Dynamic requirements

[AcuDefTechGuy]

my HT has morphed into 95% music and 5% movies.......so video features are WAY down the list for me.

Video is way overated. Just hook up directly from the player to the TV.

I vote for separates too.

 

[annunaki]

I am a big believer in "way more power than necessary". Dynamic headroom is an excellent thing to have when used correctly. Very dynamic sources will benefit greatly from this. With the new Dolby True HD and DTS HD formats available, headroom will prove to be more crucial as the dynamic range of the movies will (should) increase aby a fair margin. Even the down converted options of these formats seem to be more dynamic (from what I have experienced).

250 watts continuous on speakers crossed over at 80hz should suit you very well. As TLS Guy has mentioned there is more power consumed from 80hz-2,500hz than many realize. The distance from the speakers in the room will factor in as well as acoustics.

Here is the upgrade path I would take:

Get the Onkyo 805. See how you like it. If it does the trick, you did not waste any money. If it does not do the trick, add the Parasound 5 channel amplifier. The 805 will make a great pre-pro and have excellent video switching capabilities.

 

[WmAx]

I think we can all agree that more amplifier power will better control the bass drivers ability to track transients and just allow better dynamics overall. But how relevant is this when the speakers are high pass filtered and set to an 80 hz crossover ?

,

The actual power required comes down to 4 basic things: (1) Sensitivity of speakers (2) Listening distance (3) Your preferred SPL (4) Dynamic range of music/source you intend to use.

Generally, 100 watts per channel on an average sensitivity speaker (88-90dB/1watt/1meter) is sufficient for normal uses with common music tracks. But do you have special requirements that would require more power, when you consider the 4 factors above? As an example, my computer monitoring speaker system utilizes over 1000 WRMS per channel. But normally, I may use 10 watts per channel when I use it for normal listening purposes. But this system is intended to do live music editing of uncompressed live recordings, which can have dynamic range over average level of up to 40dB. As a result, extreme power is required to prevent clipping. But this is a special application. If this was only intended for music listening to commercial recordings, I would have used far lower power amplifiers.

-Chris

 

[Vaughan Odendaa]

First, sorry for not responding. My insistance in avoiding a seperate processor/preamp stems from the fact that it isn't cost effective for me. There are few processors available which support Dolby True HD and DTS master lossless decoding, and those that do, cost an arm and a leg.

Hence my reasons for wanting the Onkyo 805. Feature-wise, it's got everything I need. Power-wise, it's got a heck of a lot of that too, especially within it's price band. But I don't know if the 805 will have the "kick" and without using the Parasound power amplifier, I won't know what to look out for.

My requirements, my listening levels are, on average, would be -8 dB's from reference calibrated at 0. But I may occasionally want to listen at -5 or below. At this point, I'm unable to listen at below -10 dB's because it's simply sounds too harsh.

The Parasound power amp delivers more than 250 watts of power into a 6 ohm load. My speakers a nominal 6 ohm load. My speakers have a sensitivity of 88 dB's. I currently have an av receiver putting out about 90 watts into a 6 ohm load. Yes, impedence varies with frequency and all that. I know.

I'm just trying to understand if high passing a speaker at 80 hz will simply not utilize the huge current reserves that the Parasound has to offer. It was said that the power divide is 400 hz.

Is there documentation that supports this assumption ?

--Regards,

 

[gus6464]

Can you hear an audible difference when you give a speaker more headroom in terms of power?

 

[TLS Guy]

First, sorry for not responding. My insistance in avoiding a seperate processor/preamp stems from the fact that it isn't cost effective for me. There are few processors available which support Dolby True HD and DTS master lossless decoding, and those that do, cost an arm and a leg.

Hence my reasons for wanting the Onkyo 805. Feature-wise, it's got everything I need. Power-wise, it's got a heck of a lot of that too, especially within it's price band. But I don't know if the 805 will have the "kick" and without using the Parasound power amplifier, I won't know what to look out for.

My requirements, my listening levels are, on average, would be -8 dB's from reference calibrated at 0. But I may occasionally want to listen at -5 or below. At this point, I'm unable to listen at below -10 dB's because it's simply sounds too harsh.

The Parasound power amp delivers more than 250 watts of power into a 6 ohm load. My speakers a nominal 6 ohm load. My speakers have a sensitivity of 88 dB's. I currently have an av receiver putting out about 90 watts into a 6 ohm load. Yes, impedence varies with frequency and all that. I know.

I'm just trying to understand if high passing a speaker at 80 hz will simply not utilize the huge current reserves that the Parasound has to offer. It was said that the power divide is 400 hz.

Is there documentation that supports this assumption ?

--Regards,

That last request was a little tough on the net. I have textbooks and my own observations of my spectrum meter. There are papers from the AES, but as a non member they would cost you. I did find this commercial site that is quite good, and has the standard chart of the frequency range of acoustical instruments. I have copies of this chart going back to the fifties. It is still valid. The black areas show the fundamentals of instruments. This is were their power outputs lie. The open areas are the harmonic content were there is much less energy. In it you will see that the mean of the black bars is somewhere around 400 HZ. There is also good commentary about the power in the frequency divisions on this site.

http://www.dak.com/reviews/Tutorial_frequencies.cfm

Anyhow it will correct the myth prevalent in these forums that if you have a sub with a powerful amp, you don't need much power anywhere else. This is a common myth that leads to poor performance of audio systems.

It is the upper bass and midrange were the action is.

 

[WmAx]

That last request was a little tough on the net. I have textbooks and my own observations of my spectrum meter. There are papers from the AES, but as a non member they would cost you. I did find this commercial site that is quite good, and has the standard chart of the frequency range of acoustical instruments. I have copies of this chart going back to the fifties. It is still valid. The black areas show the fundamentals of instruments. This is were their power outputs lie. The open areas are the harmonic content were there is much less energy. In it you will see that the mean of the black bars is somewhere around 400 HZ. There is also good commentary about the power in the frequency divisions on this site.

http://www.dak.com/reviews/Tutorial_frequencies.cfm

Anyhow it will correct the myth prevalent in these forums that if you have a sub with a powerful amp, you don't need much power anywhere else. This is a common myth that leads to poor performance of audio systems.

It is the upper bass and midrange were the action is.

It is true that in statistical analysis of the spectrum energy distributions of the average music; that energy will usually rise substantially under about 300-400Hz, and with classical music, it can even be substantial to 1000Hz in some specific cases. But the situation is worse than what may initially appear from examining such an analysis. Another important consideration is the additional power needed for that up to 400Hz mid-bass/lower mid-range band, because most speakers have their baffle step diffraction starting at the 400-600Hz range. That means, on average, under 250-350Hz, power level into this lower mid-range and upper bass section requires yet at least doubling of power(to compensate for the average 3dB baffle step correction) compared to what could be assumed from the statistical graphs alone.

-Chris

 

[TLS Guy]

what Chris says about the range below 400 Hz is absolutely true, especially for narrow fronted cabinets. We did get into a discussion yesterday about the wisdom of narrow fronted cabinets. The whole weight of the argument is not necessarily all in favor of narrow fronted cabinets by any means.

 

[davidtwotrees]

..... The whole weight of the argument is not necessarily all in favor of narrow fronted cabinets by any means.

As someone who is on my second set of narrow fronted cabinets with side firing woofers.........I have loved the sound.......my inital mentors in audio were both owner's of famous classic speakers, JBL Hartsfields, Altec VOT, and Klipshorns. I have owned JBL Jubal L65s as well as the really large Altec Valencias. I would take my current Cantons over any of those......although the Hartsfields were really something, imho. James Lansing RIP.

What does a narrow fronted cabinet give up in terms of performance?

What does a narrow fronted cabinet gain in terms of performance?

 

[Vaughan Odendaa]

TLS Guy, thanks for providing the link. I'll have a look.

--Regards,

 

[TLS Guy]

As someone who is on my second set of narrow fronted cabinets with side firing woofers.........I have loved the sound.......my inital mentors in audio were both owner's of famous classic speakers, JBL Hartsfields, Altec VOT, and Klipshorns. I have owned JBL Jubal L65s as well as the really large Altec Valencias. I would take my current Cantons over any of those......although the Hartsfields were really something, imho. James Lansing RIP.

What does a narrow fronted cabinet give up in terms of performance?

What does a narrow fronted cabinet gain in terms of performance?

Dear David,
I was not intending to confuse anyone. This problem basically relates to diffraction loss. Here is the issue, reflections from the baffle reinforce a speakers output below a frequency determined by the width of the baffle. For most practical designs today this amounts to a 6db roll off starting between 500 and 400 Hz. Now this is best compensated for in some way. However you cut the slice this is going to double the power the amp provides at the 3db point and progressively. Remember there is a call for twice the amp power with every 3db that has to be boosted. So if the step response starts at 500 Hz say then at 250 Hz there is need for a 6db correction.
Now this is in theory. Most speakers are in small rooms and not that far from the boundaries, and this blunts the diffraction loss effect to varying degrees.

Now if you have a wide fronted cabinet, diffraction loss becomes a non issue. Ted Jordan has maintained for years that we should not have moved to narrow fronted designs. The purists will say that the large baffle reflections will reinforce at some frequencies and cancel at others, and the response will be irregular. This they say this will cause uneven frequency response and spoil imaging. Now there is truth to this argument.

Now bear in mind that even the best speakers have evils we would rather not talk about. So it comes down to how do want to take your various poisons? The problem is magnified by the fact that superb speakers are expensive to engineer and build. The reverse is not true. All expensive speakers are not good speakers, far from it! However most of the speakers frequently mentioned in these forums are in the budget to low midrange price category. They are used with receivers that often are not comfortable with the lowered impedance that diffraction correction requires. The drivers in the speakers in this price range are going to suffer thermal compression issues and often worse. Many times in these designs the diffraction loss is not corrected. I have noted a desire for powerful subs. I'm pretty sure many of these are operating at a higher level than they should to mask lack of upper bass from this diffraction issue. This is not good practice.

So you see you can have a legitimate debate about this. There is no right answer. I don't know if I have explained this well enough for you to understand an issue that is not easy to grasp.

So what do I do. I expect you have seen my pictures, and see that they are narrow fronted. I think I have a preference for this. However I have selected drivers that are used in only a few very expensive speakers, and certainly could not be used in budget speakers or even mid price point ones. I have lots of amp power available, and even amps and drivers that are dedicated to filling the diffraction void. This is far from a viable commercial solution. I suppose you could market them to a view rich guys that Highfihoney is so fond of, but they likely would never get all the terminals on the back of the speakers sorted out!

 

[annunaki]

First, sorry for not responding. My insistance in avoiding a seperate processor/preamp stems from the fact that it isn't cost effective for me. There are few processors available which support Dolby True HD and DTS master lossless decoding, and those that do, cost an arm and a leg.

Hence my reasons for wanting the Onkyo 805. Feature-wise, it's got everything I need. Power-wise, it's got a heck of a lot of that too, especially within it's price band. But I don't know if the 805 will have the "kick" and without using the Parasound power amplifier, I won't know what to look out for.

My requirements, my listening levels are, on average, would be -8 dB's from reference calibrated at 0. But I may occasionally want to listen at -5 or below. At this point, I'm unable to listen at below -10 dB's because it's simply sounds too harsh.

The Parasound power amp delivers more than 250 watts of power into a 6 ohm load. My speakers a nominal 6 ohm load. My speakers have a sensitivity of 88 dB's. I currently have an av receiver putting out about 90 watts into a 6 ohm load. Yes, impedence varies with frequency and all that. I know.

I'm just trying to understand if high passing a speaker at 80 hz will simply not utilize the huge current reserves that the Parasound has to offer. It was said that the power divide is 400 hz.

Is there documentation that supports this assumption ?

--Regards,

The only thing you forgot to mention is the listening position distance from the speakers. Once we have that we can get a better idea of actual power output needed to deliver completely unclipped playback.

 

[annunaki]

Can you hear an audible difference when you give a speaker more headroom in terms of power?

Yes, however it will depend upon the dynamic range of the recorded material, the average listening level, and the distance from the speakers. The closer you are the less power that will be necessary to reach a given output level.

See my post again on page one.

 

[Vaughan Odendaa]

The only thing you forgot to mention is the listening position distance from the speakers. Once we have that we can get a better idea of actual power output needed to deliver completely unclipped playback.

The distance from speakers to listening position is 3 m.

--Regards,

 

[3db]

Dear David,
I was not intending to confuse anyone. This problem basically relates to diffraction loss. Here is the issue, reflections from the baffle reinforce a speakers output below a frequency determined by the width of the baffle. For most practical designs today this amounts to a 6db roll off starting between 500 and 400 Hz. Now this is best compensated for in some way. However you cut the slice this is going to double the power the amp provides at the 3db point and progressively. Remember there is a call for twice the amp power with every 3db that has to be boosted. So if the step response starts at 500 Hz say then at 250 Hz there is need for a 6db correction.
Now this is in theory. Most speakers are in small rooms and not that far from the boundaries, and this blunts the diffraction loss effect to varying degrees.

Now if you have a wide fronted cabinet, diffraction loss becomes a non issue. Ted Jordan has maintained for years that we should not have moved to narrow fronted designs. The purists will say that the large baffle reflections will reinforce at some frequencies and cancel at others, and the response will be irregular. This they say this will cause uneven frequency response and spoil imaging. Now there is truth to this argument.

Just to add to the confusion.. and my apologies for doing so...

Is the diffraction loss of narrow fronted cabinets responsible for a dip I see around the 250 - 400Hz in frequency response curves of many a tower speakers assuming the curve doesn't take in effect off axes measurements?

How does one explain that some speakers manufacturer curves remain fairly flat across that portion of the spectrum?

 

[TLS Guy]

Just to add to the confusion.. and my apologies for doing so...

Is the diffraction loss of narrow fronted cabinets responsible for a dip I see around the 250 - 400Hz in frequency response curves of many a tower speakers assuming the curve doesn't take in effect off axes measurements?

How does one explain that some speakers manufacturer curves remain fairly flat across that portion of the spectrum?

No apologies needed.

Without knowing the speakers and conditions of test I can't give you a definitive answer. However I would think this effect is very likely to be at least part of the dip you talk about. Now speakers are compensated for diffraction loss quite frequently. There are a number of ways of doing this. Like everything else in speakers this is achieved with varying degrees of success. The best way to tell if a two way speaker with passive crossover is diffraction loss compensated is to look at the impedance curve. If the impedance does not start to drop below 400 to 500 HZ then it is not compensated. All forms of diffraction compensation will drop the impedance over the range the compensation is applied.

Now as to flat speaker curves, you have to take them with a few grains of the proverbial salt. Unfortunately minor changes in the condition of test can markedly change the curve to the sales departments advantage.

The audible effects of diffraction loss become evident the larger the room and the further the speaker is from the wall boundaries. It manifests itself as a speaker with a less than robust baritone and tenor range. The sung voice has too much head over chest. The violins, violas and cellos have too much string over body. The woodwind especially flutes have too much whistle over the end pipe sound. Trombones and French Horns and to some extent the trumpets have too much lip over bell. All in all the presentation lacks appropriate weight and body. This effect is much less obvious in pop music, because the singers generally have a nasal presentation with a glottis that is far too closed. The dynamic is therefore poor, and without amplification they would be dead in the water.

I love opera, and this problem of diffraction loss, and many other speaker problems, really make operatic voices tiring to listen to. Good singers have a huge output, and can rise over a 200 piece orchestra without amplification. They sing with an open glottis, and have both big chest and head voices. If you get too much head it is very tiring on the ear I find.

This system was primarily conceived to take me to the opera.

http://mdcarter.smugmug.com/gallery/2424008#127077317

 

[annunaki]

OK.

Your speakers have a sensitivity rating of 88db @ 1w/1m.

You have two identical speakers.

Your listening distance is 3 meters or roughly a bit over 9 feet or so.

Every meter you move away from the speaker you lose 3db.

When doubling surface area you gain +3db

When doubling power you gain +3db

That being said, with one speaker playing, at 3 meters away (assuming no room losses or gains), the output level, with 1 watt average input, would be 82db. Since you have another speaker you gain +3db. Since that speaker would also be receiving one watt you also gain another +3db.

So with 1 watt average input power at a 3 meter distance your output level would be 88db. with a 90 watt amplifier you would have dynamic unclipped headroom of about 19.5db or so.

Say you wanted to listen at a bit higher volume of about 93db average. This would require about 2.67 watts average input power, but now lowers the unclipped dynamic range to about 15db.

The biggest thing to remember here is that the sensitivity ratings are (should be) taken in an anechoic chamber with full band pink noise ON AXIS. Because you are not listening nearfield (within 1m), on axis, or in an anechoic chamber this will be skewed some. I would be will to bet by around -3db or so. Especially once room loss/gain is figured in.

Real world should be fairly close to by estimations but will vary throughout the spectrum because of the room loss/gain.

I would be willing to bet that you would need closer to the 2.67 watts continuous average output to get around 88db average at the listening position, especially with music.

For most recordings, you should be ok with 90 watts rms, however with highly dynamic recordings like classical with 25db dynamic peaks or more you would require a more powerful amplifier. Something around 350 watts rms per channel would allow for fully unclipped playback of highly dynamic recordings of up to (25db dynamic range) with average volume of 88db-93db at the listening position.

A 180-200 watt rms amplifier would get you an extra +3db dynamic range over what you have currently.

This all changes if you like to listen at higher average volumes as well. The higher the average volume/power level the lower the unclipped dynamic range becomes.


I hope this is helpful and makes sense for you.

 

[Vaughan Odendaa]

Thank you for your advice annunaki ! The rated power output of my AV receiver is 85 watts RMS into an 8 ohm load 20 hz-20 khz. This is assuming that it can actually deliver 85 watts RMS which I doubt.

Now my system is calibrated to 75 dB's for each main channel. I listen on average at -12 to -10 and sometimes I dip below that. But if I go below -10 on most current recordings, the sound becomes harsh. Now I know that my room's acoustics will be a big influence here but I must assume that my AV receiver is not cutting it.

For the playback levels that I want, it would seem that the Onkyo 805 would be sufficient. But then what would the Parasound buy me ? More headroom ? Should this not translate to even less harsh sound at the levels that I do play back music and film material ? This would seem obvious to me.

I must also assume that the quality of sound itself is going to be improved substantially going from the Onkyo 805 to the Parasound (power amp section) given the cleaner power and the far greater reserves. I know the amp sections of both pretty well .

--Regards,

 

[annunaki]

If you are listening with the volume at -10db below reference on the receiver, I would at minimum suggest the 805 and probably go ahead and suggest the Parasound right away also. IF the receiver you currently have outputs the full 85 watts rms at 0db or reference level as indicated on the front panel, I estimate your average power level at about 8 watts or so. This translates into only about 10.5db of unclipped dynamic headroom. This can easily be exceeded with dynamic recordings and may explain why it is sounding a bit harsh.

Assuming the power output to be 8 watts average, anechoically, on axis, the ouput at the listening position should be 97db average with that amount of power. I assume, obviously that is not the case as that is very loud and can cause hearing damage over prolonged exposure.

Keep in mind that these are just assumptions and in no way should be taken as fact or totally accurate. However, they do seem to fit the scenario fairly well.

You can also look into the Behringer EP2500 which will offer 450 watts rms x 2 into 8 ohms and around 650 or so into 6 ohms. It s not a pretty amplifier but is solidly built with high quality parts and performs very well. I would suggest swapping out the fan for a low noise version. it costs about $8.00 to do so. I should add that it can be had for about $350.00 or less.

 

[Vaughan Odendaa]

Once again, thank you for the advice. Much appreciated. To be honest with you, I have no experience using pro amps. There is a shop nearby that stocks Behringer equipment but I have no idea what kind of components they use.

What is the amp section like ? Do they make a 5.1 power amp and will it be sufficient for a very high quality home theater and music system ? $350 does not seem like much for the rated power. Not that I have anything against inexpensive components.

--Regards,