Bass anechoic vs in-room

[DJBonoBobo]

Your answers tell me to measure my room.

My questions are not about my room.

Therefore your answers don’t answer my questions.

I’m not being rude, it’s just how the English language works.

This is a misunderstanding. The room sim in REW does not require a measurement. You just enter some parameters and you see how a virtual speaker behaves in a virtual room. It works completely independent from measurements. I just included a measurement to show the difference between the simulation and an actual measurement, so you can see what the limits of the simulation are.

Edit: I see, i wrote "in your room" in my post. Edited to make clear you can use it for any room you want to simulate.

 

[sarumbear]

I’m very happy that you’ve answered my questions, rather than posting reams of writing from which I find it difficult to extrapolated answers which may be implicit, but which require drawing out.

You are asking questions where there are no clear-cut answers. Acoustics is a complex subject and you cannot learn anything via quiz answers. You are not at an exam yet, you are learning.

I’m very grateful of anyone trying to answer my questions, but it has to be said that some posts appear almost wilfully obtuse.

They certainly are not obtuse. Your lack of knowledge and not willing to assimilate what is written is confusing you.

It really is the easiest thing in the works to start with “On question 3, I’d say…”

One cannot ask teacher to change their methods but can change the teacher.

 

[Yorkshire Mouth]

This is a misunderstanding. The room sim in REW does not require a measurement. You just enter some parameters and you see how a virtual speaker behaves in a virtual room. It works completely independent from measurements. I just included a measurement to show the difference between the simulation and an actual measurement, so you can see what the limits of the simulation are.

Edit: I see, i wrote "in your room" in my post. Edited to make clear you can use it for any room you want to simulate.

Cool, cheers.

Nonetheless, I’d offer this.

I suspect some people here have run many, many rooms through that. And, based on what they’ve seen, they have a very good idea of what usually happens, and could state that without prompting me to enter hundreds of different rooms myself to see if a pattern emerges, a pattern they already know exists.

Sorry, I’m just being a grump old sod.

 

[Yorkshire Mouth]

You are asking questions where there are no clear-cut answers. Acoustics is a complex subject and you cannot learn anything via quiz answers. You are not at an exam yet, you are learning.


They certainly are not obtuse. Your lack of knowledge and not willing to assimilate what is written is confusing you.


One cannot ask teacher to change their methods but can change the teacher.

I wasn’t demanding clear cut answers.

I’m more than happy with either “always”, “almost always”, “usually”, or “it’s 50:50”.

By definition, the answer has GOT to be one of those, or very similar.

By the way, I was a (very) successful secondary school teacher for a quarter of a century, so I know a little about clear questioning and clear answers.

Thanks again.

 

[Purité Audio]

The ‘sim’ feature is really useful, but obviously you can’t beat measuring the actual room with a microphone, initially the ‘moving mike’ option might be useful to give you an idea of the least worse placement options.
Keith

 

[DJBonoBobo]

Cool, cheers.

Nonetheless, I’d offer this.

I suspect some people here have run many, many rooms through that. And, based on what they’ve seen, they have a very good idea of what usually happens, and could state that without prompting me to enter hundreds of different rooms myself to see if a pattern emerges, a pattern they already know exists.

Sorry, I’m just being a grump old sod.

Man, if you were a teacher you maybe know that you best learn from doing something on your own? By the way it really is not clear what it is you want to know exactly.

Last try from me, look at this - same room, just slightly different placement. Left: No, you will probably not hear more/deeper bass from you 50Hz speaker, because that whole area is pretty low. Right: Yes, probably you get more/deeper subjective bass, because of the peak around 42Hz. So you may hear something from your 50Hz speaker there as well:

 

[Yorkshire Mouth]

It is not clear what I want to know exactly?

Okay, I’ll try to make this completely clear. Let’s take one question at a time.

In his video, Erin says the speaker goes down to 30hz anechoic. He then says, but it’ll go down to 20hz or so in your room.

Is he (a) definitely right (b) usually right, or (c) incorrect, it’s completely random?

I don’t know how to ask it more clearly.

 

[sarumbear]

I wasn’t demanding clear cut answers.

I’m more than happy with either “always”, “almost always”, “usually”, or “it’s 50:50”.

By definition, the answer has GOT to be one of those, or very similar.

You are mistaken. Physical phenomenon cannot explained like that.

By the way, I was a (very) successful secondary school teacher for a quarter of a century, so I know a little about clear questioning and clear answers.

No wonder…

 

[sarumbear]

It is not clear what I want to know exactly?

Okay, I’ll try to make this completely clear. Let’s take one question at a time.

In his video, Erin says the speaker goes down to 30hz anechoic. He then says, but it’ll go down to 20hz or so in your room.

Is he (a) definitely right (b) usually right, or (c) incorrect, it’s completely random?

I don’t know how to ask it more clearly.

I’ll try one last time as I also do not know how to explain more clearly.

The questions you ask are about the same phenomenon where parameters interact with each other, hence there are no correct answers to them individually. The answer permutations are too many.

 

[DJBonoBobo]

It is not clear what I want to know exactly?

Okay, I’ll try to make this completely clear. Let’s take one question at a time.

In his video, Erin says the speaker goes down to 30hz anechoic. He then says, but it’ll go down to 20hz or so in your room.

Is he (a) definitely right (b) usually right, or (c) incorrect, it’s completely random?

I don’t know how to ask it more clearly.

I have not seen Erin´s video, but he writes: "In-room performance can extend even lower, down to 20 Hz."
I would say this is optimistic, because you would need a gain of +25dB at 20Hz.

But to answer your question i actually used the room sim. I played around and saw that i had to use a big room to get a good peak below 30Hz. With 7m room length i see +20dB at 24Hz. So, with a big room and when positioned close to the wall, the JBL probably gets much deeper than 30Hz. In a small room that is less likely.

 

[TurtlePaul]

It is not clear what I want to know exactly?

Okay, I’ll try to make this completely clear. Let’s take one question at a time.

In his video, Erin says the speaker goes down to 30hz anechoic. He then says, but it’ll go down to 20hz or so in your room.

Is he (a) definitely right (b) usually right, or (c) incorrect, it’s completely random?

I don’t know how to ask it more clearly.

(b) usually right

 

[Yorkshire Mouth]

I’ll try one last time as I also do not know how to explain more clearly.

The questions you ask are about the same phenomenon where parameters interact with each other, hence there are no correct answers to them individually. The answer permutations are too many.

That’s not logical. I think we’ve got our wires crossed.

If you place 1000 speakers in 1000 rooms, you’ll get different results in each for the reasons you gave. No argument there.

But over time either more of the speakers will go lower in a room than anechoic or not, no matter how complex the reasons.

If you measure a speaker in a room and it’s lower than anechoic, either you’re shocked, or you’re not. Or you’re mildly surprised it you’re not.

It’s either common or uncommon. It just is or it isn’t.

 

[DJBonoBobo]

But over time either more of the speakers will go lower in a room than anechoic or not, no matter how complex the reasons.

If you place a speaker that usually reaches 70Hz at the same position as the speaker in my post #30, it will not "go lower", because there is a huge dip just below 70Hz. But the 30Hz speaker will go "lower" due to the peak at 24Hz,

 

[sarumbear]

That’s not logical. I think we’ve got our wires crossed.

If you place 1000 speakers in 1000 rooms, you’ll get different results in each for the reasons you gave. No argument there.

But over time either more of the speakers will go lower in a room than anechoic or not, no matter how complex the reasons.

If you measure a speaker in a room and it’s lower than anechoic, either you’re shocked, or you’re not. Or you’re mildly surprised it you’re not.

It’s either common or uncommon. It just is or it isn’t.

I have a Masters degree on acoustics. I designed and sold more than 10,000 pair monitor speakers. However, it’s your prerogative to believe what I say.

 

[Yorkshire Mouth]

I have a Masters degree on acoustics. I designed and sold more than 10,000 pair monitor speakers. However, it’s your prerogative to believe what I say.

It’s because of your expertise (and that if those like you) that I feel I can ask questions here and get an authoritative answer.

But I still respectfully feel you’ve misunderstood my question.

Best wishes.

 

[NTK]

That’s not logical. I think we’ve got our wires crossed.

If you place 1000 speakers in 1000 rooms, you’ll get different results in each for the reasons you gave. No argument there.

But over time either more of the speakers will go lower in a room than anechoic or not, no matter how complex the reasons.

If you measure a speaker in a room and it’s lower than anechoic, either you’re shocked, or you’re not. Or you’re mildly surprised it you’re not.

It’s either common or uncommon. It just is or it isn’t.

Have you had a chance to read through René's thread on room gain that was referred to in posts #7 & #20? It is OK to say you don't fully understand it, because the post's contents are quite technical.

For example, here is one of René's simulation plot. The red line represents a speaker with a perfectly flat anechoic response down to 1 Hz. The blue curve is the in-room response. You can see from the in-room response that it has an "averaged room gain" easily >10 dB higher than the anechoic response. That shouldn't be surprising since some of the sound energy hitting the room walls is reflected back into the room in a reflective room, and therefore not all the sound energy hitting the room walls is lost. They would have been if the room is anechoic.

Note that the in-room response depends on both the locations of the speaker and of the listener relative to the locations of the room modes. Moving either the speaker or the listener will result in a different response. Also, this assumes the woofer is omnidirectional, a dipole or cardioid woofer will behave differently.

 

[Purité Audio]

That’s not logical. I think we’ve got our wires crossed.

If you place 1000 speakers in 1000 rooms, you’ll get different results in each for the reasons you gave. No argument there.

But over time either more of the speakers will go lower in a room than anechoic or not, no matter how complex the reasons.

If you measure a speaker in a room and it’s lower than anechoic, either you’re shocked, or you’re not. Or you’re mildly surprised it you’re not.

It’s either common or uncommon. It just is or it isn’t.

Anechoic means there are no reflections ( no anechoic chamber exists that accurately measures really low bass) the bass passes you once and is absorbed, room gain ( and cancellations ) are caused by the reflected bass, the more solidly constructed the room the higher the percentage of returned bass potentially the larger the room gain.
Keith

 

[Yorkshire Mouth]

(b) usually right

Superb.

 

[Yorkshire Mouth]

Anechoic means there are no reflections ( no anechoic chamber exists that accurately measures really low bass) the bass passes you once and is absorbed, room gain ( and cancellations ) are caused by the reflected bass, the more solidly constructed the room the higher the percentage of returned bass potentially the larger the room gain.
Keith

That’s also superb, and with a little more detail.

A question. If the speaker goes down to 30hz, and in a normal (non-anechoic) room, that 30z is reflected and its gain increases, surely that’s not 20hz. That’s just “more 30hz”.

Which suggests I’m missing something. How does “more 30hz” become 20hz?

Can you help me out? Cheers.

 

[NTK]

That’s also superb, and with a little more detail.

A question. If the speaker goes down to 30hz, and in a normal (non-anechoic) room, that 30z is reflected and its gain increases, surely that’s not 20hz. That’s just “more 30hz”.

Which suggests I’m missing something. How does “more 30hz” become 20hz?

Can you help me out? Cheers.

I think what Erin meant is that, with the help of an estimated room gain of 10 dB, the 20 Hz output from the speaker will see a gain of 10 dB (above the anechoic numbers), making the 20 Hz sounds stronger/louder than the anechoic measurements suggest. This can make the speaker more "usable" to 20 Hz, if you don't need a copious amount of it.