All speakers change "Q" ( tuning ) as they are driven at different levels. As such, they all have a specific point where they will operate most linearly. The problem with a multi-way design is that it is possible for each of the drivers used to experience their "optimum Q" after warm-up in different spl regions. The end result is a lack of cohesivity unless one can find an SPL that presents a happy medium to all of the drivers simultaneously. Most of the time, this won't be at a low listening level either.
Now factor in that all ported / bass reflex designs are subject to variations in the flow velocity of air within the vent as SPL is varied. Unless a vent uses a gentle radiused flare at both the inlet and outlet side, the bass tuning will be optimized over a very narrow SPL range. Once again, if one is trying to listen outside of that range and / or in a range where the other drivers aren't hitting their stride in sequence, the end result is less cohesive sound. In this regards, sealed designs are more linear over a MUCH wider spl range and retain a higher percentage of "bass weight" as spl's are reduced.
As such, it is easy to see why / how speakers using one dynamic driver ( Walsh's / Lowther's / Fostex, etc ) and / or full range planar / E'stat type speakers excell at low volumes. That is, there's only one driver or type of driver to excite and all of the operating characteristics will remain consistent over the entire band. In effect, the speaker is more uniform in its' presentation, regardless of spl range. There is no "confusion" as to when each of the drivers is working optimally as they are all working in unison sharing the same load and electrical characteristics. On a dynamic multi-way system, each driver has individual electrical characteristics and they are VERY different from one another. If they weren't, there wouldn't be a difference between a woofer, a tweeter and a mid.
On top of that, many of these designs, especially E'stat's and Planar's, have very considerable surface area to radiate signal from. Even though one is not moving a lot of air due to a lack of excursion, spreading the sound that is being radiated out over a larger surface tends to present a slightly different tonal and transient presentation to our ears and brain due to the way that it excites the room. The fact that ambience cues remain more consistent with omni & dipolar radiators regardless of spl range also factors in too.
Outside of that, you also have to consider the noise floor of the electronics, how linear they are at low power levels, etc... Most high powered amps don't do all that well at very low power levels, hence the move to lower powered levels and / or higher bias Class A or richer Class AB designs. SET amps are a "double blessing" in that regards as most are both lower powered and Class A biased. The reason that the higher powered amps don't do well is that they make use of a multitude of output devices, which typically aren't matched all that well. At low levels, they are all doing their own thing and it isn't quite in perfect unison. It is not until the drive levels are increased that they begin to work as a team and everything begins to fall into place. The end result is that there is greater "slack" or "tolerance" in the circuit at lower levels, resulting in poorer, less cohesive sound.
As such, there are many factors that add up to "good sound" at low listening levels. If one is going to do a LOT of listening like this, one might want to build their system specifically for this purpose. It is tough to achieve stellar performance levels at both high and low spl levels with good extension and it typically takes a LOT of money to do so. Factoring in realistic expectations as you build your system may make for both a more enjoyable and less costly experience than having to change everything as you find out your listening habits aren't quite as "wild" or "mild" as one originally thought.
As a side note, one of the things that i like most about my Ohm's was the fact that i could listen at low spl's and still achieve staggering bass extension out of this design. It is the only speaker that i know of that can shake the floor at very low spl's. Then again, in stock form, this speaker is not capable of high spl's with good linearity, so it is somewhat of a specialized speaker. As i mentioned above though, i took this factor into consideration when building the system that i use them in. That system is right in the same room as my computer, where i do a lot of late night, low volume listening. The fact that the amps driving them run in Class A up to 50 wpc with 800 wpc at actual impedance of the Ohm's ) assures both high levels of linearity with an iron fist in terms of control : ) Sean
>
PS... These speakers are about 82 dB's and present a nominal 2-3 ohm load to the amp. NOT an easy speaker to drive and many amps aren't up to the task, even though their power ratings say they should be.
Currently listening to Cake: Pressure Chief on Redbook CD
Now factor in that all ported / bass reflex designs are subject to variations in the flow velocity of air within the vent as SPL is varied. Unless a vent uses a gentle radiused flare at both the inlet and outlet side, the bass tuning will be optimized over a very narrow SPL range. Once again, if one is trying to listen outside of that range and / or in a range where the other drivers aren't hitting their stride in sequence, the end result is less cohesive sound. In this regards, sealed designs are more linear over a MUCH wider spl range and retain a higher percentage of "bass weight" as spl's are reduced.
As such, it is easy to see why / how speakers using one dynamic driver ( Walsh's / Lowther's / Fostex, etc ) and / or full range planar / E'stat type speakers excell at low volumes. That is, there's only one driver or type of driver to excite and all of the operating characteristics will remain consistent over the entire band. In effect, the speaker is more uniform in its' presentation, regardless of spl range. There is no "confusion" as to when each of the drivers is working optimally as they are all working in unison sharing the same load and electrical characteristics. On a dynamic multi-way system, each driver has individual electrical characteristics and they are VERY different from one another. If they weren't, there wouldn't be a difference between a woofer, a tweeter and a mid.
On top of that, many of these designs, especially E'stat's and Planar's, have very considerable surface area to radiate signal from. Even though one is not moving a lot of air due to a lack of excursion, spreading the sound that is being radiated out over a larger surface tends to present a slightly different tonal and transient presentation to our ears and brain due to the way that it excites the room. The fact that ambience cues remain more consistent with omni & dipolar radiators regardless of spl range also factors in too.
Outside of that, you also have to consider the noise floor of the electronics, how linear they are at low power levels, etc... Most high powered amps don't do all that well at very low power levels, hence the move to lower powered levels and / or higher bias Class A or richer Class AB designs. SET amps are a "double blessing" in that regards as most are both lower powered and Class A biased. The reason that the higher powered amps don't do well is that they make use of a multitude of output devices, which typically aren't matched all that well. At low levels, they are all doing their own thing and it isn't quite in perfect unison. It is not until the drive levels are increased that they begin to work as a team and everything begins to fall into place. The end result is that there is greater "slack" or "tolerance" in the circuit at lower levels, resulting in poorer, less cohesive sound.
As such, there are many factors that add up to "good sound" at low listening levels. If one is going to do a LOT of listening like this, one might want to build their system specifically for this purpose. It is tough to achieve stellar performance levels at both high and low spl levels with good extension and it typically takes a LOT of money to do so. Factoring in realistic expectations as you build your system may make for both a more enjoyable and less costly experience than having to change everything as you find out your listening habits aren't quite as "wild" or "mild" as one originally thought.
As a side note, one of the things that i like most about my Ohm's was the fact that i could listen at low spl's and still achieve staggering bass extension out of this design. It is the only speaker that i know of that can shake the floor at very low spl's. Then again, in stock form, this speaker is not capable of high spl's with good linearity, so it is somewhat of a specialized speaker. As i mentioned above though, i took this factor into consideration when building the system that i use them in. That system is right in the same room as my computer, where i do a lot of late night, low volume listening. The fact that the amps driving them run in Class A up to 50 wpc with 800 wpc at actual impedance of the Ohm's ) assures both high levels of linearity with an iron fist in terms of control : ) Sean
>
PS... These speakers are about 82 dB's and present a nominal 2-3 ohm load to the amp. NOT an easy speaker to drive and many amps aren't up to the task, even though their power ratings say they should be.
Currently listening to Cake: Pressure Chief on Redbook CD