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Amp question

Discussion in 'AV Receivers' started by snake, Sep 2, 2012.

  1. snake

    snake Active Member

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    Hey guys, I've got a question. Let me tell you what I've got for context, then I'll ask the question. Got an Onkyo NR809 avr, Polk Audio RTi12 towers, and a CSi5 center. I've been working up to a nice Polk Audio HT and music system using the RTi stuff.
    Since I listen to music 80% of the time, I've been thinking about amplifying the towers. My thoughts were about getting a Parasound 2125 to give them a boost. If I get a second amp and run them mono to each tower, they are bridged and good for 400wpc and that sounds really good right? I'm thinking that'd be plenty of power but do people have good luck and sound with bridging amps?
     
  2. snake

    snake Active Member

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    I meant that the idea of having 400 watts sounded really good. I had heard that bridging amps may not always have good results. Just curious. I also was thinking i may need an amp so that the center and surrounds would get more power from the avr.
     
  3. gene c

    gene c Well-Known Member

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    I'm far from an amp expert but I'd get one 2125 amp first and use it in stereo. 125 w from a good quality outboard amp should be much better than a claimed 135 w from a receiver. If one amp used in stereo for the fronts isn't enough then get another. And you could always use he amps in stereo to bi-amp the fronts if bridging doesn't sound like a good idea to you.
    But my guess is one of those amps in stereo driving both RTi12's will be enough.
    Also consider Emotiva if you're looking for high outoput on a budget. http://shop.emotiva.com/
     
  4. Dave Upton

    Dave Upton Owner
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    I'll echo the above posters - don't make the mistake of assuming lots of power always equates to better sound. It will certainly give you headroom - but that's not necessarily a problem. What sort of SPL do you listen at normally? Do you find that you can hear noticeable compression/clipping with your AVR?
    The spec I tend to look at most in an amplifier (other than class - A,D etc) is the measured THD or Total Harmonic DIstortion. This to me is the specification that usually has an audible difference - and if you buy something with more wattage but a much higher THD than your Onkyo, you could actually be downgrading your overall sonic experience.
     
  5. schan1269

    schan1269 HTF Expert
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    Buying an amp to relieve the burden of 2 channels off your AVR is never a bad thing. I would have chimed in earlier...but I have zero experience with a bridged Parasound...
    It has been a while since I knew how much power the 809 sucks off the wall, bit I'll guess just north of 800watts.
    We'll assume 100 watts of power for the video section(there is no real way of knowing). That leaves 700 divided by "however many" channels you are currently using...
    So, stressed to the limit if you are running 7 channels...gives you 100. Not the "stereo based" 125(or whatever it is). More importantly is the DYNAMIC POWER it no longer has. If you "check the specs" you'll see dynamic ranges of 140, 160...maybe even 190(been awhile sinve I've browsed the manual). Since you are already at 100...you don't have those dynamic peaks. And EVERY AVR not labeled HK is this way. Marantz used to be.
    So, when you relieve the AVR of having to do 2 channels and it drops to 5, you'll have 140 per channel for the "dynamic aspect" of the power. If you are on 5 now...then when you go to 3, you'll have...233. Which that is enough power for this thing to produce its "claimed power"...cause you've given it less work to do.
     
  6. snake

    snake Active Member

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    You make a good point about better power from a dedicated amp! Using one will get me by for a good while I'm sure til I can get a second (if I feel its needed). Does Bi-amping actually work in this type of setup with 2 amps? 125w to the top and bottom both? Is that advantageous??
    Forgive me but SPL?? I really haven't heard clipping to know whats going on but I don't think thats happening. I will start comparing the THD as you suggest! Really good idea!
    I'm going to go with a 5.1 system so the AVR will only be driving 3 speakers. According to what your saying that ought to help powering the center and surrounds. Thanks for the info Schan! I'm still re-reading everything you said lol!
    One more thing. Until adding the amp, if listening in 2.0 stereo for just music, will having the other 3 speakers hooked up still draw power away from the towers?
     
  7. gene c

    gene c Well-Known Member

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    From what I know (which ain't much) and from my own experiences (few and far between), bi-wiring doesn't offer any noticable improvement in sound quality. Maybe in precise lab tests with extremely delicate measuring equipment it might show an improvement, but youl'd never actually hear it. Same with bi-amping from the same power source, like using the Back-Surrounds to bi-amp the fronts. Like adding 4-wheel drive to your truck. Better traction but no more power (unless you add another engine*. But when using to identicle amps to bi-amp speakers there might be an improvement depending on how much you want ther to be one. I've never heard on in my very few attempts but others say there was. For most users, just getting a single amp of the proper output is better than all this bi-amping/b-wiring stuff. Unless maybe you have very expensive speakers with an outboard crossover but then you're really way out of my league.
    Citroen actually did this in the '50's with their front engine/front wheel drive 2CV model sold in Africa. They added an engine in the rear to power the rear tires. Those silly Frenchmen!
     
  8. Dave Upton

    Dave Upton Owner
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    Sorry :) How loud do you listen in decibels if you happen to have a meter to measure that? If not - simply telling us where on the dial you generally have the volume set will still be a start.
     
  9. schan1269

    schan1269 HTF Expert
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    Bi-wiring in your Onkyo is a "whole 'nother" bag of worms...and the owners manual won't be any help...
    It depends if your AVR is set-up(and this is NOT IN THE MANUAL) actual bi-wire...or bi-amp.
    There is a difference. Bi-amp in the "context of AVR" is a throwback to the days of "non-powered subwoofers". In AVR that are ACTUAL "crossover" BI-AMP, the terminals are beholden to the INTERNAL crossover...
    I proved this once with a Yamaha 6180(this is one receiver that is REALLY bi-amp...it actually has both settings...bi-wire and crossover bi-amp...although the Yamaha 6180 manual makes no mention of the crossover being involved. In Bi-Wire it isn't...in Bi-Amp it is).
    The only way to find out if this receiver is a "true bi-amp" is connect the speaker terminals(the appropriate ones) to a pair of speakers. If you get full-range sound...it is Bi-Wire. If you get nothing but bass rumble, it is Bi-Amp.
    It is sad the AVR manufacturers mash together bi-wire and bi-amp. It adds to the confusion.
    What also "adds to the confusion" is Bi-Amp itself isn't separated as two different terms. There should be a difference in the terminology between crossed over Bi-Amp...and full range Bi-Amp...but there isn't.
     
  10. snake

    snake Active Member

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    Wait are you talking about B-amping the AVR? I've tried that and noticed no difference. I just wondered if bi-amping from an amplifier would be better than bridging it for more wattage, Wondering which setup would sound best.
    Normally not very loud at all. When I do crank it I'd say its at 1 or 2 oclock.
    I'm talking about bi-amping from an outboard amp. I've tried bi-amping from the AVR to no avail. I probably didn't make that clear.
     
  11. schan1269

    schan1269 HTF Expert
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    I have a feeling, if you noticed no difference...
    Then the Onkyo internal crossover is involved...so what you did...in effect...
    Drive 80hz and up with the regular terminals...
    Drive 80hz and lower with the secondary...
    Connected to the same speaker, you wouldn't notice any difference...cause there isn't one. (unless it is a proper "crossover not involved, meant to be bi-amped" speaker)
    By the way, I have no idea what crossover you used...just threw out 80hz...same difference if you raised or lowered it...
     
  12. snake

    snake Active Member

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    Yeah its set at 80. Would it make a diff for an outbard amp to one speaker?
     
  13. schan1269

    schan1269 HTF Expert
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    Yes. You connect the pre-out to the amp, then you can connect the amp to the speaker. I would not attempt to connect the speaker terminals and an amp(from the pre-out) to the same speaker...cause I'm sure the "synchronization" isn't exact...it would have to be.
     
  14. gene c

    gene c Well-Known Member

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    Quote:
    "Wait are you talking about Bi-amping the AVR? I've tried that and noticed no difference. I just wondered if bi-amping from an amplifier would be better than bridging it for more wattage, Wondering which setup would sound best."
    I just gave my opinion on all three, Bi-wiring, bi-amp/receiver and biamp/outboard amps.
    I've never bridged amp terminals but I'm sure it works fine otherwise there would be "don't do it!" warnings plastered all over the net. I have no idea if bridging is better than bi-amping other than looking at the specs to see which has the higher output. Like I said, amps aren't really my thing (but I do have a couple laying around here somewhere). Volume is an amps biggest contribution and I can't turn things up too high so I never really got into them very much (or subwoofers for the same reason). But I stick by my first recommendation. Buy one and see if it's enough. If it isn't, then get another. At that point you can hook them up both ways (bridged and bi) and decide for yourself. That's always the best way anywho as we all have our own opinions. But that's all they are...opinions.
     

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