Guess How Big My Speakers Are

If you read any of my threads on here or looked at my virtual system you probably already know the answer to this question, but for those who have not, try this as a thought exercise. Given this plot alone how big a speaker do you think this is?

Frequency response plot showint extension to 20 Hz



  • 2’ from sides, 1.5’ from rear
  • Ported
  • Not horns
  • No EQ applied. This is the natural in room response using short sine sweeps.
  • For a living room this is a well treated room with GIK soffit traps, bass traps and diffusion panels strategically placed.

I’ll reveal my answer if we get 5 guesses or more. :)


Since that bass response would make everyone thing of large floorstanders, I'd guess bookshelf monitor size...or the post would pose far less intrigue 😉 



This could be the curve of any loudspeaker because Erik has not told us where the mic is. You can get that kind of bass out of an LS3 5A if you put the mic one foot away from it. The mic is obviously farther away as you can clearly see room nodes in the bass. There is a strong one at 30 Hz which is boosting the bass but 20 Hz is 8 dB down and is down even lower at other parts of the room. I would guess without the node the speaker starts rolling off at 40 Hz. Volume also makes a difference. This is probably a smaller tower or medium sized bookshelf speaker. Something with two 8" woofers or one 10" 


Speakers are about 11' apart, with a listening/mic location about 12' from the plane of the speakers.

This is most definitely an in-room response sort of scenario as opposed to quasi-anechoic (i.e. not close microphone).

your listening situation tells me that you have medium sized floor standers similar to Paradigm Studio 100 or Sonus Faber Grand Piano.

If the amp has a high output impedance the speaker might have a much higher output in the bass resonance area than one would expect. Nelson Pass demonstrated this at a RMAF about 10 years ago using a current source amp and open baffle speakers.

The distances from the wall also influence the speakers; if inside the room boundary effect a +3dB per octave gain will be seen from about 100 Hz down.

I'm thinking this could easily be a 2 way ported box with 8" high excursion woofer.


Nope, nothing fancy like Nelson Pass published in his paper about high impedance amps and speaker matching. 


Speakers are being driven by a quite normal Luxman 507ux.  I mean, I like the Luxman, but there's nothing unique about their specs.  Just a decent solid state amp with reasonably low output impedance.

I believe you have some Monitor Audio or Wharfdale floor standing speakers?

Not that it matters that much, but my distances for the speakers and listening location were off. 


8' apart, center to center, and 8' from the plane of the speaker's to the microphone  location.

Whatever they are they need some EQ below 500hz. There's been at least 5 guesses. 

We’ve reached the 5 guess threshold.

While I am a fan of Monitor Audio, that guess was wrong, as were all floor standers. "Large monitors" with 8" woofers was also incorrect.

Also incorrect was "long throw."

The in room response you see there is generated by a 2-way ported speaker with 6.5" mid-woofers from Scanspeak. While highly regarded by makers like Fritz, YG and Wilson, I wouldn’t classify them as particularly exotic.

The main point I wanted to make though was that, with room gain, a lot of speakers go lower than we think. Maybe not as loud as we’d like, but the output at 20 Hz is not nearly as far down. Room treatment helps make t his possible by damping down the mid/hi frequencies in the room, otherwise this response would probably go upwards.  Maybe a speaker that measures down to 40 Hz on paper is actually good enough for a lot of locations.


Would I add a sub? A question I debate a lot lately. If I did though, given how much output I have already I’d surely have to introduce a high pass filter. Adding a sub without one would be madness.

I was gonna guess Fritz, but now I’ll throw out Selah as a Hail Mary.  I just hope the performance graph of your investment portfolio looks different from this. 


Fritz tunes his speakers for more punch, with smaller cabinet sizes.  These sound a lot more laid back by comparison.  I will say he is using what I consider among the best sounding mid-woofers on earth. :-)

They look real good >1khz I would smooth the peaks a bit <500hz with EQ. I thought they were  3 way Bookshelf with that much bass. 

@onhwy61  Compression is probably the least measured feature of speakers.  Only SoundStage regularly measured it, and I expect these speakers will have some of that.  I'll try taking new plots.

I can tell you one thing though, the Mundorf AMT's I use for the tweets DO NOT COMPRESS.  They have amazing power handling and incredibly low distortion.  The limits of excursion in the mid-woofers though will probably be a factor.

What does the curve look like at the listening position with the room acoustics taken into account?



The measurements you see are from my couch! :)  I use OmniMic, which will automatically blend in gated high frequency with ungated low frequency.  



I hope all you readers understand I’m not trying to sell you on my speakers or drivers, at all because I don't think this is unique to my situation.

The point of this thread was more to discuss how much bass there can be when we include the room in the measurements, and maybe to encourage everyone to think of room acoustics first, new subwoofers second.

@djones51  That's more or less how I am setting them up with Roon.  I'm still playing with the overall tilt, but I disabled it all for the sake of this posting.


I thought one of your speakers was AN HSU sub,

Do I get a 33% correct for this answer.:-)



You may be a vampire, but the HSU VT15t is currently 100% on HT duty. :) I had it set up for stereo before. Back then I had no processor, used an Oppo BluRay player as my processor and ran everything through a Parasound 7.1 preamp.

Now I have a processor and a 2 channel integrated and things got a lot more complicated.


Your speakers and $10.00 will get you 2 Whoppers, an order of fries, and a medium drink at Burger King.

Thanks for your insight, @Rokral - Let us know when you get the gist of the thread.  Give it time and breathe, it will come to you.

Gist means meaning, or central point, by the way.



Unlike the people who can afford those speakers and a house to put them in, I actually work for a living.

bone crushing bass is the soul of real music… gain ain't enough..

as I gaze fondly at my Ampeg stack with 6x10”….

I am a Fender Jazz bass in a punk band Robot

Show us something meaningful…like the waterfall…

Actually a good thread

Robot running FFT..…

Show us something meaningful…like the waterfall…


Sir, you can't handle my waterfall plot. 😂

@erik_squires what is the volume of your cabinets?   I too run Scanspeaks in  ported but don't have your measurement equipment to compare to my room.  Your stated dimensions are speakers / position.  What is room?

I pretty much stole the cabinet from the Klang/Tong Nada if memory serves. Quite a large cabinet really.  However, I deviated in my crossover design from normal practice by NOT making measurements quasi anechoic but in-room for the bass. As a result the room gain was taken into account then. Even so, I still think I should have considered a smaller cabinet for a bit of low end punch.  Nothing I can't fix with EQ and proper placement though. 😁


Are they 1cubic foot bookshelves? Say, Squires hrs-1..... Or something like that?


What size shoes and gloves do you wear?

This will tell us how big your “speakers” are!

Looks like room bass node at 30hz.  

Given the flat response above 10khz, I'd say 3 way floorstanding speaker with 8 inch woofer.

@erik_squires yep, I recall another post of yours.  I've got the "Lee Taylor" version. I don't have the room to keep as far from the wall but have highly dampened the ports with fill.  Had good extension with subs so room may be behaving differently.   I was getting 80 to 90 hz blooms until I added some DIY Knauf based panels.  Now working with new Raven amp so I have option to run 80hz HP to them.  

@erik_squires yep, I recall another post of yours.  I've got the "Lee Taylor" version. I don't have the room to keep as far from the wall but have highly dampened the ports with fill.  Had good extension with subs so room may be behaving differently.   I was getting 80 to 90 hz blooms until I added some DIY Knauf based panels.  Now working with new Raven so I have option to run 80hz HP to them.  

@erik_squires what do you account the two large dips at 150 and lesser at 250 Hz in your room? I'm guessing you used a white noise sweep as your source tone?

The kit looks pretty good mate.

it is impossible that you are actually getting as much output at 20Hz as you are in the midband.