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Understanding relationship of speaker size and type of construction on listening experience in a given room

fredstuhl

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Hi,
First and foremost, thanks a lot for this place and your contributions! Music is my hobby, I enjoy listening and playing in bands. Just recently fell into this rabbit hole hifi gear, however, the conversations in the typical "audiophile" forums frustrate me a lot... I don't know much about acoustics, loudspeaker technology and electronics, but I have a background in natural sciences and the degree of pseudoscience that is being spread in the hifi community is making me sad. Guess you can tell how relieved I was finding audio science review and seeing actual measurements, discussion of data and critical thinking.

Now, in principle I have one of this -help me decide what I should buy- questions, but more than I need a specific suggestion for a product, I'd like to understand the physics behind it.
I am living together with my girlfriend (an architect with very strong opinions about everything that goes into our living space) we live in a two-room apartment with a combined living room/ dining room/ open kitchen (this combined room has about 40 m2). We have a Bauhaus-style interior with few furniture items, mostly hard surfaces, mostly bare walls and ceiling, so while our place usually subjectively looks cool, it has never been a good environment acoustically. I have a set of old, big speakers from a German manufacturer (T+A Criterion TB 140, 3way transmission line speakers) and we use them for casual listening/ movies sitting on a couch about 5 m away. When I actively listen to music, I do that from a different spot, moving a chair closer to the speakers, with me and the speakers in an equilateral triangle (2 m length per side). We have been moving places a lot, before this kind of setup was always okay, however, in our current apartment, acoustics are now so bad that I really don't enjoy listening with the big speakers anymore. Experience from large distance when watching movies is still... good enough I guess... at rather low standards. An improvement in eg speech intelligibility would be much appreciated.

My girlfriend's opinions about aesthetics of acoustic treatment are not likely to change, hence I want to find a solution for my actual actively listening to music experience that works better in this kind of untreated, very reflective living environment. I figured that in order to get a somewhat enjoyable listening experience, I should try a near-field setup, but it would also need to double for general use eg when watching movies from larger distances. I borrowed a set of small studio monitors (Eve Audio SC205) from a friend to test this -> and indeed, given that I'd add some low end extension, they made me really happy in near-field, even in this horrible acoustical environment, much more enjoyable than my big speakers from any listening distance in this room. However, -and I'm sure this will come to less suprise for more experienced forum members here- they were completely unusable at larger distance, much worse than the big ones. Again, I have not much experience in evaluating these things correctly or even expressing myself precisely and can't describe it better than that the sound of the small speakers was -although at similar perceived volume level (and I think the Eve Audio speakers were volume-wise still very much in their comfort zone. No clipping indicated, I don't listen to music very loudly)- very diffuse in comparison to the big speakers, with very very poor stereo imaging, and it appeared that also tonality changed a lot.

Integrating this experience with what I've learned from reading in this forum and what I've learned from reading some guides on the Genelec website -> it seems to me as I have experienced different levels of balance between direct and reverberant sound caused by listening distance and speaker directivity, with the most direct sound experience when listening to the Eve Audios in near-field and the most reverberant sound when listening with the Eve Audios from far away, which must then have a much wider dispersion than my big ones, does this sound correct?

In order to understand this better, I have a set of questions:
1. Did I get it right that SPL capabilities of a speaker don't really matter as long as it is used within its limits?
2. Why is there a maximum recommended room volume for a certain speaker size - again, coming from the Genelec website and their monitor selection guide (https://www.genelec.com/correct-monitors). Let's say I am sitting right in the respective suggested listening distance of some Genelec 8330s and 8350s, so within the area where direct sound dominates the experience -> I guess room size will still make a difference for the probably still not insignificant amount of reflected sound that I hear, but why is it suggested to chose a bigger speaker in a bigger room in such a situation?
3. Following up that last question -> do the dispersion characteristics change significantly within the same speaker line with speaker (driver or cabinet) size? Is this the reason for the "critical distance" (referring to the Genelec Direct Sound Dominance graph) generally increasing with increasing speaker size (comparing speakers of the same line, the same construction style)?
4. Now, with that goal in mind of having a very good listening experience in a near-field(ish) situation, but still not completely terrible experience when listening to the same speakers from 5 m away (ideally without repositioning them), could larger near-field speakers such as the Genelec 8350 or 8351/ 8361 do the trick?
5. Are there other loudspeaker characteristics that I didn't mention, but that are important in this scenario and need to be considered?

Looking forward to your answers and thanks a lot for your help! In general, I really appreciate you sharing your knowledge and experiences here, thanks a lot!
 

NTK

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Welcome to ASR. I empathize with your room acoustics problem. Does your girlfriend (and you) like plants? They can work as absorbers/diffractors. Onto your questions:

  1. Yes. The SPL capability specs (if the numbers are real) are for exactly that purpose.
  2. Not very sure. I guess when you have a big room, it is reasonable to think sometimes someone will listen at the far end of the room. For example, sometimes studios have sofas away from the consoles for clients to listen in.
    northern-lights-1.jpg
  3. I think it is reasonable to assume speakers in the same range are more alike than different. It is not unusual to mix speaker models of the same range in surround setups due to this reason. I think in the Genelec chart the critical distances are calculated based on the room size stated, and they used bigger rooms for their bigger speakers.
  4. Looking at the SPL chart in the page you linked to, the 8351B (having the lowest numbers of the three models you listed) should give you 104 dB SPL peak and 92 dB long term at 5 m distance. I can't say for you, but I'd think it should be enough for me.
  5. The spinorama graphs will tell you the most about the sound qualities of a speaker. They'll tell you how neutral sounding (a very good thing) your speakers are, and that affects 100% of your listening time. After that will be the max SPL capabilities (which you've covered). That will tell you your limit on how wild your parties will get :D
 

Inner Space

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... we use them for casual listening/ movies sitting on a couch about 5 m away. When I actively listen to music, I do that from a different spot ...

Hey Fred, welcome aboard. Based on your description of your room, and the plural and singular pronouns quoted above, I would recommend a good pair of very directional speakers aggressively toed in so that their listening axes cross well in front of your couch. That shares the sweet spot better at the couch location, and minimizes reflections from your walls. Then, for solo music listening, move your chair to where the axes cross, for a classic triangle.

That's probably the best you can do. Not sure where you live, in terms of what models to recommend.
 
OP
fredstuhl

fredstuhl

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Welcome to ASR. I empathize with your room acoustics problem. Does your girlfriend (and you) like plants? They can work as absorbers/diffractors. Onto your questions:

  1. Yes. The SPL capability specs (if the numbers are real) are for exactly that purpose.
  2. Not very sure. I guess when you have a big room, it is reasonable to think sometimes someone will listen at the far end of the room. For example, sometimes studios have sofas away from the consoles for clients to listen in.
    View attachment 112796
  3. I think it is reasonable to assume speakers in the same range are more alike than different. It is not unusual to mix speaker models of the same range in surround setups due to this reason. I think in the Genelec chart the critical distances are calculated based on the room size stated, and they used bigger rooms for their bigger speakers.
  4. Looking at the SPL chart in the page you linked to, the 8351B (having the lowest numbers of the three models you listed) should give you 104 dB SPL peak and 92 dB long term at 5 m distance. I can't say for you, but I'd think it should be enough for me.
  5. The spinorama graphs will tell you the most about the sound qualities of a speaker. They'll tell you how neutral sounding (a very good thing) your speakers are, and that affects 100% of your listening time. After that will be the max SPL capabilities (which you've covered). That will tell you your limit on how wild your parties will get :D
Thanks for your quick answer and yes, she likes plants, very good point! :)
Okay, so in those tables the room size/ speaker size suggestions would be based on the assumption of typically greater listening distances in larger rooms, that makes sense. However, the take away message would then be that within the same range of speakers (in case contruction principle is the same in the whole range) you can chose a model purely based on sufficient max SPL at your desired listening position? So as long as you are not comparing 2way vs 3way, or different loudspeaker construction types, i don‘t have to worry about driver size etc. at all, as long as i am in the green max volume wise? That is nice.
 
OP
fredstuhl

fredstuhl

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Hey Fred, welcome aboard. Based on your description of your room, and the plural and singular pronouns quoted above, I would recommend a good pair of very directional speakers aggressively toed in so that their listening axes cross well in front of your couch. That shares the sweet spot better at the couch location, and minimizes reflections from your walls. Then, for solo music listening, move your chair to where the axes cross, for a classic triangle.

That's probably the best you can do. Not sure where you live, in terms of what models to recommend.

Thanks for your answer, this sounds cool!
Very happy about model suggestion - i am living in Germany. Genelec is on the top of my short list, because i heard some at a hifi convention and really really liked them. Then of course i read good stuff here and there is this talk by floyd toole that really impressed me - i think to remember he showed some excellent measuring „G“ speakers.
How can i generally identify high directivity speakers? In these amazing directivity plots from Amir, I‘d have to look for a long and narrow beam through, correct? How can i evaluate directivity from speakers with no such data available - do i need to look for deep waveguides? Any other cues?
 

NTK

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Thanks for your quick answer and yes, she likes plants, very good point! :)
Okay, so in those tables the room size/ speaker size suggestions would be based on the assumption of typically greater listening distances in larger rooms, that makes sense. However, the take away message would then be that within the same range of speakers (in case contruction principle is the same in the whole range) you can chose a model purely based on sufficient max SPL at your desired listening position? So as long as you are not comparing 2way vs 3way, or different loudspeaker construction types, i don‘t have to worry about driver size etc. at all, as long as i am in the green max volume wise? That is nice.
From the Genelec specs, it looks like the 8351B and 8361A use the same (or very similar) mid and treble drivers. So I'd expect that they sound very very similar. (The 8331A and 8341A also seem to have the same mid and treble drivers.) I wouldn't be surprised at less than extreme volume, you can hardly tell them apart.

The 8341A is the current ASR measurement champ with regard to the Olive preference score. Its only short coming is max SPL capability. It couldn't deliver enough bass to make Amir happy. So you may need to consider subs.

The Genelec Ones have pretty wide directivity, which is generally a good thing as they will sound more spacious. Here is an animated polar directivity plot using Amir's measurements of the 8341A. Look at how smooth they are in the front hemisphere. (I had to use only half of the frequency bins to keep the GIF small enough to upload. LOL.)

Genelec 8431A Spl Adjusted Directivity.gif
 
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