Most 3" drivers are going to exceed 3.5 inches in width..
ex. just slightly larger than 3.5"
https://www.parts-express.com/pedocs/specs/295-422--dayton-audio-ds90-8-specifications.pdf
http://feleppa.com.au/pics/speaker_imgs/plots/DS90_RawHarm.png
So for the most part your 3" driver grouping is pretty limited.
I think you mean an underhung VC as opposed to an overhung VC. Tough to determine that with most small drivers - low x-max is a likely indicator, but most would consider 2.5mm of xmax low, and most small "woofers" don't even have that.
Well unfortunately I did not get an answer I needed for my main question, lets try this a third time and maybe someone can explain this in simple terms without any technical lingo or any links where explanations are also too technical which I do not understand.
Is there a filter or combination of filters that does this to a driver?
If a driver max spl is 88db from 130hz to 20,000khz, but it’s max spl is only 73db at 50hz, can we control it’s db from 50hz to lets say 130hz with progressive lowering so let say each 10hz towards 130hz is lowered by 1db so when it gets to 130hz it’s playing at a max of 80db not 88db.
Then past the 130hz it has to stay at max spl of 80db all the way up to 2000 khz where it’s crossed with a tweeter at either 6db or 12db slope per octave.
What I don’t understand is why is there a need for a filter to keep multiplying and lowering the db with each octave?
Is there a filter that only does one 6db slope drop then stops and no longer keeps going down in db with each octave? If so, what is it called?
Perhaps continues multiplication of 6db slope per octave is the limit on laws of physics and we simply cannot control continues current with such precision as I want to control it.
In that case it’s back to the drawing board and trying to figure out another way to make this work.
Cheers.
Is there a filter or combination of filters that does this to a driver?
If a driver max spl is 88db from 130hz to 20,000khz, but it’s max spl is only 73db at 50hz, can we control it’s db from 50hz to lets say 130hz with progressive lowering so let say each 10hz towards 130hz is lowered by 1db so when it gets to 130hz it’s playing at a max of 80db not 88db.
Then past the 130hz it has to stay at max spl of 80db all the way up to 2000 khz where it’s crossed with a tweeter at either 6db or 12db slope per octave.
What I don’t understand is why is there a need for a filter to keep multiplying and lowering the db with each octave?
Is there a filter that only does one 6db slope drop then stops and no longer keeps going down in db with each octave? If so, what is it called?
Perhaps continues multiplication of 6db slope per octave is the limit on laws of physics and we simply cannot control continues current with such precision as I want to control it.
In that case it’s back to the drawing board and trying to figure out another way to make this work.
Cheers.
Yes, an active shelving filter (I think a high shelf cut, 2nd order, center frequency 90hz) would work in your example. Or a Linkwitz Transform I think, but I've less experience with those. Important caveat; these will affect the RELATIVE spl, not MAX spl. Max spl is determined by physical characteristics of the driver and amplifier.
Ok, another question, someone else outside of this forum suggested this Passive approach, but did not have time to explain, his exact quote was:
"If you use an inductor (coil) in parallel to a resistor, you should get the desired result.
The resistor is in series to the two 3" speakers and reduces their output for all frequencies, however the coil is a short for low frequencies, therefore the bass will not be lowered in loudness.
Play with the two values of L (inductivity) and R and you should be able to find the balance point"
Is this a viable alternative vs Active Shelving Filter?
"If you use an inductor (coil) in parallel to a resistor, you should get the desired result.
The resistor is in series to the two 3" speakers and reduces their output for all frequencies, however the coil is a short for low frequencies, therefore the bass will not be lowered in loudness.
Play with the two values of L (inductivity) and R and you should be able to find the balance point"
Is this a viable alternative vs Active Shelving Filter?
It would be a passive shelving filter for a loudspeaker with straight impedance plot, but as the impedance of a driver near resonance is everything but flat you will get a weird result.
(Edit: and the inductor would have to be huuuuuge)
Ok, slow progress well two steps forward and one back.
Define the word “Huge” .....Am I correct to assume that if we go back to that Dunlavy SM-1 cross-over where we know it’s 6db first order and it’s passive, it sure looks like he has a lot of inductors. Is he solving the same issue as far as, instead of one huge inductor he has multiple smaller ones in parallel?
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Well, as it has been said before, you are trying to push a loudspeaker to the absolute limit of driver size and bass extension - you will have to aquire some technical knowledge. I don't think anyone here will solve it for you ...
Back to inductors:
Your speaker will have a 2nd order rolloff towards low end and you want to compensate that.
If you want to compensate for rolloff above 50 Hz and assuming 4 ohms (low impedance keeps inductors low) you will need a 25 mH inductor.
Nothing in your picture will come near that, as far as i know - usually such inductors need iron cores.
It's a very unusual method for many reasons - "not natural way of doing things" in your words...
(Edit: And keep in mind, this would only work for an impedance compensated driver - more inductors necessary here!)
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I'm simply trying to narrow the scope of options, then pay someone to take it from there and solve it, I'll never solve it, squeezing years of knowledge into a page or two of reading material for a newbie is a useless exercise. I'm pushing the envelope only on paper trying to see what is the limit. You mentioned something about "music crest factor" what is a safe zone on these peaks, before the driver is either damaged or simply produces too much distortion. If mine are rated at 88 db SPL, is 3db to 85db enough of a head room, so that means my initial target of 50hz flat is not near 80db but 77db or maybe even much closer to 70db?
Cheers.
Here's an example of what stv was describing.
The grey curve is with just a straight forward 2nd order low pass filter. To get the blue curve, I needed to use both a shelving filter (parallel inductor L8 and resistor R10) plus an impedance compensation filter (series capacitor C2, inductor L2 and resistor R1). Inductor values are getting a little large and may need to get larger depending on the particular drivers you end up using and how you wire them.
The grey curve is with just a straight forward 2nd order low pass filter. To get the blue curve, I needed to use both a shelving filter (parallel inductor L8 and resistor R10) plus an impedance compensation filter (series capacitor C2, inductor L2 and resistor R1). Inductor values are getting a little large and may need to get larger depending on the particular drivers you end up using and how you wire them.
@k’n’h: why do you mention the dunlavy crossover? That system is in no way comparable to what you are trying to accomplish.
To keep it simple;
Otherwise the best option as already said is buying a commercial speaker as making something like you want without any knowledge (and willingness to investigate/learn) and sounding somewhat okay will be impossible.
Btw regarding;
No thus it is almost never done. Your only (realistic) option is a dsp
With your current requirements you already exhausted all your options. You ain't going to make a speaker which sounds good utilizing a 3 inch normal throw paper (fr) driver playing to 50hz in a sealed cabinet. The distortion will be horrible (I know because I have done similair tests) if that doesn't bother you enough (it will because at 80db the distortion will be audible with probably 20% or more distortion and completeling bleeding in the mids and highs causing 'muddy' sound) the chances of destroying the driver due to over excursion or excessive heat will be very high with 9db of boost. If you drop all your driver requirements and untrue prenotions about how a speaker should be build as they hold no factual grounds you may get further and allow the speaker to be 2cm wider, thus allowing a 4 inch driver with maybe a passive radiator the goal gets achievable again.
Otherwise the best option as already said is buying a commercial speaker as making something like you want without any knowledge (and willingness to investigate/learn) and sounding somewhat okay will be impossible.
Btw regarding;
Some of the best speakers I heard had side- upfiring and long throw bass drivers....
Probably should have just started there.
..and really, you already have the information you need (size driver, number of drivers, excursion vs. spl and freq.) for your base answer. Let someone you actually pay figure out the rest.
BTW, IF you go active (with amplification, "active" meaning the filter is BEFORE the amplification) then the filter components are tiny (and much less expensive) when compared to a passive approach. Normally (commercially) you would do this with a plate-amp (which is active). ..and these days it would be preferred to have DSP in the plate amp to equalize and crossover drivers as needed for a near perfect (linear/flat freq. response at the listener's position) result.
THAT should give you everything you need to move-onto "paying someone else to solve it".
If you don't yet have the driver you want - then keep looking: that you can do yourself now that you know what you are looking for.
Crest factor depends very much on the kind of music (or sound) you are listening to. 12 dB is a usual value - classical music or movie soundtracks will be much higher.
If you want to let someone design a system for you I suggest you don't limit him(her) to a driver size but define your specifications, such as desired SPL, listening distance, room size, music style, speaker size, planned expenses .... and let him(her) propose a solution.
Cannot do that, form follows function, not the other away around, Apple had the same approach for years...it was slow but good looking until technology came around where today their function caught up to form. There is a reason we don't see ugly pop stars with good voice and most good looking stars sing with autotune and lip syncing.
If it does not look certain way and you spend 6-8 hours on a laptop per day, eventually you will start hating on it no matter how good it sounds. At 1-2 feet range anything past 3-4" wide does not look good, just too big too wide. 3.5" MTM is ideal width actually.
If pure sound was priory number one, then I'd look for ATC SCM-7 and not waste time bulding anything. I do not expect too many people to understand this criteria, nor do I care. Paying someone this early is not efficient spending, you guys like solving problems so I do not get offended by any side commentary or useless lateral suggestions as we try to solve or narrow the scope of solutions. I already priced in that very few will understand my position aeven fewer will reply with solid solutions not suggestions. Human beings did not get to this point by making big compromises or setting low goals or looking for lateral improvements, if this was the case this website would not exist, we wouuld all use of the shelf products with lowered expectations.
Cheers.
You got plenty of very solid and technically based answers.
If you want to push the limits you will have to get into the technical aspects and understand what the problems are (e.g. "hoffman's iron law", maybe modified to: size-excursion-output).
By the way this website exists because many people enjoy audio as a hobby and like to understand what's going on technically.
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Sure it is when you aren't happy with (apparently) any of the suggestions offered.
As for aesthetic preference - you are just making your preference the priority (..which is fine, but it obviously has *some serious limitations that we have broached with potential solutions that you have dismissed). Those solutions that you have dismissed would EASILY find market acceptance (..and in fact already have). Really there isn't much new here and the market is saturated. Apple's hardware isn't particularly good (or even initially well accepted) design, what they have done is produced really exceptionally finished products (.."finished" as in the premium quality feel of the materials weight/texture and form-factor), that along with market dominance and some innovation with software and hardware - allows them to produce some really FUGLY products that eventually reach market acceptance (..often quickly these days).
*btw, if I had a dollar for every time a new member/poster with no real knowledge created a topic effectively saying "it has to be THIS WAY" and where there were technical complications to actually achieving that goal - I'm pretty sure I could spend that money for a really nice vacation. (..plus, the poster almost never asks a pointed well thought-out question that can be easily answered.) Bonus points though for having the balls to basically say "figure this out for me so I can make money off of it". 😉
People want to be good at something we need it for survival, we all want to be good at something, if we are not we abundant it. I'm not good at electronics and never will be, I'm good at other stuff, you guys are on the other hand good at it, if you had to solve easy problems all the time you would not be good at it and abandon it.
Part of the problem is not writing the solution or schematic whch I cannot read or understand but explaining it in such a way that regular person can understand it...... Lion vs. Mice was a good example. This is why I ignore most of links that you suggest if I start reading it and it’s too technical, many of them are written by engineers for other engineers so you can’t understand anything I abandon it.
The word Hobby is a complex subject matter, it comes with egos and competition for answers to get their 2 cents in, “my solution is better then yours”…. and many times goes sideways in arguing on too much technicality. This I why I do not want too much technical stuff so we won’t waste time in people arguing and wasting bandwidth on too much technicality.
In any case, more dumb questions until your patience runs out.
1) stv.....You said”
Yes, an active shelving filter (I think a high shelf cut, 2nd order, center frequency 90hz) would work in your example. Or a Linkwitz Transform I think, but I've less experience with those. Important caveat; these will affect the RELATIVE spl, not MAX spl. Max spl is determined by physical characteristics of the driver and amplifier.”
The 90hz center that you suggested, how did you arrive at that number, is it based on my criteria of 50 to 130 hz range and some type of computation or simply based on life experience in simply knowing that at that 90hz number it will be more or less smooth transition?
Is it always a fixed number on shelving or can be a range from 50 to 100 or to 130hz? I mean if it's an analog circuit not via DSP?
2) Is this problem better solvable with bi-aping vs. tri-amping, tri-amping would cost more and complexity it’s much more difficult task putting together 6 amps way too much, so in my case if I have two drivers behaving differently at different frequencies, is driving both with one amp a bad idea or maybe much better to keep them playing in unison up to 130hz?
3) Each driver ( 8ohm) is 30 watts nominal and 60 program, what wattage will I need to drive both drivers with one amp based on my requirements? In general are we adding any gain in the low end with the amp.
I mean lets say it was tri-amp set up since we are limited by the x-max so no matter where gain comes from, but from pure sound quality or less coloration, does it matter if full gain is from active EQ / Linkwitz Transform and non from the amp vs. some small % from the amp and the rest from the EQ?
4) Baxandall Shelving equalizer, description says its for much wider Q curve, what is considered wide vs. narrow, is it applicable to my case for more smooth transition between drivers?
Cheers
Part of the problem is not writing the solution or schematic whch I cannot read or understand but explaining it in such a way that regular person can understand it...... Lion vs. Mice was a good example. This is why I ignore most of links that you suggest if I start reading it and it’s too technical, many of them are written by engineers for other engineers so you can’t understand anything I abandon it.
The word Hobby is a complex subject matter, it comes with egos and competition for answers to get their 2 cents in, “my solution is better then yours”…. and many times goes sideways in arguing on too much technicality. This I why I do not want too much technical stuff so we won’t waste time in people arguing and wasting bandwidth on too much technicality.
In any case, more dumb questions until your patience runs out.
1) stv.....You said”
Yes, an active shelving filter (I think a high shelf cut, 2nd order, center frequency 90hz) would work in your example. Or a Linkwitz Transform I think, but I've less experience with those. Important caveat; these will affect the RELATIVE spl, not MAX spl. Max spl is determined by physical characteristics of the driver and amplifier.”
The 90hz center that you suggested, how did you arrive at that number, is it based on my criteria of 50 to 130 hz range and some type of computation or simply based on life experience in simply knowing that at that 90hz number it will be more or less smooth transition?
Is it always a fixed number on shelving or can be a range from 50 to 100 or to 130hz? I mean if it's an analog circuit not via DSP?
2) Is this problem better solvable with bi-aping vs. tri-amping, tri-amping would cost more and complexity it’s much more difficult task putting together 6 amps way too much, so in my case if I have two drivers behaving differently at different frequencies, is driving both with one amp a bad idea or maybe much better to keep them playing in unison up to 130hz?
3) Each driver ( 8ohm) is 30 watts nominal and 60 program, what wattage will I need to drive both drivers with one amp based on my requirements? In general are we adding any gain in the low end with the amp.
I mean lets say it was tri-amp set up since we are limited by the x-max so no matter where gain comes from, but from pure sound quality or less coloration, does it matter if full gain is from active EQ / Linkwitz Transform and non from the amp vs. some small % from the amp and the rest from the EQ?
4) Baxandall Shelving equalizer, description says its for much wider Q curve, what is considered wide vs. narrow, is it applicable to my case for more smooth transition between drivers?
Cheers
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