ScanSpeak Revelator 13" subs

[concorde1]

I want to build 2 subwoofers with these drivers: ScanSpeak Revelator 13" 32W/4878T00.

https://www.scan-speak.dk/datasheet/pdf/32w-4878t00.pdf

Commercial subwoofers are over double the price here than in say the USA.
So I think it would be cheaper for me to make them. I have the time and I have done some DIY (my power amp) before.

• 1x driver per box
• I want to use solid wood - not HDF+veneer
• As I will use a MiniDSP Flex, I don't think I need extra DSP?
• If I used a 1-channel external amp, with the power splitting to the 2 subs, I'd lose the individual DSP's for each sub. So I think plate amps are the answer

My room dimensions: 13 ft * 15 ft * 11 ft (l*w*h) - or ~2200 ft³

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Questions:

1. Ported vs Passive Radiator in terms of complexity of design?

2. What would be a suitable Passive Radiator model for this driver?

3. Would Hypex FA501 be a suitable plate amp?

Hypex FusionAmp FA501 with on-board SMPS and DSP

The Hypex FA501 is a 500 Wrms Ncore® amplifier suitable for active subwoofers or a one-way monitor. Output power: 4Ω: 1x 500W, 8Ω: 1 x 270W

www.hypex.nl

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I have WinISD with the ScanSpeak Driver parameters entered ready.

Side note: A Passive Radiator should be able to displace double the volume of air that the driver can, according to https://www.youtube.com/live/-gIN7QjRuGE?si=HM_J4f2Kd9M2RuaC (a bit after 37:40)
This ScanSpeak driver has effective diameter 260mm and Xmax 14mm.

 

[PKAudio]

I created 3way with this scan speak:

Ellips-A 3way loudspeaker

3way DIY loudspeaker project with revelator ellipticor bliesma

pkaudio.webnode.cz

75l closed box, no EQ needed.

Reasonable choices of bass alignment for this driver are following:
- closed ~50-70l, with EQ
- passive radiator, 2x scan speak 30W passive radiators per in box, system tuning ~20Hz

FA501 is fine for this job.

32W is great driver, likely the best in its class.

 

[Davide]

In my opinion, for what the 13" Revelator costs, you can build four units with 12" Discovery and benefit from better bass consistency and max spl in the room.
In fact, I built two of them and I'm very happy with the results.
Otherwise, to get better, it would be advisable to increase the diameter of the driver, for example with a Dayton Ultimax 15" or 18", rather than the 13" Revelator.

 

[Waxx]

And don't use solid wood, it works (change size) wat will make the enclosure crack. As a speaker cabinet must be airtight, solid wood is very hard to do right, even for a pro carpenter. Better use high quality birch ply, or if you can't find it, oak, beech and bamboo ply is also good. Birch of at least BB quality is best. Or use CLD techniques (a mdf box, with solid wood arround it in a second layer).

 

[ppataki]

If you have DSP capability then don't bother with passive radiator or ported cabinet - go for the sealed cabinet. It will yield way better phase response, better impedance graph and waaaaaay lower group delay (=more precise and tighter/'faster' bass)

ScanSpeak drivers are totally overpriced agree with @Davide , I would also go with Dayton instead (15 or 18")

Also agree with @Waxx, don't use wood, use plywood or MDF and make sure that the inside of the cabinet is properly treated (damping sheets, felt, wad and bracing if needed)

 

[Looneybomber]

It will yield way better phase response, better impedance graph and waaaaaay lower group delay (=more precise and tighter/'faster' bass)

Can you quantity any of these? How much better, 1%, 10%, 1000%?

 

[Looneybomber]

The SB Acoustics 12” with the longer throw motor (has an L in the name) has pretty good performance. I don’t know if it’s as good as the Scan Speak, but it may be worth looking at.

SB Acoustics SB34NRXL75-8 vs SB29NRX75-6 vs SB29NRX75-8

I did some measurements today of these 3 drivers in closed volumes. In my measurement room, 0,5m distance groundplane - so there is a little rrom influence left, but good enough for a comparison. Level is corrected for 1m freefield. First SB34NRXL75-8. One of the best drivers I know...

www.diyaudio.com

12″ SB34NRXL75-8 / Norex - Sbacoustics

Hard paper cone for improved piston operation (made in-house), large motor system with under-cut pole piece and dual shorting rings.

sbacoustics.com

The subwoofer version.

12″ SB34SWPL76-4 / Paper - Sbacoustics

Long stroke design, linear high stability suspension, low damping rubber surround, 3’’ copper voice coil, non-conducting reinforced fibre glass coil former.

sbacoustics.com

 

[concorde1]

I created 3way with this scan speak:

Ellips-A 3way loudspeaker

3way DIY loudspeaker project with revelator ellipticor bliesma

pkaudio.webnode.cz

Reasonable choices of bass alignment for this driver are following:
- closed ~50-70l, with EQ
- passive radiator, 2x scan speak 30W passive radiators per in box, system tuning ~20Hz

Congratulations on your speaker build - they look fantastic

Thanks for the guide

1. I'm thinking ~60L box with the 2 30W Passive Radiators, and DSP from Flex.

2. I'm thinking I'll have a Front facing driver. Then Passive Radiators on Left and Right. Plate amp on back.

3. Can I just Centre the Driver and Passive Radiators on their box faces?

4. Is it likely necessary to add weight to the Passive Radiators?

5. According to some reading I've done, a High Pass filter is needed for ported and Passive Radiator subs. Otherwise PR may be overloaded. Would I just set this at about 15Hz?

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Thanks for other comments. I want to stick to 2 subs only. I don't want 15+" drivers. This ScanSpeak seems to be one of the best 13" drivers so I don't mind paying more. It will still cost less than equivalent commercial subs by far I think.

I'm open to cheaper drivers if they have the same performance. But since I'm going to the effort of building subs, I want to overdo it a bit

 

[PKAudio]

60l volume will be fine.
See the modelling for 70l, 2x PR scan speak 30W. 2PRs will keep up with 32W well.
Adding weight will be needed to achieve tuning ~20Hz, I just do not know if indicated added mass is for one PR or total added mass. I will check in Vituix manual, and anyway you will need to verify system tuning by impedance measurement.

 

[voodooless]

If you have DSP capability then don't bother with passive radiator or ported cabinet - go for the sealed cabinet. It will yield way better phase response, better impedance graph and waaaaaay lower group delay (=more precise and tighter/'faster' bass)

If you have DSP, phase response can be fixed. Ported or PR can also yield lower distortion than closed, has much better power handling, and a decent amp doesn't care much about impedance differences. The group delay thing is also a myth. Group delay is a function of frequency response. If you EQ both sealed and ported to the same response, they will sound basically the same. For a closed box, you will already need a high pass to prevent over-excursion. That alone will destroy a lot of the apparent group delay advantage you think you'll have (and phase for that matter, because they are two sides of the same coin). And usually, any room effects trump whatever the box does on its own. In the end, you can get excellent results with either setup, you'll just have to weigh the compromises. Sound quality does not need to be one in either setup.

ScanSpeak drivers are totally overpriced agree with @Davide , I would also go with Dayton instead (15 or 18")

I fully agree there!

Also agree with @Waxx, don't use wood, use plywood or MDF and make sure that the inside of the cabinet is properly treated (damping sheets, felt, wad and bracing if needed)

Yes!

 

[PKAudio]

What is not overpriced nowadays?

32W is likely too good for just a sub duty, but performance is there, no doubts.

 

[voodooless]

What is not overpriced nowadays?

32W is likely too good for just a sub duty, but performance is there, no doubts.

For 700 Euro you can get almost 3x SB Acoustics SB34SWPL76-4, which will perform probably just as well on its own, and 3 of them will be no contest.

 

[Anonamemouse]

And don't use solid wood, it works (change size) wat will make the enclosure crack. As a speaker cabinet must be airtight, solid wood is very hard to do right, even for a pro carpenter. Better use high quality birch ply, or if you can't find it, oak, beech and bamboo ply is also good. Birch of at least BB quality is best. Or use CLD techniques (a mdf box, with solid wood arround it in a second layer).

I have always built my cabinets with solid wood, never has any cracked or split.

 

[ppataki]

Can you quantity any of these? How much better, 1%, 10%, 1000%?

If you put that ScanSpeak driver in a sealed cabinet (red) vs ported cabinet (orange) these will be the differences for impedance, phase and group delay respectively

 

[Davide]

For a closed box, you will already need a high pass to prevent over-excursion

Sorry, what is the reason for this? The problem should rather be with ported under tuning frequency, or am I wrong?

 

[voodooless]

Sorry, what is the reason for this? The problem should rather be with ported under tuning frequency, or am I wrong?

You'll need it for both actually to protect the driver. And both with impact phase and group delay.

In the end, what counts is your in-room response. You don't just hear the group delay of the driver and box, but you'll mainly hear the room. The group delay is dominated by the in-room frequency response. Reflex enclosures usually do not fit very well with the room gain profile, and therefore are generally way too loud down low, giving it the reputation of being slow and boomy. Do proper room correction, and you'll be fine either way.

 

[Davide]

You'll need it for both actually to protect the driver. And both with impact phase and group delay.

In the end, what counts is your in-room response. You don't just hear the group delay of the driver and box, but you'll mainly hear the room. The group delay is dominated by the in-room frequency response. Reflex enclosures usually do not fit very well with the room gain profile, and therefore are generally way too loud down low, giving it the reputation of being slow and boomy. Do proper room correction, and you'll be fine either way.

In a simply sealed design I can understand that the driver can overtravel. However, in the case of an acoustic suspension it shouldn't be possible, right?

 

[voodooless]

In a simply sealed design I can understand that the driver can overtravel. However, in the case of an acoustic suspension it shouldn't be possible, right?

The thing has an Xmas.. so it can overtravel. The lower the frequency, the easier it happes.

 

[Davide]

The thing has an Xmas.. so it can overtavel. The lower the frequency, the easier it happes.

Where does the energy to go beyond the limit come from if the air and the mechanical suspension oppose resistance?

 

[fpitas]

In a simply sealed design I can understand that the driver can overtravel. However, in the case of an acoustic suspension it shouldn't be possible, right?

To set the history straight. Acoustic suspension was simply an extreme example of a sealed box. The cone was exceptionally heavy and the driver suspension very soft. Some modern sub drivers approach that.