So true, for optimum performance one must design to blend with the room, which can make for some pretty sorry looking 2pi [half space] sims, especially when the speaker and/or listening position will be in a null to satisfy the decorator.
Distributed subs is about getting the smoothest bass response in room regardless of how low/loud is desired plus it opens up positioning options for optimizing the mains in room performance.
Ignoring some pipe organ symphonies, the 27.5 Hz lowest note of some pianos is as low as we need, so a worthy tuning goal, but alas, few 'FR' drivers available can get this low and they need huge horns to do it with any authority, so a distributed sub system with a 80-150 Hz XO will allow most 'FR' drivers to 'be all they can be', making it a 'no-brainer' solution for me.
GM
Really?! I got the impression from back when you were dealing with all the flooding damage that you had a pretty good sized home/property.
Regardless, a typical square/rectangular room only requires one sub per room height, width, depth unless it's has alcoves and/or is 'L' shaped, though of course like with surround channels, the more the better up to a point of diminishing returns, which allows small 'subs' and modest output amps to be used: http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/multsubs.pdf
GM
Regardless, a typical square/rectangular room only requires one sub per room height, width, depth unless it's has alcoves and/or is 'L' shaped, though of course like with surround channels, the more the better up to a point of diminishing returns, which allows small 'subs' and modest output amps to be used: http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/multsubs.pdf
GM
I wish. I don't have any property at all. My parents, who I've been stuck with (bless them for putting up with me for so long) while completing my PhD have a fairly typical 1930s 3 bed semi-detached place. It's not a shoe-box, but it's not large. The garden's very big by modern UK standards though, or at least, it's long. I did a fair bit of the work after the flooding to partly pay them back a little for keeping a roof over my head.
Yeah, the Harman page & the AES paper were what set me off; when I've had chance to fool around in the past, I usually gravitated to two or four as giving what I wanted in terms of price / performance.
Yeah, the Harman page & the AES paper were what set me off; when I've had chance to fool around in the past, I usually gravitated to two or four as giving what I wanted in terms of price / performance.
To elaborate on my "shelf port" experiments; I did not bother running any sweeps with HolmImpulse because I could easily tell by ear that none of the tunings was having a positive effect on the bass response.
Whatever Scott has going on inside the Pensil does not react to port tuning the way that I expected (just as he has been saying).
WRT subs; thanks for the input from GM and others. At this point I still don't know what I am going to do. To have huge cabinets such as the Pensils and still require a sub (or subs) seems ridiculous to me. Extra boxes, wires and whatnot reduces WAF significantly, and if I am going to use a sub, the main towers might as well be 1/3 the size/volume.
I have all sorts of options, of course, but the most attractive option would be to somehow use the Pensil cabinets. I spent time and money building them and I absolutely hate the idea of throwing in the towel. I have a few different ideas of what I could do with them, but I do not want to discuss them here, as I realize I have already been too critical of Scott's design. He doesn't need to hear about possible plans to butcher it. To be clear, I do believe the Pensils meet the design goals; they simply do not suit my particular taste.
Whatever Scott has going on inside the Pensil does not react to port tuning the way that I expected (just as he has been saying).
WRT subs; thanks for the input from GM and others. At this point I still don't know what I am going to do. To have huge cabinets such as the Pensils and still require a sub (or subs) seems ridiculous to me. Extra boxes, wires and whatnot reduces WAF significantly, and if I am going to use a sub, the main towers might as well be 1/3 the size/volume.
I have all sorts of options, of course, but the most attractive option would be to somehow use the Pensil cabinets. I spent time and money building them and I absolutely hate the idea of throwing in the towel. I have a few different ideas of what I could do with them, but I do not want to discuss them here, as I realize I have already been too critical of Scott's design. He doesn't need to hear about possible plans to butcher it. To be clear, I do believe the Pensils meet the design goals; they simply do not suit my particular taste.
Which is fair enough. If we all held out for the one true, universally applicable box, we'd be waiting around for a while. 
Since the cabinet has a reasonable amount of volume however (though I certainly wouldn't call it 'huge'), to say nothing of a removable back, you've plenty of options available, e.g. partitioning off the upper part & running it as a reflex (have to watch the vent lengths & standing waves but in principle easy enough), or perhaps sealed with dedicated woofers in the lower portion.
Since the cabinet has a reasonable amount of volume however (though I certainly wouldn't call it 'huge'), to say nothing of a removable back, you've plenty of options available, e.g. partitioning off the upper part & running it as a reflex (have to watch the vent lengths & standing waves but in principle easy enough), or perhaps sealed with dedicated woofers in the lower portion.
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Which is fair enough. If we all held out for the one true, universally applicable box, we'd be waiting around for a while.
Do you have a secret backdoor into my PC?
I am currently playing with a possible solution which puts the Alpairs sealed at the top, and the bottom is SDX10 in a 4th-order bandpass. It all fits into the existing enclosure (SDX10 would have to be on an angled internal baffle) and the componentless crossover works out quite well, right around 70Hz. F3 is 27Hz and F10 is 20Hz.
The major drawback is, of course, $300 for the woofers (after tax and shipping). That is more than I have spent on the speakers in total. Then there is the question of amplification. Since they are 4ohms, I can't really wire them parallel to Alpairs, so then I am into Bi-amping, etc. etc. ($$$)
Another thing I am going to try (since it will cost me nothing but time) is stick the two old, paper cone, 15" drivers back into the console enclosures, hook them up to a plate amp, and see if I can tune the cabinets and variable crossover to get some decent sub-50Hz out of them. Those same console enclosures pulled a ton of bass from the Alpairs, after all.
I've also considered sticking those old 15"ers on a large open baffle to see what they are like. Maybe even an H-frame, just for sh!ts n' giggles. When I tried them in open air, with no filters, they were reaching way up into the mids and lower treble.
BTW, RonVinyl, I am sorry for the hijack.
Have you made any more progress with tweaking your stuffing?
Cogitech,
When you did your shelf port experiment did you first run a WinISD calc to get the approximate length and tuning freq? Or did you just make a piece of cardboard of convenient length? It will have bass overshoot in a hump, but I believe it should be able to reach low due to the cabinet size. You will need to have some stuffing in top 2/3 or so though. It is 62 liter volume cabinet right?
When you did your shelf port experiment did you first run a WinISD calc to get the approximate length and tuning freq? Or did you just make a piece of cardboard of convenient length? It will have bass overshoot in a hump, but I believe it should be able to reach low due to the cabinet size. You will need to have some stuffing in top 2/3 or so though. It is 62 liter volume cabinet right?
Yes. I used WinISD to calculate various tunings/lengths. I could tell there was a change in the tuning, but it was so subtle that it made very little difference. It was like everything under 50Hz is -10dB, regardless of tuning. I literally had to have my ear beside the port to hear the difference; the in-room change was non-existent. So it is more a matter of amplitude than tuning. The tuning is probably pretty-much perfect, it is just that the amplitude is not balanced with the mids and highs (for my taste).
As planned, I installed the two old, paper, 12"ers (I thought they were 15", but I was wrong) in the console enclosures and hooked up a sub plate amp. So the console is essentially a massive, central, ~5 cu.ft. subwoofer with twin 12" drivers. The bass is ridiculous.
Will post a few photos and details tomorrow.
Cogitech,
Sorry it did not work out. It sounds like your idea of splitting the box into a 4th order bandpass sub on the lower section and a sealed box on the top with the Alpair is a good idea. You will have a nice FAST in a box. Bi-amping is the way to go, I would look into putting line-level cross-overs prior to the amps - or if you have a miniDSP already you are good to go.
Sorry it did not work out. It sounds like your idea of splitting the box into a 4th order bandpass sub on the lower section and a sealed box on the top with the Alpair is a good idea. You will have a nice FAST in a box. Bi-amping is the way to go, I would look into putting line-level cross-overs prior to the amps - or if you have a miniDSP already you are good to go.
I have no doubt that this solution would sound incredible.
However, the dollar signs quickly cha-ching when adding up the cost; woofers, amp, pre-amp, miniDSP... I own none of the components.
It is also impossible for me to forget how much bass I extracted from the Alpair 10.2s in the console enclosures. Now that I know it is possible, it seems silly to spend $500 on more components and complexity.
Which is why I said "what the heck" (or something to that effect) yesterday and installed the pair of 12" woofers and the plate amp into the console. I already owned all the components and it took me about an hour or so to do it. I do think it deserves its own thread, though, so look over in the Subwoofers forum a little later...
So you won't be running the console as a full range with the Alpairs and the T-amp with tube pre-amp anymore?
Btw, the bi-amping with line-level cross-overs is not that expensive as you avoid big coils and big caps and power resistors normally required for passive crossovers. A couple of class D amps will not set you back too much as you already own at least one. The line level crossovers are small coils and caps between your source and your power amp. You may need an active buffer.
Btw, the bi-amping with line-level cross-overs is not that expensive as you avoid big coils and big caps and power resistors normally required for passive crossovers. A couple of class D amps will not set you back too much as you already own at least one. The line level crossovers are small coils and caps between your source and your power amp. You may need an active buffer.
An excellent way to go actually. I'm surprised we don't see more of this. Unless someone want to cross higher than 80hz, or filter the bass out of their main (no doubt very good reason to do either of those in many cases) then just low pass a subwoofer around 60 to 80hz and enjoy.
That's how I do it in my living room with my TV setup. EL70s in sealed enclosures running full range and a little 8" sealed sub in the corner low passed around 70hz. Sounds freaking amazing and so little invested.
Spread the word, more people should do like cogitech did. It works so well.
The T-amp + tube pre was never intended for the console, or for the main system at all. Rather, it will find a home in the bedroom system, driving the (w3-881SI) nanoTowers. The main system amp will remain the Shuguang I-25 EL34 P-P. I just love that amp.
The bass of the console blew my mind with the Alpairs, but as you'll recall, I needed some serious EQ on the top end to overcome the console's wooden grilles. It sounded fantastic compared to the original console speakers, but the imaging and sound stage just didn't satisfy the way naked Alpairs in Pensils do. I put the Alpairs back in the Pensils, and then started to miss the bass of the console, so I started brainstorming on different solutions...
Both the tube pre and class D amp are destined for the bedroom, as said, and I already have a very nice tube integrated for the main system, so switching to bi-amping would mean buying a proper pre-amp, another amp, and then I am not even sure that would work with my existing integrated. Too much gain can be a bad thing, as you know. If I already had separates, I might be tempted to just get another class D and and do some playing, but at this point I think I have found the path forward.
I have one other idea regarding the Pensils, but I will keep that to myself for now. Maybe a small hint: it involves a circular saw, a jig saw, and the purchase of something which is not yet released, but highly anticipated.
I thought about maybe filtering the bass out of the mains and I might consider it in the future. For now, the Alpairs can easily handle the full signal with a flat EQ (EQ disabled actually). I need to wrap my 25 watt volume knob pretty far to get ballsy excursion, and by that point WAF kicks in and the SPL is brought back to "just loud" levels. Need to get these woofers measured and tuned right before I leave all the bass up to them, too.
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