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Kvalsvoll

Bulding the Room2 listening room

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@maxmercy, I use a modified 10" driver, it is an old discontinued seas. 10" is a good size - good area for sensitivity, not too large so it does not change the sound field it is supposed to measure.

The 3x has less velocity in the important 30-40hz range, and a little less above up to around 120hz. Changing eq or delay on the BL back unit changes velocity response.

The 3x sounds better because it fills in a dip in the response around 60hz, phase is same, spectrogram is a little better.

The loss in velocity 30-40hz is noticeable. The increased v at ulf is more noticeable, because low freq noise stands out and becomes annoying - too much is not good. Further experiments can be to move the high-pass on the BL up in frequency, this will change the phase and perhaps make the velocity smoother - less ulf, fill in the dip 30-40hz.

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Testing midbass horns in Room2.

Calibration is complicated, and benefits in this system and room are questionable. This is just to ensure they work, and to learn how to set up and calibrate the system, so that the customer can receive some useful guidelines.

Usable range around 45hz up to 200-300hz, but for cf above 150hz you should absolutely use stereo processing, so for a typical av-processor system with bass-management it can be used up to 150hz.

Capacity around 120dB+, depends on how much power you have.

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26 minutes ago, Ricci said:

What type of alignment are those? TH?

Compact Horn, basically a rear loaded horn with resonance chamber for extended usable range.

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Maximum speaker delay in processors/receivers - a critical property, which is usually not sufficiently described in the manual or product presentation.

Anyone know the limits for different types, brands? I seem to remember this issue has been up before, but oooohhh.. using the rest of the day searching will not happen, and new information and new models may be available.

 

The problem:

Getting the timing correct is crucial for high performance sound quality. For systems with front main speakers and separate bass system that means to delay the main speakers so that they sum correctly with the bass system in the frequency response AND IN TIME/PHASE.

On most processors this is done by setting a distance on the different speakers. Typically, you set the front to the measured physical distance, and end up adding several meters for the bass system (subwoofer)  - THIS WILL DELAY THE FRONT SPEAKERS.

If you know what you are doing, you set the delay using measurements, so that timing and phase gets as good as possible to achieve. If you read on-line guides and audiophile magazines and pay no attention to how things really work, you set the distance for the bass-system equal to the physical measured distance, and conclude that subwoofers always sound kind of sluggish and is best switched off for music.

Since you are smart, you want to do it the way that actually works to get better sound, and end up seeing that the distance entered can be quite huge. And in some cases it may be possible to reach limitations of the processor in use. Obviously this is a no-go limitation for a processor, so if you have an installation that you know will require large delays, you want to choose a processor that satisfies this requirement. You want to see a specification for this number.

But this number is not in the brocheur or manual, it is not in any "test" performed by on-line or paper magazines - because the don't even understand why this number is important - so the only way to know is if someone have found the data.

 

My contribution:

Denon/Marantz processors, AVR:  Max distance difference 6m / equal max delay 18ms.

Devialet amplifiers: 20ms. 

Hypex DLCP and my SA-700 amplifiers: 15ms. (Though not relevant on the sub amp, becuase it is the mains that need delay.)

Onkyo processors, AVR: ???

Some readers now realize I need those numbers for the Onkyo.

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My Denon 3313CI AVR offers up to "60 feet" distance (a bit over 50 ms, in terms of delay) and a maximum difference of "20 feet" (~17.5 ms).

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1 hour ago, SME said:

My Denon 3313CI AVR offers up to "60 feet" distance (a bit over 50 ms, in terms of delay) and a maximum difference of "20 feet" (~17.5 ms).

Same as the Marantz and Denon I tested, it is very likely they share the same processing.

Note that it is the DIFFERENCE (17.5ms/20ft) that is interesting, as this is the number that defines how much delay is possible on the closer speaker to make it match the farther.

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Testing new configuration in Room2. V6030 compact horns placed in the middle of the room, on sides. Quite close to the lp, nearfield-horn? 

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English version of the small speaker article:

https://www.kvalsvoll.com/blog/2018/10/20/can-a-small-speaker-perform-like-a-big/

To discuss or comment, you can reply here in this thread.

Small speakers without the sound compromise have always been wanted, and there are several new speaker offerings claiming the problem is solved - small sounds as good as huge. But it doesn't. This article tries to describe some of the most important reasons for this.

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Small speakers have come a long way, especially with regard to bass performance.  I believe the Apple Homepod offers usable extension in a residential room to 35 Hz or so, especially if it's near a corner.  The servo-controlled (IIRC) internal woofer probably doesn't compress much at all unless the volume limits are being approached, which probably aren't that high.  (A lot of small speakers adjust the EQ with the volume control or may rely on some kind of bass-selective compression to allow louder sound without overloading on bass).  The Homepod won't play the lowest bass that loud, but a lot of customers are OK with that.  To be clear, I'm not endorsing Apple or the Homepod product, which I've never even listened to myself.  I just want to point out what's technically possible with current technology (and big R&D budgets).

My opinion is that a great speaker can be made very small, but where size ultimately comes into play is how loud the bass gets.  Furthermore, this trade-off can be partially mitigated by spending a lot more money.  This assumes active designs.  In passive speakers, good bass extension from a small space requires severe compromise, usually poor woofer efficiency.  Poor efficiency means a lot more power is being drawn from the amp and dissipated in the coils (and maybe crossover) for the crucial 100-400 Hz range, just so that the speaker can be "flat to 45 Hz".  You said the F2 extends to 60 Hz, which means it's not only using a larger woofer but one that doesn't give up as much efficiency in order to play lower than it needs to.

Another detail I think worth mentioning that I don't see in your write-up concerns speaker linear response and voicing decisions.  Passive speaker designers rarely know where the speaker will be placed relative to room boundaries, except maybe the floor in a floor-standing design.  Many designers likely voice their speakers with deficient 100-400 Hz output to try to accommodate being placed near walls or corners and also because resonances there can be quite offensive sounding.  Resonances in this "mud range" can bury/swallow voices, so many designers probably err on sacrificing punch for clarity in poor placement scenarios.

It is true that speakers with larger baffles/cabinets interact less with nearby room boundaries, often at the expense of worse baffle/cabinet diffraction effects.  The size of woofer alone (assuming <= 12") has less effect on the radiation pattern than the baffle and cabinet at these frequencies.  For wall/corner placements the benefit of increased directivity of a larger baffle and cabinet probably outweighs the increase in diffraction problems.

Most of the above discussion may be rather moot with good in-room EQ optimization.   I suspect that with good EQ optimization, differences in speaker size can be made largely irrelevant for low frequency sound quality at low levels.  On the other hand, I've noticed that speakers placed near walls and corners almost always have a suck-out somewhere in that 100-400 Hz range, which needs EQ boost to compensate for.  So at higher levels, capacity becomes an issue much sooner than without EQ.  The bottleneck region ends up being 100-400 Hz, not < 100 Hz which I find usually needs cuts rather than boosts.  So sadly, most passive consumer speaker designs sacrifice efficiency in the range that it's badly needed in return for bass extension that's not actually needed.  To be fair, they are designed to work well when placed away from walls, but who really has room / spousal approval for that kind of thing?  Not to mention how much better the sub bass is if reproduced from near a wall or corner.

So as I see it, the discussion should be more about the merits of active designs in general (including any system using powered subs) along with in-room optimized EQ and based on high efficiency, low mass, pro-style drivers.  Size does still matter, but for many listeners who only need low or moderate levels at home, a well designed active small speaker (with or without separate subs) can do the  job very well.  It's got to be active though.  Really I think it's time for passives to just die, except in custom / specialty systems where there's likely to be some kind of active processing anyway.

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Small will still not be the same, because directivity will be different. Unless directivity is designed to be similar, of course.

Active does not make any difference, and eq can not change decay profile, which is a result from room and speaker radiation. The solution lies in the physical acoustic design of the speaker.

Active is necessary to solve some issues, such as crossover at lower frequencies, and delay between drivers where this is necessary. Proper crossover between bass system and main speaker must be active, because it is too difficult and costly to make a passive network that works, and the quite large delay needed on mains can not be solved passive. Subwoofer usually requires more power, too. But then all this is not necessarily true either, because when I designed the C2 (1992) I made a passive crossover at 150hz, so it is possible, using computer simulation. But timing will be off, this ends up as a text-book 4. order crossover, with option for individual delay it is possible to design crossovers with no timing problems.

The new F105 is a small speaker with 5" lf driver and dome hf with moderate horn loading. The cabinet is a damped dipole with resistive acoustic ports. Directivity is controlled all the way down to 100hz, where it already has started to roll of. Design f range is 120hz and up. With a small subwoofer - will be half size of a V6 - that can be placed near boundaries, with dsp and eq, this gives a small system that will work well in normal rooms. The response is much smoother and more similar in different locations and rooms due to the directivity, even when this directivity control is quite small. But it doen't sound like a big speaker, regardless of sound volume. This small speaker would not benefit from active configuration, but the system as a whole is active where the crossover to the bass system needs to be done in a processor, and the bass system need dsp with eq. The next speaker will be a little larger, with 2x 5" lf drivers of a very different type. The goal for this one is to achieve good transient response - as long as you keep the volume down.

 

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