Help understanding amplifier difference (150 watt bridged vs 200 watt non-bridged)

[MalVeauX]

Hey all,

I'm trying to wrap my head around whether or not a few things matter or how they will interact and compare. Mainly, I'm curious how a bridged stereo amplifier compared to something non-bridged with respect to actual output and overall quality of sound, but not to the nitpicking golden ears level, but at least worth mentioning in case bridged quality is extremely poor or something.

I currently have a couple of the well known AudioSource AMP100 amplifiers that I use with my towers & center. I use them as bridged monoblock amplifiers and they're supposed to do 150watts at 8ohms. I've used them in stereo mode which is 50watts at 8ohms and bridged. I realize taking the power from 50 watts on my speaker to 150 watts on my speaker is only 3x the increase in power, so maybe +4~5db SPL is gained there, but of course, I'm more interested in whether it provides more current and power needed to successfully drive the speakers fully. The speakers in question are budget Polk Monitor 70 II's. These amps drive the M70's to ear splitting levels. But I'm not necessarily looking for being super loud. I'm looking to see if they're being fully driven so that they're not able to output everything they should be capable of in a given room. Polk rates them to 275 watts which seems nuts to me, but maybe that's supposed to be for a very large room? I'm trying to keep things normal so a 20x16 room or something around 24 x 20, give or take, basically a typical living room in a house, as a reference point for what's needed. I don't have the ability to measure the SPL of them at this time, but will soon when I get my microphone in but I'd like to know whether or not it matters that the speakers are receiving 50watts or 150watts (or whatever is really delivered).

So then, assuming the 150watts is real in bridged output on the above AMP100 amps, I'm curious how that would compare both power wise and sound quality wise to an amplifier that is not bridged, such as the Monolith 200watt x 3 channel amplifier, or an Outlaw 200watt monoblock, basically any 200 watt fairly affordable amplifier that isn't bridged. I realize a better amplifier should sound better, but I don't want to fall into the whole better brand, higher price, automatically means better sound type thing as I know that's not the case as the room treatment and correction makes a big difference. So before moving into better speakers, I'd like to get a handle on being able to see if it matters if I'm using a bridged 150 watt amp into my Monitor 70 II's or if a 200 watt unbridged amp would be a significantly difference experience and worth the cost. If that's the case, and I treat and correct for the room appropriately, that I might be able to truly benefit from better speakers (such as Rti A7's maybe), then that opens doors. But I don't want to get more stuff without being able to really know it will matter in the first place. I assume it would matter. But, like many things, assuming doesn't lead to reality all the time. And I would love to avoid the hyperbole of more expensive things automatically being better no matter what from people who have never even heard them nor measured anything, but I digress...

So is there a real difference between a bridged 150 watt amplifier compared to a non-bridged 150 watt amplifier? Any references or links to information? I would like to even measure this on my own with a speaker and the amplifiers once I get my microphone and use REW to figure things out.

Will a Monolith 200watt or Emotiva 200watt or Outlaw 200watt amplifier truly be better in every way than a 150 watt bridged amplifier? Is there a way to truly know that other than listening to it? I realize this is truly difficult to answer, and that it's an automatic "yes" for most everyone reading because they're better brands, more expensive, likely better components and more power output, but, that doesn't truly mean they're literally better in a room without treatment & correction.

I'm truly curious if a $150 or less 50watt amp that can be bridged to 150watts at 8ohms is essentially junk, or if it's a useful budget approach, before dropping $400~$1000 for 50 watts more of power, and whatever comes along with it for that cost increase. And I'm trying to keep the context on current speakers, the Monitor 70's, and then extrapolate anything from there to better speakers in the future, A7's maybe, if anything can be truly figured out from this.

Will the additional power merely increase bass response while not really doing much for mids and treble?
Will the quality of the amplifier make a serious difference in the quality of the perceived sound under the same room treatment & correction?

I'm happy to see any references or reading material regarding bridge amplification performance and if it's just not worth it, I'm good with that, I just am looking for information to help validate moving to a 200 watt amplifier that is not bridged at literally 8~9x the price and if it matters also being able to know that moving on from my Monitor 70's to maybe some A7's is a worth while change up without getting nuts.

Very best,

 

[AcuDefTechGuy]

In general, most of us do NOT recommend bridging your amps because bridging stresses your amp a lot more than normal.

Let's say your speakers go down to 4 ohms.

When unbridged, your amp "sees" 4 ohms impedance.

But when bridged, your amp effectively "sees" 2 ohms impedance, which is a lot more stressful than 4 ohms.

So bridging your amp can increase stress for your amp and potentially increase distortion and noise of the amp.

 

[MalVeauX]

In general, most of us do NOT recommend bridging your amps because bridging stresses your amp a lot more than normal.

Let's say your speakers go down to 4 ohms.

When unbridged, your amp "sees" 4 ohms impedance.

But when bridged, your amp effectively "sees" 2 ohms impedance, which is a lot more stressful than 4 ohms.

So bridging your amp can increase stress for your amp and potentially increase distortion and noise of the amp.

Hi,

Thanks, so amplifiers with a switch for bridging is basically a waste? And if the amplifier can handle the stress, is it still a waste?

Thanks!

Very best,

 

[AcuDefTechGuy]

Hi,

Thanks, so amplifiers with a switch for bridging is basically a waste? And if the amplifier can handle the stress, is it still a waste?

Thanks!

Very best,

If your speakers TRULY ACTUALLY need the extra power, then it's not a waste.

But most people don't actually need the extra power.

 

[MalVeauX]

If your speakers TRULY ACTUALLY need the extra power, then it's not a waste.

But most people don't actually need the extra power.

Fair enough, that makes sense. I hope to get a microphone to test things soon to be able to have a more clinical way to figure it out, versus just A-B blind listening.

Currently my AMP100 amp supplies 50 watts at 8ohm in stereo configuration with both channels driven. There's a switch on the back to put it into a bridged configuration and it's supposed to then be a 150 watts at 8ohm monoblock. I imagine the M70's (has 4x 6.5" woofers) would need more than just 50 watts to be fully dynamic to what it's capable of at listening level. Without the ability to measure it right now, I cannot see the difference in a clinical manner to evaluate it. So it prompted the questions.

So I'm curious if the 150 watts from this bridged amplifier will be different really than what would happen with the same speaker & room as a 200 watt amplifier that is not bridged.

Very best,

 

[PENG]

Hey all,

I'm trying to wrap my head around whether or not a few things matter or how they will interact and compare. Mainly, I'm curious how a bridged stereo amplifier compared to something non-bridged with respect to actual output and overall quality of sound, but not to the nitpicking golden ears level, but at least worth mentioning in case bridged quality is extremely poor or something.

I currently have a couple of the well known AudioSource AMP100 amplifiers that I use with my towers & center. I use them as bridged monoblock amplifiers and they're supposed to do 150watts at 8ohms. I've used them in stereo mode which is 50watts at 8ohms and bridged. I realize taking the power from 50 watts on my speaker to 150 watts on my speaker is only 3x the increase in power, so maybe +4~5db SPL is gained there, but of course, I'm more interested in whether it provides more current and power needed to successfully drive the speakers fully. The speakers in question are budget Polk Monitor 70 II's. These amps drive the M70's to ear splitting levels. But I'm not necessarily looking for being super loud. I'm looking to see if they're being fully driven so that they're not able to output everything they should be capable of in a given room. Polk rates them to 275 watts which seems nuts to me, but maybe that's supposed to be for a very large room? I'm trying to keep things normal so a 20x16 room or something around 24 x 20, give or take, basically a typical living room in a house, as a reference point for what's needed. I don't have the ability to measure the SPL of them at this time, but will soon when I get my microphone in but I'd like to know whether or not it matters that the speakers are receiving 50watts or 150watts (or whatever is really delivered).

So then, assuming the 150watts is real in bridged output on the above AMP100 amps, I'm curious how that would compare both power wise and sound quality wise to an amplifier that is not bridged, such as the Monolith 200watt x 3 channel amplifier, or an Outlaw 200watt monoblock, basically any 200 watt fairly affordable amplifier that isn't bridged. I realize a better amplifier should sound better, but I don't want to fall into the whole better brand, higher price, automatically means better sound type thing as I know that's not the case as the room treatment and correction makes a big difference. So before moving into better speakers, I'd like to get a handle on being able to see if it matters if I'm using a bridged 150 watt amp into my Monitor 70 II's or if a 200 watt unbridged amp would be a significantly difference experience and worth the cost. If that's the case, and I treat and correct for the room appropriately, that I might be able to truly benefit from better speakers (such as Rti A7's maybe),then that opens doors. But I don't want to get more stuff without being able to really know it will matter in the first place. I assume it would matter. But, like many things, assuming doesn't lead to reality all the time. And I would love to avoid the hyperbole of more expensive things automatically being better no matter what from people who have never even heard them nor measured anything, but I digress...

So is there a real difference between a bridged 150 watt amplifier compared to a non-bridged 150 watt amplifier? Any references or links to information? I would like to even measure this on my own with a speaker and the amplifiers once I get my microphone and use REW to figure things out.

Will a Monolith 200watt or Emotiva 200watt or Outlaw 200watt amplifier truly be better in every way than a 150 watt bridged amplifier? Is there a way to truly know that other than listening to it? I realize this is truly difficult to answer, and that it's an automatic "yes" for most everyone reading because they're better brands, more expensive, likely better components and more power output, but, that doesn't truly mean they're literally better in a room without treatment & correction.

I'm truly curious if a $150 or less 50watt amp that can be bridged to 150watts at 8ohms is essentially junk, or if it's a useful budget approach, before dropping $400~$1000 for 50 watts more of power, and whatever comes along with it for that cost increase. And I'm trying to keep the context on current speakers, the Monitor 70's, and then extrapolate anything from there to better speakers in the future, A7's maybe, if anything can be truly figured out from this.

Will the additional power merely increase bass response while not really doing much for mids and treble?
Will the quality of the amplifier make a serious difference in the quality of the perceived sound under the same room treatment & correction?

I'm happy to see any references or reading material regarding bridge amplification performance and if it's just not worth it, I'm good with that, I just am looking for information to help validate moving to a 200 watt amplifier that is not bridged at literally 8~9x the price and if it matters also being able to know that moving on from my Monitor 70's to maybe some A7's is a worth while change up without getting nuts.

Very best,

According to the manual, the Amp100 can be bridged to produce 150 W into an 8 ohm resistor load. It is a low cost design, and likely won't offer the headroom and general robustness of the other 200 W amps that you mentioned. As such, if you do bridge them, make sure your speakers don't have any major dips to below 6 ohms. In fact, I would suggest you pretend the Amp100 are 100 W bridged instead of the specified 150 W, just to give yourself some safe margin.

The Polk Monitor 70 series two are not rated 275 W, but 80 W nominal. They can handle 275 W peak only. An amp rated for 160 W average (such as the Audiosource Amp100) is also rated for 320 W peak at the specified THD. For audio amplifier specs, Average power (often referred in error as RMS power) = 2 X peak power

If you are concerned about how much power you really need, and have on reserve, you should try the calculator linked below. The results may surprise you.

https://myhometheater.homestead.com/splcalculator.html

 

[MalVeauX]

According to the manual, the Amp100 can be bridged to produce 150 W into an 8 ohm resistor load. It is a low cost design, and likely won't offer the headroom and general robustness of the other 200 W amps that you mentioned. As such, if you do bridge them, make sure your speakers don't have any major dips to below 6 ohms. In fact, I would suggest you pretend the Amp100 are 100 W bridged instead of the specified 150 W, just to give yourself some safe margin.

The Polk Monitor 70 series two are not rated 275 W, but 80 W nominal. They can handle 275 W peak only. An amp rated for 160 W average (such as the Audiosource Amp100) is also rated for 320 W peak at the specified THD. For audio amplifier specs, Average power (often referred in error as RMS power) = 2 X peak power

If you are concerned about how much power you really need, and have on reserve, you should try the calculator linked below. The results may surprise you.

Hi, Thank you, that's quite helpful.

Using the supplied calculator, the M70II shows 101.7 dB SPL at listening position. I'm at 12 feet from the speakers placed near a wall. They're 90db sensitivity and that's with a 50 watt amplifier and two speakers arranged for the calculation. Says I'm getting +17 dB gain from the amp, losing -11.3dB from the distance, +3 dB for having two speakers and another +3 dB from placement near a wall.

Running the calculation again with a 150 watt amplifier, it's 106.5dB at the listening position. So a gain of approximately 5dB rounded, so around half the perceived loudness.

What I don't know, however, is the output from the speaker and how its response is at various frequencies with the different amplification input to them. This is where I'm most curious. For example, does it handle 60hz, 80hz, 100hz, etc, differently depending on the same configuration but with 50 watts versus 150 watts or even 200 watts and of course how that will effect the mid frequencies too. This is my real interest as I'm curious if the speaker is able to output what it's capable of, on just 50 watts in the room, or if there's room to gain output from it with more power such as with 150 watts or more.

So if the M70's handle 80 watts RMS and my amp is outputting 50 watts vs 100 watts RMS, then I'm close enough I imagine?

Very best,

 

[PENG]

Hi, Thank you, that's quite helpful.

Using the supplied calculator, the M70II shows 101.7 dB SPL at listening position. I'm at 12 feet from the speakers placed near a wall. They're 90db sensitivity and that's with a 50 watt amplifier and two speakers arranged for the calculation. Says I'm getting +17 dB gain from the amp, losing -11.3dB from the distance, +3 dB for having two speakers and another +3 dB from placement near a wall.

Running the calculation again with a 150 watt amplifier, it's 106.5dB at the listening position. So a gain of approximately 5dB rounded, so around half the perceived loudness.

The calculator shows you the peak SPL, 106.5 dB peak is a little louder than you hear in a movie cinema that adhere to THX standard's 85 dB average 105 dB peak. I would bet most people don't usually go higher than 80 dB average and 100 dB peak watch movies at home. So in your case, about 33-34 W peak, or 16-17 W RMS will get you 80 dB avg, 100 dB peak when watching a THX movie such as Star Wars, and that's only 5 dB belows what you would hear in a THX cinema. So even the 50 W amps you are using now are adequate for the job, but of course a 200 WX2 Monolith or a couple of Outlaw monoblocks will give you the extra headroom that you don't seem to need.

What I don't know, however, is the output from the speaker and how its response is at various frequencies with the different amplification input to them. This is where I'm most curious. For example, does it handle 60hz, 80hz, 100hz, etc, differently depending on the same configuration but with 50 watts versus 150 watts or even 200 watts and of course how that will effect the mid frequencies too. This is my real interest as I'm curious if the speaker is able to output what it's capable of, on just 50 watts in the room, or if there's room to gain output from it with more power such as with 150 watts or more.

A good audio amplifier should have virtually flat frequency response from 20 Hz to 20,000 Hz.

According to the Amp 100 user manual:

Freq response: +1 dB, -0.5 dB
8 ohm, Stereo Power Bandwidth......................50 W @ 8 ohms, <`%, THD+N, 20-20 kHz
4 ohm, Stereio Power Bandwidth:.....................60 W @4 ohms, <1% THD+N, 20-20 kHz

So if the M70's handle 80 watts RMS and my amp is outputting 50 watts vs 100 watts RMS, then I'm close enough I imagine?

I am not sure what you meant by vs 100 watts RMS......

Your speakers are rated 80 W nominal, 275 W peak, vs your amps that are rated 50 W/60 W/8 ohm/4 ohm average, that is 100 W/120 W/8 ohm/4 ohm peak. If you want to make sure the speakers are the limiting factor, then get yourself a 200 W (8 ohm)/300 W(4 ohm) amp, whether you need it or not.

 

[MalVeauX]

The calculator shows you the peak SPL, 106.5 dB peak is a little louder than you hear in a movie cinema that adhere to THX standard's 85 dB average 105 dB peak. I would bet most people don't usually go higher than 80 dB average and 100 dB peak watch movies at home. So in your case, about 33-34 W peak, or 16-17 W RMS will get you 80 dB avg, 100 dB peak when watching a THX movie such as Star Wars, and that's only 5 dB belows what you would hear in a THX cinema. So even the 50 W amps you are using now are adequate for the job, but of course a 200 WX2 Monolith or a couple of Outlaw monoblocks will give you the extra headroom that you don't seem to need.

A good audio amplifier should have virtually flat frequency response from 20 Hz to 20,000 Hz.

Your speakers are rated 80 W nominal, 275 W peak, vs your amps that are rated 50 W/60 W/8 ohm/4 ohm average, that is 100 W/120 W/8 ohm/4 ohm peak. If you want to make sure the speakers are the limiting factor, then get yourself a 200 W (8 ohm)/300 W(4 ohm) amp, whether you need it or not.

Thank you, again, that's very helpful.

Basically it seems that I have zero need for a 200 watt amplifier for these speakers. I was mainly looking to see if I was adequately driving the M70II's currently and if so, then having something that could do more would allow me to move into larger speakers or simply better speakers that require more, something like the A7's or A9's (Polk),or some other particular speaker setup in the future.

It's confusing to read about speakers "opening up" and other such magic regarding how much power they're fed. So I wanted to see if I could get down to the real nuts & bolts and away from the hyperbole of magical mystical sound jargon. This is why I'm curious if the speaker's performance at various frequencies changes between powering it with a 50 watt or 150 watt amp, or more. I realize the amp should have a flat response, but I'm not sure if the speaker itself on the amp will reach its best response depending on how much power it has or needs to get there at listening level. For example, if 20 watts was enough to do the same exact thing as 50 watts at the same position, distance, room, etc, and all 50 watts was doing was making it louder, then I really wouldn't need any new amplifiers at all and it's just a matter of being louder, or if I had a larger room it would help, but otherwise, it's not.

Knowing I really do not need 200 watts is very helpful since it means I don't have to shell out a lot for a good amplifier.

I was thinking of potentially getting perhaps one of the following, an Emotiva A-700 (80watts RMS at 8ohms on 7 channels to handle all my speakers, factory refurb around $500) or maybe an Outlaw 5000 which would do 120 watts at 8ohms all channels driven into 5 channels, but then only use 3 channels for the mains and center and let my AVR handle the surrounds (they're small anyways).

I of course ultimately do not see how any AVR can output enough power to properly power large speakers and lots of them, which is my main interest for discreet amplifiers, but maybe I'm wrong there too? A Denon X3400H for example is rated at 105watts/channel at 8ohms, but I seriously doubt it's able to do that across 2 channels let alone 7 channels and my understanding is that clipping is the worse thing, so I imagine using an AVR to handle a bunch of large speakers would not be the best way to go about it (more like its best to run a bunch of bookshelves or satellites compared to large speakers).

Thank you again for your help!

Very best,

 

[M Code]

When a stereo amplifier is bridged a couple things can happen...
Such as:
* Power output can increase up to 4X
How much depends on power supply capability, output stage overdesign, protection circuit settings
* Amplifier sees an 8 Ohm loudspeaker as 4 Ohms as Peng advised above..
Depending upon the amplifier topology/design, sometimes the THD may decrease
* Caution using external devices such as speaker switching boxes as now both the loudspeaker output terminals, +/- are above ground

I would caution U to listen to the amplifier in the standard unbridged mode and bridged mode then decide which sounds better...

Just my $0.02...

 

[lovinthehd]

Thank you, again, that's very helpful.

Basically it seems that I have zero need for a 200 watt amplifier for these speakers. I was mainly looking to see if I was adequately driving the M70II's currently and if so, then having something that could do more would allow me to move into larger speakers or simply better speakers that require more, something like the A7's or A9's (Polk),or some other particular speaker setup in the future.

It's confusing to read about speakers "opening up" and other such magic regarding how much power they're fed. So I wanted to see if I could get down to the real nuts & bolts and away from the hyperbole of magical mystical sound jargon. This is why I'm curious if the speaker's performance at various frequencies changes between powering it with a 50 watt or 150 watt amp, or more. I realize the amp should have a flat response, but I'm not sure if the speaker itself on the amp will reach its best response depending on how much power it has or needs to get there at listening level. For example, if 20 watts was enough to do the same exact thing as 50 watts at the same position, distance, room, etc, and all 50 watts was doing was making it louder, then I really wouldn't need any new amplifiers at all and it's just a matter of being louder, or if I had a larger room it would help, but otherwise, it's not.

Knowing I really do not need 200 watts is very helpful since it means I don't have to shell out a lot for a good amplifier.

I was thinking of potentially getting perhaps one of the following, an Emotiva A-700 (80watts RMS at 8ohms on 7 channels to handle all my speakers, factory refurb around $500) or maybe an Outlaw 5000 which would do 120 watts at 8ohms all channels driven into 5 channels, but then only use 3 channels for the mains and center and let my AVR handle the surrounds (they're small anyways).

I of course ultimately do not see how any AVR can output enough power to properly power large speakers and lots of them, which is my main interest for discreet amplifiers, but maybe I'm wrong there too? A Denon X3400H for example is rated at 105watts/channel at 8ohms, but I seriously doubt it's able to do that across 2 channels let alone 7 channels and my understanding is that clipping is the worse thing, so I imagine using an AVR to handle a bunch of large speakers would not be the best way to go about it (more like its best to run a bunch of bookshelves or satellites compared to large speakers).

Thank you again for your help!

Very best,

Generally larger speakers are more sensitive than smaller speakers....

 

[MalVeauX]

When a stereo amplifier is bridged a couple things can happen...
Such as:
* Power output can increase up to 4X
How much depends on power supply capability, output stage overdesign, protection circuit settings
* Amplifier sees an 8 Ohm loudspeaker as 4 Ohms as Peng advised above..
Depending upon the amplifier topology/design, sometimes the THD may decrease
* Caution using external devices such as speaker switching boxes as now both the loudspeaker output terminals, +/- are above ground

I would caution U to listen to the amplifier in the standard unbridged mode and bridged mode then decide which sounds better...

Just my $0.02...

Thank you,

That is a good point and I have been listening A-B style to the amplifier in its native stereo settings at 50 watts and also two of them as 150 watt monoblocks bridged, one per main speaker. I don't honestly hear a difference that matters much and I've been doing it without my subwoofers so that I can examine maybe if its only going to show up in the lower bass frequencies from my listening position, but again, without a means to measure it, it's mostly just too subjective. I normally wouldn't even care, other than I'm getting interested in measuring things and this is a good exercise to help me avoid any major costly pitfalls later falling into the rabbit hole of hyperbole with respect to expensive high powered stuff when its not even needed.

Very best,

 

[MalVeauX]

Generally larger speakers are more sensitive than smaller speakers....

That's interesting, I'll keep that in mind! It would make sense from a design standpoint. I think I likely misspoke with the reference however as I was more meaning to describe that larger speakers would require more energy to generate the SPL with (larger was the misnomer, really I was referring to having lots more drivers in a large cabinet at play here), sort of similar to how a subwoofer needs more energy than a tiny high frequency base speaker would. Again, I might be totally off with that, which is why I'm here to learn.

Very best,

 

[lovinthehd]

Something called Hoffman's Iron Law https://sites.psu.edu/speakerdesign/2013/01/24/hoffmans-iron-laws-of-speaker-building/

Sensitivity (efficiency) dictates how much amp you need to get your speaker to a certain spl.

 

[MalVeauX]

Something called Hoffman's Iron Law https://sites.psu.edu/speakerdesign/2013/01/24/hoffmans-iron-laws-of-speaker-building/

Sensitivity (efficiency) dictates how much amp you need to get your speaker to a certain spl.

That puts a lot of light on the idea of larger speaker cabinets (more volume) and more sensitivity! Thank you!

Very best,

 

[Leemix]

If you get an opportunity to try a powerful amp in your system you really should, that way you will know for sure.


Sent from my iPad using Tapatalk

 

[MalVeauX]

If you get an opportunity to try a powerful amp in your system you really should, that way you will know for sure.


Sent from my iPad using Tapatalk

That's a part of the plan. I would like to get a decent power amplifier for my L/C/R at the very least as I don't think I'll live with the Monitor II series that I have forever and whatever I get next will likely occupy a larger room dedicated to audio and media in general and will likely go for a little larger even. I have used AVR's forever and only recently in the past few years started using dedicated amplifiers in stereo setups and only very recently started using dedicated amplifiers in my home theater arrangement as it's the only system I have that is not essentially near-field and so it requires a lot more effort to setup nicely and get the results I like within my budget and effort.

I'm currently considering a Monolith 200 watt x 3 channel amp refurb (just overkill and lots of headroom for a long time), or an used/refurb Emotiva A-700 or Outlaw 5000 and running just the L/C/R from them and let the other channels idle, and then if I want to use the other channels later I can. I'll let the AVR handle the surrounds and all in a 7.2 or 9.2 setup depending on where I go later down the rode. The Outlaw 5000 looks great and has more power at 120watts at 8ohms with all channels driven and would likely cover any of my needs in the future for a long time. Then again, the A-700 would also be nice, while it has less power, it handles 7 channels at 80 watts and would totally off-load from my AVR so that it is basically just a processor. I like that idea too. But of course I wonder if the 80 watts RMS will truly handle everything for the next 10+ years. Maybe it's overkill even. I just don't know yet. I would rather have more power and need less than the other way around, so if I do go down this rabbit hole, I'd like it to hurt only once, rather than twice!

Very best,

 

[AcuDefTechGuy]

the Amp100 can be bridged to produce 150 W into an 8 ohm...

If his speakers are 8 ohms, won’t the bridge mode make the amp see the speakers as “4 ohm”.

And if his speakers are 4 ohms, the bridge makes the amp see “2 ohms”?

 

[MalVeauX]

If his speakers are 8 ohms, won’t the bridge mode make the amp see the speakers as “4 ohm”.

And if his speakers are 4 ohms, the bridge makes the amp see “2 ohms”?

The speakers are 8 ohm, the amplifier is 50 watts at 8ohm and the load it will "see" will be approximately 4 ohm with the 8 ohm speakers attached in the bridged arrangement. However, it's still 8 ohms, the load is just similar to what 4 ohm would be and the amplifier handles 4 ohm loads natively, so its not being asked to do something it was not designed to handle (4ohm loads).

At least, that's my understanding based on everything here?

Very best,

 

[PENG]

It's confusing to read about speakers "opening up" and other such magic regarding how much power they're fed.

That can be true, but it is 100% BS if stated as a rule. The fact is, you can "feed" your M70 II with a 1kW McIntosh mono blocks, and the speaker will only take what it needs to provide you the spl you need. If you only need 70 to 75 dB average like I do, and sit less than 12 feet from those speakers, the extra "power" will be there acting like a reserve that you may never tap into. Yes you can force feed any speaker by cranking the volume way up, but then you risk damaging it.

So I wanted to see if I could get down to the real nuts & bolts and away from the hyperbole of magical mystical sound jargon. This is why I'm curious if the speaker's performance at various frequencies changes between powering it with a 50 watt or 150 watt amp, or more. I realize the amp should have a flat response, but I'm not sure if the speaker itself on the amp will reach its best response depending on how much power it has or needs to get there at listening level. For example, if 20 watts was enough to do the same exact thing as 50 watts at the same position, distance, room, etc, and all 50 watts was doing was making it louder, then I really wouldn't need any new amplifiers at all and it's just a matter of being louder, or if I had a larger room it would help, but otherwise, it's not.

All else being equal, yes 50 watts simply allow you to achieve higher spl, i.e. louder, but as you already know, speakers don't behave like resistors. A so called 8 ohm loudspeaker's impedance would vary with frequency, and the phase angle between the current drawn and the applied voltage also varies with frequency. For example, Polk Audio specified the M70 II's impedance 8 ohm nominal, but at certain frequencies, it may dip well below 8 ohms and may have phase angles large enough to challenge less capable amps. If you figure you need 100 W, get a 200 W amp at the minimum, and you won't likely have to worry about your speaker's impedance characteristics.

Knowing I really do not need 200 watts is very helpful since it means I don't have to shell out a lot for a good amplifier.

Again, your 50/60 W 8/4 ohm amp seems adequate, but based on your seating distance and room size, it certainly wouldn't hurt to get yourself a 100 to 200 W amp.

I of course ultimately do not see how any AVR can output enough power to properly power large speakers and lots of them, which is my main interest for discreet amplifiers, but maybe I'm wrong there too? A Denon X3400H for example is rated at 105watts/channel at 8ohms, but I seriously doubt it's able to do that across 2 channels let alone 7 channels and my understanding is that clipping is the worse thing, so I imagine using an AVR to handle a bunch of large speakers would not be the best way to go about it (more like its best to run a bunch of bookshelves or satellites compared to large speakers).

Don't underestimate the AVR-X3400H. It is twice as powerful as your Amp 100. It can drive your mains nicely for sure. I tried one briefly on my KEF R900, no issues at all.

https://www.soundandvision.com/content/denon-avr-x3400h-av-receiver-review-test-bench