So closed box speakers are pretty much a dead?

[617]

The way this shakes out is that the 8535 requires a sealed cabinet of 1 cubic foot, which is quite a bit for a driver of this size, but it goes all the way down to 47hz! The 8545 on the other hand will give you a flat sealed alignment in a tiny box (.2 cubic feet) but only goes down to about 100hz.

I guess you intended to say, that they go flat (-3dB?) to 47/100Hz. Below that typical roll-off happens. And this is just a 6,5" midwoofer, typical for bookshelf two-way speakers.

That is correct. A sealed f3 of 47hz for an ~6.5 driver is very, very low.

I was curious as to what low EBP drivers existed and I managed to create this list

Manufacturer    Model    EBP
Seas    CA25RE4X/DC    36.4
Visaton    GF200-4    36.6
SB Acoustics    SB34NRX75-6    44.2
Scan-Speak    25W/8565-00    45.5
Seas    CA21RE4X/DC    46.8
Beyma    BF-8R    47.3
Visaton    B200    48.2
Seas    W26FX001    48.8
Seas    P25REX    50.2
Seas    L26RFX/P    51.3
Fountek    FW200    52.5
Visaton    W13E    53.2
Scan-Speak    25W/8567-SE    53.7
Scan-Speak    25W-8565-01    54.3
Scan-Speak    18W-8535-01    54.3
SB Acoustics    SB34SWPL76-4    54.5
Scan-Speak    32W/8878T01    54.6
Scan-Speak    26W/8534G00    54.8
SB Acoustics    SB29NRX75-6    55.3
Scan-Speak    18S-8535-00    55.3
Beyma    12BR70    55.4
Dayton Audio    RS225-8    55.5
Eminence    ALPHA_12A    55.7
Seas    CA22RNX    55.8
SB Acoustics    SB34SWNRX-S75-6    55.9
Beyma    10BR60V2    56.4
Eminence    LAB_12    56.4
Beyma    8WOOFER/P-V2    56.5
Scan-Speak    26W/8861T00    57.6
Scan-Speak    18W-8535-00    57.8
Scan-Speak    26W/4867T00    58.1
Seas    A26RE4    58.1
SB Acoustics    SATORI WO24P-8    59.8
Peerless    HDS-P835026    59.8
Visaton    TIW200XS    60.0
Seas    L22RNX/P    60.5
Scan-Speak    21W-8555-00    60.6
Scan-Speak    21W-8555-10    60.6
Seas    W22EX001    61.0
Scan-Speak    26W/8867T00    61.3
Scan-Speak    26W/4534G00    62.2
Beyma    8BR40/N 8Ω    62.5
SB Acoustics    SB23NACS45-8    62.5
Vifa    M17WG09-08    62.6
Seas    W21EX-001    63.3
Dayton Audio    RS225-4    63.5
Seas    C16N001/F    63.8
Seas    Exotic F8, 8 ohm    64.0
Scan-Speak    18W/16531G1    64.3
SB Acoustics    SB29SWNRX-S75-6    64.5
Dayton Audio    RS180-4    65.1
SB Acoustics    SB23NACS45-4    65.7
SB Acoustics    SB23NRXS45-8    65.9
Seas    W26FX002    66.0
Scan-Speak    25W/8561    66.4
Seas    L16RN-SL    67.3
Eminence    LAB_12C    67.6
Seas    W21EX-002    68.3
Visaton    KT100V    68.5
Seas    W18E001    69.4
Scan-Speak    22W/8534G00    69.8
SB Acoustics    SB17NAC35-8    70.0
Scan-Speak    21W-8555-01    70.4
Wavecor    WF223BD02    70.4
Visaton    W170S-4    70.6
Dayton Audio    ND140-8    71.5
Scan-Speak    18W-8531G00    71.8
Scan-Speak    22W/8857T00    71.9
Seas    Exotic F8, 4 ohm    72.1
Seas    L22RN4X/P    72.4
Vifa    BC18SG59-08    72.5
Seas    CA26RFX    72.5
Scan-Speak    15W/8530K01    72.7
Vifa    P22WO03-08    73.0
Vifa    NE265W-08-HS    74.1
FaitalPRO    10FE200    74.3
Seas    21F-WB    74.5
Visaton    BG20    74.5

 

[600lbs of Sin]

FWIW, I have Revel f208’s and use the foam port plugs that came with them. I pair them with 2 JL audio e112’s (sealed). Along with the phase knob on the sw’s, its the first time I have been able two get subs and mains to play in unison. I also run the mains full range with a 2 channel preamp. No eq or dsp. Formerly I tried several different ht preamps with dsp/room correction/eq and those options didn’t sound remotely as good as my current set up. I would explore dsp/room correction/ eq again, provided it doesn’t ruin the transparent sound I have now. Yah know, 2 steps forward 3 steps back. I’ll take suggestions, otherwise I’m super happy with my current set up.

 

[JohnBooty]

The efficiency bandwidth product, or EBP of a woofer, is the ratio of the driver resonance frequency and it's electrical Q.

http://redspade-audio.blogspot.com/2011/03/efficiency-bandwidth-product-ebp.html Good article outlining the issue.

EBP < 50 - use only for a sealed box
EBP 50 - 100 - can be used in either
EBP > 100 - vented box only

Most drivers are in the middle range - drivers which are around 50 or below are pretty unusual. In the middle range, you get the tradeoffs seen in my graphs earlier - vented box is big but not ludicrous, sealed box is less efficient at producing bass but is half as big. For your average midbass, plugging the port will result in an essentially sealed, slightly oversized enclosure, which works fine.

The SS 8535 has a Qes of .46 and a Fs of 25hz, resulting in an EBP of 54, close to the low end of normal.
For comparison, the SS 8545, essentially the same driver, has a Qes of .22 and a Fs of 25hz, resulting in an EBP of 113, strongly suggesting a vented box.

The 8535 (sealed friendly) is a bit less efficient. That tends to be the tradeoff, often called Hoffman's iron law, as of yet unviolated, that between high efficiency, small enclosure size and low bass extension you can only have 2 of 3.

The way this shakes out is that the 8535 requires a sealed cabinet of 1 cubic foot, which is quite a bit for a driver of this size, but it goes all the way down to 47hz! The 8545 on the other hand will give you a flat sealed alignment in a tiny box (.2 cubic feet) but only goes down to about 100hz.

Wow, my friend. Thank you so much for taking the time to explain that. In a wonderfully clear way, no less. I really appreciate it.

 

[Burning Sounds]

Good post, @617.
For reference, here is what may be possible at normal listening levels (< 85dB SPL) using a so-called Linkwitz Transform (afaict, he did not invent this) on a 10" Dayton RSS265-HF in a 30L (1 cu.ft) sealed enclosure. I moved the -3dB cutoff down to 20Hz and shifted the Q to 1/sqrt(2).

I'm curious as to why you think Linkwitz didn't invent the "so-called Linkwitz Transform" - as far as I remember it was first published in an article he wrote in one of the first editions of Speaker Builder magazine - but maybe you know of it being done by someone else at an earlier date?

 

[Juhazi]

LT has became almost synonyme to low end boost, but it is actually a circuit design, analog eq device
https://sound-au.com/project71.htm
https://sound-au.com/linkwitz-transform.htm

With DSP user has freedom to make custom application with specific driver, box, tuning, low cut etc.
The boost doesn't come free, more power is needed so more excursion and distortion!

 

[March Audio]

I think a lot of the sealed appreciation comes from how those two curves interact with real rooms, particularly small rooms with solid walls. I've noticed I often end up using DSP on ported speakers that isn't that far from what sealed would do. Plus you can tune the bass a bit with distance to wall, where they like the wall support more than ports do. Basically I'm convinced it's at least 90% frequency response that people respond to between the systems, as with most off hifi.

Indeed, don't forget the boundary gain which compliments the sealed roll off. I find my preference is for sealed.

 

[dc655321]

I'm curious as to why you think Linkwitz didn't invent the "so-called Linkwitz Transform" - as far as I remember it was first published in an article he wrote in one of the first editions of Speaker Builder magazine - but maybe you know of it being done by someone else at an earlier date?

The technique is a general one - Frequency Compensation, or pole/zero compensation is commonly used in DSP/Control Theory.

Given a transfer function, H = B/A, devise a filter to (in this case) alter the system's resonance characteristics (frequency Fs and shape Q).
Let this compensating filter be F = A/X, where the design resonance conditions are described by X.
Then, filtering H in series with F gives, Y = H*F = B/X. We've replace the system's intrinsic characteristics with our more desirable set.

 

[Deleted member 2944]

I believe the analog implementation with a single op-amp was demonstrated first by SL. I don't recall seeing this form of bi-quad equalizer before the Wireless World article in 1978.

At that time CD's were non-existent and LP rumble issues were a significant effect to be considered with bass-boosting of this sort. Vertical rumble cancelling via a summing scheme was incorporated in the first iteration.

Dave

 

[jhaider]

The efficiency bandwidth product, or EBP of a woofer, is the ratio of the driver resonance frequency and it's electrical Q.

http://redspade-audio.blogspot.com/2011/03/efficiency-bandwidth-product-ebp.html Good article outlining the issue.

EBP < 50 - use only for a sealed box
EBP 50 - 100 - can be used in either
EBP > 100 - vented box only

Those rules apply to low frequency in a passive system. They fly out the window if you have processing available. In a processed system, you can use a higher motor strength driver in a closed box and EQ below cutoff to extend the bass. Excursion for a given output is the same either way. Only the power requirements change. Sensitivity and efficiency may not correlate as expected in such alignments, so less power than expected may be required for a given excursion. Data-bass has good information on this phenomenon.

 

[dc655321]

I believe the analog implementation with a single op-amp was demonstrated first by SL. I don't recall seeing this form of bi-quad equalizer before the Wireless World article in 1978.

I would believe that SL pioneered or introduced the idea of this filter to the audio domain.
But, as I'm sure you're well aware, control theory and dsp does find use beyond this one application space

 

[Soniclife]

Indeed, don't forget the boundary gain which compliments the sealed roll off. I find my preference is for sealed.

Have you decided which way you are going to go with your speakers?

 

[Ron Texas]

NHT has some reasonably priced sealed bookshelf speakers:

https://www.nhthifi.com/products/16...r?category_id=1964854-surround-speakers#specs

And towers:

https://www.nhthifi.com/products/16...aker?category_id=1964844-tower-speakers#specs

 

[chebum]

The boost doesn't come free, more power is needed so more excursion and distortion!

Not much power is needed. Max volume is mostly limited by excursion capabilities of the driver. Here is a simulation for Peerless 830452 subwoofer:

You need just 37W to exceed its excursion capabilities (12mm one side, or 24mm peer-to-peer). On my chart power consumption exceeds rated 150W at 250Hz, but nobody listens to them that high. Only frequencies below 100Hz matter. Below 100Hz, you will need less than 40W to get to the limit of linear cone travel.
On "Power" chart blue line is Watts, gray line is VA.

 

[Ilkless]

Since there was some Scanspeak talk above in this sealed speaker thread, thought I'd share about the Opera Seconda SE (3k euro/pounds retail price). It uses OEM Scanspeak Classic midwoofers and the Scanspeak-built version (D2608/9130) of the HDS tweeter (the latter a very robust high-end tweeter) in a sealed floorstanding enclosure. I was damned impressed with these at a local store. They sound good, look great and are stunningly built (in Italy to boot, with Danish drivers!)

I can't think of any speaker that offers the combination of well-engineered sealed, floorstanding, built in Europe, robust (45kg), beautiful (wood and leather like Sonus Faber) for the price.

They also measure very well, but data available is only out to 30 degrees, though the unusually good vertical performance for a non-coax is promising (+/- 1 to 1.5 dB throughout the listening window; black curve is with grille):

 

[mhardy6647]

A pair of old socks can turn most existing BR speakers into sealed ones

Actually, more like lossy (aperiodic) damping

High sensitivity is not a must, watts are cheap.

Yeah, but, unfortunately, good quality watts (still) ain't cheap.

 

[MattHooper]

View attachment 44147

Since there was some Scanspeak talk above in this sealed speaker thread, thought I'd share about the Opera Seconda SE (3k euro/pounds retail price). It uses OEM Scanspeak Classic midwoofers and the Scanspeak-built version (D2608/9130) of the HDS tweeter (the latter a very robust high-end tweeter) in a sealed floorstanding enclosure. I was damned impressed with these at a local store. They sound good, look great and are stunningly built (in Italy to boot, with Danish drivers!)

I can't think of any speaker that offers the combination of well-engineered sealed, floorstanding, built in Europe, robust (45kg), beautiful (wood and leather like Sonus Faber) for the price.

They also measure very well, but data available is only out to 30 degrees, though the unusually good vertical performance for a non-coax is promising (+/- 1 to 1.5 dB throughout the listening window; black curve is with grille):
View attachment 44148

Interesting to see these speakers brought up here. Though I’ve been aware of opera speakers they haven’t been on my radar. But I encountered that model playing at the recent Toronto audio show and...wow!..to my ears some of the most impressive sound of the show. Super clear, clean, yet not lean, a nice rich quality. Would love to hear them again with my music. (And I may do that - a local store sells them)

 

[Ilkless]

Interesting to see these speakers brought up here. Though I’ve been aware of opera speakers they haven’t been on my radar. But I encountered that model playing at the recent Toronto audio show and...wow!..to my ears some of the most impressive sound of the show. Super clear, clean, yet not lean, a nice rich quality. Would love to hear them again with my music. (And I may do that - a local store sells them)

US pricing is $4k, but Sonus dominates the wood-and-leather-Italian speaker sector when there are in fact many more brands. Opera, Chario, Diapason, Care Orchestra, Rosso Fiorentino and maybe even more.

It also shows luxurious Italian build does not have to come with eccentric design choices (eg. Sonus Faber in the 2000s). Did some digging, turns out there were three versions of the Seconda: a flat baffle one, a sealed one with the faceted baffle, and the current Seconda SE with twin reflex ports, but still purport to work well with ports plugged. I find that a disappointment because a well-designed sealed floorstander with good pricing is a very rare thing on the market. The previous gen with the faceted baffle and sealed construction was a rare and beautiful beast. I wouldn't hesitate to get a set if it were in closeout on favour of the new reflex one.

 

[q3cpma]

Why is everyone mentioning only group delay and not cumulative spectral decay when talking about a resonance based system?

 

[Ron Texas]

Like vampires, nothing in audio is really dead. People still buy tube amps and listen to vinyl. Sealed speakers, while rare, are still around. It's possible they could get popular again.

 

[JJB70]

Aren't the Harbeth P3ESR speakers sealed? They're superb, I was very, very tempted to buy a pair last year but in the end couldn't really justify the 3x cost relative to the Technics I ended up buying.