Looking to run a true 5HZ signal to my Sub woofers but think my anthem receiver will Bottle neck this.

[lovinthehd]

So pray show me the math, that shows a speaker with and Fs of 23 Hz, in an optimal sealed box, rolling off as predicted around 40 Hz can produce a 5 Hz tone above a whisper and be largely distortion products. If you can show how that can happen then you are a revolutionary genius in loudspeaker design.

Curious, you're not including eq and other aspects? Why don't you do the other way around and show proof or your assertion with math?

 

[TLS Guy]

Curious, you're not including eq and other aspects? Why don't you do the other way around and show proof or your assertion with math?

You can read the Eq required from the FR graph, that is not rocket science. You can see output going flat, as FR drops below driver F3, and the power the driver is able to handle going down. The data is all there. Bullock and White's programs to make complex math a computer program is an industry standard. Prior to that, doing it manually was a massive task. I was an early adopter, of using computer software in speaker design. I am still using the first speakers I designed using Bullock and White's original software. Those are my side surrounds, which were originally my locations monitors for live recording. Measurements showed the software to be valid. They were really good speakers then and still are.

 

[Allen Vos]

Curious, you're not including eq and other aspects? Why don't you do the other way around and show proof or your assertion with math?

Notice his response says "It's all there," but he just explains the complexity instead of answering. He still hasn't explained why he uses a 34mm Xmax for my sub when the designer specifies 29mm.

While I know it was mentioned that the difference doesn't matter because I am nowhere near Xmax, my point stands: if he got this fundamental input wrong, what else is wrong? That inaccuracy likely explains why his graphs look different than my own

He also completely ignored the two very specific questions I asked in post #147, choosing instead to reiterate his personal opinion in post #164.

]It is hard to trust this skewed data. I am sticking with the manufacturer's specs, which align with what other FTW-21 users report

]It is crazy how a simple thread about whether my receiver passes a 5 Hz signal turned into this mess. While I have learned a few things, the opinionated, chest-thumping comments are exhausting

 

[TLS Guy]

Notice his response says "It's all there," but he just explains the complexity instead of answering. He still hasn't explained why he uses a 34mm Xmax for my sub when the designer specifies 29mm.

While I know it was mentioned that the difference doesn't matter because I am nowhere near Xmax, my point stands: if he got this fundamental input wrong, what else is wrong? That inaccuracy likely explains why his graphs look different than my own

He also completely ignored the two very specific questions I asked in post #147, choosing instead to reiterate his personal opinion in post #164.

]It is hard to trust this skewed data. I am sticking with the manufacturer's specs, which align with what other FTW-21 users report

]It is crazy how a simple thread about whether my receiver passes a 5 Hz signal turned into this mess. While I have learned a few things, the opinionated, chest-thumping comments are exhausting

It will make no difference as the model shows the driver does not get close to either xmax, so it would make no difference. Actually the lower number would show it to be even more power limited. That number does not affect the FR curves in any way at all. As I said, it only would if the driver reached xmax which it does not, as it is limited by the pressure in the enclosure.

 

[Allen Vos]

It will make no difference as the model shows the driver does not get close to either xmax, so it would make no difference. Actually the lower number would show it to be even more power limited. That number does not affect the FR curves in any way at all. As I said, it only would if the driver reached xmax which it does not, as it is limited by the pressure in the enclosure.

Oh look, you managed to completely miss the point. Again. Truly an impressive streak you have going there.
We are all deeply moved by your thrilling lecture on how there is "no difference" between 29mm and 34mm Xmax. Truly, groundbreaking stuff. We also already know—since we can actually read a data sheet—that the Xmax at 5Hz with 1200 watts is only 23mm. But thank you so much for repeating it. Again.


The actual issue—which you are dodging with the skill of a seasoned politician—is your magical 34mm Xmax spec. You know, the one you pulled out of thin air that flat-out contradicts the manufacturer's official 29mm rating? I asked how you calculated that. Your response? Absolute silence. I asked about the enclosure volume. Your response? Complete amnesia.



Instead of providing a single shred of actual data, you decided to copy-paste your personal opinions, dress them up as facts, and thump your chest about how much "experience" you have. Because who needs math and physics when we can just basket-weave your massive ego into the simulation?

Dealing with you is an absolute joy. If by "joy," I mean an exhausting exercise in frustration with someone who would rather act like a defensive gatekeeper than answer a basic technical question.

Honestly, I am completely done wasting my breath on you. I have already explicitly asked you to stop responding, but apparently, reading comprehension and basic respect are also specs you are completely missing. Do us all a favour and finally take the hint.

 

[m. zillch]

Mini DSP Flex HTx hooked to the CVR amp via TRS to XLR cords for a true balanced signal

You may have a stumbling block here.
Their specs:
"

Frequency Response

20 Hz – 20 kHz ± 0.1 dB"

If it was meant to do lower than 20Hz I'd think they'd state their spec differently, but who knows.

The good news is yesterday I saw an extended frequency response measurement of an Anthem's pre-outs measured the correct way, electrically, and it was down only 1dB at 5Hz; so not very much.

[Normally I'd include an expected JND {just noticeable difference in level detection value in dB] for 5Hz for reference, to judge against this 1dB loss, but it doesn't exist because we fundamentally don't hear 5Hz in the first place.]

Normally Gene doesn't usually set his AP analyzer to measure these useless frequencies but he did for at least some of the response curves, for some reason, here.

 

[Allen Vos]

You may have a stumbling block here.
Their specs:
"

Frequency Response

20 Hz – 20 kHz ± 0.1 dB"

If it was meant to do lower than 20Hz I'd think they'd state their spec differently, but who knows.

The good news is yesterday I saw an extended frequency response measurement of an Anthem's pre-outs [although it was not a sub out but rather a full range out] measured the correct way, electrically, and it was down only 1dB at 5Hz; so not very much.

[Normally I'd include an expected JND {just noticeable difference in level detection value in dB] for 5Hz for reference, but it doesn't exist because we fundamentally don't hear 5Hz in the first place.]

Im assuming you are reffering to the Mini DSP spec?

If thats what you meant, I have already confirmed with mini DSP that the mini dsp flex htx will process down to 10hz. I sent a question back asking if it would still pass through anything below 10hz but im still waiting for a responce. Here is the graph they sent me

Honestly, 10hz is likely as low as I will ever need to go anyways.

Heres a question for you, does this diagram they sent me, tell you much of anything else about the mini dsp?

I have been looking into how to setup the Mini DSP and it looks like it will be an entirely new learning experience.

 

[m. zillch]

Yes I'm discussing the mini DSP thingy.

My vision isn't very good but after blowing up the image it seems to be not a measurement but rather an expected performance in some modeling program? At least that's my call. . . .other than a curious yellow line that looks a bit odd (almost looks hand drawn ?!) it looks to show a very significant loss of 16dB at 10Hz if I'm reading it right, so problematic to your quest I'm afraid.

More: The purple button at the bottom left seems to show (by my read) their program was depicting expected performance in Basic mode set specifically to "look for data between 10Hz-20,000". It is possible that had they select a different range possibly obtainable in "advanced mode" we could know more?

 

[m. zillch]

Upon further examination I'm reading that image not as "the measured performance of our product" but rather "here is what the parametric equalizer can be set to do".

 

[m. zillch]

And now upon even further examination I think it is showing "with one of the parametric filters (#1 of 10 possible ?) set by the user to 'reduce the output by 16dB, with a Q factor of 50, at 10Hz', here is the expected output shown graphically".

So they haven't answered your valid question at all, by my (current) interpretation.

 

[Allen Vos]

And now upon even further examination I think it is showing "with one of the parametric filters (#1 of 10 possible ?) set by the user to 'reduce the output by 16dB, with a Q factor of 50, at 10Hz', here is the expected output shown graphically".

So they haven't answered your valid question at all, by my (current) interpretation.

OK, thanks you for that . I have asked them specifcally if it could process down to 5HZ so I will wait and see what they say. Mini DSP is right in china/asia so there is definitley a language barrier.

I have found an online room simulator for room gain for my "L" shaped/non rectangular room. I am working on putting all my data in it and will post it shortly. Are you cool with taking a look at it and giving me your honest opinion?

 

[m. zillch]

I'll look at it, sure, but "expected calculations" are never as good as properly executed measurements with good gear, in an acoustically isolated environment. Those sort of simulators only give a ballpark idea of what's possible.

You getting into REW even with just a introductory mic like the UMIK is a good idea in my mind. I've never owned that particular one myself but I have owned other measurement gear and I'll tell you it is very informative to have personal, hands on experience like that.

People don't realize their "silent" rooms aren't silent at all! There are all sorts of sounds lurking at quiet levels that fall below our thresholds of hearing (audible detection levels). REW and other programs can show you that! It also can show you that all sorts of things those simulator programs don't factor in are important. For example, here is a measurement I took (with my iphone) showing a quick, basic, down and dirty measurement of my "silent" room. My written overlay text is denoting that my building's dryer vent fan was temporarily turned off [it's usually "on", 24/7/365] and that the door to my bedroom closet was shut [which changes the volume of air in the room]. I bet your simulator program doesn't ask such picky questions yet I assure you, they matter!

 

[Allen Vos]

I'll look at it, sure, but "expected calculations" are never as good as properly executed measurements with good gear, in an acoustically isolated environment. Those sort of simulators only give a ballpark idea of what's possible.

You getting into REW even with just a introductory mic like the UMIK is a good idea in my mind. I've never owned that particular one myself but I have owned other measurement gear and I'll tell you it is very informative to have personal, hands on experience like that.

People don't realize their "silent" rooms aren't silent at all! There are all sorts of sounds lurking at quiet levels that fall below our thresholds of hearing (audible detection levels). REW and other programs can show you that! It also can show you that all sorts of things those simulator programs don't factor in are important. For example, here is a measurement I took (with my iphone) showing a quick, basic, down and dirty measurement of my "silent" room. My written overlay text is denoting that my building's dryer vent fan was temporarily turned off [it's usually "on", 24/7/365] and that the door to my bedroom closet was shut [which changes the volume of air in the room]. I bet your simulator program doesn't ask such picky questions yet I assure you, they matter!
View attachment 80062

OK great! This is just an online on I found as REW would only do rectangular rooms, so using that would be a waste of time for me. It was definetly not asking me questions like that, but keep in mind, this is my first ever attempt at moddelling a room in this manner, so this is a very simple approach. Ill post shortly, but here is the link for the one I just used.

Room Mode Calculator

Calculate room modes, standing waves, and resonant frequencies for any room shape. Free online acoustics tool with pressure mapping and source optimization.

www.vesalaasanen.com

I mainly did this to get an idea of room gain in the sub 20hz frequencies to see what kind of room gain i would get, that would in turn help boost sub output.

Yes I know this wont be 100% accurate, but it at least gives somewhat of an idea.

Maybe I should invest in some proffesional software for this, but who knows? lol

I will definitley be using REW with a UMIK-1 mic for calibrating EQ boost and delays for sure once that time comes.

 

[Allen Vos]

Here is the room Layout with the subs directly behind the couch/listening area and the frequency responce graph.

I was quite surprised with the results. You can see at 15 hz the room gain starts climbing and by 10hz there is 10db of room gain and by 5hz it was showing 24db gains. What I wasnt expecting was a room gain loss from 15-25 hz. and huge loss from 40 -80hz give or take.

So I decided to move the subs from the couch area to the back corner of the room which you can see in these graphs and I have included the frequency response graph.

As you can see I got the 40-80hz back up considerably but did lose a bit of gain from 5-17 hz it improved slightly from 17-26 hz.

So I may stand to be corrected here but the room gain from 15 hz and lower should more than help these subs hit a decent DB level without driving the crap out of them.

What I didnt expect is to lose room gain at 15-25 hz. Since actual sub output is quite high in this area to start, the little bit of room db loss here will just mean I may have to use the full 1200 watts to get a good level of output, which should not be an issue as the sub is in more of a sweet spot between 20-30 hz.

Your thoughts? I believe I am looking at this correctly but keep in mind you will need to explain this in simple terms so that I can fully grasp this one.

Ultimatley, I will still need to setup and calibrate, and it is what it is.

Yes its likely a goofy room size for sound reproduction, but its all I have to work with lol

The other thing I wanted to talk about is box size. Ideally the sub will work better with an 8.2 cubic foot box to hit the low frequncies more efficiently. However this would come at the expense of the tighter punchier bass from 30-40 hz and up. This is where the 6.2 cubic foot box would shine. However at the lower frequencies its harder on the sub. With room gain it adds significant output, so I feel I am better to stick with the 6.2 cu boxes. I think with movie watching 10-15hz would be the lowest frequencies one would see, depending on the movie.

For context, sub cross over is set at 80 hz

 

[m. zillch]

Room placement is important but there isn't ever a single best position for them because we all have varying goals. Some examples:

-- best for flatness of response, without applying EQ, for the more critical 40-80Hz range, heard at listening chair X
-- best for flatness of response without applying EQ, for the more critical 40-80Hz range, heard at listening chair Y
-- best for flatness of response without applying EQ, for the more critical 40-80Hz range, heard at listening chair Z
- best for smooth integration to the mains at the currently selected crossover freq.. . . for X, then Y...then Z
- best for smooth integration to the mains at the currently selected crossover freq.. . . on average
- best for specific music such as deep pipe organ
- best for watching Edge of Tomorrow, early release version, from seat X, Y, Z, on average
- best for highest output level regardless of flatness. . . X, Y, Z, on, average
- best for highest output level specifically in the less musically important 20-40Hz range
- best for "that scene I like where the Death Star explodes"
- best for highest output level specifically in the infrasonic range
- best for "giving me the kick I like in electronic music"
- best for low level listening. . . X, Y, Z, average
- best for not disturbing the next room occupants

. . . and then there's the most important method described by the inventor of the very first sealed box (specifically acoustic suspension) loudspeaker (the AR-1) and then later the first dome tweeter speaker (the AR-3), Edgar Villchur:

"There are so many variables involved in placing speakers in a room that prediction of performance on a scientific basis is extremely difficult. One quantitative approach is to take the square root of the area of the triangle formed by two stereo speakers and the midpoint of the listening area, note it carefully, and then have your wife tell you where the speakers sound best."

HA-HA!

 

[Allen Vos]

Room placement is important but there isn't ever a single best position for them because we all have varying goals. Some examples:

-- best for flatness of response, without applying EQ, for the more critical 40-80Hz range, heard at listening chair X
-- best for flatness of response without applying EQ, for the more critical 40-80Hz range, heard at listening chair Y
-- best for flatness of response without applying EQ, for the more critical 40-80Hz range, heard at listening chair Z
- best for smooth integration to the mains at the currently selected crossover freq.. . . for X, then Y...then Z
- best for smooth integration to the mains at the currently selected crossover freq.. . . on average
- best for specific music such as deep pipe organ
- best for watching Edge of Tomorrow, early release version, from seat X, Y, Z, on average
- best for highest output level regardless of flatness. . . X, Y, Z, on, average
- best for highest output level specifically in the less musically important 20-40Hz range
- best for "that scene I like where the Death Star explodes"
- best for highest output level specifically in the infrasonic range
- best for "giving me the kick I like in electronic music"
- best for low level listening. . . X, Y, Z, average
- best for not disturbing the next room occupants

. . . and then there's the most important method described by the inventor of the very first sealed box (specifically acoustic suspension) loudspeaker (the AR-1) and then later the first dome tweeter speaker (the AR-3), Edgar Villchur:

"There are so many variables involved in placing speakers in a room that prediction of performance on a scientific basis is extremely difficult. One quantitative approach is to take the square root of the area of the triangle formed by two stereo speakers and the midpoint of the listening area, note it carefully, and then have your wife tell you where the speakers sound best."

HA-HA!

I understand what you are saying, but I was hoping for an opinion or your thoughts based on what I presented as I did list my goals.

I also want to add that I did not do anything with the sub delays.

I know thats important but some of the frequncies may be cancelling each other out.

This will all be setup using REW and the mini dsp

If its too much for you, I understand

 

[m. zillch]

I listed 14 or so different goals and I don't know which you prioritize so I can't answer your question. [and again these images are hard for me to read with my vision issues].

If your goal is to have the best shot at experiencing the 10Hz sound at the start of Edge of Tomorrow (early release version) then very close placement to the listening chair with the drivers all coupled close together, stacked (like I showed earlier from the Dolby commercial theater document) would be what I'd do.

The only tiny problem with this video (which is otherwise quite good) is they fail to mention that for people with measurement mics (and ideally live, real-time analysis display panels) should more easily obtain comparably good data by holding their microphone on a boom (pole) and then much more conveniently walking, not crawling, around the room with the mic held down low at the same height as where the center of the subwoofer cone height will be for its final placement:

The term "subwoofer crawl" got its name before many people had microphones to make such decisions, so in order to get their mic ear at the correct height for this test they needed to be down low on their knees. Me? I'd rather stand and keep the mic down low.

 

[Allen Vos]

I listed 14 or so different goals and I don't know which you prioritize so I can't answer your question. [and again these images are hard for me to read with my vision issues].

If your goal is to have the best shot at experiencing the 10Hz sound at the start of Edge of Tomorrow (early release version) then very close placement to the listening chair with the drivers all coupled close together, stacked (like I showed earlier from the Dolby commercial theater document) would be what I'd do.

The only tiny problem with this video (which is otherwise quite good) is they fail to mention that for people with measurement mics (and ideally live, real-time analysis display panels) should more easily obtain comparably good data by holding their microphone on a boom (pole) and then much more conveniently walking, not crawling, around the room with the mic held down low at the same height as where the center of the subwoofer cone height will be for its final placement:

The term "subwoofer crawl" got its name before many people had microphones to make such decisions, so in order to get their mic ear at the correct height for this test they needed to be down low on their knees.

No worries at all. You really need to see the graphs to understand the whole picture, but this definitely looks like a room null causing frequency cancellation. I'm going to stop guessing and just build the 6.2 cubic foot boxes, get everything hooked up, and see what the actual numbers look like. Once they're ready, I'll use REW to build a miniDSP profile with proper sub delays, do an acoustic phase alignment, and maybe run Multi-Sub Optimizer (MSO). Thanks a lot for the help so far!

 

[m. zillch]

This positioning doesn't often align with where one's spouse says the subs work best though. Haha

 

[TLS Guy]

Oh look, you managed to completely miss the point. Again. Truly an impressive streak you have going there.
We are all deeply moved by your thrilling lecture on how there is "no difference" between 29mm and 34mm Xmax. Truly, groundbreaking stuff. We also already know—since we can actually read a data sheet—that the Xmax at 5Hz with 1200 watts is only 23mm. But thank you so much for repeating it. Again.


The actual issue—which you are dodging with the skill of a seasoned politician—is your magical 34mm Xmax spec. You know, the one you pulled out of thin air that flat-out contradicts the manufacturer's official 29mm rating? I asked how you calculated that. Your response? Absolute silence. I asked about the enclosure volume. Your response? Complete amnesia.



Instead of providing a single shred of actual data, you decided to copy-paste your personal opinions, dress them up as facts, and thump your chest about how much "experience" you have. Because who needs math and physics when we can just basket-weave your massive ego into the simulation?

Dealing with you is an absolute joy. If by "joy," I mean an exhausting exercise in frustration with someone who would rather act like a defensive gatekeeper than answer a basic technical question.

Honestly, I am completely done wasting my breath on you. I have already explicitly asked you to stop responding, but apparently, reading comprehension and basic respect are also specs you are completely missing. Do us all a favour and finally take the hint.

Actually, I did not pull it out of thin air, I used the info I had, but I accept your info is likely correct, but it has made no significant difference except to minimally reduce the power handling with the lower number. This xmax is not worth arguing over, as it has no practical significance. If you don't high pass the driver as it reaches its excursion limit, then you stand a very good chance of ruining the driver. Look it up, sealed designs need low and high passing and all commercial sealed designs have that, and plate amps for sealed designs also have that ability. This is part of speaker design 101.