I have just finished CAD and CAM design for a bass module inspired by XRK's SLOB speaker. It is using 8 x 6.5" no name drivers which have similar specs. It will be made out of Paulownia glued planks, since it is actually cheaper, lighter and much stronger than MDF. The finish will be just oil, or maybe some not too dark stain, I yet have to try on some scraps.
It is intended to play below ca 400 Hz with a large horn with DCX464 on top of it (that one will be revealed later).
Tomorrow, I am getting the wood and hope to start cutting soon.
It is intended to play below ca 400 Hz with a large horn with DCX464 on top of it (that one will be revealed later).
Tomorrow, I am getting the wood and hope to start cutting soon.
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Thanks for sharing your SLOB adventure. Using the Paulownia wood is smart compared to MDF - better for you (less toxic dust or gasses) and the environment. I read it can be hard on cutting edges with high silica content so i wish you well with the cutting today. I hope you can share some pictures of your build.
- Finding a driver substitute in Europe is a great find - is there a link?
- is the SLOB driver module the same as the design XRX with the same slot dimensions and frequency band?
- is the wide baffle variation and top plate designed to match and be a stand for the horn?
This is remarkably similar to a design I've been working on. I like it 🙂
I have had in mind a SLOB with a similar aesthetic to the klipschorn, minus shoving them up against a wall of course..
I have had in mind a SLOB with a similar aesthetic to the klipschorn, minus shoving them up against a wall of course..
@kazap I found out that the wood was actually on sale and will not be available any more, so I bought a little extra. I will share the pictures from the build process. The drivers I use have two important parameters - are the correct size and cheap🙂 And Fs is also sort of OK. https://hadex.cz/q311-repro-165mm-65-basovy-8ohm---60w-rms/ Yes, the wide plate is meant as the stand for the horn.
What the hell is a SLOB? Acronyms without an explanation drive me crazy.
me too
slob: a person who is lazy and has low standards "he's a slob and expects others to google slob + audio for them"
https://www.google.com/url?sa=t&rct...art_slob.pdf&usg=AOvVaw2H6X1CSsMcEPPL9Lc6tcMM
I forgot to mention that the slot is the same width (3x18 mm) but the other dimensions are dictated by the driver to be used.
Slot Loaded Open Baffle.
Slot Loaded Open Baffle.
Nice find with the driver. $10 is the most important parameter for most of us when you need sixteen of them. I see QTS is high so they should go low OK and think the slot loading lowers Fs too?
Thats great you scored the wood too.
I posted the link to the classic Nelson Pass article on SLOBs above ...
Hi Pelanj
I just wanted to say that I built something very similar using (6) Peerless W8 12P-12T…which was a buyout driver NP recommended in one of the early threads related to his SLOB article.
https://www.parts-express.com/Peerless-India-W8-12T-12P-8-Paper-Cone-Woofer-12-Ohm-299-068
Their combined Sd was probably equivalent to if not slightly higher than the (8) 6.5 inch drivers you are considering using. They were rated at 91.5 dB…so not inefficient.
I wired them series parallel to create an 8 Ohm load and powered them with a pair of Rotel HT amps that were bridged to about 100 watts each.
I did not get the performance I was hoping for in regards to bass extension or sensitivity. They lacked the midbass impact I was hoping for.
I tried a few other amps and played with level adjustments on my First Watt B5 to try and get things to sound right… but never got where I wanted to be.
I had to try and fill in the bottom end with a Jamo subwoofer much higher up the frequency band than I wanted. It never sounded right.
I suspected that a lot of these problems were due to the limited baffle size I was using to make them manageable in the living room.
I had thought of taking another shot with them by extending the baffle to a “U” shape as baffle size appeared to be the limiting factor.
If you take a look at XRK’s recent design, you will see that is exactly what he did.
I don’t know if you did any modeling in Hornresp/Edge or otherwise. You might want to try that and/or talk things over with XRK.
Just food for thought and sharing my experience.
I just wanted to say that I built something very similar using (6) Peerless W8 12P-12T…which was a buyout driver NP recommended in one of the early threads related to his SLOB article.
https://www.parts-express.com/Peerless-India-W8-12T-12P-8-Paper-Cone-Woofer-12-Ohm-299-068
Their combined Sd was probably equivalent to if not slightly higher than the (8) 6.5 inch drivers you are considering using. They were rated at 91.5 dB…so not inefficient.
I wired them series parallel to create an 8 Ohm load and powered them with a pair of Rotel HT amps that were bridged to about 100 watts each.
I did not get the performance I was hoping for in regards to bass extension or sensitivity. They lacked the midbass impact I was hoping for.
I tried a few other amps and played with level adjustments on my First Watt B5 to try and get things to sound right… but never got where I wanted to be.
I had to try and fill in the bottom end with a Jamo subwoofer much higher up the frequency band than I wanted. It never sounded right.
I suspected that a lot of these problems were due to the limited baffle size I was using to make them manageable in the living room.
I had thought of taking another shot with them by extending the baffle to a “U” shape as baffle size appeared to be the limiting factor.
If you take a look at XRK’s recent design, you will see that is exactly what he did.
I don’t know if you did any modeling in Hornresp/Edge or otherwise. You might want to try that and/or talk things over with XRK.
Just food for thought and sharing my experience.
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Very nice! I actually built a smaller SLOB subwoofer (shown in another thread) and it works fine even without the side wings - and it was even a bit narrower than this design. I have some extra wood to add the wings to the inside if it would be needed.
Your SLOB and horn design is visually beautiful. Its such a pity the SLOB didnt perform well after all your work.
Your SLOB design looks very nice with the unobtrusive side profile in the room. It would be a pity to add wings as it would turn the SLOB into an imposing rectangular box in your living room.
It would be really nice to get good bass out of your SLOB. I think a forum problem solving analysis is warranted. Im no expert so please will the SLOB experts correct my errors.
Issues:
Poor bass output could be from a combo of inadequate dipole baffle length, inadequate driver ability to move air, the amplifier not controlling the woofer, not having adequate DSP EQ to do the lowfreq brute EQ needed while controlling the quarter wave slot resonance.
Controlling the upper mids could be a big issue and overwhelm the bass if:
- the slot depth is deeper for the 8"driver bringing down the 1/4 wave resonance
- the SLOB is being pushed into higher freq to meet the horn
- the Xmax is exceeded down low with high HD into the mids
- theres no measurement mic or DSP XO control
Possible solutions:
- Adding dipole baffle length is easy with wings but may only add a few extra dBs to the lowest frequencies
- Driver Volume displacement capacity can be worked out to find a good driver
- the slot rear could be in-filled with foam to push up its bandwidth
- Hornresp can model the above
- DSP is cheap
- Class D amps directly connected might control high Qts drivers
With driver choice Volume Displacement Vd (at peak to peak displacement) in OB is an indicator of the ability to displace air: Vd total = Ndrivers x SD x 2.Xmax eg one Acoustic Elegance Dipole 12" designed for OB has Vd: 1.26L (p-p)
As a SLOB success guide XRX got good bass dB with GRS drivers with estimated VdT = 8 x 140(?) x 0.3x2 = 0.67L.
For the OP plan with his drivers, assuming the speced Xmax is one way : VdT = 8 x 126.7 x 0.55x2 = 1.12L = 167% of XRX. That looks promising.
With your Peerless India W8-12T 8" Paper Cone Woofer, the Xmax is low:
| Maximum Linear Excursion (Xmax) | 2mm |
VdT = 6 x 212 x 0.2x2 = 0.5L =75% of XRX
So your current driver combo is only moving about 3/4 the air as XRX at Xmax. Could that be limiting bass output? Also Xmax could be easily exceeded with high HD into the mids?
Would a a different 8" driver with better Xmax help? pelangs store link has affordable drivers eg https://hadex.cz/spec/q312a.pdf: VdT = 6 x 209 x 0.45x2 = 1.13L = 225% of XRX assuming the specs are OK for the driver and Xmas is one way and the high Qts can be controlled.
Add a directly connected Class D amp with great dampening to control the high Qts drivers and effortless power plus DSP EQ and it might be the start of an answer.
If you need more SPL you could just use the sealed sub under 80Hz to unload the SLOB and allow it to do higher SPL above 80Hz.
So the first baffle is cut and I have mixed feelings about the wood. The board itself seemed to be fine, but when the holes were cut, it became a bit bendy. I hope the chamber and top/bottom panels will stiffen it up. It also seems to be too soft for just oiling it, so I will most probably finish it with satin transparent lacquer to get a more resistant.
I guess bracing the outer edges from the back will be necessary and in worst case, I will add a layer of 4 mm beech plywood to the outer surfaces. That will be decided when the first one is built fully.
I guess bracing the outer edges from the back will be necessary and in worst case, I will add a layer of 4 mm beech plywood to the outer surfaces. That will be decided when the first one is built fully.
The wood for the first one is cut now. I have read on the internet that small chips can be torn out by machining and they are indeed. Nothing a bit of putty would not fix.
Hi kazap
I don’t want to step on the OP’s toes.
This project may be behind me at this point as I have moved on to AE Dipole 15 driven by Hypex amps in OB using a First Watt B5 and various FW clones I’ve built to drive a variety of speakers above them.
I do still have the panels in the garage.
To answer a few of your questions.
I was using the B5 to split the signals with the SLOB panels.
They were driven at that time with a pair of Rotel HT amps that put out about 100 watts bridged for each channel.
I did not use DSP at the time. I had a miniDSP…but was not happy with its sound quality.
I took gated near field and room measurements in my living room using my U-Mic and REW.
It was obvious that the panels didn’t have the low frequency extension I was looking for. They were only effective for about an octave and a half (maybe) from where I was rolling the horns off at about 150-300Hz.
The slot chambers were just deep enough to allow the drivers to be mounted and the front baffle attached (see pic).
Finding other affordable drivers that I could similarly wire in a series/parallel manner to achieve an 8 Ohm load seems a dead end.
I did come across this GRS driver which wasn’t too pricey at Part Express…
https://www.parts-express.com/GRS-8...MI-tqn_7um-gIVRQJMCh0ZNwVzEAQYCiABEgIkPPD_BwE
Not sure if its a better choice. It has a bit more xmax and is slightly more efficient…albeit 8 Ohm.
I would say that if I was going to give them another shot that I would have to figure out a way to extend the baffles, try another driver and use the hypex amps with DSP.
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Do you need to sand and fill? A soft irregular slot might even sound better - less hard resonance.
The wood is so soft you might like to try different screws on off cuts, to see what can grip the drivers well. A large diameter self tapping screw with no drill hole might grip better?