pass filter (some of these have a subsonic filter set above 30 hz watch out!), amp draw from outlet may cut the breaker on power up if anything else is already on (my other equipment, namely the TV flickers when I power mine up there might be a possibility on some of the older homes with a 10 amp outlet), might have to buy adapters to go unbalanced to balanced to use, another shelf space eaten, weight/size too big/heavy for current audio furniture, SAF, another outlet slot eaten (for those that are lacking an extra slot on their line conditioner), another set of wires to run (your choice interconnect to plate or hi-level to sub for some of us), lack of integrated features common in a plate amp, esthetics of the color (most pro-amps have red lettering, odd color {blue, red, or very glossy or flat black vs the standard in most AV gear} or big bold white lettering and sort of stand out on the shelf), and rack mounting shelfing to look good instead of looking awkward sitting on a shelf (for some just simply esthetics).

    Imho I currently use a pro-amp and love it but when some of these Diy company come out with a quality plate amp in a rack mount chassis, I'm going to jump ship for some of the features alone (I want a variable phase and para eq).
     
  11. Tracy_L

    Tracy_L Stunt Coordinator

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    Hey Jeff

    I just bought the QSC RMX850 from Northernsound for $269 shipped. I bought to use in an IB configuration, I just haven't gotten around to building it yet. It just got shipped this week and I'm itching to get some free time to get started.

    Here's a link to their website. They list it at $299, but the discount price (shows one star behicnd the price meaning a 10% discount) I got was $269.10 or so with free shipping. Cheapest price I could find.

    http://www.northernsound.net/Sales/P...s/qsc/qsc.html

    Just a little heads up on a good price....

    Tracy
     
  12. Rob Formica

    Rob Formica Stunt Coordinator

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    Just wondering what kind of line level output (Volts and Impedance?) do typical preamps have versus the Pro AMPs? Any links to line drivers and info on them?

    thanks
    Rob
     

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