That's interesting.
So do manufactured wave guides, such as the Brandon, take care of the correct baffle shape and positioning of your selected driver?
One consideration which enclosure dimensions may restrict is to have the mid & tweeter offset vertically in order to restrict possible cancellation of reflected sound waves. I think in some designs the the mid & tweeter are fitted towards the outside edge of each baffle to remove symmetry???
Lying the enclosures side ways with your rotating wave guide/mount would achieve this.
So do manufactured wave guides, such as the Brandon, take care of the correct baffle shape and positioning of your selected driver?
One consideration which enclosure dimensions may restrict is to have the mid & tweeter offset vertically in order to restrict possible cancellation of reflected sound waves. I think in some designs the the mid & tweeter are fitted towards the outside edge of each baffle to remove symmetry???
Lying the enclosures side ways with your rotating wave guide/mount would achieve this.
@op, did you consider copying the OSMB?
A lot is happening here, and I am not sure one sees the forest thru the trees. Numerous posts on Vd and SPL, a subject that is quite easily caught in simple iterations (while the boundary and room effects stir that up) don’t exactly help on getting focus. Nor do posts on midranges to be used as woofers. Let alone it is left unclear the means and knowledge to fulfill a design are available. You probably have to deliver at some point. Does this all help?
A lot is happening here, and I am not sure one sees the forest thru the trees. Numerous posts on Vd and SPL, a subject that is quite easily caught in simple iterations (while the boundary and room effects stir that up) don’t exactly help on getting focus. Nor do posts on midranges to be used as woofers. Let alone it is left unclear the means and knowledge to fulfill a design are available. You probably have to deliver at some point. Does this all help?
3d printed, the ongoing open source project by @augerpro. I have access to a guy with a CNC to cut the mid/dome baffle/waveguide from one piece of BB ply. Might have to try it in separate parts to begin.
It might be better to just make the tweeter moveable like in the high end ATC models, but this makes the baffle a bit longer than absolutely necessary.
Yeah, the posts have been very varied, but I can see clearly enough, and my friends are in no rush. I will deliver when the end result is right. Or right enough. ATM, the big choice is between the Dayton 10 sub vs the 18S 12" pro driver. My test boxes are big enough to compare the 2.
The Neumann is a lovely monitor... I heard a comparison with a much more expensive ATC model (cant remember which one) in "Funky Junk" London studio and was well impressed, they really do sound great as near/midfield monitors.
This is a very interesting review of them https://www.soundonsound.com/reviews/neumann-kh310a
" The KH310A is capable of producing 116dB SPL between 100Hz and 6kHz at one metre (for three-percent distortion), and around 105dB SPL between 50 and 100 Hz. That is pretty loud for a nearfield speaker but, more importantly given that this is supposed to be a reference monitor, when delivering a still generous level of 95dB SPL at one metre the total harmonic distortion remains below 0.5 percent for all frequencies above 85Hz. Now that really is impressive. Neumann quotes the acceptable frequency response tolerance as ±2dB, but typically achieves better than ±1dB...
Confirming its 'full-range' status, the published -3dB frequency response limits are given as 34Hz and 21kHz, and the overall response is very well controlled, remaining within a ±2dB tolerance between 36Hz and 20kHz. Returning to the issue of peak loudness, when measured with unmusical pure sine-wave signals, the new KH310A manages 3.5dB more SPL throughout the mid-range and 3.9dB more below 100Hz compared to the O300. This may not sound much, but with normal music material it is claimed to translate into around 7dB more SPL in typical listening conditions — and that really is quite a lot when 3dB represents a doubling of acoustic power! For the head-bangers who still want more, adding the matching (and enormous) KH810 subwoofer removes some of the LF workload from the KH310A, allowing a further 7dB increase in the maximum output level, while also extending the LF response down to 18Hz."
If you do decide to add your 18 inch subs and cross them over around 70Hz this will greatly increase max SPL of the whole system and greatly reduce distortion when you free up the 10 / 12 inch drivers from all the heavy lifting.
I have just ordered a pair Beyma 18 QLEX 1600 Fe...
With 128 watts = 103dB SPL @ 30Hz. Pair = 106dB plus 3dB room gain = 109dB with +/- 3.3mm cone travel (26% of 13mm Xmax). Vb = 69 liters + 8 liters driver = 77 liters.
I have just ordered a pair Beyma 18 QLEX 1600 Fe...
With 128 watts = 103dB SPL @ 30Hz. Pair = 106dB plus 3dB room gain = 109dB with +/- 3.3mm cone travel (26% of 13mm Xmax). Vb = 69 liters + 8 liters driver = 77 liters.
PS I needed to keep the cabinet volume small as possible so am happy to trade sensitivity for happy wife!
If I want to increase SPL I can just feed in more power and accept a bit more cone travel, but to be honest for family room music and movies this is plenty loud!
Art and Jim,
I think I will actually get more room gain / speaker coupling as you explained in a previous post, so the above sim/estimates are conservative but I have not adjusted the Sd / driver diameter as per your suggestions... This is an old sim from last month.... Gave up trying get those Co Drive bass units!
If I want to increase SPL I can just feed in more power and accept a bit more cone travel, but to be honest for family room music and movies this is plenty loud!
Art and Jim,
I think I will actually get more room gain / speaker coupling as you explained in a previous post, so the above sim/estimates are conservative but I have not adjusted the Sd / driver diameter as per your suggestions... This is an old sim from last month.... Gave up trying get those Co Drive bass units!
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It was a review I read a while back. While I accept the subjective analysis and the enthusiasm of the reviewer, it's clear no measurements were made. All the data cited is straight from Neumann. 🫤
I would love to audition the 310s but not sure where in Vancouver or Victoria BC. And the long sessions I'd want with them would probably not be looked on favorably by the retailer. CA$6500/pr here.
They are obviously well designed high performance products. I've set my sights high and with the help of the diy enthusiasts here, I think I can get close. If my bargain hunted components can be used, the pair parts cost will be CA$2500~3000. That's including the Hypex amps.🤞🙏
Conclusion.
I'd suggest reading some of Tom Danley's posts, the work with Georgia Tech and perhaps some AES papers. I recall one about a ~ 900 hp big block chevrolet engine driving 3 superchargers, with the blower output funneled into a concrete two chamber enclosure with variable flaps. In one of the chambers humans were subjected to a high purity sinewave of around 2-3 hz IIRC.
In a vehicle with large displacement subwoofers and a signal chain that is not rolled off it's not really hard to generate 10 hz and lower with enough amplitude that it is audible. No, I am not talking 2nd HD, or 3rd HD being generated.
"..... 900 hp big block chevrolet engine driving 3 superchargers, with the blower output funneled into a concrete two chamber enclosure with variable flaps. In one of the chambers humans were subjected to a high purity sinewave of around 2-3 hz IIRC...."
Some humans... "Stupidity is more dangerous than evil, as evil takes a break every now and then".
Some humans... "Stupidity is more dangerous than evil, as evil takes a break every now and then".
I did indeed try scanning through the insanely long threads. Hard to even read through them all, even harder to keep track of info in them. I need to get systematic about bookmarking when studying such in future.
I chose not to pursue that design because right from the start, it seemed too big for my "clients". It's also built around the Volt 252 mid dome which retails for CA$800 each at Solen before taxes & shipping. >$900 on a single part is too rich for my project, which is also being built around the JA0801 domes, so...
I've actually avoided remeasuring the JA0801s more fully -- I have 4 -- partly because I fear that time will have been unkind to them. That's one of my tasks for this week. 🤞🙏 Might just cut a waveguide to use as a test baffle for the mid domes. Their thick non-circular facia makes it really hard to get measurements free from diffraction, so might as well measure them in the state they are intended to be used.
For the longest time, I dithered between... leaving these old drivers untouched in order to avoid damaging them or modifying them for the best performance they can provide using the latest tricks. Now that I've opted to mount them in waveguides, the front mesh and "acoustic diffuser" need to come off, as the drivers have to be mounted from behind. So now, it's open season on modifications. 😉 I've started experimenting to absorb more of the back wave by enlarging & further damping the back chamber, and with multiple resonance-damping tubes. (Aka, DIY interpretations of KEF metamaterial absorbers used in their coax.)
Or you could just simply do what I did.
Get yourself some high quality headphones rated frequency response 5Hz to beyond 20kHz, plug them into a Low Frequency Oscillator as found on many analogue synthesizer and turn down the frequency. Mine went down to around 0.01Hz, it is used mainly to manipulate control voltages.
You will most likely find like I did that below about 16 to 20 Hz you hear nothing at all any more but you feel an unpleasant pressurization.
Get yourself some high quality headphones rated frequency response 5Hz to beyond 20kHz, plug them into a Low Frequency Oscillator as found on many analogue synthesizer and turn down the frequency. Mine went down to around 0.01Hz, it is used mainly to manipulate control voltages.
You will most likely find like I did that below about 16 to 20 Hz you hear nothing at all any more but you feel an unpleasant pressurization.
Here are some pics of the test enclosures and various drivers being considered.
Clockwise, from bottom left:
1. 90 degree opposed OB bass enclosure for LX521 inspired build. It was abandoned after I discovered how much the cabinets vibrate with bass energy. 180 degree vibration cancellation "W" OB bass is far better in this regard. Two Dayton RSS265HF-8 are still there. They were my original choice for the LX521 clone.
2. 12" Eighteen Sound 12NW430 woofer. Anyone who has seen @Juhazi 's Aino Gradient project will understand the odd way this driver is set up.
3. One of the old Yamaha JA0801 beryllium 68mm mid domes atop the other original enclosure for LX521 bass.
4. Vifa/Tymphany NE265W 10". It's an impressive looking driver.
5. Dayton RSS265HF-8 on test baffle clamped along with back panel, using the original enclosure for LX521 bass. The enclosure is stuffed with at least a pound of poly fibre from a sewing shop (meant for pillows). This test enclosure is easy to set up and take apart; the seal with the clamps and heavy foam weather-stripping along the joins is good enough.
The18S woofer is very well ventilated. Weighs just 9 lbs due to the neodymium magnets.
The internal "V" baffles of the abandoned LX521 bass box were left in place. They brace the sides. Top & bottom panels need better bracing, but I think it's OK for sweeps. For now anyway.
The reference Neumann KH310 has external dimensions of 10" x 15 1/8" x 11 1/2". My text box is way bigger -- 13"W x 23"T x 17". Estimating 3 liters for the driver & internal panels, internal volume is 60 liters -- 50% bigger than the 40 liter target for this build. I will stuff the box with a couple of big blocks of wood or concrete to bring it closer to 40l.
Clockwise, from bottom left:
1. 90 degree opposed OB bass enclosure for LX521 inspired build. It was abandoned after I discovered how much the cabinets vibrate with bass energy. 180 degree vibration cancellation "W" OB bass is far better in this regard. Two Dayton RSS265HF-8 are still there. They were my original choice for the LX521 clone.
2. 12" Eighteen Sound 12NW430 woofer. Anyone who has seen @Juhazi 's Aino Gradient project will understand the odd way this driver is set up.
3. One of the old Yamaha JA0801 beryllium 68mm mid domes atop the other original enclosure for LX521 bass.
4. Vifa/Tymphany NE265W 10". It's an impressive looking driver.
5. Dayton RSS265HF-8 on test baffle clamped along with back panel, using the original enclosure for LX521 bass. The enclosure is stuffed with at least a pound of poly fibre from a sewing shop (meant for pillows). This test enclosure is easy to set up and take apart; the seal with the clamps and heavy foam weather-stripping along the joins is good enough.
The18S woofer is very well ventilated. Weighs just 9 lbs due to the neodymium magnets.
The internal "V" baffles of the abandoned LX521 bass box were left in place. They brace the sides. Top & bottom panels need better bracing, but I think it's OK for sweeps. For now anyway.
The reference Neumann KH310 has external dimensions of 10" x 15 1/8" x 11 1/2". My text box is way bigger -- 13"W x 23"T x 17". Estimating 3 liters for the driver & internal panels, internal volume is 60 liters -- 50% bigger than the 40 liter target for this build. I will stuff the box with a couple of big blocks of wood or concrete to bring it closer to 40l.
Late to the party ... did you find my measurements to the Sb drivers? https://www.diyaudio.com/community/...rxl75-8-vs-sb29nrx75-6-vs-sb29nrx75-8.402671/
I would not use the 10" in a 3 way - but when 12" in closed volume is possible the SB34NRXL is one of the best candidates available. Depending on the needed upper crossover the more expensive ScanSpeak 12" could be preferable.
Your Yamaha midrange ... has a pretty high resonance frequency which doesn't fit to the recommended crossover frequency? Did you make good measurements of the drivers you have on hand?
And most of the big studio monitors use PHL low frequency drivers - for a reason. But they have higher resonance frequencies and are tailored to ported enclosures. As far as I know they area often used in custom versions with a different membrane weight/suspension to get a lower Fs. So not sure if you can find a stock PHL driver fitting your needs - but taking a look is for sure recommended, these one of the few PA drives which behave perfect at lower levels.
yes. It's too bad about the SB 10s.
What do you mean? Recommended by who?
All of the Yamaha mid domes on hand measure 330~365 Hz Fs. Easy to lower Fs frequency and amplitude by increasing the back chamber volume and acoustic damping within. But I haven't measured FR of all of them recently. I suspect 2 are pretty good, and 2 are not so good. Will find out later this week when I have a test baffle ready.
As for a 12", the SB34 -- I have a pair. Just too big at nearly 13.5" diameter. If the 18sound 12" on hand is good the way I've been advised to try it (sealed 30 liter, Linkwitz transform), it is just about usable, the 12.5" diameter will just fit on a 13" wide baffle if mounted from the front.
I really would like to get this box down to about 13 x 21 x 13" external dimensions. It can be done without difficulty with a 10" but 12" is pushing it.
There's the Hypex plate amp to consider. I don't want it to share space with the woofer, which means it will eat up to 3 liters of internal volume. Again, with a sealed system, not critical, but still have to keep an eye on Vbox.
I opened up the test enclosure and discovered I'd actually taken some care to ensure both front and back baffles are sturdy -- a 3/4" MDF piece and rib supports were added to the BB board. (I admit not recalling just when I did this! I checked out my pile of leftover big timber parts from our house rebuild a few years ago and found a triangular piece that fits perfectly to reduce the volume by 10 liters. So the internal volume is closer to ~46 liters. Still high but in a seal enclosure, the Q for the 2 prospective woofers changes maybe 0.05 with another 10 liter reduction.
I checked out my pile of leftover big timber parts from our house rebuild a few years ago and found a triangular piece that fits perfectly to reduce the volume by 10 liters. So the internal volume is closer to ~46 liters. Still high but in a seal enclosure, the Q for the 2 prospective woofers changes maybe 0.05 with another 10 liter reduction.
Oh ok, the datasheet shows a resonance frequency >600Hz.
Yeah, the outside diameter of the SB Acoustics is restricting. Did you have a look at PHL drivers? They are a pain to route but have extremely small outside diameters, 12,1" for the 12".
Here a version with heavier membrane (probably whats used in big studio monitors) https://en.toutlehautparleur.com/br...uce/speaker-phl-audio-4021-8-ohm-12-inch.html
Their traditional Studio series - these should have very low THD also at low levels: https://en.toutlehautparleur.com/br...uce/speaker-phl-audio-4531-8-ohm-12-inch.html
And a long Xmax, modern version: https://en.toutlehautparleur.com/br.../speaker-phl-audio-4310ndu-8-ohm-12-inch.html
They all should need less EQ as the 18Sound, not sure if they fit in the volume you want to use.
There is also an interesting 10" but I would use that with a subwoofer for lower frequencies or plenty of correction EQ: https://en.toutlehautparleur.com/br...uce/speaker-phl-audio-3411-8-ohm-10-inch.html
I have my Hypex amps in separated boxes - just small wooden cabinets. With such a big woofer and 3" coils you can think about the 500W version - the fan only switches on when a lot of power is needed, so they are 100% control room compossible.
No kidding!!! What is the logic behind such a profile? I'd stay away a mile away. Or mount from the rear. But rear mounting takes up more space -- inner width has to at least equal driver frame diameter.
The PHL driver specs look OK but the sensitivity looks low for my purposes. They're hard to get hold of in Canada, which makes them lesser choices for me.
In PA speakers the chassis often don't get sunken and in speaker production a front baffle always get's CNC routed. No problem with the outline in both situations. And you have a smaller footprint of the woofer, can put them closer together, larger roundings etc. In most Studio Monitor uses they just use a decoration ring above it, then you could also use a simple, round routing.
Sensitivity is as high as possible if you want to get some low end? Until you do a LOT of boosting - which is ok but doesn't help with more over all SPL level.
Sensitivity is as high as possible if you want to get some low end? Until you do a LOT of boosting - which is ok but doesn't help with more over all SPL level.