Axiom Home Page Forums General Discussion Advice from Axiom Owners Subwoofer design, ported vs closed, ep600 vs ep800

I read I think on Professor Hsu's site that he believes ported speakers sound better for HT and have more of an exciting impact in that context whereas closed box designs are better for music and have more deep bass extension, he supposedly has somehow engineered his designs so you can change settings with the same subwoofer to best fit your particular application, hopefully I have not garbled the above info too badly.

To me that possibly begs the question, how will the closed box ep800 perform with HT material?

It seems like a silly question, I know, but I am wondering what experience people have with regard to ported versus closed box designs for HT. For example, folks are reporting great HT results with the closed HSU 15 which does not seem to fit the above theory at all, niether does the report from one long term poster (sorry can't locate) regarding the ported EP600 lacking the "thump" which he has grown to enjoy from other subs (could this be a result of smoothing due to built in DSP?).

I have wood floors and no basement so I must admit the wireless aspect of the HSU 15 is appealing with regard to placement options, on the other hand my monolithic character drives me to match the epic 80 system with one or two ep600s or ep800s.

some of the really good high end HT subs are closed designs, such as Jl audio's gotham sub.
http://home.jlaudio.com/products_subs_pages.php?page_id=3

I got to hear this sub at a local HT store and watched some clips from spiderman 3 on bluray, as well as others.

Let me tell you, that thing sounded AWESOME. IT was actually the first non-ported HT sub I have heard, and was def. impressed.

I believe that what Alan has said is that it's the actual design that matters, not whether it's ported or not. I seem to remember him being rather animated about it, but this may have been after a beer or two.

David - good to see your old Avatar back!

SK - when I first bought the 600, I also ordered a SVS PB13 Ultra to compare. The PB13 ultra has 3 plugs you can remove for a ported sound or leave in for a sealed box sound. I have to say, I loved the extra pressure I felt in the room from the sealed design, but in their case, the tradeoff is a decreased SPL output running it sealed.

I actually preferred the sound for both HT & music, but ultimately returned the PB13 because of two things. 1) lack of DSP allowed the sub to "bottom out" (distort audibly) at high volume levels, which was annoying, 2) it was an ugly coffin-shaped box that didn't match the rest of my system nearly as well as the 600 in HG Cherry did. If the sound had been night & day better than the 600, I would have kept it, but the fact was, at normal listening volumes it was very similar to my ears, and not enough to overlook its ugly looks.

With that said, there are a few others here who kept the PB13 over the Axiom sub... they might have other stories to tell on how they feel about running a sealed versus ported sub.

Given how much I enjoyed the sealed sound of that particular sub, I'm very interested in getting my hands on an 800. From the early graphs, it appears to play considerably lower than the PB13 without a sacrifice of SPL. Looks fun.

Jason

Well that put's it in perspective quite nicely, but aren't we then talking about spending nearly $5k to run 2 ep800s? Yikes! I truly am leaving my senses!

Actually, the Ep800 has no price tag yet. I might just be nearly 4.9K for 2 after all.

You could go one EP800 and one 600 this way you still get the lower extension from the 800 and the extra smoothness of dual subs with some savings.

To continue Jason's thoughts, I am an owner of a PB13 Ultra and I have not played much with the ability to run it sealed. All I can confirm is it is one huge box and plays as well as the 600, but to my ears has more punch at lower volumes than the 600 does, which is why I kept it. I found the 600(actually, all Axiom subs I have heard) has a certain expansive sound that blends better, allows it to be more transparent with music. He is correct in that the PB13 can be bottomed out, but the SPL levels are very high in order to get it to do so, around 105-110db IIRC, I highly doubt it is ever run in normal use at those levels, I know mine certainly never gets near those levels, 100 tops.

Myrison,

Yeah my team is actually looking decent this year so I had to give em some credit. OU is looking REALLY good though, our bedlam game should be good... Actually I think all of the big 12 teams are looking pretty good this year... Should make for an interesting season

Jason - interesting that you don't run it sealed. I thought that for 'punch' (which I know is what we both were after back then), the sealed mode delivered best.

SK and others - to Jason's (jakewash's) point, it is very true that the SVS doesn't bottom out until extreme volumes. Just to be clear, I'm definitely not SVS-bashing here. That monster was capable of awesome sound and I would have been happy having it or the 600 from an audio perspective. If I hadn't had the chance to do the side by side, I would never have looked back either way. Like I said, I do miss the sealed sound though.

Jason

Terzaghi - yes, the Big 12 is looking awfully good this year, though it looks like one more "rebuilding" year I'll have to suffer through with the Huskers. I'm terrified of what Mizzou is going to do to us Saturday night.

Hi Satkartr,

With all due respect to Per Hsu, this is one of those hoary old audio myths that won't go away (that ported subs are "better for home theater" and "sealed subs better for music.")

kcarlile is correct. I likely did get quite animated when I explained that it is the design, linearity and bass extension of the subwoofer that matters, not the programming material or the enclosure design.

The main advantage of a sealed subwoofer like the EP800 is that you can extend the deep bass response down to frequencies like 12 or 13 Hz without having to deal with issues of audible port noise. If you try to get the same bass extension from a ported design, the noise of the air rushing through the port at such low frequencies begins to dominate the sound of the subwoofer.

The disadvantage of a sealed subwoofer is that you lose some sensitivity (efficiency) because you are "throwing away" all the rear energy from the drivers that would be used to augment the output of a ported sub. That's why in the EP800 we have to use two dual-voice-coil drivers and more power (800 watts) to compensate for the loss in sensitivity of a sealed design. The additional driver and larger amplifier power output let us bring the EP800's SPL up to 114 dB anechoic and 125 dB SPL in a room.

The "punch" that some listeners attribute to some subwoofers is simply a non-linearity; a hump in the subwoofer's bass response. Because of their linearity, which is DSP-controlled, the EP600 and EP800 do not have the false coloration of "punch". The latter is analogous to the upper bass hump that some floorstanding and bookshelf speakers have, which listeners subjectively call "warmth". It's pleasant at first, but then you'll hear it adding fatness and coloration to everything--male vocals and any instruments whose frequencies occur in the 60 to 200 Hz range. You get sick of it pretty quickly.

In double blind tests, I've never heard a qualitative difference between well-designed sealed or ported subwoofers with music or home theater, and I'd challenge anyone to consistently and reliably pick out a sealed or ported subwoofer in a double-blind controlled test.

Regards,

Alan

!

Eh, I think you need to go for the theoretical physical limit of loudness. Kick it up a notch!

From what I understand you could also increase cabinet and port size, but then you end up with a monster that only it mother, or confirmed bachelors could love.


Alan. How does that non-linearity show up in measurements. Would you start to see greater than expected distortion?

Sad as it sounds, I had the same reaction to buying a single EP350 initially. I had a hard time getting my head around the idea of paying 1/2 again the price of my mains just for one more speaker. Now that I am enjoying a little 'subbage' with my movies, I see things a little differently.

I do have to admit that 5k for good bass still seems a little much for me.

Indeed Fred, I felt the same way except my EP500 cost more than my mains M22s, But a good sub adds so much even with towers.

OK, Alan....
I'm completely neutral on this, so I'd make a good juror.

Send me both, and I'll do exhaustive tests over a few years and report back!

My ported subwoofer is far superior to my old sealed subwoofer, so I think Alan's wrong.



Of course, my ported subwoofer is an EP350v3 (300 watt amp, 12" woofer), and my old sealed subwoofer was a Cambridge Soundworks Powered Subwoofer 1 (120 watt amp, 12" woofer).

Hi Fred,

If you graphed the frequency response, the non-linearity should show up as a gently rounded hump in the frequency response, likely starting around 100 Hz and reaching a peak that's perhaps 6 dB to 10 dB higher at 60 Hz, then gradually rolling off as you get to lower frequencies.

There might be increased harmonic distortion, but the reality is low-bass distortion is really hard to detect with music or effects until it rises to huge levels.

Regards,

Alan - thanks as always for the informative response.

The more I hear about the 800, the more I like it. Please release it to the masses!

Jason

or at least feed us some more info! can we have a release date by quarter? by year? something!

I should clarify my comment about the PB13 having more punch. The sonic signatures of the 2 subs is different. The PB13, IMO, appeared to hit harder and have a lower note to it, at quieter volumes. The EP600 has a smoother sound and to me just didn't hit me like the the PB13 does at low volumes. I have used the term expansive to describe the sonic signature of the EP subs, because it seems to really resonate through out the room.

Jason - at the risk of putting words in your/Alan's mouth, it could be that you/Alan are saying the same thing. Since the PB13 plays a little lower than the 600, it could be a bump you're hearing at the lowest frequencies from the PB13 that changes the overall impression (though not much music goes that low, HT definitely does).

Jason

I believe we are. I am making my asertations based on HT for sure, I actually liked the EP600 a little better for music, but really missed the low end thump I could feel with the PB13 while watching movies, especially at the lower volumes required while the kids are sleeping.

I really do need to start experimenting with the sealed part of the equation, as I have mine corner loaded at the momment so I should see some significant gains down low.

I think you'll like it... here is the difference I saw between 20 Hz mode and 10 Hz (sealed) mode in my room. A difference of 23 dB at 10hz (whoa) and ~9 dB at 14 Hz. It is definitely a noticeable change.

I think I know what I am doing this weekend, well besides my youngests birthday party

Mine's this weekend too (10/4). Though with our own little one keeping us busy, I imagine we'll stay fairly subdued.

(I hope to be spending my weekend installing my Algonquins... I'm making a bit assumption my wife actually picked them up for me. She doesn't know how disappointed I'm going to be if she didn't!

Keep us updated and let me be the first to wish you an early happy birthday!

Although I never ended up posting my impressions of the PB13 Ultra Vs. EP500, my view is essentially the same as Myrison and Jakewash, only more so, perhaps because I compared a 500 as opposed to a 600. I kept the PB13. (I still have the 500, tho!).

For me, both subs were basically the same sounding until I found the correct phase setting for the PB13. The thing came alive, and I was finally able to dial in the clean 'punch' I so desired thru the SMS-1 for movies and music. What I dialed in isn't perfectly linear, but I like what I hear and feel, chest thump and all. It's deep, powerful and clean.

The EP500 is no slouch by any means. I do enjoy the 'expansive' sound it has, as Jakewash puts it, for music. Hmm Myrison...I must give the sealed mode a try again...

Glad to hear I've given you both something fun to play with over the weekend. That is definitely one fun thing about that SVS sub. There are a lot of different options to enjoy. (It's not for everyone to be sure as it makes setup quite complicated with all the bells & whistles it has, but it's quite nice for those among us who like to tinker).

Jason

Very interesting, thank you for the detailed response, that was very informative.

Your post left me wondering about one detail regarding the upcoming ep800 though; you state that it is driven by 800 watts of amplifier power but the audioholics writeup of the most recent tour reported it as 1,000: "Since both drivers are wired in parallel, the rated amplifier output jumps up from 600 watts to 1000 watts making me wonder why they just don’t call it an EP1000."

yeah I read that too.. just assumed that Audioholics was wrong.