Hi all, it has been a few years since I have spent much time at DIY audio forums. Now I think I need to build a new end of life time speaker. Or the last speaker I will ever need. I have been happy with the Watt/Puppy quazi clone that I made about 25 years ago. But now I'm in a slightly larger room and I want a lower bass response.
The design will be roughly similar to the Wilson Sophia. It will use a 10 or 12 inch subwoofer for the bass speaker. I don't have a large budget and I see that the price of raw drivers has greatly increased since I have built my last 3 way system.
I have pretty much decided on all of the drivers but the 8-9 inch mid bass. My Puppy clones used the VIFA P21W drivers which are very excellent sounding and very easy to get to work with a 12 db crossover. They were only about 60 bucks back then. The drivers will operate in an approximately 1 cubic foot aperiodic enclosure.
I have some new ideas to extend the quality of DIY MDF speaker cabinets that I would like to explore with this design. Inspired by the Rockport technologies speakers.
My budget is about 120-130 bucks each for these 8 inch drivers.
Here is a shape concept worked up for this speaker. I will go into the cabinet design later. But now I am seeking ideas for where to look for a great sounding easy to crossover driver for a reasonable cost.
Speakers I am planning to use:
Tweeter: Morel high end tweeter. these are never used tweeters I have had for some time. I forget the model number.
Upper mid bass: Audax hm170c
Lower mid bass: undecided 8-9 inch driver
Bass driver: Dayton RSS265HF-8 10" Reference HF Subwoofer 8 Ohm
The design will be roughly similar to the Wilson Sophia. It will use a 10 or 12 inch subwoofer for the bass speaker. I don't have a large budget and I see that the price of raw drivers has greatly increased since I have built my last 3 way system.
I have pretty much decided on all of the drivers but the 8-9 inch mid bass. My Puppy clones used the VIFA P21W drivers which are very excellent sounding and very easy to get to work with a 12 db crossover. They were only about 60 bucks back then. The drivers will operate in an approximately 1 cubic foot aperiodic enclosure.
I have some new ideas to extend the quality of DIY MDF speaker cabinets that I would like to explore with this design. Inspired by the Rockport technologies speakers.
My budget is about 120-130 bucks each for these 8 inch drivers.
Here is a shape concept worked up for this speaker. I will go into the cabinet design later. But now I am seeking ideas for where to look for a great sounding easy to crossover driver for a reasonable cost.
Speakers I am planning to use:
Tweeter: Morel high end tweeter. these are never used tweeters I have had for some time. I forget the model number.
Upper mid bass: Audax hm170c
Lower mid bass: undecided 8-9 inch driver
Bass driver: Dayton RSS265HF-8 10" Reference HF Subwoofer 8 Ohm
Here is the shape concept for this design. The bass module is 14 inches wide and about 24 inches deep. The head module is a separate cabinet and the goal is to cast the head module out of epoxy granite with rough uneven surfaces on the interior and integrated braces. Possibly some kind of internal reinforcement inside the EG casting. Maybe welded rebar if magnetic induction will not be a problem.
The bottom cabinet is a combination of UHPC for the baffle and a special sandwich of MDF and polyeurathane for the main cabinet. It will be heavy. Probably over 300 pounds. Bass unit baffle alone weighs about 90 pounds.
The bottom cabinet is a combination of UHPC for the baffle and a special sandwich of MDF and polyeurathane for the main cabinet. It will be heavy. Probably over 300 pounds. Bass unit baffle alone weighs about 90 pounds.
Attachments
Passive? You're on your own. Active? MiniDSP 4x10HD.
If your heart is set on an 8-9, then maybe the SB NRX23. Personally, I'd be going for a 10 or 12 and a pair of 12s (proper sub drivers not midbasses) on the sides push push.
Hi there!
Is this the right model?
Audax HM170CO
My experience after over 40 years of DIY is that it will be very difficult to get things done with a 4 way passive crossover.
You will have to work with a decent measurement system and import the stuff in some kind of simulation software like VituixCAD 2.
Here you can assess the behavior of the system in the frequency domain also off axis without spending a large amount of money only for all variations of coils capacitors and resistors in a passive crossover.
May be a step by step approach could work - start with the passive crossover between tweeter and high mid range drive unit, but there is a high probability that the low midrange high midrange crossover will affect the high midrange crossover behavior for the high midrange drive unit.
Is this the right model?
Audax HM170CO
My experience after over 40 years of DIY is that it will be very difficult to get things done with a 4 way passive crossover.
You will have to work with a decent measurement system and import the stuff in some kind of simulation software like VituixCAD 2.
Here you can assess the behavior of the system in the frequency domain also off axis without spending a large amount of money only for all variations of coils capacitors and resistors in a passive crossover.
May be a step by step approach could work - start with the passive crossover between tweeter and high mid range drive unit, but there is a high probability that the low midrange high midrange crossover will affect the high midrange crossover behavior for the high midrange drive unit.
Out of 8" woofers SB makes probably three best value, on paper SB23NRX looks very good, alu version is also popular. Dayton RS line is also well regarded. There's also Seas 🙂 You have a decent volume box for it but what would be Your intended crossover points? How high and low do You expect this midbass woofer to play?
I have little experience with passive crossover but still I agree that 4 way gets complicated unless You go active, there's plenty of overlap between drivers. Hypex fusion amps are also a worthy alternative to MiniDSP.
I have little experience with passive crossover but still I agree that 4 way gets complicated unless You go active, there's plenty of overlap between drivers. Hypex fusion amps are also a worthy alternative to MiniDSP.
If you're determined to go the 4 way route, the RS225 seems like a no-brainer to me. Your budget allows for some options, but I'm not sure they'd be better.
thanks for the SB NRX23 suggestion. I really love that cast frame design. I think I like that speaker enough on paper to buy one and listen to it.
Measurements here.
https://hificompass.com/en/speakers/measurements/sbacoustics/sb-acoustics-sb23nrxs45-8You might need to join to see them all, but you won't get spammed or anything.
Edit: I'll ditto Paul too with the suggestion of the RS225. Measurements on HiFi Compass too.
Last edited:
Yes. it's an older design but still an amazingly good driver after all of these years. I have the ability to measure these drivers thoughI will need to get a new measurement mic since I damaged my old one. I have now developed and built three different crossovers in Vituix CAD and I think I can do this four way. I will describe later one m design choices.
So here is my idea for improving the sound dampening qualities of DIY speaker cabinets made with primarily MDF. I have mocked up a section of side speaker wall to illustrate. please imagine screws and bolts similar to the ones shown in all of the holes.
The speaker cabinet is essentially built as an envelope design with spacing between the inner and outer MDF panels. They are rigidly held together to strengthen and stiffen each other and held apart by a large quantity of bolts that are threaded to maintain the spacing. The spacing of the bolts will be close and vary a little bit to spead out the resonant nodes. Unusual patterns can also be used. But in this mockup they are spaced evenly to make easier to model.
On the inside of both panels are many small screws partially driven into the MDF so that the heads protrude but do not touch the opposing MDF panel.
After the all of the small screws are put in place the inner cabinet is placed within the outer one and then the larger bolts are placed to bolt all of the inner and outer cabinets rigidly together. Then high hysteresis pourable polyurethane that has strong bonding properties is poured between the MDF panels to fill the space between.
Analysis: The larger bolts make the total wall system more rigid and the close placing of the bolts drives the panels into producing higher frequency modes in each section of the wall panel. These are higher frequency and high Q resonant modes. These high Q modes are easier to damp than lower frequency low Q modes. All of this is done with basic tools that the DIY'er can do. This is a kind of hybrid constrained layer damping. The inner screws are just grabbing points for the poly to wrap and cling to which should increase bonding between the poly and the MDF.
Tests have shown that thick fillings of pliable material between two equal mass panels do not reduce vibration much at all. But in this situation we have added structural elements (bolts) that will cause tension between the panels as the middle layer vibrates. Thus driving the middle layer into more stress and losing energy by heat release.
The speaker cabinet is essentially built as an envelope design with spacing between the inner and outer MDF panels. They are rigidly held together to strengthen and stiffen each other and held apart by a large quantity of bolts that are threaded to maintain the spacing. The spacing of the bolts will be close and vary a little bit to spead out the resonant nodes. Unusual patterns can also be used. But in this mockup they are spaced evenly to make easier to model.
On the inside of both panels are many small screws partially driven into the MDF so that the heads protrude but do not touch the opposing MDF panel.
After the all of the small screws are put in place the inner cabinet is placed within the outer one and then the larger bolts are placed to bolt all of the inner and outer cabinets rigidly together. Then high hysteresis pourable polyurethane that has strong bonding properties is poured between the MDF panels to fill the space between.
Analysis: The larger bolts make the total wall system more rigid and the close placing of the bolts drives the panels into producing higher frequency modes in each section of the wall panel. These are higher frequency and high Q resonant modes. These high Q modes are easier to damp than lower frequency low Q modes. All of this is done with basic tools that the DIY'er can do. This is a kind of hybrid constrained layer damping. The inner screws are just grabbing points for the poly to wrap and cling to which should increase bonding between the poly and the MDF.
Tests have shown that thick fillings of pliable material between two equal mass panels do not reduce vibration much at all. But in this situation we have added structural elements (bolts) that will cause tension between the panels as the middle layer vibrates. Thus driving the middle layer into more stress and losing energy by heat release.
Attachments
Last edited:
I'm planing on looking at those SB drivers. they look really nice. I agree 4 way can get complicated but there are at least three very accomplished floor standers that are built this way. If I have to I will go active on the low bass driver, but I'm going to try and do all passive at first.
Let me explain, for me the fundamental frequencies from about 80-600 Hz are the most important fundamentals in music and I want the best timbre quality and dispersion here. For transient response, timbre and just excellent pitch definition, I have found aperiodic enclosures the best to my liking. So the 8 inch will be in an aperiodic enclosure of about 1 cubic foot volume. I have gotten amazing results with this setup in the past. But alas the aperiodic enclosure does not have the best bass extension, only the best sound to me. I will use a bass reflex port to get the lowest bass in the low bass driver to kind of act as low level foundation to the music. These drivers will be isolated so that they do not effect each other. This is important. If the 4 way becomes too complicated to build I will go active on the low end.
I was just thinking of if 4 way then with active low end for bass in the room correction like the 4 way designs of this guy here:
4 way active Troels Gravesen
4 way active Troels Gravesen
@Hezz 1 cuft net for an aperiodic enclosure is plenty, most 8"/9" woofers dont need that much (assuming aperiodic box acts like a 50-100% larger closed box - its an oversimplification just to arrive at a ballpark volume). How do You perform/calculate the aperiodic vent?
Dispersion is not a problem for 8/9" as these usually are good up to ~1kHz.
Dispersion is not a problem for 8/9" as these usually are good up to ~1kHz.
You want to avoid using bolts like you are thinking of. They will just act as a bridge that transfers all of the energy to the out side of the cabinet. Different people here on the forum have tried any number of different combinations of materials trying to find that prefect combination with varying degrees of success. The general idea is to add mass to the panels and or bracing to stiffen them. Another way is to combine different materials in a panel sandwich. That's usually two ridged surfaces with something more mailable like a layer of cork glued in between but not attached with bolts. The whole idea is to decouple the inside from the outside and using bolts does the exact opposite.
I'm currently building a set of threeway floor standers. I'm in the process of constructing the cabinets right now. I will be posting a build thread in a day or two. In my designs i have plenty of bracing to stiffen everything up. Plus on the inside panels I adhere a layer of cork underlayment, the kind you put under hardwood floors to dampen the sound of people walking on them, directly to the panels with general purpose carpet and flooring adhesive with a notched trowel. Then to that I use a bare minimum of screws to attach a layer of 3/16" lead sheets to the walls using 2 or 3 cork squares about 2" x 2" stacked one on the other to hold the lead sheets off the walls just a bit. This method works astonishingly well. It makes for a dead silent cabinet all be it a very heavy one. Being that lead is heavy screws are the most logical means of attaching it to the sidewalls but I use a bare minimum to avoid creating a bridge that couples the inside to the out side and would defeat the whole purpose.
My choice of drivers are all SB Acoustic.
tweeters- TW29TXN-B-8
mids- MW16TX-4
woofers- SB23MFCL45-4 (x2) Highly recommended
In my test box I was very pleased with the performance of these drivers. They played nice together. The sound was revealing and allowed you to hear individual interments within the music. They are a bit bright so I needed to roll off the high end a bit between 12,000 and 20,000 hrz and boost the low end starting around the cross over point by about 3 DB to get a good strong base response out of the speaker. These 8 " woofers do a good job at handling subwoofer duties. They use a mineral filled polypropylene cone that sounds great. If you want a warmer sound and will be using a sub for sure and only want one woofer you might want to look at the wool cones of the Silver Flutes. These are well built but inexpensive drivers that perform well above their price point. They may not look like it on paper but I can atest that they have a very clean warm sound and they play well with fabric dome tweeters.
Cheers and have fun building them and try not to get the speaker building bug or these might be anything but your last pair of speakers that you will ever own or build I should say.
I'm currently building a set of threeway floor standers. I'm in the process of constructing the cabinets right now. I will be posting a build thread in a day or two. In my designs i have plenty of bracing to stiffen everything up. Plus on the inside panels I adhere a layer of cork underlayment, the kind you put under hardwood floors to dampen the sound of people walking on them, directly to the panels with general purpose carpet and flooring adhesive with a notched trowel. Then to that I use a bare minimum of screws to attach a layer of 3/16" lead sheets to the walls using 2 or 3 cork squares about 2" x 2" stacked one on the other to hold the lead sheets off the walls just a bit. This method works astonishingly well. It makes for a dead silent cabinet all be it a very heavy one. Being that lead is heavy screws are the most logical means of attaching it to the sidewalls but I use a bare minimum to avoid creating a bridge that couples the inside to the out side and would defeat the whole purpose.
My choice of drivers are all SB Acoustic.
tweeters- TW29TXN-B-8
mids- MW16TX-4
woofers- SB23MFCL45-4 (x2) Highly recommended
In my test box I was very pleased with the performance of these drivers. They played nice together. The sound was revealing and allowed you to hear individual interments within the music. They are a bit bright so I needed to roll off the high end a bit between 12,000 and 20,000 hrz and boost the low end starting around the cross over point by about 3 DB to get a good strong base response out of the speaker. These 8 " woofers do a good job at handling subwoofer duties. They use a mineral filled polypropylene cone that sounds great. If you want a warmer sound and will be using a sub for sure and only want one woofer you might want to look at the wool cones of the Silver Flutes. These are well built but inexpensive drivers that perform well above their price point. They may not look like it on paper but I can atest that they have a very clean warm sound and they play well with fabric dome tweeters.
Cheers and have fun building them and try not to get the speaker building bug or these might be anything but your last pair of speakers that you will ever own or build I should say.
A CLD construction does rely on the shear movements between the two outer layers, leading to friction/energy conversion in the constrained damping layer. Bolts will reduce the amplitude, but will also effect the friction in the constrained layer because the shear is reduced. So in essence this setup will not be as 'lossy' as a traditional CLD build (higher Q).
The gains on applying CLD to bass enclosures can be disputed anyway. Sound transmission in loudspeaker enclosures tends to peak at mid frequencies (500-1500Hz), depending on the usual parameters size, stiffness, weight and friction losses. So for a sub up to 200Hz they are more not than often of concern. And besides, the room response likely will be dominant by far: you won't notice the enclosure resonating.
The gains on applying CLD to bass enclosures can be disputed anyway. Sound transmission in loudspeaker enclosures tends to peak at mid frequencies (500-1500Hz), depending on the usual parameters size, stiffness, weight and friction losses. So for a sub up to 200Hz they are more not than often of concern. And besides, the room response likely will be dominant by far: you won't notice the enclosure resonating.
I don't really have a formula for this. Just experience of which gives me the best sound. Most designers will try to put the midrange or midbass into the smallest enclosure they can to make more room for the bass speaker in a three way. This is good if the bass is your highest priority. However, all of the fundamentals for music are in the mid-bass and the lower midrange so I consider this area the most important of the speaker. So I am designing more for best quality sound instead of low bass or power handling.
I have found that aperiodic enclosure size is pretty forgiving. But what gives the best sound is getting an enclosure volume that is close to a critically damped volume for a sealed enclosure or at least 50 percent the size of the critically damped volume. The naturalness of the sound and timbres really open up when you do this. It probably does not handle power as well as having a better air spring behind the driver but the sound is closer to what you get with an open back system. Fast, natural transients. The larger space behind the driver also gives you more room for damping the rear cone acoustic energy. This has to be done or these acoustic forces interact too strongly with the back of the cone and smear the sound quality.
Thanks for your comments. I agree that at least for the bass enclosure and the low bass total rigidity is more important. I have seen a few empirical tests of CLD and the only ones that worked very well were certain kinds of thin center layers and equal mass outer layers. The big problem is that the area from 80-500 Hz is perhaps the most important range for music and if only a small amount of resonance control could be enacted in this range it would be helpful.
I have never seen a test on a panel that is designed like this one and it would be interesting to design one to see how well it performs in a test and what it's waterfall chart looks like.
Please undersand that I am not trying to forgo lots of internal bracing. Lots of internal bracing is necessary for any attempt at the highest quality speaker cabinet. I am just trying to push the boundry of what can be attained with the typical two layers of MDF. I don't know if this would work. I have not followed speaker building much for a couple of years but I have never seen anyone build a cabinet like this and combine it with lots of internal bracing.
If you have any links to any speaker builders on the internet that have done something like this and you have the links and you could post them. I would be much interested in looking at the results.