See this, there is screenshot from Velodyne servo sub explanation https://www.audiosciencereview.com/forum/index.php?threads/motional-feedback-mfb.27956/ which basically reads that ear is less sensitive to low frequencies and distortion products of low sound is very audible simply because hearing is a lot more sensitive there. For this reason the distortion needs to be low if one wants to really reduce their effect to perceived sound but also the fundamental needs to be very loud in order to be heard correctly. Small woofers just can't do this very well, demanding loud and low requires lots of volume displacement, excursion, and distortion rises.
Some kind of baseline trend from the quick voice coil test bench journey seems to be that many +6" drivers seem reach ~1% distortion around 50Hz at ~94db and below that the distortion just shoots up with all drivers as more and more excursion is needed for the lower frequencies. Some bigger drivers in PA category measure similar performance with 104db test level like this 14" woofer from B&C https://audioxpress.com/article/test-bench-b-c-speakers-14na100-8-14-pro-sound-woofer
To me this reads, if your driver can do 1% distortion at 50Hz for the listening level you are listening to then its fine but if it doesn't then look if slightly better ones are available and prepare to pay some high price on it because the differences don't seem to be that big. That said the purifi data posted few posts back shows it has towards ~10db less thd at 50Hz than the Dayton rs series in the bunch, which is probably audible difference.
Or just use bigger/more woofer(s). Also, make sure your port doesn't output noise, box resonances, rattling glassware, these add all up and could be improved without swapping the driver. Big topic, fixing all problems in a loudspeaker 🙂
To me this reads, if your driver can do 1% distortion at 50Hz for the listening level you are listening to then its fine but if it doesn't then look if slightly better ones are available and prepare to pay some high price on it because the differences don't seem to be that big. That said the purifi data posted few posts back shows it has towards ~10db less thd at 50Hz than the Dayton rs series in the bunch, which is probably audible difference.
Or just use bigger/more woofer(s). Also, make sure your port doesn't output noise, box resonances, rattling glassware, these add all up and could be improved without swapping the driver. Big topic, fixing all problems in a loudspeaker 🙂
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Sure this is correct but not so much in the context of this thread (low bass quality). I think when you are talking over 10% distortion below 50Hz there is room to "improve". I am currently using an 8-subwoofer (4x 12" per side) system with some not-very-expensive and mediocre performing subs drivers and I can say that the distortion is definitely apparent in the lowest 8ve or two. I am building up some other subs with lower distortion drivers now, but there will not be 8 of them. Then I can compare quantity to quality and see what I think.
We've crossed a line I think, which I alluded to when I referenced 'normal conditions', ie not running at or beyond the limit or unable to produce a reasonable level and so forth.
Good bass is difficult to get and one has to look much further afield to get there. Could the subject have done with expanding?
In any case, I'm reminded of the time I thought "what is that?" and it was just the former gently hitting the stops. Situationally dependent but it can still be easy to ignore and very satisfying.
Good bass is difficult to get and one has to look much further afield to get there. Could the subject have done with expanding?
In any case, I'm reminded of the time I thought "what is that?" and it was just the former gently hitting the stops. Situationally dependent but it can still be easy to ignore and very satisfying.
So are we saying a $20 PE 10”and a $225 Dayton ref 10” both in proper size enclosures, both capable of 22Hz will have the same quality of sound? Or are we saying our ears ( and instruments) are incapable of discerning distortion or other fundamental sound quality differences at this frequency? What if you ran 2 or 4 $20 subs vs 1 Dayton ref? Does a the Dayton ref sound better at 75% of excursion then the cheap sub(s) does at 25%? How does one make this determination if distortion is not the indicator?
Even Dr Geddes who was behind one of the distortion studies specifies a particularly well made woofer in his designs, but it's not for the prestige or for the harmonic distortion. I just can't remember the reason right now. Was it to do with the 4" voice coil, maybe thermal modulation.. or was it because the 15" are used to around 1kHz, maybe something else?
It's one thing when you have a reason, but on a more general level it seems to matter less.
It's one thing when you have a reason, but on a more general level it seems to matter less.
Just from reading, it seems there are 2 views that are not necessarily contradictory. The first is there is no replacement for displacement, which physics would back up, and the second is that drivers working less hard to achieve the same SPL as drivers working harder (more excursion) will tend to sound better. Also seemingly backed up by physics.
Just seems to me, being relatively new to this, that if you just keep both in mind, you will be headed in the right direction.
Just seems to me, being relatively new to this, that if you just keep both in mind, you will be headed in the right direction.
Yup, same applies for cars as well.
Or other way around.
Select engine big enough, no need to push it to red.
Or other way around.
Select engine big enough, no need to push it to red.
I think he mentioned quite recently on some thread that the woofer was selected for good midrange performance. Size is to set high directivity below 1kHz for the whole system and make/model was selected looking at cone resonances, cone edge or surround resonance was mentioned being the problematic one I think. Performance on bass is secondary for the 2-way speaker woofer, its what it is after optimizing the midrange performance. The bass is better handled by separate bass system, multiple subwoofers. Not because the 15" woofer wouldn't do it but because the room dominates the room sized wavelengths one needs room sized solution to have control over it.
This is very logical loudspeaker system optimized for full bandwidth sound with good enough SPL capability so that distortion can be ignored as insignificant. Its almost like going for high directivity, and the bass system, was the main motive and the SPL and distortion part just rendered themselves as non issue. Very good system from audio quality perspective with about all trade-offs in size and cost.
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Yes, what else you can do than buy better driver if you have limits like that? Whats the question, is it do I get better bass by buying better driver?
Well yes. That is exactly the question I've been struggling to ask easily. I didn't want to just ask it out right, without the specific parameters I used for a guideline. I guess I could have asked it, why would Jim Holtz choose these inexpensive drivers when there are so many nicer ones out there?
I apologize, but I reject this completely. I've been a recording engineer for 35 years. You don't just record the Ambient sound in a room. That's not at all how recordings are done. Occasionally you will choose a room due to its natural Reverb. But the sound is always tailored by putting the instrument amplifiers in a closet, separate small room, separate enclosure etc. Or the instruments plug directly into the mixing console itself. You're not ever dependent on the sound of a room for the quality of your recording LOL.
This could only be true for electronic instruments. What do you record? In every big studio I've been in, the room is highly acoustically treated, because the room matters a lot. Much is made over what mic to use, which largely comes down to how much of the room, or other players you want to capture.
That's what I took the post to mean.
You actually are...unless you're doing completely synthesized or electronic music and I trully doubt you need audiophile equipment to listen to electronic music...Even that electronic music is listened by the master engineer on some amp+ speakers in a room with one pair of ears and decisions are made based on that... I bet we can call that an amprent ... not going to argue indefinitely, as I undestand I don't hold the absolute truth, but just a small example:
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That is not necessarily true depends on the application. It's also beside the point of actively using new tech to reduce the effects of power compression.
Rob 🙂
Most listening rooms will of coarse mangle the frequency response of any woofer by the time the sound gets to your chair. Having said that, I prefer small woofers (6 or 8 inch) in a vertical array, in sealed cabinets, with active EQ forcing them to be somewhat flat down to at least 30HZ. I may be wrong but small diameter woofers seem cleaner sounding to my ear, even though I know that they should have more frequency modulation distortion from the larger cone movement, per unit of SPL, and usually have a more limited Xmax. The vertical array means a smaller footprint, and perhaps a slightly more focused emission vertically, so less interaction with the floor and ceiling at the higher frequencies. When you have decent bass down to 30HZ and below, drums sound way better IMO. I hooked up a spectrum analyzer in my stereo system, and noticed that with real world music, there is usually significant energy happening all the way down to 20HZ, even when the bass instrument was taking a break. If you put most woofers in a sealed box, they typically roll off by the time you get down to 50HZ. Better ones are still arguably useful down to 40HZ (the lowest note on a 4 sting bass guitar). Active EQ for a woofer isn't that difficult if you've already got a chassis and power supply for an active crossover (which I'm a big fan of). I run my woofers (four 6.5 inch Peerless brand drivers on each side) from 30HZ - 100HZ, then use an MTM cabinet for 100HZ - 25kHZ.
Without knowing mr. Holtz and his motives and further context we should always remember to think the business side of things. DIY is often emotion driven and audio quality and what not but those who sell products, or have been into somekind of business have lots of experience but also some kind of marketing perspective on things. Like for example he could have heard so many systems that perhaps the distortion is irrelevant, or perhaps he knew that there is no point improving the bass if there are other weak links on the system, or a budget or just pure marketing.
Things get more clear, to think about audio systems like quality of bass, what one should do to improve sound. If one is able to identify and put the marketing part in any system or in received guidance aside and think about mostly the audio related design desicions. Well, also DIY projects usually have budgets, and size constrains so it is not irrelevant, but separating them in a way that one knows what he is doing makes stuff in perspective and easy to reason about. And eventually figure out what is it that you need and not what you want since they might be separate things due to some kind of marketing at some point in life or at the moment affecting in the process. Basically it is just questioning things, like you have by starting the thread. Hopefully you find youre answer 🙂 if you want new driver I'd buy purifi as it seems to be the current pinacle and if that is not an improvement then you know answer to your question, you need more volume displacement 😉
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Fr ranges were defined decades ago. Sub buss 20-60Hz, bass 60-250Hz. That is easy.
As for second question. Goodness of it, and how you measure it, i can not be of much help.
All i can say when i hear great bass, i know it.
Anectodal story: during the last long weekend i embarked on repairing/repainting my open baffle bass in the main system. While i was doing so, i borrowed two 15" subs from my ht system. Big ugly closed boxes. Well, i set it up, adjusted crossovers and plate amps, and ultracure to measure all flat as before, and guess what. I did not like the boominess of closed box bass. While i can tolerate it in ht system for movies, it bothers me tremendously for main system, where clarity of open baffle is evident. It took me two days to finish repairs on my main ob subs, and i could not wait. What a relieve.
When i hear great bass, i know it. It just all fits with the rest of the system.
How to measure it is up to you.
As for second question. Goodness of it, and how you measure it, i can not be of much help.
All i can say when i hear great bass, i know it.
Anectodal story: during the last long weekend i embarked on repairing/repainting my open baffle bass in the main system. While i was doing so, i borrowed two 15" subs from my ht system. Big ugly closed boxes. Well, i set it up, adjusted crossovers and plate amps, and ultracure to measure all flat as before, and guess what. I did not like the boominess of closed box bass. While i can tolerate it in ht system for movies, it bothers me tremendously for main system, where clarity of open baffle is evident. It took me two days to finish repairs on my main ob subs, and i could not wait. What a relieve.
When i hear great bass, i know it. It just all fits with the rest of the system.
How to measure it is up to you.
