Guess How Big My Speakers Are

Hi @herman - Yes, I can hear 20 Hz.  I have to turn up the volume a bit, I feel it a lot sooner than I hear it. It does not sound like chuffing or distortion.

It's real.  It's not as prounounced as 32 Hz, as you'd guess from the graphs but it's really there.

This was played from digitally created test tones.

@herman 

What can I say, I have measured using OmniMic and Room EQ Wizard with two different calibrated mics.  The two mics were in agreement except for the range from 20Hz to 30 Hz where UMIK was 3-5 dB down @ 20Hz  depending on exactly how I placed the mics. It then merged with the measurements with OmniMic at 30.

I even tried using two different DAC's, one direct and one via Roon.  This may not be lab quality work but I'm satisfied it's in the ballpark.

@james633  - Absolutely right.  No way we are getting live level performances out of these.

One thing this shows too though is that if we wanted to use a sub we absolutely have to high pass these speakers or the combination would be a hot mess.

@herman 

I did retest using Room EQ Wizard and OmniMic.  REW measures about 5 dB lower at 20 Hz than OmniMIc.  It also shows a weird clipping at the top octaves.

While I agree 100% that you can't get loud at 20 Hz with small drivers (this is pure physics) I hope you see that my argument that rooms are complicated and we can't assume we know what's going on without measurement is worthwhile. :)

@herman but it is, and I’ve measured it. It’s not "real." It’s not the capability of the speaker so much as the resonance of the room.

Rooms can add 20 dB or more in a node, so this is totally possible. However, it is very much range limited. :)

From my new blog entry, you can see that compression eventually must set in...

Here you can see the output at 60, 70 and 80 dB is fine, only when we get to 90 dB is the output compressed.

At some point over the holidays I'll take measurements at different volumes, I am pretty sure that we won't be able to maintain the bass output, so it will be fun to see how it cuts out as the power goes up.

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?

That and the peak at 30 Hz is all room/speaker/microphone location related.  Some of this would probably get smoothed out if I used multiple locations for the mic and averaged them out.

OmniMic uses swept sine waves, not really noise for these measurements.

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

@herman In an anechoic room you’d be correct. The room however bedevils those expectations, and that’s the point of the posting. Without these measurements I could do sooooo many things wrong in attempting to improve the quality of the bass.

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. 😁

Show us something meaningful…like the waterfall…

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

@lucky_doggg7 

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

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.

@alucard19

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.

@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 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.

@pedroeb 

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

@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.

@larry_sioux

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. :-)

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.

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.

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.

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).