Bi Amping (weirdly)

deronb1
deronb1 Posts: 5,021
edited January 2012 in Basic Hookup/Wiring Questions
I am powering my RTi12s w my receiver to the top and an external amp to the bottom. Is this going to screw anything up over time? It sounds great, but I don't want to start a fire or screw up my system.
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  • gp4jesus
    gp4jesus Posts: 1,988
    edited September 2011
    nope. many, many others before you have done the similar/same w/out problems.

    Heck, carefully read my sig for RTi A7s. I have a Hafler powering tops; Belles for the bottoms.

    Enjoy! tony
    Samsung 60" UN60ES6100 LED, Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga: LCR mids “Foamed & Plugged**”, inside* & out
    8 ga Powerline: LR woofers, inside* & out
    *soldered **Rob the Man (Xschop) LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & Mids - 981, connected w/Monoprice Premiere ICs
    Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s
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  • deronb1
    deronb1 Posts: 5,021
    edited September 2011
    Thanks gp...good to know.
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  • FTGV
    FTGV Posts: 3,649
    edited September 2011
    One possible issue would be a imbalance in the frequency response if the voltage gain of the receivers amp secton and the amplifier are not identical.
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  • F1nut
    F1nut Posts: 50,665
    edited September 2011
    I'll expand on Fred's comment. There is no way your AVR and amp share the same gain levels. You may think it sounds great, but it doesn't.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • mdaudioguy
    mdaudioguy Posts: 5,165
    edited September 2011
    Why not just use the amp and forget about bi-whatever for the time being?
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  • deronb1
    deronb1 Posts: 5,021
    edited September 2011
    F1nut wrote: »
    I'll expand on Fred's comment. There is no way your AVR and amp share the same gain levels. You may think it sounds great, but it doesn't.

    By gain level, do you mean a certain sound at a certain volume level?
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  • deronb1
    deronb1 Posts: 5,021
    edited September 2011
    mdaudioguy wrote: »
    Why not just use the amp and forget about bi-whatever for the time being?

    I am getting way better low end response doing it this way in 2 ch audio. Have the fronts set to large and the xover on the elite set to 50hz.

    For HT, I don't even turn on the amp. I have the AVR settings to small and 80hz and just use the top half of the 12s running, with the subs doing a lot of the work. To me, it sounds better for HT applications.
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  • deronb1
    deronb1 Posts: 5,021
    edited September 2011
    F1nut wrote: »
    I'll expand on Fred's comment. There is no way your AVR and amp share the same gain levels. You may think it sounds great, but it doesn't.

    Overall Frequency Response 18Hz-27kHz
    Lower -3dB Limit 30Hz
    Upper -3dB Limit 26kHz
    Nominal Impedance 8 ohms
    Recommended Amplifier Power 50-500 w/channel
    Efficiency 90 dB
    Crossover
    (mid-high array) 1.8kHz, 12dB/octave low and high pass. 120Hz 12dB/octave high pass
    Crossover
    (subwoofer) 120Hz, 12dB/octave low pass
    Inputs Dual (bi-amp) gold plated 5-way binding posts

    I have listened to these with just the lower connectors hooked up and they sound like a subwoofer. I would tend to agree with you if they were a bi-ampable two way system, or had a different xover config, but in this case of these speakers, gain level is a non issue. The three 7s are xover at 120hz. They just need power, and lots of it.
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  • nwohlford
    nwohlford Posts: 700
    edited September 2011
    deronb1 wrote: »
    I am getting way better low end response doing it this way in 2 ch audio. Have the fronts set to large and the xover on the elite set to 50hz.

    For HT, I don't even turn on the amp. I have the AVR settings to small and 80hz and just use the top half of the 12s running, with the subs doing a lot of the work. To me, it sounds better for HT applications.

    I would say skip the biamping as well and just use the amp. I am not sure what the 50Hz crossover does in 2 ch if the fronts are set to large (does the pioneer still send sound to the subwoofers here?).

    If you are going to biamp, I would still use the amp for HT. Right now you have the 120 Hz low pass in the high frequency section of the RTi12 and the 80 Hz crossover setting in the receiver which is a mess. The high frequency section of the RTi12 is seeing both crossovers and what is above the receiver crossover and below the low pass on RTi12s is going nowhere. If you leave the amp on, it will send the frequencies in the gap to the low frequency section of the RTi12s. The low frequency section of the RTi12s will not have to do a lot of work here, but this should give you a more even sound than what you are getting now.

    The only reason that I can think that this sounds good is that during set up you may have overemphasised the the below 80 Hz signal in order to try to reduce the hole between 80 Hz and 120 Hz. This may give you a bass heavy sound for HT which somepeople prefer.
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  • deronb1
    deronb1 Posts: 5,021
    edited September 2011
    nwohlford wrote: »
    I would say skip the biamping as well and just use the amp. I am not sure what the 50Hz crossover does in 2 ch if the fronts are set to large (does the pioneer still send sound to the subwoofers here?).

    If you are going to biamp, I would still use the amp for HT. Right now you have the 120 Hz low pass in the high frequency section of the RTi12 and the 80 Hz crossover setting in the receiver which is a mess. The high frequency section of the RTi12 is seeing both crossovers and what is above the receiver crossover and below the low pass on RTi12s is going nowhere. If you leave the amp on, it will send the frequencies in the gap to the low frequency section of the RTi12s. The low frequency section of the RTi12s will not have to do a lot of work here, but this should give you a more even sound than what you are getting now.

    The only reason that I can think that this sounds good is that during set up you may have overemphasised the the below 80 Hz signal in order to try to reduce the hole between 80 Hz and 120 Hz. This may give you a bass heavy sound for HT which somepeople prefer.

    The Elite has a bass setting of "plus" that allows the subs to run when fronts are set to large. 50hz is the lowest setting on the AVR. Direct would allow the full range of sound to the speakers. This of course depends on the source.

    As far as HT goes, I will play around with it and set the xover to 120hz and see if I can hear a difference. One reason I may have not is because of the center and surround channels handling a more broad sound range than the fronts.
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  • zingo
    zingo Posts: 11,258
    edited January 2012
    I'm going to bump this thread as it's an interesting topic I'm getting back into.

    I would not recommend adjusting the filters in your AVR for biamping as that is not what they are designed for. As mentioned before, the second amp needs to have adjustible gain if you are passively biamping as the balance betweeen highs and lows usually needs tweaking.
    Jake
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  • Tour2ma
    Tour2ma Posts: 10,177
    edited January 2012
    Dammit, zingo... I am so bummed. I'd missed that this was an old thread and got so excited that Jessie might have set a new record for earliest, Dick-post-of-the-year... but, no... his was a plain old, late September Dick-post...
    F1nut wrote: »
    I'll expand on Fred's comment. There is no way your AVR and amp share the same gain levels. You may think it sounds great, but it doesn't.
    ROFLMAO... He didn't even care what AVR, amps, or speakers the OP had... I mean sometimes MFG's use their AVR amp design to build a 2 or 5-ch power amp. At least it appears the OP had the good sense to ignore him.

    It still may have to go in my sig though. After all, it is really dickish...
    deronb1 wrote: »
    By gain level, do you mean a certain sound at a certain volume level?
    Since Jessie, not surprisingly, never bothered to reply. I'll explain in case you are still around...

    Gain is the power ratio of an amplifier's output signal to its input signal. Most of the time the values you ratio are voltages divided by impedances using Ohm's Law [ P = V2/R ]. In any case the units for gain are decibels (dB) so the equation is:
    Gain (dB) = 10 x log (Pout/Pin)
    Substitutions and simplifications go from there, but very often what you can get to is:
    Gain (dB) = 20 x log (Vout/Vin)

    Mismatched gain in bi-amping will lead to increasingly dissimilar SPL levels from a speakers' HF and LF sections as the input voltage rises. At some point a mismatch will be audible. Maybe yours isn't great enough, but even if it is, if you enjoy the sound, rock on... no matter who tells you that you shouldn't.
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
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  • F1nut
    F1nut Posts: 50,665
    edited January 2012
    You want a war, you got it.
    At some point a mismatch will be audible. Maybe yours isn't great enough, but even if it is, if you enjoy the sound, rock on...

    That's pathetic advice. You're not helping the guy improve the quality of his audio by telling him that, which just goes to prove that you don't care what you write here as long as you get a shot in at me and all because I used the term **** Bag to refer to what they are commonly called. Pffft

    Could you possibly be a more immature, sad excuse of a man!?!

    Speaking of not responding.....look in the mirror!
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • F1nut
    F1nut Posts: 50,665
    edited January 2012
    One other thing, one that reinforces my previous point about you.....
    ROFLMAO... He didn't even care what AVR, amps, or speakers the OP had... I mean sometimes MFG's use their AVR amp design to build a 2 or 5-ch power amp.

    His gear is listed in his sig,
    Pioneer VSX-23
    Kenwood Basic M2 (220 wpc)

    Aren't you the fool.......ROFLMAO
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited January 2012
    Easy guys! Let's take a deep breath and calm down, let the new year get out of diapers before we get into a battle? Maybe send each other a few PMs and clear the air? Get a fresh start?
    Thanks!
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  • tonyb
    tonyb Posts: 32,983
    edited January 2012
    Thats the best " wooo Horsey" I've seen yet. Good advice.

    Maybe a bar chair and a game of Rock'm Sock'm Robots is in order.
    HT SYSTEM-
    Sony 850c 4k
    Pioneer elite vhx 21
    Sony 4k BRP
    SVS SB-2000
    Polk Sig. 20's
    Polk FX500 surrounds

    Cables-
    Acoustic zen Satori speaker cables
    Acoustic zen Matrix 2 IC's
    Wireworld eclipse 7 ic's
    Audio metallurgy ga-o digital cable

    Kitchen

    Sonos zp90
    Grant Fidelity tube dac
    B&k 1420
    lsi 9's
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  • Drenis
    Drenis Posts: 2,871
    edited January 2012
    I always enjoy some good humor on a Monday morning. :)
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  • SDA1C
    SDA1C Posts: 2,072
    edited January 2012
    Agreed!^ Didn't take long to bring out the stakes and pitchforks. LOL
    Too much **** to list....
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  • Tour2ma
    Tour2ma Posts: 10,177
    edited January 2012
    Thank you... we'll be here all week... unless Papa Ken says otherwise... :cool:

    Jessie,
    Since you were obviously on top of the equipment ID from the get-go:

    - What do you estimate the gains of the AVR and the amp to be?

    - Does the fact that the AVR's input sensitivity is roughly one-third of the amp's, offset the fact that the AVR is also roughly one-third less powerful? Does it compound the mismatch?

    - How different do gains typically have to be before a mismatch is clear?

    - Why didn't you mention my equipment oversight until your second reply?


    Oh, and yes, I did miss the signature info... I'm guessing that made two of us...

    And know what I saw when I looked in the mirror? An explanation of what gain was... how unresponsive of me...
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
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  • F1nut
    F1nut Posts: 50,665
    edited January 2012
    Obviously, you didn't get the gist of Ken's post and sorry, you guessed wrong.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • chumlie
    chumlie Posts: 8,658
    edited January 2012
    /\reported/\
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  • Tour2ma
    Tour2ma Posts: 10,177
    edited January 2012
    F1nut wrote: »
    Obviously, you didn't get the gist of Ken's post and sorry, you guessed wrong.
    OK... so ignore my inaccurate guess and the question associated with it. That one question aside...

    I do not believe I asked anything that you would not have considered prior to your first reply in this thread. So it should not take much time for you to simply reveal your thought process... to share how you brought your vast experience to bear upon the specifics of the OP's situation and determined that the sound that was pleasing him was only doing so because he does not know what good sound is.

    I have found that investing a little more time in an explanation of the basis for my opinions often yields big time savings down the road. It leaves me with a post I can reference/ link when a similar situation arises. Alternatively the fellow member I helped understand something may be able to help someone in a similar situation down the road.

    Helping Ed (Dr. Spec) is what I did, or at least tried to do, on sub set-ups, HT calibration, etc., when I started out around here. At least 90% of what I know on those topics, I learned from his patient, detailed posts. In return Doc caught a break and I reinforced what I learned from him by helping others. If and when my help was sub-par, Doc chimed in.

    But that's me... sorry, if I asked too much of you.

    As for Ken's gist... I am pretty sure he was telling us to play nicely. I thought simply asking you questions was a way to do that. If I'm incorrect, I am sure that Ken will let me know.
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
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  • SpiderMan1
    SpiderMan1 Posts: 10
    edited January 2012
    Thats the best " wooo Horsey" I've seen yet. Good advice.
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  • michael1947
    michael1947 Posts: 775
    edited January 2012
    This has gotten way too complex for my confused brain. The original question/statement was : use his receiver to power the top section and his additional amp to power the lower section. I am about to try it in an attempt to get proper power to my A9's...so should I use some "Y" cables out of my pre-outs of my receiver to two additional amps each 150wpc and then would I have proper juice to each section of the speakers...probided both amps are identical, which they are. Michael
    Main Family Room: Sony 46 LCD, Sony Blue Ray, Sony DVD/VCR combo,Onkyo TXNR 708, Parasound 5250,
    Polk SDS-SRS with mods, CSI 5 center + Klipsch SC2, Polk RT2000P rears, Klipsch KG 1.5's sides, Polk Micro Pro 1000, Polk Micro Pro 2000, Polk SW505, Belkin PF60, Signal Cable Classics,Monster IC's, 2 15 amp circuits & 1 20 amp circuit.

    Living Room: Belkin PF60, Parasound HCA2200, MIT ProlineEXP balanced IC's,Emotiva XDA-1 DAC/Pre,Emotiva ERC2 transport,MIT AVT2, Polk LSI 9's.
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  • michael1947
    michael1947 Posts: 775
    edited January 2012
    for any of you guys...Question: can my Onkyo txnr 708 supply enough voltage or whatever to supply both of my extorrnal amps to drive the high and low sections of my rti a9's without having a melt down or doing harm to my two external amps.
    Main Family Room: Sony 46 LCD, Sony Blue Ray, Sony DVD/VCR combo,Onkyo TXNR 708, Parasound 5250,
    Polk SDS-SRS with mods, CSI 5 center + Klipsch SC2, Polk RT2000P rears, Klipsch KG 1.5's sides, Polk Micro Pro 1000, Polk Micro Pro 2000, Polk SW505, Belkin PF60, Signal Cable Classics,Monster IC's, 2 15 amp circuits & 1 20 amp circuit.

    Living Room: Belkin PF60, Parasound HCA2200, MIT ProlineEXP balanced IC's,Emotiva XDA-1 DAC/Pre,Emotiva ERC2 transport,MIT AVT2, Polk LSI 9's.
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  • tonyb
    tonyb Posts: 32,983
    edited January 2012
    Short answer is yes, you can run both amps with the receiver without doing harm to anything.
    HT SYSTEM-
    Sony 850c 4k
    Pioneer elite vhx 21
    Sony 4k BRP
    SVS SB-2000
    Polk Sig. 20's
    Polk FX500 surrounds

    Cables-
    Acoustic zen Satori speaker cables
    Acoustic zen Matrix 2 IC's
    Wireworld eclipse 7 ic's
    Audio metallurgy ga-o digital cable

    Kitchen

    Sonos zp90
    Grant Fidelity tube dac
    B&k 1420
    lsi 9's
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  • Tour2ma
    Tour2ma Posts: 10,177
    edited January 2012
    Yup... what tb said...
    michael1947 wrote: »
    for any of you guys...Question: can my Onkyo txnr 708 supply enough voltage or whatever to supply both of my extorrnal amps to drive the high and low sections of my rti a9's without having a melt down or doing harm to my two external amps.
    When you "Y-split", voltage differentials (the bit that matters) are unaffected. You can even split the splits again and again and again, and the voltage differential between any of the L/R pairs will be the same.

    While Pre-amp clipping is a real phenomenon, it's related almost exclusively to voltage gain limitations caused by a source's unusually low input voltage, e.g. a low-output Phono-pre. Normally current limitation is not a Pre-amp issue because power amp input impedances are high, 1000's of Ohms. So a reasonable number of Y-splits to supply multiple, parallel amp hook-ups are not an issue.

    By contrast power amps clip into relatively low speaker impedances due to either voltage gain or current limitations, with the latter the major cause in the cases of multichannel amps/ AVR's, 4-ohm (or lower) speaker designs, and speakers wired in parallel.

    In other words... yup... :wink:
    michael1947 wrote: »
    This has gotten way too complex for my confused brain. The original question/statement was : use his receiver to power the top section and his additional amp to power the lower section. I am about to try it in an attempt to get proper power to my A9's... Michael
    OP's case was amps of different MFG's and power ratings driving his 9's 2 sections. "Discussion" from that point revolved around whether his two-amps could sound good together. In your case you're using identical amps, so that's not a question.

    If you really want your head to hurt, start another thread on the merits of your passive bi-amping scheme. :cheesygrin:
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
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