Sure it is, it is coming from the front wall behind the speakers, but you still have the wave from the environment behind you too. It is different, but that does not make it bad. As said, it actually conceals a defect in Stereo reproduction. As you actually have more energy (with similar FR content as mains, but down in SPL level) it averages out more than speakers missing that energy and probably resembles the tonal balance better due to that.
Even most horns feature a delayed wave front (the reflection back through the horn) as seen in the paper from JMLC (may he rest in peace).
Ask around how those horns do and I'm sure some of them will be highly regarded. The more you fight/avoid diffraction, the cleaner it will become.
But other things like the cross talk I mentioned might become more noticable too.
I'm not bashing any of these concepts. I'd rather learn from it and learn why they are as popular as they are. The missing side wall reflections is a big plus for OB!
Even most horns feature a delayed wave front (the reflection back through the horn) as seen in the paper from JMLC (may he rest in peace).
Ask around how those horns do and I'm sure some of them will be highly regarded. The more you fight/avoid diffraction, the cleaner it will become.
But other things like the cross talk I mentioned might become more noticable too.
I'm not bashing any of these concepts. I'd rather learn from it and learn why they are as popular as they are. The missing side wall reflections is a big plus for OB!
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I like that approach, but at the end of the day I also believe that there are things you hear that you really may not measure.... I do have a set of small standmount speakers designed by late John Dunlavy. He had that approach of being instrumental on measuring and making them as perfect as he could by measuring. Then he would start that long process of listening tests that would end up with products that measure perfectly and also have that magic to them.
I guess that poor measuring speakers by no way can sound good
I think ...There may be no full guarantee that well measuring speakers sound incredible
I guess that poor measuring speakers by no way can sound good
I think ...There may be no full guarantee that well measuring speakers sound incredible
We have to listen, that's for sure! But that same listening also made me notice (become aware of) the stereo cross talk.
I've only measured it very recently (*), but when you know or heard what you're looking for it becomes easier to find.
(*) = I actually looked at what the ambiophonic guys said to learn from them first. After having done my first experiments Pano started a thread on the subject and it became quite a study for me.
The hardest thing to account for is that brain of ours. Even our eyes play a role in listening. That brain is trained to listen,
but you can influence its (life long) training by learning to listen. I won't recommend that though, as it might spoil a lot of fun.
I've only measured it very recently (*), but when you know or heard what you're looking for it becomes easier to find.
(*) = I actually looked at what the ambiophonic guys said to learn from them first. After having done my first experiments Pano started a thread on the subject and it became quite a study for me.
The hardest thing to account for is that brain of ours
. Even our eyes play a role in listening. That brain is trained to listen,but you can influence its (life long) training by learning to listen. I won't recommend that though, as it might spoil a lot of fun.
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Looks like we are completely 100% in line and I already learned a lot from you .... and what I know now is that my next project will be so non-compromising .... I will look for the best at every single area
Guess you are showing the rest of us the right way to go here
Thx for all the good input and learning lessons
EDIT: I never fancied horns, even the highly rewarded models, even they seem to have some ”shouty” character to them, I don’t bash them; I just personally don’t like them....
I don’t have that much experience with OB products and I don’t think it’s a discussion for this thread... I just still don’t see how we can get there fully with what type of damping and how much we want, without a combination of measuring and listening, but I understand now you can get really way way far with the measuring part....
I spent my last 20 years going through all sorts of hi-end shops listening to whatever best products they have.... learning a lot and it’s great fun.... highly recommended and it’s for free
Guess you are showing the rest of us the right way to go here
Thx for all the good input and learning lessons
EDIT: I never fancied horns, even the highly rewarded models, even they seem to have some ”shouty” character to them, I don’t bash them; I just personally don’t like them....
I don’t have that much experience with OB products and I don’t think it’s a discussion for this thread... I just still don’t see how we can get there fully with what type of damping and how much we want, without a combination of measuring and listening, but I understand now you can get really way way far with the measuring part....
I spent my last 20 years going through all sorts of hi-end shops listening to whatever best products they have.... learning a lot and it’s great fun.... highly recommended and it’s for free
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I'm pretty sure I don't even know half of what I would need to know (lol).
I may think I know a lot, but that probably isn't true either.
If you get something out of my ramblings I'm pleased with that! Don't trust me blindly, all I want to accomplish is to think about this stuff a little harder. Look at it a little different. I'm fascinated by it and it has payed off in my room to please me.
I'm not in the business to sell anything, that may help.
So take everything with a grain of salt (or at least some doubt) but do know I actually mean what I typed here. But future experiments might prove me wrong again, there simply are so many variables we deal with here.
I mean well, but that doesn't make me right. But I could be!
(that's quite the disclaimer, isn't it?)
I may think I know a lot, but that probably isn't true either
.If you get something out of my ramblings I'm pleased with that! Don't trust me blindly, all I want to accomplish is to think about this stuff a little harder. Look at it a little different. I'm fascinated by it and it has payed off in my room to please me.
I'm not in the business to sell anything, that may help.So take everything with a grain of salt (or at least some doubt) but do know I actually mean what I typed here. But future experiments might prove me wrong again, there simply are so many variables we deal with here.
I mean well
, but that doesn't make me right. But I could be! (that's quite the disclaimer, isn't it?)
I think I understand you very well on these matters
We need to have confidence in what we do and still be open and learn and exchange experiences.
I only built my own speakers once, quite many years ago now and they were insanely overbuilt, d-apollito with Seas softdome and two 13 cm Seas mid woofers using 44mm sandwiched mdf and three layers of bitumen inside, time aligned and phase coherent ... one person could hardly carry them ... Magico and Gryphon: your cabinets are not even close ... it was fun and very rewarding
Sorry, pics don’t exist ... I believe ...
Would be fun to take that approach to subwoofers
Guess I need to call Arnold Schwarzenegger then to help me carrying, and maybe strengthen the floor structurally
We need to have confidence in what we do and still be open and learn and exchange experiences.
I only built my own speakers once, quite many years ago now and they were insanely overbuilt, d-apollito with Seas softdome and two 13 cm Seas mid woofers using 44mm sandwiched mdf and three layers of bitumen inside, time aligned and phase coherent ... one person could hardly carry them ... Magico and Gryphon: your cabinets are not even close ... it was fun and very rewarding
Sorry, pics don’t exist ... I believe ...
Would be fun to take that approach to subwoofers
Guess I need to call Arnold Schwarzenegger then to help me carrying, and maybe strengthen the floor structurally
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Hi all....nice to see everybody having fun, cool things going on
Totally agree with looking at THD to determine pass-off to the subs.
I like to take the mains or line arrays, and measure THD at the loudest I ever plan to run.
Then, using the same SPL level on the subs, measure its THD.
Find THD intersect like we would for normal crossover, and build crossover around that intersect frequency.
A good smell test for this process and what I use to skip THD measurement, is applying the displacement rule....that a 4x displacement increase is needed for each octave decrease to achieve equal SPL.
So working backwards from the bottom up, I start with what kind of displacement do I have at my lowest freq, and decrease that value by 4x per octave up to the chosen crossover freq.
Then compare that calculated displacement needed at crossover (or technically just above crossover where you are relying solely on the main or line) and see if you have the necessary displacement from the line.
As an example, my 18" with sd of 1219 and xmax of 19 has a displacement of 2318cm^3. 24 TC9's with sd of 36.3 and xmax of 2.6 have a displacement of 227cm^3.
For a ratio of 0.098. So starting at 30Hz and decreasing at 4x per octave, I get a freq of 96Hz to be where the line array has the same relative displacement as the sub at it's bottom end.
nc535 could no doubt write the math equation...I have to long hand it lol
So I'd say cross no lower than 96Hz for best odds of low distortion.
A good bet is to raise crossover frequency from there a little, to lessen excursion on the line array, for probably a bit cleaner overall sound. Just have to stop raising xover when sub can be audibly localized.
So for me, without measuring, those are the two xover bounds:
displacement equalization for the low bound,
and sub audibly localized for the upper.
But measuring THD is surely the better way, it's just hard to do with a sub ...
Hope that all made sense...
I mean well
If you ever decide to change your signature that’ll do nicely!
Yep, simple works
You know, ironically, I think the displacement rule of thumb is more applicable to home audio than PA.
I never considered it until tying subs into my line arrays, and then rethinking some of the smaller projects I've worked on that lost clarity in the upper bass when turned up.
My PA boxes all have enough headroom that displacement equalization is mostly immaterial.
imho, the biggest separation between home and pro audio is headroom throughout the spectrum...
First impedance tests (sadly ran out of time to try some damping/filling)
Note that this is a new driver measured at ~11 degree temperature in the garage. Driver has never been powered up before.
Yet these plots do align with the WinISD predictions. Damping will bring down the peak some and shift it to a lower frequency. After all, the net volume of the box will be about 35 liters. I expect some run hours on the sub to bring down it's free air peak closer to spec (19 Hz) as I've seen samples from a friend tested new and after 100 hours (specs did not alter anymore after about 90 hours) come down to that 19 Hz value.
We'll have to wait for another bit to see what I can do with damping. It looks clean aside from some small stuff that I expect to be able to solve with damping. It's already out of band (see ~400 Hz). With a bit of luck it will go down even further after playing enough hours for break in to settle.
Mounting the driver baffle was a joy (not). I decided to use nyloc nuts to fix the baffle together (with some ~1mm neoprene inbetween) and it wasn't fun bolting it down 8 times along the threaded rods. Bought me a ring rattle key wrench to avoid going nuts.
I ran each plot about 4 times, they all look alike, no surprises. I'm pretty happy about being spot on with the predicted peak at ~44 Hz, as damping will bring it down to about 40 Hz (or so I hope).
Note that this is a new driver measured at ~11 degree temperature in the garage. Driver has never been powered up before.
Yet these plots do align with the WinISD predictions. Damping will bring down the peak some and shift it to a lower frequency. After all, the net volume of the box will be about 35 liters. I expect some run hours on the sub to bring down it's free air peak closer to spec (19 Hz) as I've seen samples from a friend tested new and after 100 hours (specs did not alter anymore after about 90 hours) come down to that 19 Hz value.
We'll have to wait for another bit to see what I can do with damping. It looks clean aside from some small stuff that I expect to be able to solve with damping. It's already out of band (see ~400 Hz). With a bit of luck it will go down even further after playing enough hours for break in to settle.
Mounting the driver baffle was a joy (not). I decided to use nyloc nuts to fix the baffle together (with some ~1mm neoprene inbetween) and it wasn't fun bolting it down 8 times along the threaded rods. Bought me a ring rattle key wrench to avoid going nuts
.I ran each plot about 4 times, they all look alike, no surprises. I'm pretty happy about being spot on with the predicted peak at ~44 Hz, as damping will bring it down to about 40 Hz (or so I hope).
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Nice looks good
I assume that any standing waves issues within the box itself will be non-issues as the cabinet is so small That any standing waves easily will be out of the passband of the woofer, I guess that is also what the impedance curve shows
is there something at 55 Hz though?
I assume that any standing waves issues within the box itself will be non-issues as the cabinet is so small That any standing waves easily will be out of the passband of the woofer, I guess that is also what the impedance curve shows
is there something at 55 Hz though?
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I can see Merford does three different types of mats where the TS and KE are the heaviest ones, is there any specific reason you picked TS above KE?
It is not obvious from the descriptions what would fit different use cases
Merford Isomat
Translations, courtesy of google translate...
The Isomat KE plate has been assembled from a polymer filled with barium.There are none in this heavy weight plateheavy metals present.
Isomat TS is a flexible, sound-insulating plastic sheet, justified from thermoplastic, unvulcanized rubbers (EVA copolymers) and mineral fillers
Isomat VM is a sound insulating plastic sheet, made from softf lexible thermoplastic plastic(PVC) with a 0.5 mm thick wear-resistant top layer. The back is provided with a 4 mm resilient layer of PVC foamw hich provides an 'acoustic' decoupling between substrate and insulation board. This also ensures resilient layer ensure that unevenness in the substrate (eg bolt heads,r ivets). Theg reat flexibility means that the material is easy to apply to irregular shapes and round surfaces.
It is not obvious from the descriptions what would fit different use cases
Merford Isomat
Translations, courtesy of google translate...
The Isomat KE plate has been assembled from a polymer filled with barium.There are none in this heavy weight plateheavy metals present.
Isomat TS is a flexible, sound-insulating plastic sheet, justified from thermoplastic, unvulcanized rubbers (EVA copolymers) and mineral fillers
Isomat VM is a sound insulating plastic sheet, made from softf lexible thermoplastic plastic(PVC) with a 0.5 mm thick wear-resistant top layer. The back is provided with a 4 mm resilient layer of PVC foamw hich provides an 'acoustic' decoupling between substrate and insulation board. This also ensures resilient layer ensure that unevenness in the substrate (eg bolt heads,r ivets). Theg reat flexibility means that the material is easy to apply to irregular shapes and round surfaces.
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If I remember correctly, the KE type has jute on one side. I didn't need that. I believe the material is identical aside from that.
So I opted for the vanilla TS mat. It is very easy to cut them to size. All it takes is a simple cut, depth about 1/3 to 1/2 of the matt and break it. As said, it's a dead material and it simply breaks, leaving a very clean and even surface. I've been using a piece of it as a mouse matt for years.
So I opted for the vanilla TS mat. It is very easy to cut them to size. All it takes is a simple cut, depth about 1/3 to 1/2 of the matt and break it. As said, it's a dead material and it simply breaks, leaving a very clean and even surface. I've been using a piece of it as a mouse matt for years
.
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55 Hz, hmmm... for taking a more critical plot I must remember unplugging the laptop and use it on its battery.
If I remember correctly, the KE type has jute on one side. I didn't need that. I believe the material is identical aside from that.
So I opted for the vanilla TS mat. It is very easy to cut them to size. All it takes is a simple cut, depth about 1/3 to 1/2 of the matt and break it. As said, it's a dead material and it simply breaks, leaving a very clean and even surface. I've been using a piece of it as a mouse matt for years
Thx, I think these are interesting products, but only the 6 mm one
Yes, could easily be measurements anomalies, I guess that frequency is not a coincidence