Originally Posted by Lambofmetalgod
the reason i want to bi amp is because my reciever is rated at 90watt X 7 and i do have a sub, and am usually satisfied with my sound, however, the rear and center are rated at 80watts, but the ADS towers are rated 150watts nominal and 300 max.
My background includes a lot of bench testing of power amplifiers and receivers (over 40 years experience), careful tuning and subjective testing of real world music and AV systems, as well as a lot of experience with real world audio signals due to my experience with live recording and live sound (over 10 years experience.
What I see in real world systems and on the test bench are so different that my first piece of advice is that people don't take receiver power ratings very seriously, and I mean this in a good way. Most receivers are vastly overbuilt in the power amplifier department, even the ones that have far less impressive ratings than yours.
The big criticism I have with the above statement is that people are taking receiver power ratings too seriously, and not reading between the lines about what is actually there.
The first problem with audio amp power ratings is that in general, bench testing is far, far more stressful than actual use because real world audio signals have far less energy in them on the average than the test tones used on the test bench. The difference is a minimum of from 2:1 to 3:1 and is often 10:1 or more presuming that the music is playing at a continuous crescendo just below clipping, which of course never happens.
Bottom line, there's a good chance that your receiver is already capable of delivering 130-150 watts to any of your speakers, should that actually be required. Remember that the power sent to your speakers is based on the recordings you play, not the maximum power ratings of your speakers. Remember that driving speakers with amps that are rated below the speaker's maximums is mostly just cheap insurance against you damaging them with excessive power.
The way most receivers work is that they have a power supply that is capable of putting out the maximum concurrent ratings of the receiver. Your receiver has a power supply that is rated at 90 x 7 = 630 watts. Its power amplifiers are rated at 95/110/130/150 (8/6/4/2 ohm loads) watts "dynamic power" which is what the actual individual channel power amp electronics can do if it was running all by itself.
The speakers have the following specs:
The Stereo Review's Stereo Buyers Guide 1983 edition has the following description of the ADC L1530 speaker:
Acoustic suspension 3-way floor standing professional monitor speaker system with 2 10" high-compliance Stifflite woofers in separate chambers, 2" soft-dome midrange, 1" samarium-cobalt soft-dome tweeter. Features single switch biamplifier conversion, tweeter level switch, tweeter, midrange protection fuses; mirror symmetrical midrange/hifrequency baffles for minimum diffraction; walnut veneer finish with radius-edged solid walnut corner inserts, removable black cloth grille. Frequency response 25-20,000 Hz +\- 3dB crossovers 500 and 4k Hz; sensitivity 95 dB SPL/W/m; power rating 150 W nominal, 300 W peak program, impedajnce 6 ohms
Two most important specs are that these speakers are rated at 6 ohms, so the 110 wpc rating for the receiver would appear to apply, and if the speakers actually have the claimed 95 dB/W efficiency, they will be putting out about 116 dB SPL @ 1 meter (AKA very, very loud!) when the amplifier clips.
The receiver is going to perform at its optimal level until you load all the channels up in such a way that the voltage output of its power supply starts collapsing significantly (10% or more). If I was worried about this happening I'd hook a DVM up to the power supply capacitors in the receiver and monitor its voltage under the worst case program material I can find in my collection of recordings. This could be about as much fun as watching paint dry! I don't expect a lot of action
on the DVM.
The other thing to consider is where you can actually go.
Looking at the option to bi-amp the speakers using the receiver's internal amps, it is unclear where that would provide any advantage. The weakest link in this receiver on the test bench would probably be its power supply, and no matter which output channels you connect your speakers to, they are all powered by the same power supply. There's no evidence that your 6 ohm speakers are taxing the power amps in your receiver since they are rated for 4 and even 2 ohm loads, and your speakers are rated as 6 ohm loads. Since you appear to be using this receiver in 2 channel mode, there is little possibility that you are overtaxing its power supply.
The source of any actual benefits to using the receiver in bi-amp mode seems to be very hard to find!
Now, lets look at a potentially more fruitful approach, which is to add more powerful outboard amplifiers which would actully offload the receiver.
Looking at the owner's manual for your receiver right here in front of me, your first problem with adding external amps is that your receiver has no line level analog output jacks that are active for all of its inputs. It has no line level audio output jacks for just the front channels, or any of the surround channels. So, it is an interesting question to ask what you would actually plug your outboard amplifiers in to? The necessary output jacks do not appear to exist! Of course we can use outboard attenuators to turn the power amp outputs of the receiver into an appropriate signal for an external power amp.
The second question is that presuming that you could come up with an appropriate signal for an outboard amplifier, what would its ratings be and how much extra sound would that give you? I guess you could get a 300 wpc power amp. Increasing amplifier power from 110 watts to 300 watts would allow you to go about 4 dB louder, IOW from 116 dB SPL to about 120 dB SPL. Not much of a benefit for all of the trouble, no?
My logical thinking suggest that bi amping would split the workload of the reciever for the ADS?? does that makes sense?
Splitting workload only makes sense if some part of the system is overtaxed. I see no evidence that your receiver's power supply is overtaxed or even could be overtaxed. The final answer would be based on things like: "Is the receiver power supply gettting over-taxed and loosing voltage significantly? Are any of the power amps in the receiver actually getting overtaxed and clipping. I think that the best presumed answers to both questions is "No!"
It would take some in-situ measurements to shed further light on this question. If you have the resources, I can tell you what to measure and what to look for.