Closed box

[Thom]

Time and again I read that a closed box will actually have less distortion, be cleaner, I think I've captured what I think I've read, than a reflex box but you loose efficiency. So one would expect all PA stuff to be reflex or horn and it pretty much is. But, with the power and efficiency and power handling available I would expect many closed box solutions for home use and except for the occasional recommendation to close the hole in the 100 I don't seem to see any.
Every time I think I see something every one else has missed I fall flat on my face so I'm guessing I missed something. Would someone explain. I'm pretty sure I didn't misread but I may have misunderstood.

[Zilch]

A driver must be appropriately designed to function optimally in an closed box. JBL didn't make many woofers that are suitable for such application:

http://audioheritage.org/vbulletin/showthread.php?t=12036

Of note, however, the current Performance Series is closed box, exploiting some of the advantages you mention.... :thmbsup:

[Thom]

I guess I had in mind maybe le14 but in particular LE15A and 2245 so you use it it's just sort of like lp's and CD's. You can't hear a difference if you put your CD deck on your chess board on 4 water tumblers etc. Closed boxes arent as much fun. I'm at least partly kidding I "grew up" with speakers you had to use the cabinet on but it just seamed like there wasn't any reason anymore. Given enough speaker and amp for the room. Plane box was what I had in mind. More infinite baffle than acoustic suspension but I guess not exactly maybe. Do you need some support for an LE15A or a 2245? Seems a low filter could be important but probably less without a turntable. Yes/ no?

[moldyoldy]

Zilch provided good insight in his thread on sealed systems. Generally (but with exceptions), sealed offers lower distortion (no port boom), accurate transient response (better control/less overshoot/less stored energy), and potentially-lower cutoff (system resonance produces the LEAST cone motion, so Fb is no longer the low limit, and current dissipation replaces displacement as the SPL limit). The cost is considerably lower sensitivity (but greater power handling) and usually the need to provide EQ boost to get down where you're going.

Sealed systems are power-hungry, so they weren't very practical until transistors made bulk power affordable (which is ironic as the damping characteristics are better suited to tubes). AR made the first big waves for consumers, and several others improved on the art. I think the fact that they need EQ/LF boost eluded most consumers, so when Joe Blow took them home to replace his old reflexs, he was often disappointed. Your old buddy Roger Russell designed what I consider one of the best sealed systems (the ML series), and made an EQ system (+3 to +17dB at 20Hz) specifically for them that took them flat to 20Hz in most rooms. Unfortuneately, the EQ was optional, and lots of speakers went out without them. I've got a pair on the workbench (with the EQ) that I use for all workbench needs, as they're pretty much full-band flat.

[Thom]

Not quite on subject but every mac speaker I ever listened to, and I was seriously looking to buy something. Sounded to me like it needed a tweeter. I don't know if I was comparing it to JBL's with the tweeters turned up but they all sounded like they would have been the answer to the hiss on my Revox at
7 1/2 ips.

[Zilch]

Do you need some support for an LE15A or a 2245? Seems a low filter could be important but probably less without a turntable. Yes/ no?2245 is on the "intermediate" list, and should work.

Early S7 systems with LE15A were closed-box, but they don't model well. I'd have do do some refoams to hear how they actually sound.

[Ain't gonna happen; it'd drop their value by half.... :( ]

[Thom]

2245 is on the "intermediate" list, and should work.

Early S7 systems with LE15A were closed-box, but they don't model well. I'd have do do some refoams to hear how they actually sound.

[Ain't gonna happen; it'd drop their value by half.... :( ]

??? You have LE15's with good Lansaloy or whats the "drop there value by half?
I've seen listed an LE15 (notice no suffix) the rest of the description sounds like a 30 frame and magnet. Could be a misprint for all I know as I've never seen one but I've seen it in print a couple of times. Most generally if there is an A there is something without one but sometimes if there is going to be a B there will be an A. Never saw an S7 without ports or an R but then I've never seen lots of things. Never saw an old man looking for a "good 5 watt amplifier but I hear he used to exist. I think I should have already quit.

[Zilch]

I believe the earliest LE15s had no suffix; that can be ascertained in the Library catalogs, probably.

The earliest Olympus S7 and C50SM were closed box. Superbee and I each have a pair. I have a second pair which I converted to ported three-ways years ago.

I have never pulled the drivers on my originals, so they may be LE15, but I'm callin' them LE15A for now.

The Lansalloy is intact, yes. I'll probably treat them with brake fluid for resale. For now, I'm not going to play them, lest the surrounds crack.

If I put new surrounds on them, their value would likely drop by half, yes....

[Joe Alesi]

Hello Thom,

If you are interested in closed box subs try the NHT1259. I have these, they sound good, but need power. They are designed for closed boxes, fs=20Hz, long excursion, 300W?. They are listed in WinISD for modelling. That said I adore the 2235 and 2245 with eq.

Best
JA

[Maron Horonzakz]

Putting brake fluid on LE 15 will drop value by two thirds.....Thom I,m an old guy with 5 watt amps & proud of it ( strapped to Klipschorns);)

[Zilch]

Putting brake fluid on LE 15 will drop value by two thirds.....We'll see.... ;)

Last pair with Lansalloy surrounds I shipped, they didn't make it to Hong Kong intact.

The buyer was kinda unhappy, to say the least.... :(

[Thom]

Putting brake fluid on LE 15 will drop value by two thirds.....Thom I,m an old guy with 5 watt amps & proud of it ( strapped to Klipschorns);)

I guess I was referring to the father of your speaker who tho a pioneer apparently became stuck in a rut but the referral was probably out of place. (not necessarily wrong, just wasn't any reason for it to be there) I was particularly thinking of some excellent JBL drivers that it would seem would be well suited for closed box but I haven't tried it and I never see anyone write about it. I realize that there are tons of woofers out there that people use closed box but some of them have efficiencies such that if you were playing them and then pushed the mute button and hooked them up to a JBL they would drive you from the room without ever taking the mute off. At this point perhaps 12 ga speaker wire does effect performance. There is a certain amount of sarcasm there but not that much. I do thank you for the recommendation. I guess I want(by now some may have guessed I don't always finish things. But if my wife threw me out she would have to figure out what to do with all this stuff and she might not be able to make the TV talk) A clean system that will sound as good as some things I threw together when I had less money but a lot more real estate for the speakers to occupy. One setup I had if you were playing it at moderate volume and you put the flip side of the JG album with the synthesizer on the cover about 30 seconds in it about threw you out the window if you weren't expecting it. I want to be able to do that but I want to be able to accurately play any music I want and If I had the money and you could buy it off the shelf plug and play, I don't think I could do that. I'm still not sure why I bought the 2435's (more than one pair) except that they seemed like such a steal. Who knew that they would keep being there?

My experience with the brake fluid is that once you have the compliance you are looking for, if you don't do something to clean it off as well as you can it will continue to work and you can end up with compliance you never dreamed of. I applied it less than a year ago and I really don't expect much longevity, though I have seen others write in disagreement. I used a small artist brush. Perhaps this is to generous a quantity and one could do better with the corner of a hand kerchief. I don't know. I know I would only do it to a surround that I was going to replace anyway.

[Zilch]

I was particularly thinking of some excellent JBL drivers that it would seem would be well suited for closed box but I haven't tried it and I never see anyone write about it.HUH?

Have you got me on "Ignore?"

Also, I have offered to measure your 2435s and show you how I use them in another thread....

[toddalin]

Never saw an S7 without ports or an R but then I've never seen lots of things.

Seen two now. These are C50s with an S7 load (LE15A, LE85, HL-91, LX-5). Note that before JBL went to the 43** series, the components were mounted higher in the cabinet, which is probably better for floor standing speakers as opposed to soppet-mounted units.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/DSC_0005.jpg

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/DSC_0002.jpg

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/DSC_0007.jpg

BTW, these are for sale and include matching 6-foot stands. Woofers were reconed by OCS in Dec 1994. I seem to recall that the wax seals on LE85s are intact. I'll take $900/pr.

[kingjames]

I remember a friend of mine had 2 sets of 4311's and one pair just sounded so much better than the other pair from a distance, then being the amateur's that we are we put our ear next to each speaker because we both heard the difference. All the speakers were working but one set seem to have more of the bass punch then the other. The other woofer's on the other pair was working with no noises but did not have that JBL punch.

I use to show my friends sometimes on the L100's what happened when you put a big match or bic lighter next to the port how it would blow it out everytime when running power to them.

This is how we checked both sets of speakers with a bic lighter and found out that the pair that sounded good blew out the lighter and the other pair didn't. We looked in the hole and seen that someone had plugged the other side of the port.This was the difference because after we unplugged the port they sounded identical.

Because of this and how that pair sounded I would never buy a closed system. IMO a ported system sounds much better especially in the low end. Does this make sense to anyone?

[hjames]

We looked in the hole and seen that someone had plugged the other side of the port. This was the difference because after we unplugged the port they sounded identical.

Because of this and how that pair sounded I would never buy a closed system. IMO a ported system sounds much better especially in the low end. Does this make sense to anyone?

Makes sense - but neither the L100 nor the 4311s were designed as a closed box - they were supposed to be ported. Closing the port changed the working parameters. I think something else would have needed to change to make the L100 drivers work in a "closed box" system. Maybe a larger box would be needed, maybe a different woofer, but something in the design would have to change.

[Zilch]

Does this make sense to anyone?It's a matter of taste, James.

The bass in L100s is artificial, contrived. It does not reproduce the actual performance.

Impressive, yes, but fake, and intentionally so.

That's not true of all ported systems, of course, but it's well acknowledged that a properly designed closed-box system can produce a more "natural" bass response.

The accuracy of bass in L100 may be much improved by closing the port:

http://audioheritage.org/vbulletin/showthread.php?p=122841#post122841

[Thom]

I think the L100 was designed to be a bookshelf speaker that sounded just like a big JBL if you were down the hallway. It didn't of course because the 075 made most tape decks unlistenable a trait not shared with the LE20.

[duaneage]

Does this make sense to anyone?

The transient response of the best ported system will be inferior to a critically damped or optimally damped sealed box. This would be Qtc in the range of .5 to .707 and even the QB3 alignments don't have as good a transient response compared to sealed.

The issue really is a combination of the sharp rolloff that ported boxes have combined with poor delay curves on the driver. The sharp rolloff means the ported system actually cuts off the last part of a decay more than a sealed system does. A sealed box is a close to a snare drum (or any percussion instrument) as your going to get.

The delay curves are a result of driver loading by the port and can get very wild near the box tuning frequency or cutoff. The driver has different amounts of excursion caused by the port damping the driver's movement. Below the tuning frequency the driver begins to excurse a lot more. The port in effect dynamically changes the damping effect of the box whereas a sealed system has a constant value for box compliance with predicable results.

On a more practical note sealed boxes are easy to get right and vented boxes involve a lot of compromise, design, testing and variables. It's not hard to make a proper sealed box sound good, and it's also easy to make a vented box sound bad.

Most of my builds have been vented because that's what everone associates with great big sound. But my best results were with sealed and sealed bandpass systems because I was able to tune them easier and focus more on the rest of the system.

Just my .02, no refunds available