Amp questions

[PENG]

Yes I have 250wx2 stereo Macs that I want to run one per speaker passive biamp. I just want to be sure that give 250 to the highs won't fry the tweeter on the s8s.

Again, your 250W McIntosh won't be giving 250W to the highs because the crossover network will block the low frequencies. AVRat is probably right, if the bass is getting 250W the highs may get 25W or less. So do not worry, just do it and be prepared to enjoy the high quality sound you are bound to get from those S8 and the Macs.

 

[mtrycrafts]

... I believe the S8 is designed to split the incoming power evenly between the two sections so it doesn't matter which way you use the amp.

How would that be designed? The input signal to the receiver determines how much signal is needed and will go to the lows, mids or highs. If you alter power delivery to the lows or the mids and highs to equal the lows, your spectral balance is upset.

But, I could be misunderstanding what you are trying to say here with 'power evenly split.'

 

[mtrycrafts]

So I'm safe biamping and sending 250 watts to the highs and 250 watts to the lows. My tweeter's not going to bite the dust?

That can depend on how loud you play your system, what is the relationship as to signal levels of the music recording in the low band and high band, and the power capability of that tweeter. You can blow it with unclipped sine wave if you exceed its limits and tweeters are anything but power beasts

 

[PENG]

That can depend on how loud you play your system, what is the relationship as to signal levels of the music recording in the low band and high band, and the power capability of that tweeter. You can blow it with unclipped sine wave if you exceed its limits and tweeters are anything but power beasts

I think few people can tolerate the sound level generated by power levels that exceed the S8's limit in an average family home. However, you are absolutely right to point out the fact that tweeters can be damaged by unclipped (I would say even pure) sine wave signals, given enough power that exceed the tweeter's thermal limit. I sure hope the OP understands that while he is getting encouragement to go ahead with his plan, he should not get carried away with the volume control. This same warning applies whether he bi-amps or not. He can blow that expensive S8 tweeter just the same with one single Mac amp if he cranks his preamp right up.

 

[bandphan]

autoformers within his amp help with some of these issues, not the case all units.

 

[TLS Guy]

How would that be designed? The input signal to the receiver determines how much signal is needed and will go to the lows, mids or highs. If you alter power delivery to the lows or the mids and highs to equal the lows, your spectral balance is upset.

But, I could be misunderstanding what you are trying to say here with 'power evenly split.'

For most program material the power divide is in the region of 400 Hz. Half above and half below. However for diffraction compensated speakers the impedance will usually drop in half below 400 Hz so the amp will have to double its power output in that region, making it 2/1 below 400 Hz for the power the amp actually delivers, under that load condition.

 

[PENG]

For most program material the power divide is in the region of 400 Hz. Half above and half below. However for diffraction compensated speakers the impedance will usually drop in half below 400 Hz so the amp will have to double its power output in that region, making it 2/1 below 400 Hz for the power the amp actually delivers, under that load condition.

Okay, but if we are talking about the tweeter only, the crossover point is much higher than 400 Hz.

 

[TLS Guy]

Okay, but if we are talking about the tweeter only, the crossover point is much higher than 400 Hz.

That is absolutely correct. That is why biamping most two or two and a half way speakers is a complete waste of time and money. To biamp a tweeter there would be no advantage unless you custom designed a low power amp for the purpose. In fact there is every reason not to biamp a tweeter along the lines suggested here.

 

[codexp3]

That is absolutely correct. That is why biamping most two or two and a half way speakers is a complete waste of time and money. To biamp a tweeter there would be no advantage unless you custom designed a low power amp for the purpose. In fact there is every reason not to biamp a tweeter along the lines suggested here.

The reason I wanted to biamp the speaker is that I have two Macs at 250wx2. I want to use all the amp's power to drive one speaker (500w per speaker). From what I've read most people suggest not to bridge the amp. (Is this best practice?) The only way I can get all the power to the speaker to passive biamp.

If I just run the fronts off of one amp. And use the other amp for the center channel, then I have an extra 250 watt channel sitting there unused. I'd hate to waste the extra channel. Passive biamping the fronts isn't the way to go?

 

[TLS Guy]

The reason I wanted to biamp the speaker is that I have two Macs at 250wx2. I want to use all the amp's power to drive one speaker (500w per speaker). From what I've read most people suggest not to bridge the amp. (Is this best practice?) The only way I can get all the power to the speaker to passive biamp.

If I just run the fronts off of one amp. And use the other amp for the center channel, then I have an extra 250 watt channel sitting there unused. I'd hate to waste the extra channel. Passive biamping the fronts isn't the way to go?

You can gain nothing with using your extra amp with your speakers. If you bridge you will gain nothing because the impedance of the speakers will be the same. I have been on the Paradigm site, and unfortunately for you one set of terminals drives the low pass/band pass filters, and the other only the high pass filter. In other words one amp would drive the bass mids and handle 99% + of the power. The other amp will be delivering milli watts most of the time. It just might peak at 5 watts occasionally. This just is not worth it. There are far better uses for your other MAC amp. Use it on the center channel for instance, or to drive a second system.

You might not want to hear it, but that's the truth, the whole truth, and nothing but the truth.

 

[codexp3]

You can gain nothing with using your extra amp with your speakers. If you bridge you will gain nothing because the impedance of the speakers will be the same. I have been on the Paradigm site, and unfortunately for you one set of terminals drives the low pass/band pass filters, and the other only the high pass filter. In other words one amp would drive the bass mids and handle 99% + of the power. The other amp will be delivering milli watts most of the time. It just might peak at 5 watts occasionally. This just is not worth it. There are far better uses for your other MAC amp. Use it on the center channel for instance, or to drive a second system.

You might not want to hear it, but that's the truth, the whole truth, and nothing but the truth.

Looks like it's one amp to the fronts and one channel of amp 2 to the center. 250 extra watts of power and no where to go...This does save me the extra cost of adding a mono for the center, but what a waste of that second stereo channel.

Thanks for all the help, at least I know how to run the system now.

 

[TLS Guy]

Looks like it's one amp to the fronts and one channel of amp 2 to the center. 250 extra watts of power and no where to go...This does save me the extra cost of adding a mono for the center, but what a waste of that second stereo channel.

Thanks for all the help, at least I know how to run the system now.

You've got it. Your making sense now! Glad to help.

 

[bandphan]

Looks like it's one amp to the fronts and one channel of amp 2 to the center. 250 extra watts of power and no where to go...This does save me the extra cost of adding a mono for the center, but what a waste of that second stereo channel.

Thanks for all the help, at least I know how to run the system now.

not a waste its great amp, you could always use it for the rears as an extreme remember 10watts is loud, its all about headroom and dynamics, watch those watt meters when your jamming, it makes you think and want to learn more. btw im barley hitting .025 watts listening right now peaking around 2.

 

[AVRat]

I have been on the Paradigm site, and unfortunately for you one set of terminals drives the low pass/band pass filters, and the other only the high pass filter.

Just curious where you found this info as I've looked all over their site trying to locate those specifics? It doesn't make sense that they would design a high-end bi-ampable speaker and divide the sections at such a high crossover point. It makes more sense to segment it at the 250 Hz crossover point.

Has anybody with bi-ampable speakers ever done a sensitivity measurement between the sections to see if there is any disparity to determine their amp requirements?

 

[TLS Guy]

Just curious where you found this info as I've looked all over their site trying to locate those specifics? It doesn't make sense that they would design a high-end bi-ampable speaker and divide the sections at such a high crossover point. It makes more sense to segment it at the 250 Hz crossover point.

Has anybody with bi-ampable speakers ever done a sensitivity measurement between the sections to see if there is any disparity to determine their amp requirements?

Download the user manual and the information is there. I suspect the lowpass/bandpass interface is not easily divisible for some reason. Or else they never thought about it.

If you passively biamp there will be no sensitivity issue, as the L-pad trimming always comes after the filters. At least that's the way I do it, and I have never seen it done differently.

Now with active biamping the sensitivities have to be set in the crossover prior to amplification. Really passive and active crossover design is similar, except that passively you are dealing with chokes resistors and caps, only. For active filters you are working in the feedback poops of opamps and cascading the filters. However there are the same rules for orders, crossover points and level matching. With active analog filters, phase and time shift problems are the same.

Really this thread has further convinced me that enthusiasts on this forum need to up their tech knowledge and skills. I think it would be good for as many members as possible to design a two or two hand a half way speaker and build it. It would be highly educational for those that complete the task. I don't mean building a kit either.

 

[PENG]

That is absolutely correct. That is why biamping most two or two and a half way speakers is a complete waste of time and money. To biamp a tweeter there would be no advantage unless you custom designed a low power amp for the purpose. In fact there is every reason not to biamp a tweeter along the lines suggested here.

Please be reminded that according to the believers bi-amping (even passively) is not just about power. It supposedly has a lot to do with the ability to separate out the low (in this case if you are right, the mid frequency signals as well for the S8) and the high frequency signals thus minimizing the effect/interference of the woofer such as the back emf, the electromagnetic effects on the heavy current etc., on the high frequency signals. I have been to at least several British speakers sites and that's what they are saying. For NA manufacturers, at least Vandersteen Audio talks about such benefit even in bi-wiring, though to a lesser extent. I shouldn't have brought this topic up again, in fact I am not one of those believers who can hear the anticipated sound quality improvements. I believe in the theory, that's all.

 

[mtrycrafts]

For most program material the power divide is in the region of 400 Hz. Half above and half below. However for diffraction compensated speakers the impedance will usually drop in half below 400 Hz so the amp will have to double its power output in that region, making it 2/1 below 400 Hz for the power the amp actually delivers, under that load condition.

Going over a number of the speakers tested

http://www.soundstageav.com/speakermeasurements.html

Some do, some don't. But, the impedance curves are anything but nice looking.

 

[TLS Guy]

Going over a number of the speakers tested

http://www.soundstageav.com/speakermeasurements.html

Some do, some don't. But, the impedance curves are anything but nice looking.

Impedance curves having nothing to do with how a speaker sounds or as to whether it s any good or not. We seem to be heading down a route of massive ignorance, misunderstanding and pseudo science. I other words a huge BS factor.

 

[TLS Guy]

Please be reminded that according to the believers bi-amping (even passively) is not just about power. It supposedly has a lot to do with the ability to separate out the low (in this case if you are right, the mid frequency signals as well for the S8) and the high frequency signals thus minimizing the effect/interference of the woofer such as the back emf, the electromagnetic effects on the heavy current etc., on the high frequency signals. I have been to at least several British speakers sites and that's what they are saying. For NA manufacturers, at least Vandersteen Audio talks about such benefit even in bi-wiring, though to a lesser extent. I shouldn't have brought this topic up again, in fact I am not one of those believers who can hear the anticipated sound quality improvements. I believe in the theory, that's all.

This is nonsense! The back EMF is going to be the same whether the speaker is passively biamped or not. In active biamping there is no inductor between the amp and speaker. This does in theory allow the woofer to benefit from the damping factor of the amplifier. This is considered one of the advantages of active crossovers. I think this benefit is of questionable benefit, but may be significant in some systems. This possible benefit can not be realized with passive biamping, where the only possible advantage would be reduction in inter modulation distortion from the amplifier. However an amp that needs to be relieved of driving a tweeter to reduce inter modulation distortion is not worth the time of day.

We are descending to the level of rags like Absolute Sound here.

 

[PENG]

This is nonsense! The back EMF is going to be the same whether the speaker is passively biamped or not. In active biamping there is no inductor between the amp and speaker. This does in theory allow the woofer to benefit from the damping factor of the amplifier. This is considered one of the advantages of active crossovers. I think this benefit is of questionable benefit, but may be significant in some systems. This possible benefit can not be realized with passive biamping, where the only possible advantage would be reduction in inter modulation distortion from the amplifier. However an amp that needs to be relieved of driving a tweeter to reduce inter modulation distortion is not worth the time of day.

We are descending to the level of rags like Absolute Sound here.

You are talking like you are the authority, know more/better than the manufacturers. What is nonsense, the theory? Come in, how much do you know about electrical theory? Now I am done...