The manifold I mentioned is a cube 18x18x18 inches. One 18 inch driver mounted on each of 5 sides. The 6th side is open and mounted to a wall. The wall has an 18x18 inch hole to let the sound channel into an adjacent room on the other side of the wall. So this 18x18x18 inch cube will house five 18s.
If you want fifty 18s you need 10 of these 18x18x18 inch cubes and you need ten 18x18 inch holes in the wall.
The manifold cube can be mounted on either side of the wall, so the fifty woofers can all be in the adjacent room, not in your listening room so they take up zero space in the listening room.
Not many people have dc coupled equipment, is that even safe? If you amp actually passes any dc your drivers are all going to fry.
Danley has some nice recording of fireworks and a passing train on his website for download with no compression (not sure if it's still there or not).
My dog has excellent hearing but he barks when he hears a doorbell on tv. Sometimes I get fooled when a phone rings on tv. So recordings can be extremely lifelike.
None of this has anything to do with anything though, you are completely changing the topic. We were talking about absolute spl reference. If you buy 10 spl meters, even the cheap ones will do, and measure a tone at 1 khz, I'm sure they would all measure within 1 db of each other. If cheap spl meters can be that accurate, how accurate do you think the really expensive reference mics are? How accurate do you think your personal measurement mic needs to be?
And why is measurement mic accuracy even important in this thread? I just mentioned I had a professionally calibrated mic, which is true. Why you mad?
No i'm saying that innacuracy is a problem. Unreliable reference made a universally accepted standard doesnt make it true.
A WEIGHT or a VOLUME reference doenst lead to such problem. It's a convention. You pay 10$ for 750ml wine, everybody is happy, right? Unless you like 343ml beer ;-)
On the other hand, a misleading so-called mic reference is a problem, because that reference is non-existing in the absolute and it's unstable in time and people are using calibrated and non-calibrated or badly calibrated or falsy calibrated mics, all mixed, everywhere, to make music, to make amateur stuff, to make pro stuff, etc.. It it NOT as reliable as a Kg or a ml. Not as easy to control, not as easy to test, not as easy to confirm... And that's even for a false (primo) reference (!)
and the mic... the mic is not the biggest problem there. Innacuracy becomes a MAJOR problem only when it adds up. To other innacuracy, of course. Such as the F&M curve, ISO226 stuff.. Then, like if its not enough, comes the game of ''how am i pleasing?'', where Hi-Fi is thrown away and rather adjusted to everyone tastes... Dynamic compression, to make it more earable... and so on.
There is a word in french: BANCAL.
It's all fragile, like a cards castle. Yeah, we got an average but sure as hell don't have anything close to an absolute reference. Other than NATURE, of course!
Show me any sound system that can mimic a lion's roar, a real trumpet, a V8 engine... Nothing will come close.
The measurement tools are perfectibles, the measurements methods are perfectibles and most importantly the end product of all that is far from perfect or even accurate. Oh, its somewhat accurate in a very limited way... but in 100 or 1000 years from now, we'll probably laugh about this jurassic part of the audio reproduction history.
Phone rings and doorbells are easy to reproduce, you are right.
You know why they're easy? Because they are simple, man-made, tones-generating stuff.
As soon as you stumble into music instruments (also man made) you hit a wall, most of the time. Piano (complex), Trumpet and drum (dynamics), violins (subtelties)...
With a lot of work, from the sound take ,up to the reproduction in a very controlled-room, you might be able to mimic almost perfectly some instruments, but not all of them in every situation.
If you add voices, other instruments, mixing with other sounds! Oh man, forget it.
You know why they're easy? Because they are simple, man-made, tones-generating stuff.
As soon as you stumble into music instruments (also man made) you hit a wall, most of the time. Piano (complex), Trumpet and drum (dynamics), violins (subtelties)...
With a lot of work, from the sound take ,up to the reproduction in a very controlled-room, you might be able to mimic almost perfectly some instruments, but not all of them in every situation.
If you add voices, other instruments, mixing with other sounds! Oh man, forget it.
Why do you insist on an absolute reference? Go out and buy 100 different spl meters and measure a 1 khz tone. They will likely ALL come in at +/- 1 db. How accurate do you really need to get?
I'm pretty sure the scientists know how to calibrate spl. Spl is based on phons, I believe, which are measurable quantities. Why would they even make up names for this stuff if they couldn't measure it?
Sound reproduction is an entirely different topic which you insist on returning to over and over. Reproduction accuracy will depend a lot on sound source size, directivity and spl. Spl is especially important for the transients. That's where most speakers fail miserably when attempting to produce a drum or lightning strike. BUT if you have a speaker that can do directivity well and do 150+ db transients, I'm pretty sure even you could be fooled.
I don't know what parts of the forum you hang out in but I don't see you here much. We do horns here. Sometimes really big horns. Drivers and power are cheap these days. 150+ db at 30 hz and higher really isn't that difficult anymore.
I'm pretty sure the scientists know how to calibrate spl. Spl is based on phons, I believe, which are measurable quantities. Why would they even make up names for this stuff if they couldn't measure it?
Sound reproduction is an entirely different topic which you insist on returning to over and over. Reproduction accuracy will depend a lot on sound source size, directivity and spl. Spl is especially important for the transients. That's where most speakers fail miserably when attempting to produce a drum or lightning strike. BUT if you have a speaker that can do directivity well and do 150+ db transients, I'm pretty sure even you could be fooled.
I don't know what parts of the forum you hang out in but I don't see you here much. We do horns here. Sometimes really big horns. Drivers and power are cheap these days. 150+ db at 30 hz and higher really isn't that difficult anymore.
the lower,the better
I was an engineer of electrical equipment and built my house and audio room after retiring. My favorite is classic music. I want to make my room like a concert hall though I know it's impossible physically.
The most important thing for classic is bass. The most difficult source for audio is also bass.
A 45cm woofer is not enough for classic as long as I did trial and error. An electrical EQ is also not good.They are lifeless.The only solution for classic is mulch woofers without an enclosure(open baffle).If you make a room rather than an enclosure, mulch open baffles are the best, as long as I have examined.
They operate as architectural EQ below 100Hz since they have the same phase.They have almost nothing to do with mid or high freq.This EQ is very natural which you can't achieve by another way.
What I have learned from my self-build for classical music audio is the importance of bass.The lower the better. You can't hear below 30Hz through your ears.Below 30Hz is the sense of touch where you don't listen but feel through your body.I think the bass is as low as possible if you want to feel music lively.
I was an engineer of electrical equipment and built my house and audio room after retiring. My favorite is classic music. I want to make my room like a concert hall though I know it's impossible physically.
The most important thing for classic is bass. The most difficult source for audio is also bass.
A 45cm woofer is not enough for classic as long as I did trial and error. An electrical EQ is also not good.They are lifeless.The only solution for classic is mulch woofers without an enclosure(open baffle).If you make a room rather than an enclosure, mulch open baffles are the best, as long as I have examined.
They operate as architectural EQ below 100Hz since they have the same phase.They have almost nothing to do with mid or high freq.This EQ is very natural which you can't achieve by another way.
What I have learned from my self-build for classical music audio is the importance of bass.The lower the better. You can't hear below 30Hz through your ears.Below 30Hz is the sense of touch where you don't listen but feel through your body.I think the bass is as low as possible if you want to feel music lively.
Attachments
It does make me wonder whether these films with massive sub 20Hz content were actually mastered on a system flat to ~5Hz. I doubt there are many commercial theaters that can reproduce bass that low.
Could it be that the very low stuff has been boosted during mastering on a system that 'only' goes to ~20Hz ?
Could it be that the very low stuff has been boosted during mastering on a system that 'only' goes to ~20Hz ?
I like organ music, so for me the holy grail is 16 Hz (32' pipe, low C pedal note). My room isn't huge, so I can get there at a sufficiently entertaining SPL with a couple of high Xmax sealed 12s (EQ'd of course).
I watch movies on this system too, but I also live in an apartment, so I can't get too crazy... But I am going to look for of that movie you guys are talking about (The Edge of Tomorrow is it?), as the unit above mine is currently unoccupied.
I think the old "pick 2 out of 3" list as it applies to bass is: loud, low, & small (enclosures). I've picked the latter 2.
I watch movies on this system too, but I also live in an apartment, so I can't get too crazy... But I am going to look for of that movie you guys are talking about (The Edge of Tomorrow is it?), as the unit above mine is currently unoccupied.
I think the old "pick 2 out of 3" list as it applies to bass is: loud, low, & small (enclosures). I've picked the latter 2.
Last edited:
I was an engineer of electrical equipment and built my house and audio room after retiring. My favorite is classic music. I want to make my room like a concert hall though I know it's impossible physically.
The most important thing for classic is bass. The most difficult source for audio is also bass.
A 45cm woofer is not enough for classic as long as I did trial and error. An electrical EQ is also not good.They are lifeless.The only solution for classic is mulch woofers without an enclosure(open baffle).If you make a room rather than an enclosure, mulch open baffles are the best, as long as I have examined.
They operate as architectural EQ below 100Hz since they have the same phase.They have almost nothing to do with mid or high freq.This EQ is very natural which you can't achieve by another way.
What I have learned from my self-build for classical music audio is the importance of bass.The lower the better. You can't hear below 30Hz through your ears.Below 30Hz is the sense of touch where you don't listen but feel through your body.I think the bass is as low as possible if you want to feel music lively.
What's a "mulch woofer"?
Wrong!
There IS a absolute reference: 20 uPa (micro pascals) sound pressure = 0 sone = 0 dB (at 1 kHz)
There IS a standard called IEC 61094-5 for calibrating microphones with accuracy better than 0.14 dB, for frequencies from 0.1 Hz up to 251 Hz.
There IS a standard called IEC 61094-2 for calibrating microphones with accuracy better than 0.05 dB, for frequencies from 20 Hz up to 20 kHz.
JonBocani, I don't know why you are not accepting perfectly good, correct and detailed answers by just a guy and other members here? Even your first post/question is not the correct one, as BesPav pointed out:
JonBocani, please don't argue if you don't know the audio basics. If you want to learn something about microphones, ask good gentlemen from Bruel&Kjaer (or just google it).
Last edited:
50 18's seems like overkill. I'm experimenting with just a single 2245's in IB configuration and am pretty sure 8 would be enough to float my boat. Even the single sounds fantastic at medium listening levels and I've never bottomed it.
Direct coupling is Very common nowadays
Electronic equipment with DC response seems very common to me. I have a collection of about 10 amplifiers covering the past 50 years, and more than half are DC coupled. It used to be a very big marketing thing in the 1970's and 80's, and ever since. I'm surprised it seems uncommon to you, and yet you know about a lot about even more esoteric stuff in the woofer arena.
A fairly early amp which a friend has used for 50 years is the Sony 3200F from 1968. It has a "test" switch on the front panel. If you select "test" mode, it is DC coupled. Historically lots of people used it that way, but it is NOT a servo type DC amplifier, and the "test" designation does give you the idea this should not be the standard mode, but a switch on the front panel invites experimentation anyway.
James Bongiorno designed many of the G.A.S. and Sumo amplifiers as direct coupled with servo. In 1977 he introduced the Thaedra preamp which he claimed was the first DC coupled preamp with servo. (And, even a servo MC phono amp!) Nowadays, in higher end transistor equipment, one has to look harder to find the non-DC coupled equipment. I have an Aragon preamp from 1995 which has servo also, the same company made cheaper non-DC amplifiers and preamps under the Acurus label.
Pretty much all the Parasound amplifiers are DC coupled for the reason that John Curl doesn't like the sound of capacitors. They all have DC servos to "eliminate" DC from the output, so they don't actually have response to DC. However typically servos run at very low frequencies, such as 0.03 Hz, so response below 1Hz is typical.
Spectral, however, took the oppose track in the 70's and 80's and made only capacitor coupled products because the designers felt that servos were less transparent than the best capacitors (an idea I find ludicrous, but YMMV).
It is safer to have servo DC amplifier than non-servo DC amplifier. My Krell FPB 300 has a DC servo, and also a 6800 class microcontroller that monitors DC at the output and shuts down if it exceeds a certain point for a certain amount of time. Response is down to way below 1Hz and it pretty much looked like DC response on my scope.
A problem I had recently was when a DAC blew it's servo. That is the only time that has ever happened to me, in 50 years. And I'm not actually sure my speaker damage resulted from the DC, it might have been from high amplitude high frequencies. Mistakes and failures can never be completely avoided.
Electronic equipment with DC response seems very common to me. I have a collection of about 10 amplifiers covering the past 50 years, and more than half are DC coupled. It used to be a very big marketing thing in the 1970's and 80's, and ever since. I'm surprised it seems uncommon to you, and yet you know about a lot about even more esoteric stuff in the woofer arena.
A fairly early amp which a friend has used for 50 years is the Sony 3200F from 1968. It has a "test" switch on the front panel. If you select "test" mode, it is DC coupled. Historically lots of people used it that way, but it is NOT a servo type DC amplifier, and the "test" designation does give you the idea this should not be the standard mode, but a switch on the front panel invites experimentation anyway.
James Bongiorno designed many of the G.A.S. and Sumo amplifiers as direct coupled with servo. In 1977 he introduced the Thaedra preamp which he claimed was the first DC coupled preamp with servo. (And, even a servo MC phono amp!) Nowadays, in higher end transistor equipment, one has to look harder to find the non-DC coupled equipment. I have an Aragon preamp from 1995 which has servo also, the same company made cheaper non-DC amplifiers and preamps under the Acurus label.
Pretty much all the Parasound amplifiers are DC coupled for the reason that John Curl doesn't like the sound of capacitors. They all have DC servos to "eliminate" DC from the output, so they don't actually have response to DC. However typically servos run at very low frequencies, such as 0.03 Hz, so response below 1Hz is typical.
Spectral, however, took the oppose track in the 70's and 80's and made only capacitor coupled products because the designers felt that servos were less transparent than the best capacitors (an idea I find ludicrous, but YMMV).
It is safer to have servo DC amplifier than non-servo DC amplifier. My Krell FPB 300 has a DC servo, and also a 6800 class microcontroller that monitors DC at the output and shuts down if it exceeds a certain point for a certain amount of time. Response is down to way below 1Hz and it pretty much looked like DC response on my scope.
A problem I had recently was when a DAC blew it's servo. That is the only time that has ever happened to me, in 50 years. And I'm not actually sure my speaker damage resulted from the DC, it might have been from high amplitude high frequencies. Mistakes and failures can never be completely avoided.
Most people would think 50 18s is overkill. I'm just suggesting that's what you could have as an alternative to the rotary woofer. I'm not suggesting that anyone needs to go out and buy 50 18s. But if you can I don't see why not. I sure would like to.
Hi my friend. Actually, BPM isn't the same as Hz ! For eg, a kick drum of say 80Hz on a 4/4 120BPM track = 2 beats per second. But, the beats just reproduce 80Hz every 2 seconds
Apart from that, as usual you provide good info, backed up with nice data etc
About this - a 4 hz sine wave is definitely not the same thing as beating a drum 4 times per second, but in this context it's not that different. It's the pulses that are important in this context, not the sound the pulses make.
This leads to the question - can church organs create the same type of crazy brain activity that rythmic drumming and chanting can? I say absolutely yes.
Even if you study infrasound on it's own, the answer is pretty obvious. I'll post a portion of the wiki text here, highlights added by me and I've deleted some portions not extremely relevant. This is just one source but sources about the effects of infrasound are all over the internet and generally agree with this one. And once you get into low single digit frequencies it's even more exaggerated because the pulses cause brainwave entrainment, making your brain waves slow down into alpha and beta wave territory which leads to surreal and dreamlike states of conscientiousness.
Last edited:
large audio test facility
Hi there J: A long time ago, I visited an Air Force test chamber, sized to fit a whole fighter aircraft, the sound generators were mechanical driven by compressed air and produced super high SPL levels. No one was permitted inside the chamber during tests. As I recall NASA has similar test facilities for space systems to simulate launch conditions. Actually, I agree with you about lions, trumpet(s) and large block V8s, especially burning nitro. ...regard, Michael
Hi there J: A long time ago, I visited an Air Force test chamber, sized to fit a whole fighter aircraft, the sound generators were mechanical driven by compressed air and produced super high SPL levels. No one was permitted inside the chamber during tests. As I recall NASA has similar test facilities for space systems to simulate launch conditions. Actually, I agree with you about lions, trumpet(s) and large block V8s, especially burning nitro. ...regard, Michael
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.