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JTR Noesis 215RT Measurements Discussion

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Mine measure flat to 12 hz but I realized they are measuring like that when the bathroom door in the back of the room is open. When I close that door it is closer to 17hz.  Not that it matters that much, I cross them at 60hz now for movies and for music (I run them full range) my style of music doesn't go that low anyway.  It's nice that either way I don't have to worry about a HPF. 

 

Scott, I remember when you were here you were telling me I should keep that bathroom door open all the time, I can't remember what your reasoning was though, do you remember saying that?

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Stand there in the door jam and then watch the club sequence from John Wick at Ref with your subs set how they were and then you can tell me what I meant. ;)

 

 

Yep, you'll basically be standing inside what your sealed setup is essentially making a "Port" out of the bathroom door. You could do this @popalock 's old house and almost feel like you were levitating. 

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Bandpass, but yeah. Essentially that is what is happening.

 

Was pretty fun though! You really need to visit the KC gang sometime, B. Carp's room is pretty cool. Yours and his mains reminded me of mine and felt relief when experiencing them. :P

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The lowend of the Noesis 215RT was carefully designed for a flat response in room. The half space, out door response doesn't give a good indication of the in room response.  The Noesis 215RT was very difficult to design because of the horn's directivity transition to the direct radiating woofers and then the spatial and room gain. The attached measurement is a Noesis 215RT, 1ft from the front wall and 3ft from the side wall, in a large, open basement, on a concrete floor.

Noesis 215RT_right side_5_100hz.png

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On 10/22/2017 at 8:50 AM, Jeff Permanian said:

The lowend of the Noesis 215RT was carefully designed for a flat response in room. The half space, out door response doesn't give a good indication of the in room response.  The Noesis 215RT was very difficult to design because of the horn's directivity transition to the direct radiating woofers and then the spatial and room gain. The attached measurement is a Noesis 215RT, 1ft from the front wall and 3ft from the side wall, in a large, open basement, on a concrete floor.

Hi Jeff!  I think this is an interesting strategy, but I guess I have two concerns to raise:

First, I'm not aware of there being any kind of typical room gain profile.  I believe there is enormous variation in the real world.  Certainly the room gain you see in that basement looks nothing like what I see in my room.  Second, I'm not sure that a flat in-room bass response is ideal, particularly for music.  I haven't pinned down what sounds "best" yet, but it seems that music is typically mastered to expect some room gain in the sub bass.  I haven't worked out an ideal amount of boost yet, and I wouldn't be surprised if it's a lot less consistent between masters, but I'm leaning toward approximately 1-2 dB/octave below 80 Hz.  That's in addition to a bigger +5 dB or so increase roughly in the 100s, which arises due to gain from the floor reflection (when using an otherwise anechoic flat speaker), plus any rise that naturally occurs due to the speaker's sloping power response above the baffle step region.

With movies, consistency is poor in general because of flawed theatrical calibration standards, relying on power averaging instead of direct sound level along with the prevelance of "home mixes", which aren't even standardized at all.  Though a bit of rise at the bottom doesn't seem to do those mixes any harm as far as I can tell..

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On 10/27/2017 at 2:32 PM, SME said:

Hi Jeff!  I think this is an interesting strategy, but I guess I have two concerns to raise:

First, I'm not aware of there being any kind of typical room gain profile.  I believe there is enormous variation in the real world.  Certainly the room gain you see in that basement looks nothing like what I see in my room.  Second, I'm not sure that a flat in-room bass response is ideal, particularly for music.  I haven't pinned down what sounds "best" yet, but it seems that music is typically mastered to expect some room gain in the sub bass.  I haven't worked out an ideal amount of boost yet, and I wouldn't be surprised if it's a lot less consistent between masters, but I'm leaning toward approximately 1-2 dB/octave below 80 Hz.  That's in addition to a bigger +5 dB or so increase roughly in the 100s, which arises due to gain from the floor reflection (when using an otherwise anechoic flat speaker), plus any rise that naturally occurs due to the speaker's sloping power response above the baffle step region.

With movies, consistency is poor in general because of flawed theatrical calibration standards, relying on power averaging instead of direct sound level along with the prevelance of "home mixes", which aren't even standardized at all.  Though a bit of rise at the bottom doesn't seem to do those mixes any harm as far as I can tell..

100% of home audio speaker go into homes. Advanced room modeling software can pretty accurately predict frequency response of a speaker in room. While all rooms are different, the speaker placement is usually similar, 3-5 feet from the side walls and 1-3 feet from the front wall. Averaging the predicted in room responses in a variety `of different rooms will produce a target curve. However, this isn't as easy as is sounds because the Noesis 215RT isn't a simply subwoofer. The Noesis 215RT  woofers are up in the air and receive very little boundary gain while the port is on the floor (1/2 space) and producing very large frequencies which are reinforced by the front and side walls (1/8 space).

There isn't an ideal amount of boost because it is personal preference, depends on subwoofer's ability and varies with content. With movies, boosting the very bottomend is fun but then when you play music, boosting 40-120hz will give you more chest thump. Most people end up elevating from 80hz and below with the ramp starting in the 120-160hz range. Higher than that will start to hurting intelligibility. 

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Jeff is right, if you design a full-range speaker with anechoic response flat down to 20hz and below, you will experience a huge low frequency boost. All commercial speakers for home use are designed with some roll-off in the low end, and they all end up with a more or less balanced level down to where the speaker finally rolls off. 

Most full-range systems are set up with a separate bass system / subwoofers, and the bass system is level matched and usually equalized. What you see in the measurements when adjusting the eq is of course the in-room response.

Now one can argue that the radiated sound energy falls at lower frequencies, but if you eq for flat energy level - or have a flat speaker - the sound pressure will be too loud at low frequencies.

Very, very few speakers are true full-range. This one is the rare exception. Some very small speakers with dsp claim to have response down to 20hz or 14hz or whatever, but that is pure nonsense, because they do not have the output capacity required for those low frequencies to even be noticed. But this speaker has, confirmed by the measurements.

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It's hard to argue with Jeff's approach, being that it's a passive full-range speaker.  Room variations are so great that the result will be hit or miss regardless of the room.  I'm pretty adamant that EQ is a must for high quality sub-bass because of room differences.  On the other hand, it may still come across a bit shy in the low end, on average.

For comparison, here's a picture of anechoic measurements of the Revel Salon 2:

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Note that it runs a tad "warm" in the 100-250 Hz range, which IMO adds just a bit more chest punch (which IMHO depends on this range as well as 40-120 Hz) and impact at the expense of some slight intelligibility loss with some content.  If you ignore that bit, it's pretty much flat all the way down to 30 Hz, and only -3 dB @ 25 Hz.  Of course, it has nowhere near the sensitivity, output capability, or ultimate extension of a JTR 212RT, but the speaker is probably used in a lot of music mastering studios where it may or may not be used with EQ.  In a typical room without EQ, that's going to exhibit quite a bit of a ramp toward 25 Hz.  Maybe it'll be too much in a lot of rooms.  I liked the bass on these quite a bit, but they were placed several feet from the walls, and the room opened up into a fairly large space.  Presumably the room gain was not as substantial as in a smaller room, but I'm sure there was still a fair bit of ramping.

That doesn't mean that mastering engineers necessarily tweak the bass to perfection under such conditions.  I believe both mixers and mastering engineers strive for consistency with preceding content when working with music.  I'm only guessing here, but I'm thinking that the precedent is for around 1-2 dB/octave gain to be present in the playback system, based on what I hear on my precisely calibrated system in my room.  Yes this is based on my preference, but I don't think my preference is too far off from most peoples'.  I like a weighty bottom end, and I like definition and punch.  I want both, without sacrificing mid/high intelligibility, and to achieve all this requires a response that fits within a fairly limited shape range.  With a flat in-room response, the bottom end tends to be either subtle or lost entirely to masking with a wide variety of music content that I listen to.  A little bit of boost goes a long way to bringing the bottom end content to life.

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Kinda off topic from the 215RT...

In general if I was selling subs or speakers I'd probably aim for a flattish response to 30-35Hz and a gentle 6 to 12dB/oct roll off below there. Rooms vary a LOT but if you look at the broad trends vs individual samples most rooms seem to have some moderate boost by 20-25Hz and a large amount by 10Hz. Mine has about 3.5dB at 20Hz and about 14dB by 10Hz. There are always those examples that don't and you have your usual room issues such as the dip in the 12-17Hz range that occurs in a lot of rooms, or the peak near 40-60Hz for seating placed near the center of the room. A lot of companies go for the flat full or half space bass response. It's really a matter of preference and design choices.

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