You can get good sound indeed from a rectangular box. Stuffing is normal, it isn't difficult and you should do it.
The other things are worth it, but you'd struggle to realise them the first time out even if you wanted to. If you keep it simple you take big steps because the learning is harder to begin with... the steps that come later are slower.
The other things are worth it, but you'd struggle to realise them the first time out even if you wanted to. If you keep it simple you take big steps because the learning is harder to begin with... the steps that come later are slower.
ldarieut, build it simple at first like AllenB suggests, you'll have fun and learn along the way. On the next project you can optimize more things if you want!
But yeah, suspicion is good to have, it leads to questions which lead to answers and help navigate towards better sound. The big picture is that you are going to listen the acoustic output. The "box" and room affects the acoustic output after the sound has passed your electronics and transducers. It all comes together for the acoustic output, interplay of the electronics, transducers and "box". You might learn that your listening room ruins the bass with +-10dB peaks and nulls so different alignments are not too important as long as the box doesn't ruin the bass already or deliberately sacrifice some bass for the other aspects like mid range or size or cost or what ever reasons.
You can optimize the alignment because it is fun and should be done but don't let "better bass" take over mid range. Due of long wavelengths and small rooms you can always add more or better bass (boxes) later but can't fix mid range that was ruined by the bass box and the fine bass was ruined by the room, no victory. I suggest you build the box with your current knowledge and interests and if you notice a problem you should then investigate what is going on and then try to fix it. It is too much information to pour in at once, learning by doing is the quickest way even if it took 10 prototypes and two years to make. After all, millions of various speaker boxes get listened everyday. It is about music and having fun. The optimizations are diminishing returns and successfully applying them depends on how much you are willing to put time into the learning and prototyping. For most enthusiastic it is life time hobby so there is enough time. Have fun!
But yeah, suspicion is good to have, it leads to questions which lead to answers and help navigate towards better sound. The big picture is that you are going to listen the acoustic output. The "box" and room affects the acoustic output after the sound has passed your electronics and transducers. It all comes together for the acoustic output, interplay of the electronics, transducers and "box". You might learn that your listening room ruins the bass with +-10dB peaks and nulls so different alignments are not too important as long as the box doesn't ruin the bass already or deliberately sacrifice some bass for the other aspects like mid range or size or cost or what ever reasons.
You can optimize the alignment because it is fun and should be done but don't let "better bass" take over mid range. Due of long wavelengths and small rooms you can always add more or better bass (boxes) later but can't fix mid range that was ruined by the bass box and the fine bass was ruined by the room, no victory. I suggest you build the box with your current knowledge and interests and if you notice a problem you should then investigate what is going on and then try to fix it. It is too much information to pour in at once, learning by doing is the quickest way even if it took 10 prototypes and two years to make. After all, millions of various speaker boxes get listened everyday. It is about music and having fun. The optimizations are diminishing returns and successfully applying them depends on how much you are willing to put time into the learning and prototyping. For most enthusiastic it is life time hobby so there is enough time. Have fun!
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OMG, that book directly led to me becoming a loudspeaker design engineer! Though actually it is a simplistic take on things. Some observations I didn't notice yet in this thread:
Hofmann's Iron Law: states that box size, efficiency, and how low the bass goes are all tradeoffs. If we stir in the physical limitations of designing woofers in the real universe, I'd rephrase it as "small woofers + small boxes = small bass" though some designs and some DSP can give illusions otherwise.
Efficiency/Sensitivity: this is how many watts of sound come out per watt of electrical power going in.
BUT #1: when calculated from Thiele-Small parameters, it's a handy theoretical guideline, but only applies to lower midrange. Bass frequencies naturally roll off, and higher frequencies often have big peaks.
BUT #2: specified sensitivity of store-bought speakers is one of the most lied about specifications. Don't trust these values without measuring them. Sorry! And due to #1 you can't go by manufacturer-supplied values for woofers and mids and tweeters without looking at the actual response curves. Different manufacturers? Different measurement setups and techniques, again sorry, best to measure yourself. (Room EQ Wizard aka REW + a UMIK from miniDSP could be your inexpensive friends).
Sealed versus Ported: woofers resonate like a car suspension or a hanging weight. The woofer's cone and voice coil and part of the surround and spider and a bit of air load on the woofer contribute the mass. The stiffness of the spider + surround contribute the "spring" part.
- The sealed box also acts like a spring, stiffening the whole suspension and pushing up the resonance frequency and Q.
- In a ported box, the port is NOT like an organ pipe (that is a separate effect that can give response peaks coming out of the port). The air in the port is like another mass, which resonates at its own frequency. Near this frequency the air in the port goes crazy and the cone's excursion is reduced, most output comes from the port. BUT below this frequency the port becomes like a giant leak and the woofer cone can flap uselessly, generating a bunch of distortion.
- There are lots of generalizations about sealed versus ported boxes: sealed boxes have a tighter sound, or ported boxes have more SPL, or whatever. I think all these things are true sometimes however the truth depends on specifics. I even used to think a sealed box would always have better transient response until someone posted tone burst simulations in a thread, showing this is not necessarily always true. I've come to think it really depends on what frequency you are talking about playing compared to the frequency of the box tuning. I've been happy with "under-tuned" designs where the port is tuned lower than some electrical filter ideal, whereupon the response "droops" early but the sound is tighter.
Yes, I bought Vance Dickason's book several decades ago. But I didn't use it for the design of my current spkrs.
After nearly 30 years of owning Maggies - eventually, driven 3-way active with subs, with a miniDSP 'nanoDIGI' unit as the heart of the system - I had a hankering to get a different musical presentation ... as well as having a minimal visual intrusion into the room (to make my wife happy).
A mate had built some great-sounding OBs ... so I decided - taking inspiration from the Kyron 'Gaias' - to go one stage further. My 2-way active 'Satori ZBs' (zero baffle) are the result.
These use:
The stereo amp driving each spkr is 40w into 4 ohms, Class A - and the amps drive the spkrs magnificently. (Above the pair of green LEDs each channel that you can see in the pic (which show that the + and - DC rails are live) is a red LED which comes on when that amp channel is clipping; the clip LED on the channel driving the mid/bass drivers comes on occasionally ... the tweeter channel, never!)
XOs are 24dB - frequencies are:
Using REW, I was able to get an overall FR that I wanted - tipping down to the right! This involved the nanoDIGI delivering:
1. a 7dB low shelf boost from 600Hz
2. a -13dB peak at 1000Hz
3. a -12dB cut in the subs' output
4. and a -8dB cut in the tweeters' output
5. plus some room EQ ... and time alignment between subs and mains.
Imaging and transient response are sensational - I do not miss my Maggies at all!
Andy
After nearly 30 years of owning Maggies - eventually, driven 3-way active with subs, with a miniDSP 'nanoDIGI' unit as the heart of the system - I had a hankering to get a different musical presentation ... as well as having a minimal visual intrusion into the room (to make my wife happy).
A mate had built some great-sounding OBs ... so I decided - taking inspiration from the Kyron 'Gaias' - to go one stage further. My 2-way active 'Satori ZBs' (zero baffle) are the result.
These use:
- 4x SB Acoustics 6 1/2" 4 ohm Satori 'Textreme' mid/bass drivers. (The 4 drivers are connected as 2 parallel pairs of 2 drivers in series - resulting in a 4 ohm load.)
- plus the SB Acoustics 4 ohm ribbon tweeter.
The stereo amp driving each spkr is 40w into 4 ohms, Class A - and the amps drive the spkrs magnificently. (Above the pair of green LEDs each channel that you can see in the pic (which show that the + and - DC rails are live) is a red LED which comes on when that amp channel is clipping; the clip LED on the channel driving the mid/bass drivers comes on occasionally ... the tweeter channel, never!)
XOs are 24dB - frequencies are:
- 90 - 150Hz from 15" sealed subs to mid bass (depending on the degree of bass in the track being played; 4 different configs are stored in the miniDSP unit)
- and 2800Hz for mid/bass to tweeter.
Using REW, I was able to get an overall FR that I wanted - tipping down to the right! This involved the nanoDIGI delivering:
1. a 7dB low shelf boost from 600Hz
2. a -13dB peak at 1000Hz
3. a -12dB cut in the subs' output
4. and a -8dB cut in the tweeters' output
5. plus some room EQ ... and time alignment between subs and mains.
Imaging and transient response are sensational - I do not miss my Maggies at all!
Andy
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Very very good. I have been making speakers long enough I know a lot of what not to do. If there is a mistake, I probably did it. What to do, you have to discover for yourself
We can make great .zma files ( I like my old Woofer tester ) and with practice, very good .frd files. We then can learn that it is best to actually measure in a prototype box and use those files for the simulation. I fell for trying to get great .frd files of drivers on large test baffles. Accurate response of the driver, but I want accurate response how I will use it. Some one else's, like the ones supplied by PE, are great for making purchase decisions, but not for actual design.
What we need to know is where to use a driver not just by the frequency response, but by distortion. I see so often, even by experienced designers, using drivers way too low because the frequency response looks pretty. Here is the catch-22: Distortion. In measuring a pile of drivers, I have concluded that distortions begins to rise at about 1/2 X-Max. By the time you get close, it skyrockets. Ever notice a tweeter that has a wonderful 2nd order roll off @ 1500, the manufacturer says use from 2000? Yup. Actually, probably much better @ 2200 unless a very steep crossover. Folks look at a woofer response and think they can eq that last 20 Hz out of them, but distortion goes from 2% to 20. Hint, an XT-25 is horrible crossed @ 2K. Wonderful @ 3500. Reasonable @ 2500.
What I see as mistakes:
Failure to prototype. Do a complete build, but plain old MDF. Attach the crossover on the outside so you can modify it. There is one risk to this. My current mains sounded so good, I rattle caned them thinking I would do nice cabinets later. 10 years later, there they are.
Way too much time and pride put into a cabinet before the performance is as good as you can get it
Falling for magic parts. Sure, if I am buying the top ScanSpeak, Purifi or A beryllium dome, I will buy higher end caps and coils. If your first build, epically when you may be changing a lot of them, plain old Dayton are great. Even electrolytic. Expensive wire, stuffing, stick-on something will make it great.
Poor baffle layout. Darn, I see so many $5000 speakers with terrible baffles! Sharp edges, symetrical layout, drivers too far apart.
Falling for old hacks. Transmission lines are one of the worst. Sure they can sound great, but they were a hack before we under T/S. No advantage at all.
Unrealistic frequency response. No, you don't want flat 20 to 20 unless you are building a PA speaker for outside. Investigate room gain and the Peter Walker curve. My next pair will be adjustable for top end slope. Test the prototype in the room where it will be used. This is the advantage we have over store bought. We can, they can't. This is why I build critical Q subs and roll the tweeters off about first order.
Failure to pay attention to the amplifier load. How easy to drive. Dick Small wrote about this at Keff.
Failure to put a LOW PASS on the tweeter. It is surprising, test yourself, but by keeping any harmonics out of the tweeter, you kill the resonances even more. You want to because tweeter break-up causes IM. The result is sub harmonics that make the sound harsh. A big part of "digital hash" is we got tweeters that have such good HF response about the time we got digital. Knock off the top end and you can have less slope gaining small details without over sibilance, harsh top-hats and horns that sound like nails on a chalkboard. Be carful not to cause an impedance issue.
Bumps in the wrong place. The worst thing you can do is have a bump around 3000. Bumps lower will change the character, move the image forward or back,. Bumps higher may seem too bright, but 3000 is where the "glare" comes from. I believe this is due to out genetic need to hear a baby scream. Just a little high, fatigue. Too high; edgy, harsh, glare.
A hard one. Not dealing with phase over a wide enough band around crossover. Don't fret too much, but pay attention of you can.
I do not understand the trend for low impedance speakers. So many are 4 Ohm nominal with dips down to 3. This will cause a large increase in distortion in the amplifier. The best amplifiers handle it better, but many AVRs will shut down. Some can be unstable and oscillate blowing up. Transistors are better at amplifying voltage than current.
We can make great .zma files ( I like my old Woofer tester ) and with practice, very good .frd files. We then can learn that it is best to actually measure in a prototype box and use those files for the simulation. I fell for trying to get great .frd files of drivers on large test baffles. Accurate response of the driver, but I want accurate response how I will use it. Some one else's, like the ones supplied by PE, are great for making purchase decisions, but not for actual design.
What we need to know is where to use a driver not just by the frequency response, but by distortion. I see so often, even by experienced designers, using drivers way too low because the frequency response looks pretty. Here is the catch-22: Distortion. In measuring a pile of drivers, I have concluded that distortions begins to rise at about 1/2 X-Max. By the time you get close, it skyrockets. Ever notice a tweeter that has a wonderful 2nd order roll off @ 1500, the manufacturer says use from 2000? Yup. Actually, probably much better @ 2200 unless a very steep crossover. Folks look at a woofer response and think they can eq that last 20 Hz out of them, but distortion goes from 2% to 20. Hint, an XT-25 is horrible crossed @ 2K. Wonderful @ 3500. Reasonable @ 2500.
What I see as mistakes:
Failure to prototype. Do a complete build, but plain old MDF. Attach the crossover on the outside so you can modify it. There is one risk to this. My current mains sounded so good, I rattle caned them thinking I would do nice cabinets later. 10 years later, there they are.
Way too much time and pride put into a cabinet before the performance is as good as you can get it
Falling for magic parts. Sure, if I am buying the top ScanSpeak, Purifi or A beryllium dome, I will buy higher end caps and coils. If your first build, epically when you may be changing a lot of them, plain old Dayton are great. Even electrolytic. Expensive wire, stuffing, stick-on something will make it great.
Poor baffle layout. Darn, I see so many $5000 speakers with terrible baffles! Sharp edges, symetrical layout, drivers too far apart.
Falling for old hacks. Transmission lines are one of the worst. Sure they can sound great, but they were a hack before we under T/S. No advantage at all.
Unrealistic frequency response. No, you don't want flat 20 to 20 unless you are building a PA speaker for outside. Investigate room gain and the Peter Walker curve. My next pair will be adjustable for top end slope. Test the prototype in the room where it will be used. This is the advantage we have over store bought. We can, they can't. This is why I build critical Q subs and roll the tweeters off about first order.
Failure to pay attention to the amplifier load. How easy to drive. Dick Small wrote about this at Keff.
Failure to put a LOW PASS on the tweeter. It is surprising, test yourself, but by keeping any harmonics out of the tweeter, you kill the resonances even more. You want to because tweeter break-up causes IM. The result is sub harmonics that make the sound harsh. A big part of "digital hash" is we got tweeters that have such good HF response about the time we got digital. Knock off the top end and you can have less slope gaining small details without over sibilance, harsh top-hats and horns that sound like nails on a chalkboard. Be carful not to cause an impedance issue.
Bumps in the wrong place. The worst thing you can do is have a bump around 3000. Bumps lower will change the character, move the image forward or back,. Bumps higher may seem too bright, but 3000 is where the "glare" comes from. I believe this is due to out genetic need to hear a baby scream. Just a little high, fatigue. Too high; edgy, harsh, glare.
A hard one. Not dealing with phase over a wide enough band around crossover. Don't fret too much, but pay attention of you can.
I do not understand the trend for low impedance speakers. So many are 4 Ohm nominal with dips down to 3. This will cause a large increase in distortion in the amplifier. The best amplifiers handle it better, but many AVRs will shut down. Some can be unstable and oscillate blowing up. Transistors are better at amplifying voltage than current.
Did you read all the Linkwitz stuff on OB? Good physics even if many found the Orion a bit hot. I have never gone to them as I have never had a room suitable.Yes, I bought Vance Dickason's book several decades ago. But I didn't use it for the design of my current spkrs.
After nearly 30 years of owning Maggies - eventually, driven 3-way active with subs, with a miniDSP 'nanoDIGI' unit as the heart of the system - I had a hankering to get a different musical presentation ... as well as having a minimal visual intrusion into the room (to make my wife happy).
A mate had built some great-sounding OBs ... so I decided - taking inspiration from the Kyron 'Gaias' - to go one stage further. My 2-way active 'Satori ZBs' (zero baffle) are the result.
View attachment 1012022
These use:
- 4x SB Acoustics 6 1/2" 4 ohm Satori 'Textreme' mid/bass drivers. (The 4 drivers are connected as 2 parallel pairs of 2 drivers in series - resulting in a 4 ohm load.)
- plus the SB Acoustics 4 ohm ribbon tweeter.
The stereo amp driving each spkr is 40w into 4 ohms, Class A - and the amps drive the spkrs magnificently. (Above the pair of green LEDs each channel that you can see in the pic (which show that the + and - DC rails are live) is a red LED which comes on when that amp channel is clipping; the clip LED on the channel driving the mid/bass drivers comes on occasionally ... the tweeter channel, never!)
XOs are 24dB - frequencies are:
- 90 - 150Hz from 15" sealed subs to mid bass (depending on the degree of bass in the track being played; 4 different configs are stored in the miniDSP unit)
- and 2800Hz for mid/bass to tweeter.
Using REW, I was able to get an overall FR that I wanted - tipping down to the right! This involved the nanoDIGI delivering:
1. a 7dB low shelf boost from 600Hz
2. a -13dB peak at 1000Hz
3. a -12dB cut in the subs' output
4. and a -8dB cut in the tweeters' output
5. plus some room EQ ... and time alignment between subs and mains.
Imaging and transient response are sensational - I do not miss my Maggies at all!
Andy
That's an interesting concept - deliberately limiting the HF extension of a tweeter. Very easy to implement when the XOs are provided by a miniDSP unit!
Given the tweeter I am using (SB Acoustics Satori AT60NC-4) supposedly has a useful range to over 30kHz ... what frequency do you suggest I should apply a LP filter at?
And what slope?
How does applying a LP filter on a tweeter cause an impedance issue? (By which I assume you mean lower the impedance at HFs?)
How do you do this? Surely the phase behaviour across an XO is the direct result of the HP & LP slopes used?
Andy
@wintermute - this is really good. I know you have other things to do, but you should try to complete this. This is a great resource to point people to...except it is incomplete.
I am a big fan of checklists and have been thinking of the steps (and the order) required to design a speaker. So I went through and created a Table of Contents for your "article" so far. I thought this might be nice for those who want to see what is coming before they read through all of the words.
I am a big fan of checklists and have been thinking of the steps (and the order) required to design a speaker. So I went through and created a Table of Contents for your "article" so far. I thought this might be nice for those who want to see what is coming before they read through all of the words.
1. Determine your basic needs
2. Short list some drivers
3. Doing some simulation (introduction)
3a. Box modeling
3b. Simulating baffle step
3c. Tracing manufacturer’s data
3d. Checking polar response
4. Designing some cabinets
4a. Introduction to enclosure construction
5. Designing the crossover
5a. Using manufacturer’s curves
5b. Doing a real crossover sim ...stay tuned
I am missing actually quite some proper literature in the opening post.
The suggested books are ok'ish, but a little dated and mostly their focus is a little off imo.
Highly recommended books;
Ideally some literature in psycho-acoustics as well.
(I can look them up, don't know them on the top of my head)
When reading those books, it's important NOT to focus to much on the details and (especially) math just yet, but try to get a grasp on the bigger picture.
A general good approach, is a top-down approach.
First make a list of priorities, needs, variables and constraints (including budget!!!!)
Think about the expectations and be realistic with them!
You will see that very quickly you often already end-up with just a handful of drivers to choose from.
Earl Geddes and I were very briefly mentioning this in another topic, but in my (our) opinion most people just make it themselves difficult. The choice of components (incl drivers) comes from the design choice, not the other way around.
A certain design choice automatically results in priorities in things like directivity, distortion, max SPL etc etc.
Also, maybe a bit obvious, but good drivers don't make a good design and a very well made design can make cheap drivers sound like state-of-the-art (whatever that means...).
Short-listing drivers basically comes at the same point as box modelling/simulations, it's like a tango dance.
Although it depends a little what system we are talking about.
In general one will go through this process a few times with some iterations.
Tracing and using curves beforehand isn't super useful.
I mostly use it just to compare graphs from manufactures (since a lot of them have different scales, sigh)
Still, quite often it's apples vs oranges unfortunately.
The same goes for bafflestep simulations.
Quite often this is a constraint, so there isn't much to change to begin with.
Although it might be useful when going for a less standard design or dimensions.
It does help in the later stage when designing a crossover.
Keep in mind that there is a difference between baffle-step and diffraction.
In general bafflestep can be simulated pretty well and accurate (unless you're using a very crazy shaped baffle).
Diffraction is a total hit or miss (often more a miss).
Crossover design only works well with actual measured data.
Traced curves (don't forget the impedance) can help with determining the ballpark figures beforehand.
Which can be very handy when going for less common filter designs (super low crossover frequency or something).
After a while you can also start skipping steps and you base your choices on experience.
The suggested books are ok'ish, but a little dated and mostly their focus is a little off imo.
Highly recommended books;
- Loudspeaker Handbook - John Eargle
- Loudspeaker and Headphone Handbook - John Borwick
- Sound Reproduction - Floyd Toole (!!)
- Acoustics - Leo Beranek
- Acoustics: Sound Fields and Transducers - Tim Mellow & Leo Beranek
Ideally some literature in psycho-acoustics as well.
(I can look them up, don't know them on the top of my head)
When reading those books, it's important NOT to focus to much on the details and (especially) math just yet, but try to get a grasp on the bigger picture.
A general good approach, is a top-down approach.
First make a list of priorities, needs, variables and constraints (including budget!!!!)
Think about the expectations and be realistic with them!
You will see that very quickly you often already end-up with just a handful of drivers to choose from.
Earl Geddes and I were very briefly mentioning this in another topic, but in my (our) opinion most people just make it themselves difficult. The choice of components (incl drivers) comes from the design choice, not the other way around.
A certain design choice automatically results in priorities in things like directivity, distortion, max SPL etc etc.
Also, maybe a bit obvious, but good drivers don't make a good design and a very well made design can make cheap drivers sound like state-of-the-art (whatever that means...).
Short-listing drivers basically comes at the same point as box modelling/simulations, it's like a tango dance.
Although it depends a little what system we are talking about.
In general one will go through this process a few times with some iterations.
Tracing and using curves beforehand isn't super useful.
I mostly use it just to compare graphs from manufactures (since a lot of them have different scales, sigh)
Still, quite often it's apples vs oranges unfortunately.
The same goes for bafflestep simulations.
Quite often this is a constraint, so there isn't much to change to begin with.
Although it might be useful when going for a less standard design or dimensions.
It does help in the later stage when designing a crossover.
Keep in mind that there is a difference between baffle-step and diffraction.
In general bafflestep can be simulated pretty well and accurate (unless you're using a very crazy shaped baffle).
Diffraction is a total hit or miss (often more a miss).
Crossover design only works well with actual measured data.
Traced curves (don't forget the impedance) can help with determining the ballpark figures beforehand.
Which can be very handy when going for less common filter designs (super low crossover frequency or something).
After a while you can also start skipping steps and you base your choices on experience.
There is no illusion at all? (plus the word "small bass" doesn't make any sense or mean anything)
Point is that nowadays amplifier output power isn't really an issue anymore.
So of those parameters, sensitivity goes out the window to optimize for smaller boxes.
There is no limitation for preventing you getting 20Hz out of a tiny enclosure at decent SPL's
It will just cost you a lot of electrical power, since there won't be any "acoustical power" anymore.
But in theory it can certainly be done.
Obviously not taken any other side effects (like distortion).
But Hofmann's Iron Law is idealized by itself anyway.
This is a little extreme example, but in the "real universe" there is definitely room for stretch.
Btw, Hofmann is seen from all other things being constant, so saying small woofer + small enclosures doesn't fit in Hofmann's Iron Law anymore anyway, than you're misinterpreting the meaning.
*side note;
Besides, the "law" part is extremely debatable actually.
Because those parameters are just intrinsic consequences of ANY control system or linear phase mass-damper-spring system.
It's the law of conservation of misery.
For a piston or an engine, light or LASER systems etc you have exactly the same kind of compromises.
Ah yes I'm quite familiar with the latter
and "small bass" is just a grammatically kludged shorthand to try and connect the concept to audio nonexperts. As for "doesn't fit in Hofmann's", which other things are you saying are constant? Your words seem correct but I feel the meaning is eluding me.Power IS cheaper these days though if you want a lot it's still not cheap in an absolute sense to average consumers who won't home-build a Hypex module or hook up prosound amps. Plus running high power gets into power compression though if used just for musical peaks that's maybe not much of an issue. But as Fielder and Benjamin pointed out, small woofers won't generate enough sound pressure at low frequencies to be audible. Hence I like to try and warn people (my WIFE) that NO those little speakers AREN'T going to have huge bass, sorry. They've gotten pretty good though! I have some JBL Control X, two active and one passive (driven by Aiyima A07). They can fill a house or yard with decent low end, enough to satisfy if you don't crank it too loud and don't listen for the lowest notes.
Greets!
The 15PR400 specs near enough like Altec's '80's 3156 wide range [low inductance] mid-bass 'kicker', so an excellent choice! the sim can handle 250 W, so will need a big vent if wanting this much performance, otherwise base it on your amp's rating.
With a 3" VC, up to a 1200 Hz XO same as Altec's Model 19 studio monitor/most popular ever HIFI model, though ideally would be somewhat lower at 500 Hz with 15" the historical norm, 800 Hz the compromise for horn size reduction/wider polar response.
By 'birchwood' I assume you mean > 18 mm BB ply.
As for the rest, cab width is your friend as it lowers the baffle step [if any] and should be at least as wide as the horn up to ~ 30" where BSC normally is no longer required.
I've built one set of speakers from a proven design (Zaph BAMTM) but would eventually like to try my hand at building something that's my own design. What has helped me to learn is taking a documented proven design and model the parameters & crossovers in VituixCad. I learn how to use the software and can make changes to see how it affects outputs.
Many thanks to wintermute for this great guide. I am very new to speaker building and would be thankful, if someone here could answer the following question:
How do I correctly read the cone excursion graph? With 50W input. Is the peak excursion of the driver at 50Hz and 11mm (green area number 2), or is the peak at 10Hz and 42,5mm (red area number 1)?
From the theoretical information I have read and watched so far, It should not be the area number 1, since the driver response would drop sharply after the tuning frequency. Max output level would drop below the port tuning frequency.
However, since I am a total noob, I need to ask this dumb question. I am kind of stuck on it.
How do I correctly read the cone excursion graph? With 50W input. Is the peak excursion of the driver at 50Hz and 11mm (green area number 2), or is the peak at 10Hz and 42,5mm (red area number 1)?
From the theoretical information I have read and watched so far, It should not be the area number 1, since the driver response would drop sharply after the tuning frequency. Max output level would drop below the port tuning frequency.
However, since I am a total noob, I need to ask this dumb question. I am kind of stuck on it.
I believe this is showing the excursion when tested at each frequency separately and applying 50W to it in each case.
Sure, the response rolls off at the low end but this is ignored which means that you get less out and still lots of excursion. The fixed point being 50W. This means you can't ignore area number 1.
One thing though, this plot also ignores the fact that music doesn't have this even power spread. If there is no recorded energy in area number 1 then you have more excursion to spare.
Vented boxes do let loose below their tuning frequency, however 35Hz isn't too bad. If you did have a problem you could always add a low bass filter.
Sure, the response rolls off at the low end but this is ignored which means that you get less out and still lots of excursion. The fixed point being 50W. This means you can't ignore area number 1.
One thing though, this plot also ignores the fact that music doesn't have this even power spread. If there is no recorded energy in area number 1 then you have more excursion to spare.
Vented boxes do let loose below their tuning frequency, however 35Hz isn't too bad. If you did have a problem you could always add a low bass filter.