"headroom" for LSiM?

F1nut

I'm not sure what you're driving at. The fact is the tweeter uses very little power regardless of anything else.

sponger

RPF65 stated that avr "bi-amping" wastes power by drawing wattage to the channels set to highs without actually using most of that wattage. When I reiterated that, you quoted that and stated "it is fact." In which case, the rationale is that channels that are set to "small" pull the same amount of power as channels set to "large."

WLDock

Bi-wire one side, normal wire the other side. Play some pure test tones, well recorder test CDs, with just voice, or single instrument recordings, etc. Also listen to your normal CDs. Pan back and forth between Left and Right. See if your ears can pick up on any differences.

Talk can only go so far.

sponger

WLDock, your point is well taken about assessing the merits of bi-wiring. But, at the moment we are focusing on whether or not there is a difference between bi-wiring and avr "bi-amping." If so, how does one explain that difference in layman's terms? Thank you.

F1nut

sponger wrote: »

RPF65 stated that avr "bi-amping" wastes power by drawing wattage to the channels set to highs without actually using most of that wattage. When I reiterated that, you quoted that and stated "it is fact." In which case, the rationale is that channels that are set to "small" pull the same amount of power as channels set to "large."

I repeat, the tweeter uses very little power regardless of anything else. That includes whether the speakers are set to small or large.

sponger

Ok, but you are then in disagreement with RPF65's explanation of why avr "bi-amping" differs from bi-wiring.

F1nut

No, I'm not. We're telling you the same thing.

sponger

F1nut wrote: »

No, I'm not. We're telling you the same thing.

What he's saying is that the channels that feed the tweets still draw the same amount of power as the lows channels.

F1nut

No, they only draw what is needed, which what he said too.

sponger

Here is what he said:

"Going back to two outputs to drive each speaker, even though the available power is there, your still sending 21 watts out of each speaker terminal. Half of the speaker is only using 9 of those 21 watts, so 12 watts is wasted."

rpf65

Going back to the example I used, 30 watts total, if conventionally wired, where 21 watts is used by the low freqs, and 9 watts is used for the mids and highs.

If you wire the speakers using two outputs, channels, and still needed 21 watts to achieve the same volume level for the lower freqs, and 21 watts was available for the higher freqs, but it only needed 9 watts, I stated, and F1 agreed it is a fact, that the power is wasted, where did it go.

Answer is simple. The power was never produced by the power supply in the first place. This is where the waste comes in. The excess power can't be diverted to another channel, it will just never be produced by the power supply. Keep in mind that a power supply must have reserve power, so available power can never be fully utilized.

Good rule of thumb is 1/2 of available power, max power, can be used to drive speakers safely for normal operation. Not exact, but a safe maximum operating level.

So, again, going back to the two outputs per speaker example, 80 watts of available power means 40 watts of usable power. You still have enough usable power to drive your speakers about 3 more decibels. That' would sound about twice as loud. If you would have wired conventionally, you could have achieved a volume level of about 40 percent more.

In other words, max usable power would achieve volumes about 100 percent above normal listening levels, while conventional wiring would achieve about 140 percent above normal listening levels.

This may seem to be irrelevant, until you start adding more speakers. The 100 watts available power, two channels driven, may drop to 70 watts, 5-channels driven, and 50 watts 7-channels driven. Think about it. Fifty watts, 7-channels driven, is 25 watts of available power, 5-channels with the front two wired with two wires, is really close to the maximum capabilities of the AVR.

Your AVR will probably run a little cooler, in the example, by conventionally wiring it. This translates into longer life span. Your speakers are in less danger of clipping, you stay farther away from the distortion range, and your allowing the speakers to run the way they were designed to run. Of the above benefits of conventional wiring, I personally think the speakers operating they way they are designed to operate is the most important.

I'm sure I missed a few benefits of conventional wiring, as I'm sure there are are an equal number of arguments for wiring one speaker with two out puts. Never heard a difference myself, but some have. Since I personally haven't heard a difference, I'll take the extra reserve power.

Again the power wasted, is because it was simply never been produced in the first place. It could have been used elsewhere, but since there was no demand, it is simply never produced, and can't be utilized where it was needed.

BlueFox

Wow. I never realized this was so difficult. LOL

sponger

rpf65: the less available power per channel with all channels driven assumes that all channels are being driven full range. Some manufacturers use @1Khz, but generally it's full range. So, that said, there isn't an arbitrary ceiling per channel simply as a result of all channels being driven.

In the case of avr "bi-amping," not all channels are being driven full-range. Therefore, the limitations on power availability per channel do not differ from that under bi-wiring conditions.

F1nut

I give up.....anyone else wanna take a crack?

sponger

I think the question at hand is whether or not avr "bi-amping" has a negative impact on my co-worker's current set-up.

We've established that avr "bi-amping" is not actual bi-amping. No disagreement here about that.

But, Polk endorses bi-wiring as a configuration that could "improve transparency" for the LSiM. If that is the case, then one might ask if avr "bi-amping" would effectively be any different from the bi-wiring that Polk endorses. So far, I don't think this thread has directly addressed that question.

Clipdat

The takeaway message I got from this is that most people who try to bi-amp are doing it wrong.

teekay0007

!!

Viking64

F1nut wrote: »

I give up.....anyone else wanna take a crack?

Sure, I'll give it a go!

When bi-amping with an AVR, it is always important to ensure that the frequency response of the left audio channel is inverted to 50% of it's western exposure so that contra-aural crosstalk evaporates evenly throughout all 7.1 channels.

By nature, bi-amping is simply an amps indecision on which way it wants to swing. It is not recommended to impose patriarchal gender roles on the amp until it has been fully burned-in, unless the amp has been properly installed in a "safe place".

Furthermore, the power supply has copper windings that will tighten beyond a recommended level when bi-wiring. This is known as trans-directional-penny-pinching and will result in any channels that don't maintain a balance of 60 cents or more to become eligible for unwanted low-balance fees, thus limiting the cents per channel to levels below that required by most speaker manufacturers.

The best technique to prevent this unwanted situation has always been "internal bi-wiring". This is the method where all 7.1 channels are bi-wired together at the power transformer, creating one giant "super-channel". With a super-channel, every speaker receives DOUBLE the amps rated watts-per-channel, and it becomes so transparent, you can see right through it.

BlueFox

Okay. That makes sense. Short and sweet. Thanks.

Viking64

sponger wrote: »

I think the question at hand is whether or not avr "bi-amping" has a negative impact on my co-worker's current set-up.

We've established that avr "bi-amping" is not actual bi-amping. No disagreement here about that.

But, Polk endorses bi-wiring as a configuration that could "improve transparency" for the LSiM. If that is the case, then one might ask if avr "bi-amping" would effectively be any different from the bi-wiring that Polk endorses. So far, I don't think this thread has directly addressed that question.

Bi-wiring is running 2 sets of wires (one to the high-pass, one to the low-pass) from one single output on the amp. This AVR bi-amping silliness would be running one set (high) from one output channel and one set (low) from a different output channel.

Nightfall

F1nut wrote: »

I give up.....anyone else wanna take a crack?

rpf65

You can make all the arguments you want, weather it be for or against using 2 outputs to drive one speaker from an AVR. The math, for instance says you'll waste about 14 percent of usable power. This would be a 5.x system using 2 outputs per speaker in comparison to conventional wiring, where 70 percent of power will be directed to the low freqs and 30 percent will be directed to high freqs.

That's the math, but in the audio world it's meaningless, like a lot of sciencie stuff.

Your ears are different than mine, or anyone else's. This is the point where it's normally advised to try it both ways. If you think bi-amping, I hate that term, sounds better, go with it.

Personally I think the money would be better spent on better wire, but what do I know.

sponger

I do not believe that one is better than the other. I'm just not sure there is a difference in the end result. Again, the wasted power rationale assumes all channels driven at full range, as that is what reduces output per channel on paper. When each channel plays a different set of frequencies, it cannot be said that any power is being lost unless we factor for opportunity cost. That is, the wattage that the highs channel does not use could in theory be used towards lows for another speaker. That would be the opportunity cost of avr "bi-amping."

Again, I want to emphasize his set-up sounds great -- fantastic in fact. The only issue if we even want to call it one is "headroom" or perceived lack thereof. Even then, I think we've ruled out that avr "bi-amping," if done according to denon's instructions, is the cause. In no way does it reduce output versus bi-wiring, which Polk has stated "improves transparency."

WLDock

sponger wrote: »

But, Polk endorses bi-wiring as a configuration that could "improve transparency" for the LSiM. If that is the case, then one might ask if AVR "bi-amping" would effectively be any different from the bi-wiring that Polk endorses. So far, I don't think this thread has directly addressed that question.

One can put bi-wiring right in the category of audio mythologies. There are a lot of things that audiophiles claim to improve transparency that the average person can't hear. One can try to explain it until one is blue in the face. However, what matters is what the ears hear. Some claim to hear a difference in speaker wire, cable, power cords, fuses, bi-amping, bi-wiring, tubes, spikes, audio stands, isolators, etc. The truth is that we do not all hear the same or know what to listen for.

IMO, the room has a huge effect on the sound. Imagine moving your stereo to different rooms. The sound will not be the same. Try moving a mono Bluetooth speaker around the room. The sound changes just by moving it a couple of feet. Now think of stereo speakers with unequal room boundaries. Bi-wiring what? Bi-Amping with an AVR? Really? What are we talking about?

Dealing with room interactions should be the first conversation over the audio mythology questions. Once you do get there if one can hear a sound difference with bi-amping then maybe one can hear a difference in wire and so on, and so on .....

Speaker designers spend a ton of time designing passive crossovers so that their speakers sound good in a lot of different scenarios. Passives are not perfect and some believe they negatively affect the sound. Bi-wiring can't bypass the fact that it's a passive crossover. Still, even the most elaborate active Bi-Amping system would have to be optimized to best a good passive design. Even more, some use DSP to help with room correction and clarity to the ears. A well optimized active Bi-Amping system is the way to "improved transparency." It's usually not cheap!

So, saying bi-wiring is an improvement is almost like saying a three-way speaker sounds better than a two-way speaker. It sounds good paper but those that listen to speakers know that there is no absolutes in audio.

If one wants headroom and clarity for LSiM speakers, power them with a quality high current amp and deal with things in the room that smear, brighten, dull the sound!

Bi-wiring with an AVR? Not so much. Just look at lab tests of AVR's with all channels driven. There are better audio improvement conversations to have. If your bud is happy with it then consider it audio mythology and let it be. We hear what we hear, we believe​ what we believe.

Here is one take in favor of Bi-wire: https://www.qacoustics.co.uk/blog/2016/06/08/bi-wiring-speakers-exploration-benefits/

tonyb

Lots of great answers here in this thread.

If your friend likes his sound as is, then leave it alone and enjoy. If he wants to further improve his sound, then he should take some advice in this thread. End of story.

Jim Shearer

I hesitate to step into this mess, but let me try.

First: what does the XO in your speaker do exactly? It is a voltage divider net work. It blocks low freqs from getting to the tweeter and blocks high freqs from getting to the woofer. How does it do this? Using inductors (coils of wire which change resistance with different freqs), capacitors (which allow only certain freqs to pass, and resistors (which act equally on all freqs). Compare the temps of the components in the XOs before and after playing music loudly through your speakers. Notice that after the loud music the components get hotter. Yes, power is lost in the XO.

What if you set the speakers to small in the AVR's menu? Then the pre/pro trims off low freqs so that the power amp section doesn't have to produce those lows which require much more power than the higher freqs. Energy saved! Less load on the power supply, less heat lost in the XO. You aren't using the full capability of the speaker, but if you have a sub, then it can do that 'heavy lifting' using a separate amp.

What if you 'bi-amp' using the AVR? Now two channels of the power amp section are used for each speaker. One feeds the tweeter, while the other feeds the woofer. If both channels are producing the same signal (all freqs), what will happen? The XO for the tweeter still shunts the lows off; some of the energy from the lows is dissipated in the XO, while some is dissipated in the output transistors; I don't have the patience to explain why that can happen, but it has to do with phase angle presented by the XO and speaker driver, along with other things that you can research if you like. The XO for the woofer still shunts off the high freqs, and again, energy will be dissipated in both the XO and the output transistors. This really isn't what you are trying to achieve by 'bi-amping'. For true bi-amping, you want to separate the freqs BEFORE they go to the power amp!

I'll stop here rather than just rambling on uselessly.

Cheers, Jim

sponger

WLDock: Very informative description that I completely read through and enjoyed. My only concerns after reading your post are that you mentioned room characteristics and lab tests of an avr with all channels driven.

Should audyssey not have accounted for room characteristics? Of course we can all agree that minor changes to the auto-calibration are usually required. But, could the software have erred to an extent that requires immediate attention?

Also, lab tests with all channels driven on an avr are done with all channels playing full range. Sure that reduces overall ouput. But, avr "bi-amping" does not have all channels playing full range.

Mr. Shearer: You have provided an informed analysis of pros and cons of bi-wiring, bi-amping, etc. I read through it and learned a great deal.

But, the issue at hand is that I have to convince my co-worker that if he takes his set-up out of avr "bi-amping," he'll experience a beneficial change. So far, I have not read anything in this thread that makes that case. I've read plenty about avr "bi-amping" and bi-wiring being a waste of time. I don't disagree with that at all. What I disagree with is the notion that he is "doing more harm than good." That case has not been made based on the responses in this thread.

But that is not to say I don't appreciate the varying viewpoints and meaningful insight.

tonyb

I don't think your grasping the concept of bi-amping with an AVR, or why it's pointless.

Do you see all wheel drive cars at the race track ? One engine powering 4 tires takes some power away from the other 3. Right ? Same with a receiver, the more channels you use, the less each has as it only has one engine/power supply and it's a weak one at best.

The top portion of the speaker, as stated already, uses little power. Dedicating a channel to that top portion does not make the rest of the power available to other portions of the speaker so it's wasted.

Tests on AVR's power ratings and other specs are done with a sine wave in a special chamber. Nobody is playing full range music to gather their specs.

The case has been made for all aspects, your just not comprehending them. My advice is to get your read on and educate yourself some as to what is marketing hype and real world results.

Much of audio is trial and error, we all have different preferences and abilities to hear things. Cost the man nothing to try his setup in a different configuration. If you don't try different things, you'll never know what will gain you positive results, or negative too. The people giving advice in this thread are pretty well seasoned in audio, we only hope to keep others from making mistakes that many of us have made in the past and this will save you time, coin, aggravation.

You really don't have to tell your friend anything, have him join here for his questions.

WLDock

No harm, no foul.
Yes, you wanted him to get the Emotiva amp that is rated at about 250 watts a channel, WITH ALL CHANNELS DRIVEN, vs the Marantz rated at 140 watts with two channels driven.

And us Polkies don't see the point in Bi-Wire or sudo Bi-Amp.

However, It sounds like he has the best system he has ever had.

That's all that matters really.

Peace!

sponger

tonyb wrote: »

Tests on AVR's power ratings and other specs are done with a sine wave in a special chamber. Nobody is playing full range music to gather their specs.

Advertised power output is based on full range playing conditions. Of course that does not mean that all freqs are being played at once. But, the advertised range represents basically the full spectrum for audio listening purposes. According to this tutorial, some manufacturers will base advertised output on @ 1Khz to increase advertised output. Therefore, it would stand to reason that full range vs selected range output does have an impact on overall output.

https://www.youtube.com/watch?v=njnRckulS2A

Again, I am not saying either configuration has any merit. What I'm saying is that there is nothing in this thread establishing that avr "bi-amping" is "doing more harm than good. "