I’d like to know your opinion. By the time making the speaker, shall I use manufacturer’s provided information or measure it by myself? The information such as frequency response, impedance curve, inductance, etc. I think that the data from manufacturer probably are more correct than self-measuring because they may use the more precise equipments and methods in measurement. However, as someone says that since it was a commercial, the spec might be fabricated to have more beauty, and probably just a sample from a lot. So I thought would it be better to measure with our moderate precision equipments and method ourselves. But that also the question for the purpose of spec from manufacturer. Thanks in advance
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If you have the facility to measure, then measure.
Different speakers in the same production batch may have slightly different parameters.
Different speakers in the same production batch may have slightly different parameters.
Your box will influence frequency response, impedance and phase. Also, manufacturers don’t always give you off-axis response, nor do they always spec the measurement methods. Consequently designing crossovers on that data is generally sub optimal al best.
Or look at this Introduction to designing crossovers without measurement
Or look at this Introduction to designing crossovers without measurement
I also wonder if we measure drivers by ourselves, how can I to know that the result is correct compared to manufacturer’s data. One example is to measure the inductance of a driver. While many people usually use a typical method of using LCR meter directly measure the value, I used to read on somewhere the correct method is to measure at 1kHz feeding to the driver. The question is how manufacturer did to their data compare to ours? And does every manufacturer use the same method?
You don't need to know inductance for passive crossover design. You need to know impedance. Sure. high inductance will give rising impedance... but it is the impedance that matters.
REW can do sweeps with a home made jig. I use DATS because I am lazy, it is seems accurate and reliable.
That's why you have to measure with the correct tools, and an LCR meter is not the correct tool to measure impedance. For measuring TSP parameters, there are only a few methods, and the results should be comparable. Not so for frequency response measurements.
In regard to impedance, simulations can give you a good indication, as long as you can trust the numbers the manufacturer gave you. Predicting impedance of an enclosure and also general frequency response is something that simulations are currently quite good at.
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You don't need to be correct to the manufacturer's data, you need your own data for best result.
I hope a slightly different view is allowed...
The underlying question seems to be how well a project would turn out if you didn't measure the drivers for yourself and fuss over every last minute detail... Let me suggest that it would most likely turn out just fine. It would be a decent speaker.
Keep in mind that unless you are willing to make 6 or 8 different box designs and modifications, it is likely the cabinet isn't just right either.
In the design process of a commercial speaker, provided the company isn't just making a toss in for use with a cheap player, the engineers will typically go through multiple configurations, drivers and box designs before settling on one that is ready to make and sell. This is something well beyond most DIY builders and it is very expensive.
Unless you are either a) willing to go through that kind of intensive design effort or b) have a functional magic wand at your disposal, what you're going to get is your "best guess"... which in many cases can and will produce some truly great sounding speakers.
The big trick here is not to go kitch or get lost in the minutia. If you stay with proven design concepts, treating speakers as the "broad strokes" devices they really are you'll do okay.
The ones who do not do okay seem to be the people who spend their time sweating small issues like a 1db dip in a simulation, wildly over priced parts or which colour of wire to use. These guys seem bent upon a perfection that will never be achieved without million dollar funding and extensive lab equipment at their disposal... and even that won't buy them what they're looking for.
It's been a while since I built a set of speakers from the ground up. But when I did, I roughed out the box, purchased the drivers, designed a bare-minimum crossover and gave them an in-use test before I ever decided to get all fussy and hyper technical with them... and most often after weeks of tinkering I would end up putting them back to my original parts and design, finishing the cabinets and then simply deciding to enjoy them. Am I that good? No. But speakers are that general.
The things to avoid are highly complex crossovers, extravagant box designs and extravagant finishes. Now you're building conversation pieces, not speakers...
Good solid general design principles pretty much guarantee a reasonable outcome.
The underlying question seems to be how well a project would turn out if you didn't measure the drivers for yourself and fuss over every last minute detail... Let me suggest that it would most likely turn out just fine. It would be a decent speaker.
Keep in mind that unless you are willing to make 6 or 8 different box designs and modifications, it is likely the cabinet isn't just right either.
In the design process of a commercial speaker, provided the company isn't just making a toss in for use with a cheap player, the engineers will typically go through multiple configurations, drivers and box designs before settling on one that is ready to make and sell. This is something well beyond most DIY builders and it is very expensive.
Unless you are either a) willing to go through that kind of intensive design effort or b) have a functional magic wand at your disposal, what you're going to get is your "best guess"... which in many cases can and will produce some truly great sounding speakers.
The big trick here is not to go kitch or get lost in the minutia. If you stay with proven design concepts, treating speakers as the "broad strokes" devices they really are you'll do okay.
The ones who do not do okay seem to be the people who spend their time sweating small issues like a 1db dip in a simulation, wildly over priced parts or which colour of wire to use. These guys seem bent upon a perfection that will never be achieved without million dollar funding and extensive lab equipment at their disposal... and even that won't buy them what they're looking for.
It's been a while since I built a set of speakers from the ground up. But when I did, I roughed out the box, purchased the drivers, designed a bare-minimum crossover and gave them an in-use test before I ever decided to get all fussy and hyper technical with them... and most often after weeks of tinkering I would end up putting them back to my original parts and design, finishing the cabinets and then simply deciding to enjoy them. Am I that good? No. But speakers are that general.
The things to avoid are highly complex crossovers, extravagant box designs and extravagant finishes. Now you're building conversation pieces, not speakers...
Good solid general design principles pretty much guarantee a reasonable outcome.
Yes please! 😀
Well, what wrong with a conversation piece 😉 ? Psychoacoustically it makes a lot of sense, and a lot of high-end companies probably get away with very expensive awful sounding pieces of art. For some it's the only means to get something in the living room. But I understand your general idea. Keeping it simple is very often the best approach, specially for a beginner. Don't get lost in to many details. But for that to know, you need to know what things are details, and what things are not...
If, and only if you have the experience or are willing to put in a vast amount of time to actually learn these.
A crossover should be as simple as possible, but no simpler. If it needs to be complex, then so be it.
For instance, the crossovers in my current speakers are fairly complex (15 components per cabinet, for a 2-way design), but since the drivers an unlikely pairing*, quite a lot of work was needed to get them to play nicely.
* An 8" metal-coned driver with strong cone breakup in the kHz range, and a high-efficiency compression driver on a horn.
Chris
No offense but 15 parts for a 2 way does seem a little like overkill to me. But then, as you say, difficult combo... I generally get away with about 4 to 6 on most two ways.
Nothing at all... so long as you know that's what you're building.
As a friend of mine once quipped ... "HiFi and SciFi aren't the same thing"
True ... but I think most people grasp that spending a week worrying about which brand of woodscrews to buy is probably getting just a tad lost in details.
I've always thought that learning is an integral part of just about any hobby. Think about it... how could you do it if you don't want to learn about it?
Going back to the original question. The answer IMHO is, it depends.
There are reputable manufacturers for which you can rely on the datasheets they provide (Scan-Speak just to name one), while there are others that sort of lie on the datasheets (overly smoothed FR charts and the like), or don't provide some useful info like off axis FR graphs. With the proper software tools you can simulate a complete speaker (box effect, diffraction and baffle step effect, crossover) with only the datasheet info. But reliable tools for FR and impedance measurements don't cost and arm and a leg anymore, so IMHO if one embrace speaker designing as a hobby then has to own them. At least you can have a reality check. Just as a stupid example, an impedance measure of the completed crossover will show immediately if it is done as the design or some components are swapped/soldered incorrectly or whatever. And sometimes simulating baffle step/diffraction on complex shaped speakers can be difficult so you really need to measure yourself.
What I do is first simulate a box and a crossover with only the datasheet info, then if the result is to my liking I'll buy the drivers and can start building the cab (maybe first a test cab, but not always), then I measure FR on the cab to finalize the crossover with my set of test components, and only after I buy the final crossover components.
Measuring TS parameters is a little trickier, as those parameters aren't fixed values, but change with the measuring method, so sometime you can find different values than those in the datasheet, and maybe they are both correct. There are threads here discussing that.
Ralf
None taken.
The low-pass section got a 3rd order lowpass, Zobel filter (it's a fairly big and inductive voice coil), and a "bottomless" notch to kill the primary cone breakup peak, which stood about 10dB above the rest of the range.
The highpass was a 3rd order highpass, 3.5kHz notch (taming the HF horn) and an L-pad to take off the 20dB sensitivity difference.
I was hoping to get away with a lower-order crossover, but 3rd order on each was the only way to get things lined up.
More sensible implementations would use that woofer in a 3-way crossed to a cone mid at/below 400Hz.
Chris
I agree completely.
It hugely depends on what kind of speaker you are building and what compromises you are willing to accept. A 2-way with an easy 4-5" driver should be accomplished with few components: my first 2-way had 8 components (LR4 acoustic slopes, 2nd electrical order on the woofer with an additional resistor in series with the cap, and 3rd electrical order plus l-pad on the tweeter). But if you need to suppress breakup or address other problems you need extra components. My current 6.5"+1" speaker uses 8 components for the LP filter, two for reducing the breakup and one more resistor to bend better the slope. It was a less than 3 Euro per speaker price, but it measures and sounds better with the extra components. We aren't here to make a profit, so paying some more $/€/£ for some extra components is completely acceptable IMHO if it has a positive outcome.
This is highly subjective. Some people don't ever bother to finish the bare MDF, others are willing to put their effort into something more elaborate. This is all acceptable, unless they are complaining about bad results that only come from the decisions they made. This is where measurements are needed.
Ralf
Just to make one final point, while I can...
The major concern I have is the loss of efficiency. Shunt components --the ones connected to ground-- can and do carry current. The only source of that current is the amplifier. The more shunted current the harder the amplifier works, the less of it's energy actually gets to the drivers and the more heat is generated.
In extreme cases, an inefficient crossover can kill an amplifier... and I've seen it happen.
More generally I've noticed that many commercial speakers are sounding dull and lifeless these days. They just don't have that zing and sing that was the hallmark of the 1970s and 80s speakers. They also seem to need a lot more power in order to be dull sounding... This I think is largely because of fading efficiency in crossovers and perhaps in drivers themselves.
This is why my suggestion that we should worry less about small issues and tread speakers as the broad instruments they are...
The major concern I have is the loss of efficiency. Shunt components --the ones connected to ground-- can and do carry current. The only source of that current is the amplifier. The more shunted current the harder the amplifier works, the less of it's energy actually gets to the drivers and the more heat is generated.
In extreme cases, an inefficient crossover can kill an amplifier... and I've seen it happen.
More generally I've noticed that many commercial speakers are sounding dull and lifeless these days. They just don't have that zing and sing that was the hallmark of the 1970s and 80s speakers. They also seem to need a lot more power in order to be dull sounding... This I think is largely because of fading efficiency in crossovers and perhaps in drivers themselves.
This is why my suggestion that we should worry less about small issues and tread speakers as the broad instruments they are...
The above is extracted from 'More About Loudspeakers' by Gilbert Briggs, first published in 1963.
Mr. Briggs comments "I cannot help thinking that, if the technically perfect speaker ever appears, it will be short of flavour".
If you are buying a pre-designed kit, then no measurements.
If you are assembling a speaker from scratch, measurement in place is essential. 🙂
If you are assembling a speaker from scratch, measurement in place is essential. 🙂
PS - At least one case I've had drivers measure significantly better than the manufacturer's curves, confirmed to me by a professional maker, that the manufacturer knows this was an issue.