I’ve had the LS50 meta’s now for a few months and feel these are my endgame speakers (Better than what I’ve owned, BMR, Revel, Focal, Kef R3, PSBs and many more). They’re absolutely perfect in every way except for the bass. So, I want to build a 3-way woofer module of some kind. My space for SUBS is limited therefore a subwoofer stand is ideal. Also, I want it to cross around 200hz with 1st order filter to avoid changing the overall character of the LS50s as the tonal balance is spot on, but want to cross higher than a typical sub to improve max spl and reduce IMD. These are my options and I wanted to see what you guys think. Since nothing is commercially available DIY is my only option.
LS50 measurements (sensitivity ~83.5dB @200hz): https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/
LS50 measurements (sensitivity ~83.5dB @200hz): https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/
- Kits – all have passive crossovers
- Jeff Bagby - https://meniscus.lightningbasehoste...he-Kairos-and-Continuum-Three-Way-Writeup.pdf
- 1.78 cu ft or 50-liter cabinet
- Continuum 3 way module by Jeff Bagby – CSS SDX10 - Might match well with the 83.5dB sensitivity of the LS50M. (Can do ported, sealed or PR.
- Kairos 3 way module by Jeff Bagby – Seems to similar in sensitivity in the crossover regions but a bit more bass below 150z (I can always use DSP to fix boominess etc, and it’s free SPL.
- Troels (SBA10) or CSS bass modules – both of these have sensitivities above 85 dB, so a passive crossover is unlikely to work with the LS50M.
- Design my own
- Crossover - I don’t really have time to tinker for family reasons, so I have to try and get this right on the first try. If I did my own crossover, I would have to do it in the digital domain with a Minidsp 2x4HD.
- I was hoping to make my box taller than the 3 way modules listed above. This means I would end up with a larger internal volume. I could port it or run it sealed or run a PR, but again I have to get this right on the first try. Alternatively, I could use Jeff bagby’s design, increase the height but reduce the depth to keep the same internal volume.
- 12x14x32” = 2.3cu ft or 65 liter cabinet
- Build a passive kit as is
- Can the passive crossover have a detrimental affect on the LS50M impedence?
- Use JBs cabinet design but use a minidsp (someone on another forum said that the minidsp would add delay vs a passive crossover… but from what I’ve read it’s not too different than delay added by a passive crossover)
- Design my own box using a simulator to get the dimensions I want, and use the minidsp for crossover. I have read that the simulations are not accurate re port length etc. So I don’t want to mess this up. (Port noise scares the **** out of me, but I could always stuff the port and use dsp to boost the lows 😊)
Bass will require room dependent EQ anyway so you should use a digital crossover. The most simple approach would be to use a 4 channel amp with built in DSP. Perhaps a Hypex plate amplifier in a box would meet your needs.
If using a box up to 200Hz I would go sealed to avoid port issues. There is then one variable the volume of the box. Try simulating in Hornresp. The low end can be significantly boosted to extend the LF corner using the DSP amp.
If using a box up to 200Hz I would go sealed to avoid port issues. There is then one variable the volume of the box. Try simulating in Hornresp. The low end can be significantly boosted to extend the LF corner using the DSP amp.
I've posted this in a few different forums and yours is the most sane and clear reply! 👍
Im going to look into my plate amp options and try and get some modelling done. If this is the route I'm going, can you suggest any 10" woofer? Or dual 8" woofers that would be appropriate?
You are looking for a woofer with some conflicting requirements (typical engineering compromise). The maximum SPL in the low bass will be dictated by the total woofer displacement which means a high xmax value. Large xmax means that the voice coil will overhang the top plate of the motor (where the magnetic field is concentrated) by a large amount. This reduces % of the coil in the strong field region and decreases efficiency. It also generally results in more mass, larger surround. All this makes a driver less well suited for use above 100Hz and to exacerbate this 'pure sub' drivers often don't include inductance management features like shorting rings. http://www.baudline.com/erik/bass/xmaxer.html this calculator gives an idea of the xmax you will need for a given SPL at a given frequency.
8^2+8^2 = 128, 10^2 = 100 which would suggest dual 8 gets you more cone area (good). I'm not super familiar with Hi-Fi drivers but two of this look good:
https://sbacoustics.com/wp-content/uploads/2020/11/8in-SB23MFCL45-8.pdf (SB23MFCL45-8)
11.1mm xmax if Im reading the datasheet correctly. With 2 of these woofers you should get to around 101dB @ 30Hz/1m according the calculator, more beans than the LS50 meta which is not happy at 96dB/1m https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/ (this is good as if you look at typical 'house' curves you will have ~+10dB (or more) @30Hz W.R.T 200Hz).
8^2+8^2 = 128, 10^2 = 100 which would suggest dual 8 gets you more cone area (good). I'm not super familiar with Hi-Fi drivers but two of this look good:
https://sbacoustics.com/wp-content/uploads/2020/11/8in-SB23MFCL45-8.pdf (SB23MFCL45-8)
11.1mm xmax if Im reading the datasheet correctly. With 2 of these woofers you should get to around 101dB @ 30Hz/1m according the calculator, more beans than the LS50 meta which is not happy at 96dB/1m https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/ (this is good as if you look at typical 'house' curves you will have ~+10dB (or more) @30Hz W.R.T 200Hz).
How tall do you need the module to be? You may be able to find some inspiration on the fullrange forums as there are quite a few woofer assisted wideband designs. Basically sticking a wideband driver on top of a woofer box usually. A nice example is the TL on this thread (although in this case the wideband isn't just stuck on top)
https://www.diyaudio.com/community/threads/10f-8424-rs225-8-fast-waw-ref-monitor.273524/
I'd definitely go with the dsp crossover solution because you can easily tinker with the crossover and match speakers to your room
https://www.diyaudio.com/community/threads/10f-8424-rs225-8-fast-waw-ref-monitor.273524/
I'd definitely go with the dsp crossover solution because you can easily tinker with the crossover and match speakers to your room
Thanks for the reply!
I was hoping to make the unit taller than the bagby version. About 30" or so. The problem is to maintain the cabinet volume and maintain the standard tuning, I would need to shorten the depth to 12" or so.
Is there any detriment to having a equal depth and width? Ie standing waves etc.
I'm not an expert on cabinet design to be honest with you, but I don't think equal dimensions are ever a good thing, unless it's some how intentionally part of the design.
I think the bigger potential issue would be from making the cabinet longer as it could become something like a 1/4 wave TL.
I'm sure someone more knowledgeable would be happy to advise.
You could always just make the design as intended and prop it up with a 30" stand of some kind, or just look at other designs too
I think the bigger potential issue would be from making the cabinet longer as it could become something like a 1/4 wave TL.
I'm sure someone more knowledgeable would be happy to advise.
You could always just make the design as intended and prop it up with a 30" stand of some kind, or just look at other designs too
There's nothing wrong with internally subdividing a box if you want the extra height without increasing volume: [img='[URL]http://www.troelsgravesen.dk/CNO-mkIII/CNO-mkIII_cabinet.png']eg[/URL] from Troels G[/img].
If you want to help mitigate some standing waves, you could put the divider at a 45o angle.
Whether or not you'd have a problem with 2 similar dimensions would depend on your crossover - 12" will yield 1st standing wave at ~560Hz, so if you're crossing over with a steepish slope and well below there (typical of a sub-main integration), you won't really be exciting them much anyway. If you wanted a higher, shallower crossover more typical of a bass-mid in a conventional 3-way, you might just get a little extra colouration from such a standing wave.
The Seas L26roy 10in sub is a very nice driver for the purpose you are seeking.
Couple of example build.
https://vbspeakers.com/olaf-woofer-base-any-speaker
https://www.madisoundspeakerstore.com/subwoofer-speaker-kits/seas-l26roy-subwoofer-kit/
Couple of example build.
https://vbspeakers.com/olaf-woofer-base-any-speaker
https://www.madisoundspeakerstore.com/subwoofer-speaker-kits/seas-l26roy-subwoofer-kit/
Regarding crossover from your LS50 to the stereo woofer modules : imo the most transparent method that is audiophile approved is to NOT use any high pass filter, whether passive or active.
Passive high pass will arguably have less detrimental impact, but the Jeff Bagby 3 way does reduce the impedance of the speaker, and this would change the sound /interaction with the power amp.
An active high pass - this should preferably be done without any additional ADC - DSP XO - DAC... Otherwise this will definitely significantly change /degrade the sound. One way of running active xo is to use the minidsp SHD, which is a built in streamer, Dirac DSP, preamp and DAC all in one. It has 4 analog output, 2 goes to LS50 and 2 goes to the woofer modules.
Imo, an all analogue and arguably most transparent way is to just plug the port of the LS50. This reduces the excursion, which reduces distortion and strain on the coax midbass.
Run the woofer active, with either a passive xo via plate amp, or active XO via minidsp EQ to match the woofer rolloff and delays to the LS50 mains.
My 0.02, hope this helps!
Passive high pass will arguably have less detrimental impact, but the Jeff Bagby 3 way does reduce the impedance of the speaker, and this would change the sound /interaction with the power amp.
An active high pass - this should preferably be done without any additional ADC - DSP XO - DAC... Otherwise this will definitely significantly change /degrade the sound. One way of running active xo is to use the minidsp SHD, which is a built in streamer, Dirac DSP, preamp and DAC all in one. It has 4 analog output, 2 goes to LS50 and 2 goes to the woofer modules.
Imo, an all analogue and arguably most transparent way is to just plug the port of the LS50. This reduces the excursion, which reduces distortion and strain on the coax midbass.
Run the woofer active, with either a passive xo via plate amp, or active XO via minidsp EQ to match the woofer rolloff and delays to the LS50 mains.
My 0.02, hope this helps!
LS50 Metas and Subwoofers......I have four different subwoofers in the house. I've tried them all with the Metas....In every case, the addition of a subwoofer, no matter the cross over point, level, placement, miniDSP, etc....The amazing sound stage and imaging that we all love the Metas for is damaged. The only subwoofer I have that comes close to "helping" the Metas is a B&W ASW608, a little tiny 8" subwoofer. And it is barely activated.
My friend recently bought a pair of Metas and the KC62 subwoofer. But he hasn't even taken it out of the box yet, as he feels the bass responce in his room is plenty good enough. I have to agree.....When audiophile friends have visited to hear the Metas, they always, 100% of the time, think the subwoofer is engaged. Their brain will not allow that a 5.5" speaker in such a tiny box can produce this type of bass.....
I'd like to borrow the KC62 to see for myself.....
My friend recently bought a pair of Metas and the KC62 subwoofer. But he hasn't even taken it out of the box yet, as he feels the bass responce in his room is plenty good enough. I have to agree.....When audiophile friends have visited to hear the Metas, they always, 100% of the time, think the subwoofer is engaged. Their brain will not allow that a 5.5" speaker in such a tiny box can produce this type of bass.....
I'd like to borrow the KC62 to see for myself.....
Like rhapsodee, I would seal off the vented port well with a foam plug of closed cell variety. Thereafter run them full range. Think about some slim and deep subwoofers as stands for the Metas. Follow through with subs about 25cm or so with good Xmax meant for sealed enclosures. Use a miniDSP, get a UMIK and REW and a good class D amp. You need the flexibility of varying crossover points, slope and types and delays and room aspects. The sealed enclosure will allow variance to ideal alignments that can be corrected with the miniDSP.
I ran my LS50's sealed with sealed Satori 9" woofers and a simple plate amp, sounded pretty good.
Until now i played with a pair of Dayton rs225 sealed with LT (35hz, 0.577qtc) in mtm with my 1793 ( sealed too). Xover at 250hz.
With room gain they go low but i find them just enough in overall spl to keep up with the coax ( at max out 1793 can accept without becoming too compromised for my preference, ymmv i'm picky and usualy listen a bit 'louder' than average people in there). I use a classD amp with them (Ucd 180).
It's perfectly usable as is though.
With room gain they go low but i find them just enough in overall spl to keep up with the coax ( at max out 1793 can accept without becoming too compromised for my preference, ymmv i'm picky and usualy listen a bit 'louder' than average people in there). I use a classD amp with them (Ucd 180).
It's perfectly usable as is though.
The LS50 Meta is proving to be an impressively neutral, transparent & detailed speaker. It present a tidier smaller acoustic stage than my Linkwitz Orion, which is not well suited for this acoustically live big room -- 46 by 25'. The differences in bass quality and extension are obvious, but the KEF is still easily involving and more focused. This while driven by a modest Wiim Amp.
The Wiim + KEF combo is amazing, given I paid under CA$1500 for both! With LG smart TV connected to the amp via eARC HDMI, the TV remote controls the amp sound. This ease of control is so much better than the PC/miniDSP spdif complexities with the mult-amp active Orions. For some years now, Netflix/YouTube sound has been a bigger priority than just music alone for this system, so this is a welcome improvement.
The amp also switches automatically to the TV whenever it's switched on. This includes cable, streaming video & music via JRiver on my HTPC. I love that the Wiim Amp custom EQ for dialog intelligibility I created for the LS50 is automatically applied when the TV is the source of the sound, but not the PC.
When the Wiim sub output is engaged, a LR4 filter is applied as low pass for the mono sub & as well as high pass for the main speakers, at the chosen frequency, 30~250 Hz. The 10-band PEQ per ch applies as an input before the crossover, so affects both main & sub speakers. I will try this with a single SB Acoustic 12" driver in 2.5' sealed box & 1 channel of a 300W x 2 D-class amp from Eric A, targeting 140~200 Hz. I hope it gets close to the Orion's bass. Fingers crossed.
The Wiim + KEF combo is amazing, given I paid under CA$1500 for both! With LG smart TV connected to the amp via eARC HDMI, the TV remote controls the amp sound. This ease of control is so much better than the PC/miniDSP spdif complexities with the mult-amp active Orions. For some years now, Netflix/YouTube sound has been a bigger priority than just music alone for this system, so this is a welcome improvement.
The amp also switches automatically to the TV whenever it's switched on. This includes cable, streaming video & music via JRiver on my HTPC. I love that the Wiim Amp custom EQ for dialog intelligibility I created for the LS50 is automatically applied when the TV is the source of the sound, but not the PC.
When the Wiim sub output is engaged, a LR4 filter is applied as low pass for the mono sub & as well as high pass for the main speakers, at the chosen frequency, 30~250 Hz. The 10-band PEQ per ch applies as an input before the crossover, so affects both main & sub speakers. I will try this with a single SB Acoustic 12" driver in 2.5' sealed box & 1 channel of a 300W x 2 D-class amp from Eric A, targeting 140~200 Hz. I hope it gets close to the Orion's bass. Fingers crossed.
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12"+1793 can work ( even 15") but you'll have to lower xover point. This was the case in my experiment from 250hz to 100hz with a 15".
Not bad but there was too much of a step in SD: spl had to be lowered even more and i found i was able to identify drivers location (however this might have been a room acoustic issue).
With 12" i was circa 150hz xover iirc it was ok but the quality of driver used lacked imho ( car audio sub) so i dropped the idea and switched to the Dayton instead.
I could retry though, but 4 way, keeping the 8" and 1793 and add a real 'sub' way. It would make something like 20/100hz on 12", 100/400hz on 2x8", 400hz and up on 1793. I'm not sure it would help with output as there is limit within the coax about level ( they start to be really audibly degraded circa 105db spl/1m) but it could clean up the low mid even further and keep the coax behaviour of MTM and advantages in floor/ceiling bounce territory.
Preliminary test of config were ok.
Not bad but there was too much of a step in SD: spl had to be lowered even more and i found i was able to identify drivers location (however this might have been a room acoustic issue).
With 12" i was circa 150hz xover iirc it was ok but the quality of driver used lacked imho ( car audio sub) so i dropped the idea and switched to the Dayton instead.
I could retry though, but 4 way, keeping the 8" and 1793 and add a real 'sub' way. It would make something like 20/100hz on 12", 100/400hz on 2x8", 400hz and up on 1793. I'm not sure it would help with output as there is limit within the coax about level ( they start to be really audibly degraded circa 105db spl/1m) but it could clean up the low mid even further and keep the coax behaviour of MTM and advantages in floor/ceiling bounce territory.
Preliminary test of config were ok.
I'd follow SEAS KingROY advice, but keeping LS50 in it's original box. Make the subwoofer box as a stand for LSs.
Use line level signal for Hypex FA 2ch amps, install amps hiding inside subwoofer stands. with built-in dsp it's easy to match units, try different xos and handle worst room modes.
https://www.seas.no/index.php?optio...=583:seas-kingro4y-mk-iii&catid=66&Itemid=345
Use line level signal for Hypex FA 2ch amps, install amps hiding inside subwoofer stands. with built-in dsp it's easy to match units, try different xos and handle worst room modes.
https://www.seas.no/index.php?optio...=583:seas-kingro4y-mk-iii&catid=66&Itemid=345