Today I have a pair of DIY 2-way bookshelfers + 2 x SVS SB1000.
The bookshelf speakers feature a SEAS W18EX001 for bass/mid and Satori TW29B-B tweeters in a vented enclosure.
My next project is making the system higher WAF, while expanding to a 3/4-way setup.
It’s an active setup and I have a miniDSP DDRC-88D.
I need input on what I need to do going forward, so I’ll lay out my current questions/thoughts/plan.
The “increase WAF” part of the project involves building new A/V furniture (DIY). As a part of this I’ll build two cabinets that can house the SVS subs + 8” woofers for bass/mid-bass.
In the end I’m go play around with the X-overs ofcourse, but I imagine something like 60/800/1600 hz (sub/bass/mid).
None of the above might be ideal, but it’s a question of improving SQ and increase WAF, with what I’ve got at hand.
The bookshelf speakers feature a SEAS W18EX001 for bass/mid and Satori TW29B-B tweeters in a vented enclosure.
My next project is making the system higher WAF, while expanding to a 3/4-way setup.
It’s an active setup and I have a miniDSP DDRC-88D.
I need input on what I need to do going forward, so I’ll lay out my current questions/thoughts/plan.
1. My bookshelf speakers are currently in a vented enclosure. In a 3-way setup, they will only be doing midrange and treble. I don’t plan on doing anything to them, although a smaller and sealed enclosure would be more by the book. What will I be missing out on, NOT re-doing the enclosures? I could put in some port bungs in, but the cabinet volume is roughly 3 x bigger than the optimal sealed box volume.
The “increase WAF” part of the project involves building new A/V furniture (DIY). As a part of this I’ll build two cabinets that can house the SVS subs + 8” woofers for bass/mid-bass.
2. The two SVS SB1000’s will be torn apart and turned into downfiring subwoofers instead. I’ll be reusing their amps, same cabinet volume, filling etc. The distance from woofer to floor will be 4-5.5” depending on final design. Since I have the DDRC-88D I’m not too worried about doing this - but should I be…? I expect the subs to be crossed low (50-80hz). Their placement will be the same as today, which is working out quite good.
3. In the same construction as the SVS, but in it’s own dedicated cabinet I’ll throw in a SEAS W22EX001. What I can’t decide on here is wheter to go with a sealed box or vented enclosure (front ported). Having the subs tell me that a sealed box is the way to go - however the midrange sits in a vented cabinet. Going sealed means a little less room for experimenting on where to cross to the subs - however the subs are sealed box. I prefer tightness and detail above thunder loud bass. What would you do - sealed or vented for the W22EX001?
In the end I’m go play around with the X-overs ofcourse, but I imagine something like 60/800/1600 hz (sub/bass/mid).
None of the above might be ideal, but it’s a question of improving SQ and increase WAF, with what I’ve got at hand.
Should add that for the W22EX001 I can maximum do 38 liters for the vented cabinet. 42-48 liter would be more ideal, but then I won’t have room for the SVS’s.
The W18EX001 are currently in a 25L vented cabinet.
The thing I’ll end up building will be somewhat “inspired” by the CT248XXL.
https://www.lautsprechershop.de/hifi/ct248xxl_en.htm
The W18EX001 are currently in a 25L vented cabinet.
The thing I’ll end up building will be somewhat “inspired” by the CT248XXL.
https://www.lautsprechershop.de/hifi/ct248xxl_en.htm
That is OK. There are no real drawbacks, except that the boxes take up more space than required.
Why? Some woofers will sag when mounted down firing, so that is worth checking. Down firing they will also transmit stronger vibrations to the floor, which can be a good (movies) or a bad (neighbours, rattling, resonating wood floor) thing. The effect on frequency response is minor and can easily be fixed with the DSP.
What is it that you are looking for, that you consider adding a woofer?
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If You keep xo points away from system resonance (that is port freq or sealed resonance freq) then You dont need to bother with Q's, boxes too small or too big.
I concur that making SVS subs subs downfiring gives little benefit for a lot of hassle. You only get added sensitivity but are they not clean enough the way they are?
Also, keep the 8" woofer together with mid/treble module, driver center to center spacing quickly becomes important in the 200-300 range, at 800 hz You are likely to exceed the 1/4 wavel3nght rule of thumb. So if 8" woofers would go into this new AV furniture thing it could provide suboptimal spacing to mids.
I concur that making SVS subs subs downfiring gives little benefit for a lot of hassle. You only get added sensitivity but are they not clean enough the way they are?
Also, keep the 8" woofer together with mid/treble module, driver center to center spacing quickly becomes important in the 200-300 range, at 800 hz You are likely to exceed the 1/4 wavel3nght rule of thumb. So if 8" woofers would go into this new AV furniture thing it could provide suboptimal spacing to mids.
How can I check if they will sag?
I have a fairly large room now and the speakers wouldn’t suffice without the subs. I’ve been trying various XO’s to the subs and is right now running them at 150 hz - and I have made myself believe I will be off better adding a woofer and run the subs much lower.
I don’t have enough space for both adding a 8” and keeping the subs front-firing as they are, so I’ll either have to ditch them or point them towards the floor.
We have hardwood floors although with carpets in various places.
The AV furniture thing for the woofers are merely “bass modules”, the speakers sitting directly on top of them.
I have thought about the distance between mid and woofers, keeping them close. I should be able to keep CC distance around 11”.
… but the 1/4 wavelenght rule was not on my mind.
XO around ~300hz then 🙂
You have the most options with sealed to shape the acoustic roll-off for a crossover. I see only cons for ported in each use case where you want to cross lower, the roll-off is too steep and for the mids there could be port resonances. As you say you could plug the ports. From what I've read that would result in an aperiodic box that could be modeled as sealed with Ql=3.
Here's a sketch for a shallow 200Hz crossover for a 3-way: https://www.diyaudio.com/community/threads/headshakes-far-field-3way.382393/page-5#post-6960189
In your case, you could use Linkwitz-Transform to change the roll-off of your sealed mid to similar Fc, Q and add a similar 1st order HPF. Would be one way to implement it. (Though aperiodic might behave somewhat different than sealed so that it throws off Linkwitz-Transform values.)
The xo between the sub and the W22EX001 could turn into an interesting challange if you want to go beyond an LR4 xo. (Because of group delay for exmaple.) In the case of an LR4 xo, you'd also rely on sealed box response, combined with Linkwitz-Transform if necessary, and a 2nd order HPF to implement the LR4 acoustic roll-off.
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@eibergdk driver Mms can be an indicator of sag, the higher the Mms the more likely sag will become a problem.
Perhaps low values of Qms (meaning stiff suspension) would reduce sag but that's just my hypothesis. Some claim low Qms reduces fine details at low listening levels, I dunno.
This W22 reaches 56 hz f3 in about 20 litre box, really no need to go lower since You have the subs. Save some space and keep those SVS front firing 🙂
Perhaps low values of Qms (meaning stiff suspension) would reduce sag but that's just my hypothesis. Some claim low Qms reduces fine details at low listening levels, I dunno.
This W22 reaches 56 hz f3 in about 20 litre box, really no need to go lower since You have the subs. Save some space and keep those SVS front firing 🙂
I ended up just writing SVS and they said, no problem in pointing the drivers downwards.
I ended up putting the W22EX001’s in a closed 21L. box and the SVS SB1000 also in a 21L. box. Made the exterior of 26 mm. oak and 22 mm. MDF on the inside.
They are heavy as fu… And they sound absolutely awesome, way better than before. I attribute this to 1) cabinet quality and 2) the W22 combo. Currently I’m crossing at 70 hz, but I’ll do some tweaking when I find the time to do it…
I’ll post some photos of the finished boxes - just need to do the front grilles, but I just need a little more practice on gluing the fabric, before I do it on the finals fronts.
Meanwhile some random pics…
I ended up putting the W22EX001’s in a closed 21L. box and the SVS SB1000 also in a 21L. box. Made the exterior of 26 mm. oak and 22 mm. MDF on the inside.
They are heavy as fu… And they sound absolutely awesome, way better than before. I attribute this to 1) cabinet quality and 2) the W22 combo. Currently I’m crossing at 70 hz, but I’ll do some tweaking when I find the time to do it…
I’ll post some photos of the finished boxes - just need to do the front grilles, but I just need a little more practice on gluing the fabric, before I do it on the finals fronts.
Meanwhile some random pics…
