Room Acoustics, minimal treatment and measurements

@erik_squires I know, right???!!! Honestly my little Studio HDs one 8" woofer moves to beat the band...these are like a gentle wafting suggestion.  Which, I get in a way: there are two, in a big strong cabinet, they don't "need" to move a ton to move a proper volume of air.....but in this specific application they are like BARELY moving, barely generating output, and barely making 'sound'!

That’s really quite good, but seriously what are the woofers doing?  I'd expect at least a 3-6 dB boost when they were engaged.

Hey @erik_squires   Attached is a screen shot of the 45degree reading with and without the woofers.  Distance was about 5 feet.

I'll take a look at the impedance sweep. 

@erik_squires Yea I’ll do a sweep to see that potential dip. Are you thinking there’s some frequency cancelling happening or a cross-over issue?

If there is no bass to mid-bass crossover, then I expect destructive interference (frequency dips) somewhere, either horizontally or vertically. I also expect the 7" drivers would sound much better if not trying to reproduce 20 Hz.

It may be worthwhile talking to Legacy and asking if the woofers actually have a low pass filter. Your measurements, and the impedance charts from Poland suggest the answer is no.

The way to tell without opening your speakers is with an impedance sweep. REW has a way to do this if you make a custom jig, or you can purchase Dayton DATS. Measure the combined impedance, and separately. Take a look at this blog post to understand "High pass impedance" and "Low Pass Impedance"

@erik_squires   Yea I'll do a sweep to see that potential dip.  Are you thinking there's some frequency cancelling happening or a cross-over issue? 
I've read up on MINIDSP and watched a bunch of videos on their use.  I think things like DSP is a MAJOR step forward in music reproduction (which yes can also be over done).  I  agree with you though I would still do all the heavy lifting with proper room treatment (regardless of speakers or equipment), then concentrate on "better" speaker placement for a better balance of frequency response and sound staging.  Then, the DSP "should" only need to do really minor adjustments and moves which will keep all the best qualities of all aforementioned aspects.  I would 100% bi-amp:  that would be another HUGE increase in audio quality and presence..

Morning @mapman .  The speakers are (now) 4 year old Legacy Focus SE, (link below).  From all I have seen so far, the woofers are working properly---but I want to try running pink or white noise thru them and measuring what the voltage is at/on the speaker terminals (inside the speaker).  I am 100% certain there is no way dad would change them for anything else.  Again, to him, things sound perfectly fine but he isn't aware of how much the basement is swallowing the sound.  What is that saying about how humans bias their hearing....?  😆  With that much bass fall off, honestly the only thing to fill that void would be subs.  Bi-amping and obviously making those best practices of balancing proper speaker placement for frequency response AND sound staging combined with proper room treatment all needs to be exercised FIRST.  He's locked himself into one aspect: most accurate "best soundstaging" based on room dimensions.  (I think I'm assessing that right?).

 

OP:

To confirm what I thought I read in the polish site, can you measure the frequency response for 1 speaker 45 degrees off axis? 1 to 2 meters away (3 to 6’) is fine. I want to see if there’s a major dip there.

If you see a big dip, unplug the woofers and see if it vanishes.

Thanks!

Erik

If this was my system, I'd bi-amp, using a miniDSP as an active crossover in front of the amps.  It sounds really good.  This is going to give you the ability to properly high pass the mid-woofers, low pass the woofers, which will improve off-axis imaging and overall smoothness, give you a lot of extra headroom AND let you equalize the 12" drivers to function as subs.  Also, I'd plug the ports, which will raise the -3 dB a little, but also slow down the rolloff below 100 Hz significantly.

Fortunately, plugging the ports just takes a pair of clean socks.  I suggest organic cotton ... :D  Really anything that closes the ports and doesn't get lost. 

You may seriously want to try plugging the ports and re-measuring anyway.  You may find this extends the bass in just the right way.

Always a good idea to make sure the mains are operating properly before adding subs. So if bi-amping with EQ is what is neded for that, definitely do that first and see where you land. What make and model are the speakers again? If they turn out to be too problematic in that room at some point, it may be time to look at alternatives that might be implemented to their fullest more easily. It really all depends on what the end goal is. Also of course how much time and money you are willing to invest.

Also I would say that you are starting out with a much larger than normal bass deficiency.  Can optimizing the speakers alone resolve that?   Probably to some extent.  THen from there its a question of is that good enough or time to add powered subs to finish things off.

I was wrong btw, I found I think a polish sight that says the min impedance is 4 Ohms, but still, with bi-amping you can set levels independently. 

The site also noted poor off-axis integration, a potential sign of the effects of the overlapping woofer/mid-woofs, so I really think at the very least, bi-amped with an EQ in front of the woofer amps is going to give you everything you need.

Yes if teh speakers are operating properly then your measurements indicate teh speakers need help with the lowest octaves in a room that size.  Also yes he probably does not realize what he is missing.  Adding a powered sub or two properly almost always helps complete the entire musical experience even in scenarios less bass deprived than this one.  Cheers!.

@mapman I really think his system would benefit most from two subs like you noted.  That way he could enhance low level listening, get proper music reproduction, and NOT introduce issue while maintaining all the better aspects.  He's very old school that 'subs are of the devil' and totally useless, but there are so many aspects of the music he loves, that he has no idea he is missing out on.  My understanding was that these speakers were made and shipped during the very early stages of Covid, so it took awhile to build.  I did some basic phase testing and the woofers are working and moving in the right direction, they are just at a much lower level in comparison to the mids-highs. 

@erik_squires I was wondering myself if this is one of those rooms/spaces, speakers and systems that would be perfect for using Bi-Amping?  I honestly never knew of "active or passive bi-amping"?  My step father had given me his old Adcom GFA-555 (modified) that I bet would be PERFECT to be used just for the woofer end, and leaving the Rega Illicit for the mid-high which that amp excels at in general (details). 
As we noted, honestly a couple moderate subs would really change the whole presentation, while keeping the amazing staging and details.  Alas, that likely aint gonna happen!  But at least I learned a TON from all of this, and it has made me appreciate my baby system in my own house, that sounds just as good as this does (just NO WHERE near the same staging!)  😆

Yea closer to wall or even corners will boost bass but could also negatively impact imaging. Try it and see. If not then this may be a job for a proper powered sub or two. Gotta get that bass for best results.  Could be the speakers are just not fully up to the job  for a room that size. 

Are these older speakers that have been around prior to your involvement? Always possible woofers are damaged say detached from voice coil. Hopefully not. If you apply some pressure to woof near center while playing does it suddenly pop to life? That’s an indicator of a detached voice coil.

Normally, I say to leave a speaker be and not to try to hack it very much.  Either love it as is or get something else.  In this case though I feel you have a number of approaches which could be really worthwhile for you and your dad.

Compared to a traditional multi-way speaker, the Legacy focus seems to be "missing" the crossover between the 7" and woofers.  While we can argue about the end result, two things are happening:  The lack of a crossover = 2 Ohm minimum load, and there's some interference between the woofer and mid-woofs(7"). 

Based on that, I think in the future there are a number of ways to deal with it which improve the bass performance significantly:

I.  Passive bi-amping. The reason this is an excellent idea here is that the lack of a crossover means you have a very low minimum impedance in the bass range. Less capable amps can handle just the bass or the mid-treble section but not both. Separate the two sections and each has ~ 4 Ohms minimum.

II. Active bi-amping. Put a miniDSP in front of your two amplifiers. This will give you excellent EQ capabilities, and you’ll be able to add the "missing" filters. Again, you end up with 2 x 4 Ohm sections instead of one 2 Ohm section.

III. Low impedance capable amp, like a stiff Krell or Sanders or Coda. Something that will handle the 2 Ohm or lower load in the bass section.

@erik_squires That's interesting I didn't find that when I poked around Stereophile, but I may not have been searching right and gone back far enough to look into the prior model versions.  This bass fall off has to be room size and placement-most everything else like you are seeing and noting falls fairly in line with the measurements (mine and older that you found). That graph from the previous version shows what I would have expected (and it's not that far off of what the baby Studio HDs do in my own tiny home). 

I am completely in line with you, I'd ABSOLUTELY want to somehow reinforce some better low end presence, or just invest in two sub-woofers and very carefully integrate them to not lose the really great detail and sound stage.  I am not certain he would go for it: I'd guess he's committed to the room formula, and doesn't feel like he's missing anything.  However, I got him to agree to do the room treatment  to absorb the ringing and reverb, and that will improve all the things he does like, which makes me happy.  Like you already know, it will also bring out/unveil some of the mid upper bass and warm things a bit which I am sure he won't mind and maybe like?

I was going to look into directly connecting to my laptop and running some mild experimental parametric EQ just to hear how the speakers would react to some mild tweaking.  I'm not a fan of it, but it's a cheap and easy and fast way to hear a span of possibilities.  It's just so sad and disappointing when I -know- something has incredible drum punches or room resonating cello pulls that feel like the cellist is leaning against you.....and here I sit.....like....."bro...do you even woofer bro?!"

Thanks again Erik!! 
~alan

I found the Stereophile measurements for the predecessor. If the two units are similar, then your measurements are actually quite normal for the line. The review also goes into some details about the unique crossover choices, which your measurements kind of confirm. There’s a lot here that goes against the grain for most loudspeakers, including the unusually high -3 dB point given the size of the woofers. I suggest moving them back towards the wall, and consider re-testing after plugging the ports. You may find the slower rolloff preferable. Worth listening to it. So, all my advice about sound absorption was correct, you could even do a little more, but if it were me, I’d want more bass than you have so far.

@erik_squires   So everything is hooked up right, and phased proper (9v batter into the BASS speaker terminals-both moving at the same time......just very very little at 'nominal' volume). 

I'll try running one speaker at a time, and I'm trying to find the original straps to hook up as well.  I'm trying not to monkey too much-not my system kind of thing.  

I did do some measurements just to isolate the Tweeter from the Bass to see each for reference.  Red=Bass, Green=tweeter/Mids, Orange=full range.  You can see where the dual 7" cut off around 100hz.....and then the response just poops out. 
Without actually cracking things open to ensure something like polyfill isn't over stuffed or something, I am just a bit alarmed at a "18hz-32khz +/- 2db" speaker would in-room measure like that.  Now that I think of it I could measure at a nominal 2-3' and try to exclude the room as much as possible (more anecdotal since it's impossible to not have some room impact).
 

OP:

Maaaaaybe?

It could be as simple as your speaker cables are not hooked up right at the amp or that the ends of the bi-wire cable are swapped somewhere.  That's the bi-wiring aspect of this complicates things. It's worth getting some plain zip cord and trying the speaker out with the original straps on.

Another test you can do is to play just 1 speaker at a time.  This eliminates the possibility of left/right cancellation.  If you still have that 24 db/octave drop off then its in the speaker.

@erik_squires and @mapman I just popped the front grill off and ran a 60hz and 80hz tone thru the speakers, and they ’move’, but their output (volume) is like 1/2 of a 100hz tone. SO what you see in the REW graph is at least what I’m hearing and seeing in speaker movement. To get a similar volume, I have to really crank the volume.

@erik_squires I see what you are thinking: that potentially internal to the crossover there is one of the woofers that is hooked up out of phase (reversed)? I’ll see if I can test that without changing wiring or removing anything (I think I have an app that puts out a test tone and reads the phase output).  I also know how to do that battery test you mentioned with the 9V, I'll see if I can check that out as well to see if both are moving in and out together in sync. 

SO, yes, straps and cables are fine, but you can do some more basic tests first.

Since you are bi-wiring it’s quite possible your problem is one speaker or woofer section is wired out of phase with the other. Check for that before attaching straps. That would explain the lack of bass and lack of room mode problems.

Some basic tests with a multimeter include making sure that the two paris of terminals at the end of the biwiring have perfect continuity (disconnect the amp first!) and that the woofer sections show around 3-16 Ohms. Not sure what it should be honestly, varies by speaker.

A 1.5 to 9V battery and wires can be used to test the woofer sections. Attaching + to + and - to - should have the woofers moving in the same direction, usually towards the listener. 9V is about 10 watts if the battery could actually deliver that much current (it can’t), so it’s generally safe. The battery voltage will sag long before you get to 10W. All 4 woofers should move in the same direction when tested this way.

@erik_squires I KNOW I KNOW YOU WERE RIGHT!!!!!!!! 😆

I’m gonna sneak down and pop the baffles off when he’s in the shower, and I’ll for sure do another quick room measurement. Do you know is there any harm to an amplifier with bi-wiring AND having the terminal jumpers attached? I know the speaker wires are properly fully connected from amp to speakers (I double checked that first listen)...but I am so curious to determine if it’s possible that the woofers are somehow NOT connected (internally?!). Though at the same time I am preparing myself for things to all be working properly....  ~Alan

OP:

And I told you not to claim you had no bass problems until we got to them... 😂

Once you get your woofers pumping we may have to revisit that issue. 

@erik_squires  See, I told ya!   ....you know....I genuinely (and you already know this) thought I was going absolutely crazy, especially the first listen when I got here.  He was beaming so proud and my first thought was ".....uh.......so are the woofers on a different amp?.......are you bi-amping?  Oh that's probably it, and you forgot to flip that amp on!......."   He has the grills on the speakers, so when he's not around I am going to pop it off and check and see.  In general though there is VERY LITTLE air coming from the dual ports on the back.  He is bi-wiring them from the Rega Illicit, and does not have the straps on the dual posts (usually not needed).

@mapman thanks for helping confirm my confusion too.  So the size of the room generates no real prominent nodes.  Honest to god, there is so little to no "bass" being generated that I walked around the entire space along all walls and floor and couldn't find a single spot that 'bloomed' or resonated or any note below 150hz that even sounded a tiny bit more prominent.  It's FREAKY!  Can you imagine sitting there listening to something 70x bigger than your own speakers (I have the Legacy Studio HDs in my little home living room) and you are listening to INFINITELY LESS BASS!!!  I'll post a pic of MY tiny living room's frequency response-just the bookshelf speakers. 

@simao my step father was an electrical engineer (microwave technologies) so he's pretty keen on things involving measurement and formulas, and Jim Smiths book was right up his alley. 

Legacy Studio HD Bookshelf Speakers-Tiny Living Room

I love the Jim Smith 83% ratio for the listening triangle. It’s been a metric I’ve used religiously at every set-up

Yes.  Where’s the bass below 100hz?  Check for room modes down there once bass is restored. 

OP:

First, you are going to be very glad of the treatment, but now that I see the measurements and the specs, I think your woofers are not working at all.  You may be missing the straps that connect the woofer to the 7" drivers.

Based on specs, the 7" are crossed at 120 Hz, which is exactly what we are seeing here.  Play loud music and go touch the woofers.

Erik

Nice! I’ve learned you can’t really optimize your sound without first measuring the room acoustics. I’ve used Room EQ Wizard with a Mike similarly to first understand then correct my room acoustics (I’ve got 4 measured and corrected with 2 lesser ones to go, one is outdoors and screened, just for fun). Also thumbs up for Room treatments of any kind done right.

Thanks @milpai , well said.  I think a LOT of peoples systems would sound significantly better with some objective proper room frequency treatment: night and day, earth shattering, dramatic, game changer, deeper blacker backgrounds, wider and deeper sound stage, dead quiet noise floor, massively increased details, etc.  :D

This space has (to me) NO bass.  The REW measurements reflect that pretty well and accurately: at 100-130hz there is a peak, and then every major frequency below is at least 10-15db down at each sequential frequency.  So for his room and it's construction, bass won't ever be an issue!  It's the reverb ring and decay that will always be a coloring factor and impact.

I cannot say better...

+1

Nicely done!!
I agree - most people are better off treating their rooms and keeping their existing loudspeakers. Most folks assume that their loudspeakers are not compatible with their room and keep searching for a better one. I found that if we tame the bass which occurs near the front half of the room (besides the 4 corners of the room), then that adds a lot of clarity to the overall staging. I have not yet updated my system page with the latest sound panel config. Will do it soon.