Help choosing a woofer to anchor my 3-way floorstander

[morbo]

I'm in the planning stages of a new reference speaker to replace my venerable Modula MT. This will be a 3 way design, what I've decided on already is:

Tweeter: Peerless DA25TX
Midrange: Peerless NE149-8
Woofer: ??? with about 2-2.3 cu ft to work with
Crossover/Amplification/driver eq: Hypex FA123 plate amp: 125wpc @ 4ohms, 15 biquads per channel
Desired woofer/mid crossover: 300-400hz (in hopes of mounting the woofer near the floor, mitigating floor bounce/allison effect)

A bit of context about the rest of my system that is relevant:

• Sources are all digital through a nad t758 receiver acting as preamp
• Same receiver provides DIRAC room correction for all channels
• The receiver's bass management is unusual in that it uses symmetrical LR4 slopes for low & high pass
• because of this, I'd prefer both the new 3-way and the subwoofers to be flat to at least an octave above/below the XO point, which I'd like to set at 40-50hz.
• So, I'd like the 3-way to extend (with some light eq if needed/possible) to 20-30hz in-room
• the 3-way will be crossed to 3 x 12" Rythmik servosubs, these will be corner loaded and optimized with a minidsp and Multi-Sub Optimizer
• the room is fairly small, acoustically treated, and gets generous room gain. Listening distance is 12ft. Speakers must be toed-in aggressively due to closeness of side walls

I know this is a lot of preamble! But, I believe context is important and may help inform the choices. Hopefully you're still with me!

Where I am torn is the bass section. I have on hand a pair of Peerless SLS 12" drivers; these are oddball sample drivers I bought from a former PSB engineer. They appear identical to the 830669 except for a double stacked magnet and possibly additional coating on the back of the cone. I also have 4 x of the nomex 830869.

I am leaning to using the SLS 12" drivers, but am a little leery of crossing them so high. I am also open to spending money if the upgrade is enough of an improvement, but am stymied by lack of wide experience with the contenders, and hesitation over the relatively low amount of power available (125w) to the woofer section. I have considered a variety of upgrades to the Peerless drivers, from the RS270P-4 and NE265-4, to SB34 and SB29 NRX, even the Satori and Motus 8" drivers. My priority is musicality with these woofers over output, HT I have well covered with the 3 subs.

At this point I feel like I'm stuck in analysis paralysis, and would welcome any input. What would you do in my shoes? I am open to suggestions here both in terms of woofers used and my general approach to the mid/woofer crossover. TIA to anyone who takes the time!

[JonMarsh]

Take a look at the Satori WO24P- either the 8 or 4 ohm version. Depending on which you pick, sensitivity will be different, may be an aid to matching all the parts. It will work well in 2 cu ft. Suggest modeling it in VirtuixCAD. If you'd like some FRD and Zma files to play with, I have data in a smaller enclosure, 1 cu ft sealed. For crossover development, that is fine.

[5th element]

RS range if you need high performance on a budget. From what I've gathered over the years is that the Vifa NE line have nice motors, but the surrounds on the bass drivers are too narrow and compromise their linearity at high excursion. The SB34NRXL75-8 is an awesome driver but is also a lot more expensive than the RS range.

The Satori WO24 has an exceptionally clean midrange and is narrower than the others. If you want a more svelte cabinet this would be the way to go. You cannot go wrong with the WO24 except for the price verses some RS bass drivers.

The SLS aren't bad drivers but they aren't the cleanest with regards to distortion, especially up higher too, which is where you look like you want to cross to the midrange.

Given that you're using subs I'd either pick an RS bass driver (for price) or the WO24 (for performance).

Of course the proof is in the simulations of bass extension vs excursion vs power required vs cabinet dimensions etc.

Don't forget that you can always modify the high pass placed on the mains bass driver by your receiver using the FA123 to ease integration if the automatically applied 4th order is being a pain.

[morbo]

Thanks for the feedback gents!

The WO24-4 looks like a good fit in all ways but absolute output, I'll model it tonight. It is, however, the most expensive option on the menu (except for the sb34)... Even the motus 8" can be had for a bit less here as it's on sale now. And the RS270p-4 is about 1/2 the price, but then I can't find much feedback or bench testing about it, unlike the others.

With respect to the surround issue on the vifa NE woofers; I had heard this as well, but some folks on the PE board had indicated that this was limited to the 8" variant, and there's a decent amount of positive feedback on the ne265. I did also find a czech design on diyaudio (https://pkaudio.webnode.cz/ev/) where the designer had started an all-satori 3way, but switched out the wo24p for the ne265 due to the wo24p not sounding right to his ear. Obviously all sorts of design aspects could play into that, but it's another data point.

5th, It did occur to me that I can use the fa123 to do some eq on the woofer section. And I intend to do that, to be sure. I do expect that the modest power on tap will limit what I can do significantly. To be honest, the bigger limitation is that Rythmik takes the 'sub' part of subwoofer VERY seriously, and they roll off rapidly above 100hz even with the crossover wide open.

Jon if you wouldn't mind sharing your wo24 files, that would be great! I've never used virtuixcad before, (still on bassbox pro over here) but have been meaning to learn. I believe you've had experience with at least two of the drivers under consideration (satori and motus?), do you think the Satori is worth the price premium over the RS, NE, Motus drivers? I've no doubt it's better than the SLS (at it's pricepoint, it had better be!) but this is my first time drifting into the rare air of high end drivers, my past experiences have been decidedly in the vifa/seas prestige/dayton RS tiers.

[5th element]

Yeah I had seen that thread about the WO24 not sounding right either but that's just misuse of the product. Technically speaking both the WO and NE are low distortion drivers and when used as bass drivers have no cone breakup to speak of. There's nothing left to colour the sound except room integration and linear distortion (ie frequency response). These aren't really driver related but designer related. Sometimes you don't have flexibility to alter things as you want to get things to sound as you want and another driver ends up working better for you.

The trouble with something like the RS series is that the RS225 and RS270 inchers have performance that's extremely good and almost up there with the best. They are also very cost effective. This isn't a problem as per say but you really need to know exactly what it is you want from a 'high end' driver to actually end up with something worthwhile in terms of it actually being a clear improvement.

The WO, for example, has one of the best motors in the world and will offer better non linear distortion. The RS series of drivers have a distortion profile similar to that of SEAS drivers in that they have rising odd order with frequency. If you cross the RS225 and 270 over before this increase then they are exceptional. If you need to crossover higher than this then the WO24s lower non linear distortion (doesn't rise) makes itself a worthwhile thing to have. If you don't need that advantage then there's much less point in using the WO.

You mention the WOs lack of output and by that I am assuming it's relatively low sensitivity? There is the 4ohm version that would work well with the Hypex's ability to easily drive lower ohm loads.

Again I'm just thinking RS270, if the parameters fit. Or finding something more expensive that happens to have just the right combination of parameters and specifications that make its price worth it.

Lets be honest though, we are getting heavy on the scrutinisation here. All of the drivers mentioned in this thread would work well and end up sounding fairly awesome if used right and have the capabilities required. So don't be too hard on yourself but just be objective about your selection. First of all simulate all of your candidates and see what they can achieve in combination with the power output that the FA can provide. Clean bass is usually just a matter of how much excursion the driver has (and whether or not you're staying within it) and clean output power. Clever motor tech and shorting rings don't matter so much here as shear excursion is king. So you can ignore the motor tech when looking at which drivers would suit the best from a bass perspective (say 120Hz and down). See which drivers work best in terms of output, extension and your preferred cabinet size/geometry. After you've seen which drivers would be preferred for the bass see how they compare with midrange performance in terms of the upper crossover point to the midrange. If one of your preferred candidates at handling bass also happens to have better midrange, decide if you like it from a price/performance point of view.

[morbo]

Yeah I had seen that thread about the WO24 not sounding right either but that's just misuse of the product. Technically speaking both the WO and NE are low distortion drivers and when used as bass drivers have no cone breakup to speak of. There's nothing left to colour the sound except room integration and linear distortion (ie frequency response). These aren't really driver related but designer related. Sometimes you don't have flexibility to alter things as you want to get things to sound as you want and another driver ends up working better for you.

Indeed, I suspected that it was an integration problem and if anything would be easier to deal with if one had access to all the options triamping and DSP crossovers allow. I meant this only to mention that the NE265, along with the SB has good anecdotal reviews from experienced DIYers; what it lacks is good bench data, which the SB has lots of.

The trouble with something like the RS series is that the RS225 and RS270 inchers have performance that's extremely good and almost up there with the best. They are also very cost effective. This isn't a problem as per say but you really need to know exactly what it is you want from a 'high end' driver to actually end up with something worthwhile in terms of it actually being a clear improvement.

Agreed - I'm quite happy with the RS180 drivers in my modula MT, they perform admirably in every aspect but absolute midrange transparency. Likewise I've built a 'FAST' type design with the RS225 and the TB W3-871 a few years ago, and the RS225 is a very impresive woofer. Very noticeably better than the Vifa P21, which was the only other 'hifi' 8" driver I had experience with before. The value proposition is, and has been, amazing on the Dayton RS drivers.

The WO, for example, has one of the best motors in the world and will offer better non linear distortion. The RS series of drivers have a distortion profile similar to that of SEAS drivers in that they have rising odd order with frequency. If you cross the RS225 and 270 over before this increase then they are exceptional. If you need to crossover higher than this then the WO24s lower non linear distortion (doesn't rise) makes itself a worthwhile thing to have. If you don't need that advantage then there's much less point in using the WO.

Perhaps then I am approaching this the wrong way; my assumption has been that there is a lot of value in floor-loading the woofer, and crossing it at a frequency that will put both it's floor bounce dip and the midrange's in their respective stopbands. It is possible though, that I have over-weighted the impact of this factor in my design decisions? Certainly it doesn't seem to be something that most, or probably even half, of 3 way designs aim for; whether they miss it by driver layout or by crossover frequency. Is this a less important design consideration than I have assumed? It would certainly be much simpler to cross lower, say around 175hz... and the midrange can certainly take it, though it's distortion starts to rise around there as well. The higher crossover just seems, on paper, like a very elegant situation to the floor bounce dip.

You mention the WOs lack of output and by that I am assuming it's relatively low sensitivity? There is the 4ohm version that would work well with the Hypex's ability to easily drive lower ohm loads.

I was hasty in this remark; I meant it was likely the BEST overall choice, aside from perhaps sheer output capability. I would most likely opt for the 4ohm version for just the reason you stated.

Again I'm just thinking RS270, if the parameters fit. Or finding something more expensive that happens to have just the right combination of parameters and specifications that make its price worth it.

Lets be honest though, we are getting heavy on the scrutinisation here. All of the drivers mentioned in this thread would work well and end up sounding fairly awesome if used right and have the capabilities required. So don't be too hard on yourself but just be objective about your selection. First of all simulate all of your candidates and see what they can achieve in combination with the power output that the FA can provide. Clean bass is usually just a matter of how much excursion the driver has (and whether or not you're staying within it) and clean output power. Clever motor tech and shorting rings don't matter so much here as shear excursion is king. So you can ignore the motor tech when looking at which drivers would suit the best from a bass perspective (say 120Hz and down). See which drivers work best in terms of output, extension and your preferred cabinet size/geometry. After you've seen which drivers would be preferred for the bass see how they compare with midrange performance in terms of the upper crossover point to the midrange. If one of your preferred candidates at handling bass also happens to have better midrange, decide if you like it from a price/performance point of view.

Yes we are Certainly splitting hairs to an extent, and I have no doubt I will be happy with any of the choices. Even the 'custom' SLS; I am listening to one of them in a test enclosure as we speak, sealed, configured as a mono sub between two bookshelves. Crossed at 150hz, I am quite happy with it. Crossed at 300hz, I'm a bit unsure... but it's mono, and I have not given that configuration the full measure/tweak treatment I gave the initial 150hz crossover, so it's not a fair comparison at all.

As for objective comparison, you are so right. My next post will be my attempt to quantify the differences between these. Stay tuned

[morbo]

So taking 5th Element's suggestions to heart; I have spent some time tonight doing sims. You'll have to forgive me the use of BBpro6; I was limited on time and chose to go with what I know. I included as a reference my fallback 'custom' SLS 12" woofers.

All woofers were simmed in the same 2.3 cuft box, tuned to 28hz with a 3" port flared on one side. All drivers are the 4ohm version, and all used factory parameters (with the exception of my custom SLS 12" woofers - those are DATS measured). In all sims that required input power (cone displacement, vent velocity, maximum powers), it was set to 125w. As all drivers are nominal 4ohm, it seemed reasonable to assume they could extract the full rated power. I'm assured by hypex that these amps are not current limited until the load approaches 2ohms, so hopefully this is a safe assumption.

I've included the graphs that seemed relevant, and some datapoints that might be useful. Bassboxpro is not the best tool for graphing, almost no control over axes or size, but hopefully the idea gets across. Group delay was very close between boxes, and in the worst cast (ne265) peaked at 14ms @ 27 hz.

I'm happy to show any other graphs that I can generate or give other info. I'm going to ponder these results for a bit and come back to see what folks think; I'd rather hear unfettered opinions than bias anyone's thinking.

[morbo]

An addendum to the sims above: I incorrectly assumed the maximum acoustic power graph was based on input power, but now I see that it seems to be based entirely on rated electrical power and xmax. I am attaching another graph, the 'custom amplitude' as bassbox calls it, which does consider input power.

Also for anyone interested, I'm attaching the DATS report and images of the 'custom' SLS driver. It is one of the older made in Denmark Peerless's.



Peerless S02-140.pdf

[5th element]

They are all surprisingly similar in terms of extension although it's no surprise that the 12" driver stands out with regards to lower excursion and its ability to soak more power. You definitely need to go with 4 ohm drivers on the end of the Hypex amp. I had assumed the 125 watts was into an 8 ohm load, but this is not the case.

You are absolutely right in that a floor loaded bass driver, crossed over appropriately to a midrange will eliminate floor bounce and increase the effective output of the bass driver. The only caveat to this is that it requires the listener sits a decent distance from the speakers as the largish C2C distance between the mid and bass driver will create issues more in the near field. To put the "floor bounce be gone" idea into practice requires a decent separation between the two drivers and then a reasonably high xover too. At least higher than one would typically want to use with the drivers separated by as much as they are. Some manufacturers go the route of a line of bass drivers down to the ground, so you get a bass driver next to the mid and a bass driver next to the floor.

A bass driver on the floor, or bass driver directly below the mid both have their downsides, a line of bass drivers tries to minimise them even if it isn't as effective at solving the problems each of the others sets out to solve.

Another option that I didn't mention before, because I didn't think it would offer enough extension, would be to use something like an Eminence Deltalite 10" pro driver instead. I've used these myself sealed, but didn't realise how capable they are ported.

The 4 ohm 10" Deltalite works very well in a 2.3cuft box but only tuned to ~45Hz. This driver only has 4.2mm of one way xmax but it's really sensitive. You get an f3 of 43Hz with an f10 of 35Hz, so not as much bass as the others but the sensitivity! It's nominally around 97dB.



You get a response curve that looks like the above and that's with 37 watts into 4 ohms. You're basically never going to run out of power when driving it and it'll go stupid loud in the upper bass/lower midrange with less power compression than the other drivers when driven at equal SPLs.

Depending on how you like to listen (how loud and to what) and the fact you are going to high pass them, plus the subs, you might find the proposition of the extra sensitivity and guaranteed dynamics something that makes up for the lack of absolute extension.

[Jonasz]

Late to the thread but if you don't want to spend for two SS aluminium Revelators per side just go for the RS270 aluversion. Two in parallell gives you more power to equalize with and they're cheap enough.

A very elaborate two part 10" test:

http://www.justdiyit.com/grand-comparatif-de-10-pouces-partie-1/

http://www.justdiyit.com/grand-comparatif-de-10-pouces-partie-2/

[Juhazi]

I would go with the SLSs. Differences are minimal and not likely to be heard anyway.
And i would make them sealed, with some eq that FA has, and crossed LR2 acoustically.

Here is room response of my recent 3-way with FA123 board and sealed downfire SB29NRX-6. It can play terribly loud!

[morbo]

You are absolutely right in that a floor loaded bass driver, crossed over appropriately to a midrange will eliminate floor bounce and increase the effective output of the bass driver. The only caveat to this is that it requires the listener sits a decent distance from the speakers as the largish C2C distance between the mid and bass driver will create issues more in the near field. To put the "floor bounce be gone" idea into practice requires a decent separation between the two drivers and then a reasonably high xover too. At least higher than one would typically want to use with the drivers separated by as much as they are. Some manufacturers go the route of a line of bass drivers down to the ground, so you get a bass driver next to the mid and a bass driver next to the floor.

I had done the math on this at one point using a calculator, and it looked like the midrange, at ~35" from the floor, and the woofer, at ~14" from the floor, at my seating distance, would put the bounce just within the stopband for both if I crossed at 300hz. I'll have to double check the math to be sure.

Another option that I didn't mention before, because I didn't think it would offer enough extension, would be to use something like an Eminence Deltalite 10" pro driver instead. I've used these myself sealed, but didn't realise how capable they are ported.

The 4 ohm 10" Deltalite works very well in a 2.3cuft box but only tuned to ~45Hz. This driver only has 4.2mm of one way xmax but it's really sensitive. You get an f3 of 43Hz with an f10 of 35Hz, so not as much bass as the others but the sensitivity! It's nominally around 97dB.

You get a response curve that looks like the above and that's with 37 watts into 4 ohms. You're basically never going to run out of power when driving it and it'll go stupid loud in the upper bass/lower midrange with less power compression than the other drivers when driven at equal SPLs.

Depending on how you like to listen (how loud and to what) and the fact you are going to high pass them, plus the subs, you might find the proposition of the extra sensitivity and guaranteed dynamics something that makes up for the lack of absolute extension.

I'll have a look at this, thanks! At first blush, the price is right, but on a shallow level it's not my cup of tea in terms of aesthetics And not being great in terms of either absolute max output or extension, it's a dark horse for sure. That said, I've seen great distortion measurements for the 2512, and I am just not very experienced with higher efficiency or pro drivers in general, so I must keep an open mind.

In terms of how loud I listen; not very. I'm more a microdetail, soundstage, and imaging guy than a 'recreate the liver performance at home' guy, if that makes sense.

[morbo]

Late to the thread but if you don't want to spend for two SS aluminium Revelators per side just go for the RS270 aluversion. Two in parallell gives you more power to equalize with and they're cheap enough.

A very elaborate two part 10" test:

http://www.justdiyit.com/grand-comparatif-de-10-pouces-partie-1/

http://www.justdiyit.com/grand-compa...uces-partie-2/

Thank you Jonasz! I will review this test, very thorough and brings to my attention some contenders, specifically the cheaper scanspeak aluminum driver which looks quite decent and is reasonably priced. In terms of rs270 aluminum; it seems low sensitivity to me, and doubling up doesnt help me too much as I have only 125w to play with. But I will consider all these results!

[morbo]

I would go with the SLSs. Differences are minimal and not likely to be heard anyway.
And i would make them sealed, with some eq that FA has, and crossed LR2 acoustically.

Here is room response of my recent 3-way with FA123 board and sealed downfire SB29NRX-6. It can play terribly loud!

I'll take this into consideration as well! The SB29 is a driver I had considered but had fallen off my radar as well, do you know of any bench tests out there for these? I take it you're quite happy with them? If you have a writeup for the speaker you quoted I'd love to see it.

[Evil Twin]

Applying the somewhat dubious concept that you can never have too many options, I would keep in mind an earlier suggestion and consider the RSS315HF-4 - considering Xmax, sensitivity, a stiff cone free of breakup issues in your proposed operating range, and the ability to move air with reasonably low non-linear distortion, a good design is within your grasp...

And it is very black...

But that is true to varying degrees with all of these recommendations. For something even further far afield, consider the BMS 12N630. Hard to source in NA, but in stock at one UK dealer that ships internationally.

I do urge careful consideration of your plan to avoid floor bounce- as Matt wisely notes, integration is a problem, and near field listening not a very good option. I have found through hard experience that building a modular set of test cabinets (woofer and midrange/tweeter combo separate) and experimenting with positioning and in room measurements and listening in mono, one can better evaluate the effectiveness of your planned approach.

Just as in other endeavors, life is what happens while you’re making other plans... experiment before committing to a cabinet configuration. There were a lot of design experiments for the Three way design Study before going with an “established” industrial design- which in practice was not impacted at all with floor bounce response issues.

There are good reasons you see many commercial dual woofer systems with the woofers relatively high off the floor... I suggest you discover some of them for yourself...

https://www.htguide.com/forum/showthread.php?23683-Three-Way-Evil-Design-Study&highlight=design+study

[5th element]

It's funny that the man in the big black tin-can-for-a-head should mention the RS subwoofer because that was also a thought I'd had. I'd chosen to ingore it due to the lack of amplifier power and the assumption that high SPLs were needed.

Mixed messages seem to be coming from you morbo because you keep mentioning a lack of output in terms of maximum SPL but then say you don't actually listen very loud. If you don't listen loudly then you don't really need to concentrate on system sensitivity and max output capability as a design parameter for the choice of your bass driver. Especially because the system is active and driver sensitivities don't need to be matched.

A low sensitivity subwoofer driver with an aluminium cone and decent motor ticks all the boxes. It'll cross cleanly to your midrange driver and will go low to simplify integration with your subwoofers. Either do this in a properly optimised ported cabinet or go sealed plus linkwitz transform. The only thing this won't do is go loud.

Edit - after double checking the RS subwoofer it actually has decent voltage sensitivity and works very well in a 2.3cu.ft. vented cabinet. It also looks great. Let's face it that's important.

Choices choices! And yes the Deltalite looks like crap. Mine are hidden

[Juhazi]

SB29 was used by Trols, 25Hz low-tuned BR suits well too, but box is big. http://www.troelsgravesen.dk/SBAcoustics-10.htm



My speaker with FA123 story is here https://www.diyaudio.com/forums/mult...ml#post5644077
There is 6dB low bass boost, but of course it depends on the room and positioning. Easy piece with dsp! A single speaker can easily play a sweep at 110dB in a room.
I got the idea from Gradient 1.4

[morbo]

It's funny that the man in the big black tin-can-for-a-head should mention the RS subwoofer because that was also a thought I'd had. I'd chosen to ingore it due to the lack of amplifier power and the assumption that high SPLs were needed.

Mixed messages seem to be coming from you morbo because you keep mentioning a lack of output in terms of maximum SPL but then say you don't actually listen very loud. If you don't listen loudly then you don't really need to concentrate on system sensitivity and max output capability as a design parameter for the choice of your bass driver. Especially because the system is active and driver sensitivities don't need to be matched.

It's not my intention to send mixed messages and I will try to communicate better. I've mentioned numerous times that my priority here is musicality and extension over output. That is how I will weight the various criteria by which woofers will be evaluated. That said, max output (under the other constraints of my design) is still a criteria to consider, just a less important one. It's true that my normal listening levels are fairly low, the system will be played loud from time to time, and used for HT. And I'd rather err on the side of extra headroom.

When I've mentioned the max output of the wo24 or the deltalite, I meant relative to the other contenders. The WO24 in particular, I meant looked like the *best* of the lot by more or less every criteria *except* max output (and cost). To be clear about the max output and my needs; I am fairly confident any of these woofers will satisfy my needs.

A low sensitivity subwoofer driver with an aluminium cone and decent motor ticks all the boxes. It'll cross cleanly to your midrange driver and will go low to simplify integration with your subwoofers. Either do this in a properly optimised ported cabinet or go sealed plus linkwitz transform. The only thing this won't do is go loud.

Well, I'm open to the subwoofer driver idea; many of these contenders are sold as 'subwoofers'. The low sensitivity I'm less sold on; given that there are good higher sensitivity choices that make better use of the power available.

Edit - after double checking the RS subwoofer it actually has decent voltage sensitivity and works very well in a 2.3cu.ft. vented cabinet. It also looks great. Let's face it that's important.

Yes it does look the business! And I had also missed the sensitivity, having assumed it was at least 3db less sensitive than this! In fact this looks like QUITE a strong contender, I'll have to read up on it more. I think I had decided to look at the RS woofers over the RSS subwoofers after seeing Zaph mention somewhere that the woofers had lower distortion and could play into the midrange more cleanly, but clearly this was too hasty. The possibility of running it sealed with good extension, even if only as an option by plugging the port, is also intriguing, and may be a better fit with my room gain. As you say, spoiled for choice

[morbo]

Applying the somewhat dubious concept that you can never have too many options, I would keep in mind an earlier suggestion and consider the RSS315HF-4 - considering Xmax, sensitivity, a stiff cone free of breakup issues in your proposed operating range, and the ability to move air with reasonably low non-linear distortion, a good design is within your grasp...

And it is very black...

But that is true to varying degrees with all of these recommendations. For something even further far afield, consider the BMS 12N630. Hard to source in NA, but in stock at one UK dealer that ships internationally.

The 315HF is officially in consideration! The BMS, once freighter fare was paid, would require substantially more credits than the Emperor has seen fit to allocate to this project, and I am loathe to push for more.

I do urge careful consideration of your plan to avoid floor bounce- as Matt wisely notes, integration is a problem, and near field listening not a very good option. I have found through hard experience that building a modular set of test cabinets (woofer and midrange/tweeter combo separate) and experimenting with positioning and in room measurements and listening in mono, one can better evaluate the effectiveness of your planned approach.

Just as in other endeavors, life is what happens while you’re making other plans... experiment before committing to a cabinet configuration. There were a lot of design experiments for the Three way design Study before going with an “established” industrial design- which in practice was not impacted at all with floor bounce response issues.

There are good reasons you see many commercial dual woofer systems with the woofers relatively high off the floor... I suggest you discover some of them for yourself...

http://www.htguide.com/forum/showthread.php?23683-Three-Way-Evil-Design-Study&highlight=design+study

I am taking both of your admonitions on the floor bounce matter quite seriously. I will review the design study carefully, thanks for pointing me in the right direction.

[morbo]

On further consideration, it becomes clear that I need to test a few of the concepts I am referencing firsthand with at least a single channel of test enclosures, before committing fully to a direction. Especially given that I have the means on the crossover side to rapidly prototype and experiment; I even sprung for the Hypex remote control so I can A/B crossover configurations on the fly. I would be well advised to take full advantage of this capability. It will mean some delay in completion, but as we all know, the Emperor will not suffer a rush to completion on a project this important; such approaches reek of Rebel slapdashery! And as we always say in my home galaxy; the Emperor protects

I will update soon with an outline of the approach I will take, what design strategies/assumptions I will be testing, and how I intend to do so.

Thanks to everyone for the input so far, having experienced and knowledgeable folks to talk through a project like this is orders of magnitude more productive than rolling all the possible design decisions & compromises around in one's own head ad infinitum.

[5th element]

A/Bing with DSP at the touch of a button is really the only way to effectively compare one crossover vs another. Aural memory is terrible and if you have two very similar crossovers you wont be able to pick up on the subtle differences unless you can instantly compare one vs another. Getting up to swap between two passive crossovers between songs? No chance. You'll just make a choice based on some preference towards which crossover you think should sound better, rather than does.

I mean okay we're back to the same thing as the bass drivers, all are good contenders and both crossovers would be good choices, it's just nice to have ways of actually being able to pick the better one in a definitive way. Crossover swaps at the press of a button are about as good as it gets and I love the ability to do so - have fun with it!

Juhazi's speaker looks a lot like mine!



Very similar in concept. These are the ones with the Deltalites, one in the top firing up at the sphere and one in the bottom firing at the floor. Sort of a best of both worlds idea. Plus you don't see the Deltalites.

Don't get me wrong about the bashing of the floor mounted bass driver for eliminating floor bounce. It is a good idea. It works well. It just doesn't do well if you want to do near-field listening and most people don't. It is definitely worth trying things out to see how things suit in your environment. You may find that you prefer using two bass drivers, one at the floor, one near the midrange. If you're making test cabinets you could try this out with the 4 Peerless 8" that you have. Then we'd be back to square one for woofer choices but practical experience is worth a 'thousand simulations'. We can talk all day about the potential benefits and drawbacks or each approach but you'll only really know you've made the right choice by trying things out.

As it stands the RS315 gives you something like this...



Looks perfect if you ask me and that's saying something because I don't give praise lightly. With 125 watts @ 4ohms feeding it it just exceeds xmax at 38Hz, making full use of the driver, full use of the amplifiers power. It also appears to have better extension than any of the other drivers and goes plenty loud enough. Heck in room you'll get ~20Hz extension out of it factoring in room gain. In fact the best idea might be to tune it to 20Hz and let the shallow roll off towards low frequencies be compensated for by room gain (apply DSP boost if room gain isn't enough). You'll end up with a true full range speaker. Not that you need it with the Rhythmik subs but at least the extension would ease integration with the receivers high pass.



Zaph has measured the RSS210, which will have a very similar motor to the 315 and its HD is good/excellent.



I mean no, it's not as good as a Satori but very few drivers are!

If a single driver solution suits, so far the RSS315 would be my choice. No you might not completely need its ability to give you 20Hz extension, but at least the flexibility would be there in case you do at some point.

Dayton also do an 8 ohm version of the 315 and the 265 so if you really wanted to push the boat out and use two drivers, sealed, per speaker (one on the floor and one below the midrange) the option would be there. This is getting expensive though. If you find you do prefer dual drivers two sealed RS270s might be best.

Now we have lots of plates spinning in the air. Time to build some test boxes! The irony would be if you find the 4 Peerless drivers to be perfectly acceptable.

[wolf_teeth]

I'd like to also suggest a woofer or 2
- the Peerless SDF250. I think it bests a lot of the others in good ways, and still has some decent sensitivity.
- Eminence Kappalite 3010LF-8 or the 4 ohm model you can still get from the custom shop. These are really good bass performers, and great output! Used to be 290-4516 for the 4 ohm at PE.



Later,
Wolf

[JonMarsh]

I have a pair of SDF250’s and concur with Wolf’s suggestion to take a look and consider.

These days we almost have an embarrassment of riches to choose from, compared with even just 10 years ago.

[morbo]

Thanks again for all the suggestions gents, the SDF250 is an interesting driver, to be sure, but Solen doesn't carry it so I will keep it on the back burner for now. The Kappalite 4 ohm version looks to have some impedance/fr glitches above 200hz, not sure how much to worry about those but the other drivers considered are better behaved, so all else being equal I would probably rank them low on my list for now.

I have taken the advice above to heart, and will now be building test enclosures, both for the woofer section, and a test enclosure for the ne149/da-25tx. The goals of the test enclosure build will be:

- determine if the existing SLS drivers will be 'good enough' for me, as Juhazi suggested they may be. This is certainly worth doing before spending more money!
- test the w-m distances and floor bounce reduction strategy I was planning; I will build the woofer section asymmetrically so I can test both near-floor and near-midrange woofer configuration
- determine if the combination of the ne149/da-25tx will be sufficient to the task; I have heard the da-25tx in a quick and dirty DSP design with the CSS WR125 and was quite taken with them. I have never heard the ne149 outside of break-in testing free-air, full range. So am
going on reputation and measurements. I should have more concrete grounds to go on before committing to the build
- learn to use, and ensure suitability of the fa123 to the task, the way it must be configured in my setup

There is a lot here, and construction on prototype boxes has already begun. The prototyping will not happen quickly though, as I'm rushing to get *something* completed in time for the meniscus diy event this month. Currently I have 3 projects on the go in various states of completion, and this is both the most complex, and the least finished, so it will be lower priority.

As if this weren't all enough, I have received a terse transmission from the Emperor's envoy; it seems the Emperor is not pleased with the level of my construction, and has suggested that if I wish to remain in this galaxy unmolested, I improve it by an order of magnitude. To this end, I have secured access to a laser cutter, and begun learning its ways. I have also requisitioned a large format 3d printer (https://www.youtube.com/watch?v=d7OymY4lVRo) which should arrive any day. It's build volume should be sufficient to allow for printing of enclosure parts, and a variant of the focusing lens and frame I've seen in the Emperor's greatest project. I believe our own dark lord has had success mounting the DA-25TX in such a lens, which I would be wise to emulate.

[bbe22]

but Solen doesn't carry it try here

https://www.digikey.ca/product-detail/en/peerless-by-tymphany/SDF-250F75PR01-06/SDF-250F75PR01-06-ND/7401301

[sfdoddsy]

Applying the somewhat dubious concept that you can never have too many options, I would keep in mind an earlier suggestion and consider the RSS315HF-4 - considering Xmax, sensitivity, a stiff cone free of breakup issues in your proposed operating range, and the ability to move air with reasonably low non-linear distortion, a good design is within your grasp...

And it is very black...

But that is true to varying degrees with all of these recommendations. For something even further far afield, consider the BMS 12N630. Hard to source in NA, but in stock at one UK dealer that ships internationally.

I do urge careful consideration of your plan to avoid floor bounce- as Matt wisely notes, integration is a problem, and near field listening not a very good option. I have found through hard experience that building a modular set of test cabinets (woofer and midrange/tweeter combo separate) and experimenting with positioning and in room measurements and listening in mono, one can better evaluate the effectiveness of your planned approach.

Just as in other endeavors, life is what happens while you’re making other plans... experiment before committing to a cabinet configuration. There were a lot of design experiments for the Three way design Study before going with an “established” industrial design- which in practice was not impacted at all with floor bounce response issues.

There are good reasons you see many commercial dual woofer systems with the woofers relatively high off the floor... I suggest you discover some of them for yourself...

https://www.htguide.com/forum/showthread.php?23683-Three-Way-Evil-Design-Study&highlight=design+study

For those of us with severe cases of attention deficit, could someone summarise the issues with floor level bass drivers?

I've been using separate boundary woofers a la Lyngorf for a while now with good results, but am re-configuring everything.

[5th element]

There's nothing wrong with floor loaded bass drivers. The only problem is the overall distance between it and the midrange. If this is significant then you end up with uneveness appearing throughout the crossover region when sitting close to the speakers due to phase issues. If you never sit close to the speakers then there is no issue. It's all a matter of compromises and what suits your listening environment the best.

Floor loaded, with an appropriate bass to mid crossover, eliminates floor bounce and effectively removes baffle step losses from the bass driver. These two things are very much worth having providing the near-field issues aren't an issue.

[Scottg]

I have a love/hate relationship with floor-loading.

It gives you that pressure increase that's often so badly wanted (to partially off-set) the loss in baffle-step loss. It's also very beneficial for moving the freq. (way) up as far as floor-bounce is concerned as 5th/Matt mentions.


Objective negative could include potential issues with midrange summation/distance (from woofer). This is mostly a matter of filter-type & freq./eq.-correction. You don't want combing effects from widely spaced drivers with near average operation (for both mid. and woofer) screwing-up the linearity of your design (for any given axis).


-still,

(in most "to floor" configurations) It tends to produce a sound that is a little less "free", or often develops less subjective space - typically in image placement with respect to depth (usually in that 150 Hz and up bandwidth). It's sort of like the loudspeaker is saying: "yeah, I'm finally free of the baffle" and then "oh crap, there's the floor". Ironically it doesn't take a *lot of open space between loudspeaker and floor to largely remove this negative effect: it's not an issue with wavelength in relation to floor "bounding".

*6-to-8 inches of lift depending on floor surface is good starting-point. You are still in a bounding condition with virtually all the benefits (and potential detriments), but the sound is changed a bit, usually favorably. Note: this is cabinet lift, if it's the woofer on-baffle extending to floor - then preferably more distance from floor for that woofer.

Note: this seems true in context to loudspeaker baffle as well (..disregarding the floor). Segmenting a cabinet design a'la Green Mountain Audio tends to produce better images, sort of diffraction effect (..and screw the negatives with respect to near reflections, though preferably not). I was once reminded of this by Lynn Olsen with respect to horn/waveguides on top of loudspeaker cabinets: a bit of lift for the horn from the cabinet top usually improves subjective space and imaging overall (..though of course the horn needs to be adjusted for the new angle relative to the listener).


Also, as you go higher in freq. (into the midrange) for the woofer, there is a subjective effect that tends to center images lower to the floor.. BUT it's a pressure dominate effect, as long as the midrange is higher (guess 3+ db) in pressure than the woofer for these higher freq.s then that problem is usually averted.

[Juhazi]

I was a tiny bit worried about W/M integration in my Gradient 1.4 clone (post #17), xo LR2@300Hz, separation is roughly 80cm (30"). Shallow slope helps a lot and if I remember I didn't even test LR4! With LR2 the other driver has significant contribution an octave past xo and this both helps and makes troubles, boundary effects at around 300Hz are relevant eg. distance to front wall behind the speaker. The sound is coherent, the bass is not located on the floor list - because of low order xo transients of eg. bass drum or guitar the harmonics come anyway from the midrange speaker! Humans also have poor vertical localization ability, but we have learned where low, mid and high sounds come from, aural memory "helps" localization (in our mind, which does tricks).

I always use dsp-xo in my projects and it makes easy to try different xo points and types - and to in-room eq. Every loudspeaker suffers from small-room-effects (reflections, interferences, modes), but in my narrow experience downfire bass in a 3- or 4-way is good and easy!

[morbo]

Great discussion on floor loading here gents! I appreciate all the input, will be testing these suggestions myself soon hopefully. In the meantime, progress! 3d printer has arrived, and after getting it all calibrated, have had my first successful usable prints! I got this result on day 3 of fiddling with it, not bad at all I think. No post-processing yet (finishing), this is raw aside from the supports being removed

[Scottg]

-for an FDM print that's excellent! 8)

I'll be going the other direction in print hardware in about 1/2 a year or so (..the build volume on the SLA/LCD's are finally getting bigger.)

[digitalthor]

Any update for the project with the WF223BD?

Edit: Whoops.... wrong thread - sorry 😊