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2 12's or a 15

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  • Wolf
    replied
    "If it moves, it distorts" is your mantra it seems, so therefore do what you will. You are making it very hard on yourself with how you are making your choices. I still disagree with your localization ideals.

    I still say that if you xover the sub lower you won't have the HD profile to worry about from the sub, and the 7" woofer should be adequate even at loud volumes at 70-80Hz. Yes, xover does affect HD, but -20Hz difference on a 7" woofer will absolutely be negligible in this case. If you want a thin sounding satellite, that's your apparent problem. I think you're being cautious in the wrong driver, and should xover the woofer lower for both HD and localization. The 7" will be fine.

    Later,
    Wolf

    Edit: I just now see you have RS150 for these. Even so, I still think 80Hz will not be a problem for these being 4.5" drivers.

    Leave a comment:


  • tvrgeek
    replied
    Pastrami. By raising the crossover to the mid-bass, you lower the mid-bass excursion and so lower it's distortion which is in higher frequencies you hear more. So, crossover point does effect distortion. Do some measurements of mid-woofers. Depressing actually.

    With a traditional sealed sub, the harmonics are so strong, it is more localizable. If the sub is clean and does not produce many strong harmonics, you will not be able to localize it as easily as if it was a DR and producing more harmonics into the room. I am counting on the lower distortion of the BP and twice the sd to begin with. The current Titanic HD plot looks like a picket fence going on for ever.

    FWIW, I use slow sweeps with a tone generator to find and fix those room resonances. Back of a china closet, picture on the wall. Hardest one to fix was a window balance spring. Those velcro COmmand Strips do wonders on pictures. Just one tab at the bottom, no resonance a

    So , second RSS265 on order, BP-4 as I could not get the BW to shift high enough in a PB-6. The LF extension I could get I can't use anyway as I use a HP @ 20 Hz. I am not a super bass freak and have no heavy organ music. With a port Mach below .025 @ 110 dB, I am not going to have issues in the port. I do not have the physical space for 2X sd PRs even if I had the budget, which I do not. My model suggests under a mm of displacement @ 50 Hz, 106 dB. I came up with a solution where the tuning frequencies are a 3:5 ratio. I find it odd the simulators provide a recommendation for 1:1. Not efficient. I would think have a tendency to favor that frequency.

    Leave a comment:


  • Wolf
    commented on 's reply
    Bologna. Localization has nothing to do with distortion. The octave below 150Hz is the best method to avoid such issues, so elimination of both harmonics and localization is effective with a 75Hz compass. There really is no reason to have a sub operate to 100Hz unless you have 3" midbasses.

    Also, THD is lower in bandpass systems, as my write up states. Further going to PR exit reduces chance for turbulence and HD issues there. I think my room distorts more than the Overdrive10 does when it is playing via vibrations and resonances of things in said room. Don't knock it until you try it!

    Wolf

  • tvrgeek
    commented on 's reply
    And not a sentence here about distortion. My primary reason for changing. EQ wise, the single sealed Titanic 10 inch does fine. After the AVR does it's thing, I just turn the gain down a notch. The lower the distortion, the higher you can cross it over without localization, and then the lower the mid-bass distortion. I have a goal to see if I can produce a complete system with under 1% THD+N @ 85 dB. May not be possible, but giving it a try.

  • trevordj
    replied
    I recently built a couple of boxes with some scanspeak discovery 12s I used passive radiators but they would work sealed. Nice subs.

    Also you can’t go wrong with Dayton RSS series.

    Leave a comment:


  • djg
    replied
    Yolo:

    http://techtalk.parts-express.com/fo...d-overdrive-10

    http://techtalk.parts-express.com/fo...lding-this-one

    http://projectgallery.parts-express....-8-subwoofers/

    Leave a comment:


  • tvrgeek
    replied
    Spent the morning looking at 12's and well 10's. Working many possibilities, the CSS 12 is a really good option and the efficiency is fantastic, but I think I am going to use two RS265s in a BP-4. I happen to have one I had in a small office sub so cheap to buy another. Box is really big. 5 feet, and I will literally have to built it into the cavity. Predicted actual cone displacement after the AVR does it's thing in a real room, I should be able to get 110 dB across the band with under +/- 4mm. I have not measured to confirm that the front chamber filters higher frequencies and hence further reduces actual distortion, so that will be an experiment. But, that peerless does look good. 2 of the CSS was getting way up there in cost. Enough to generate "domestic distortion".

    Blenton,
    Tell me about the corundum tweeters. The one inch is out of stock so I have not got one yet. It was the second tweeter I was interested in after the Seas I have on order. Distortion/ Stored energy? My living room mains are the 7 inch Seas with the 27TBFC/G aluminum domes and I have considered the new Peerless as an upgrade there too.

    My elephants are my living room. Living room sub is a 12 inch Peerless, critical Q. This project is my HT. An 11 x 12 guest room.

    Leave a comment:


  • Blenton
    replied
    I am still very much liking my big Peerless 15" driver. I've flogged it pretty good and, to my ears, it is leaps and bounds beyond other drivers that I've used in both clean output and shear ability. It get's ridiculous, too, without breaking a sweat, but still blends exceptionally well with my mains. I know that ridiculous isn't exactly what you are looking for, but it's a very versatile driver, IMO. The dustcap is ginormous and helps keep the cone quite rigid. Also, the equally ginormous voice coil helps prevent compression. I run mine vented, but I'm thinking about trying it out in a sealed or passive radiator box, too. It does cost a few bucks, but it's still comparable to a pair of well-motored 12's (and cheaper then a pair of venerable CSS 12's).

    My mains right now are Seas reed/paper cones mated to corundum tweeters.

    Leave a comment:


  • AudioSQ
    replied
    My room is 15x15.5. Just a bunch of cheap $30 JBL subs that have to do very little work to get the volume I want. The price was just right to play with them.

    Leave a comment:


  • djg
    commented on 's reply
    Don't use google.

  • djg
    commented on 's reply
    Can't you put them in the elephants?

  • tvrgeek
    replied
    Yes, both would be centered high in the room on a recessed shelf above the TV. Top of a closet from the other side. No choice in that matter.
    Been searching all day. Perfect does not look possible, but just jumping to the CSS 12 is a huge improvement over the 10 inch Dayton Titianic. I was also looking at the 15 inch Peerless. Concerned with the rigidity of the big paper cone as my main driving factor is distortion. Takes a very big box for the CSS and not sure I can justify two cost wise. ( if she finds out) SB, SEAS, Dayton, older Peerless all do not work out. The Peerless is getting a bit pricy at half a big one. For either of these, I need to hunt down free shipping.

    Last time I built a sub there were dozens of companies out there. Now when I search, I get JL. They must have a good WEB team getting them up in searches. I have some time to think as all of the mid-bass drivers I want are currently out of stock, as well as the second tweeter I want to test. I was going to do the sub later.

    9 12's? Your room must be larger than mine, but a lot to be said for 1mm excursion.

    Leave a comment:


  • AudioSQ
    replied
    Would the 2 12"s be in the same spot in the room or separate locations? I have 9 12"s and an 18" so I obviously have a thing for multiples.. maybe it's because I'm a twin. I'd probably go 2 12"s either way. More cone area, motors and flexibility, but most likely more expensive.

    Leave a comment:


  • tvrgeek
    started a topic 2 12's or a 15

    2 12's or a 15

    New mains almost figured out. SB and Seas drivers on order for testing. Sub next.

    I have about 3 cu ft for my sub available. Currently a 12 inch Dayton Titanic. I may keep it, but looking for lower distortion if reasonable. Been many years since I looked for subs. Wondering what current preferences ( at reasonable prices) With the space available, I could run a pair of 12's or a 15. Either should be able to cross 100 or 120. HT, but small room and I don't like excessive special effects. CSS, Peerless, Dayton? Years ago it was Shiva, but they seem to be 8 Ohm. Expect to do sealed. I was looking BP-4 but catch-22, when I need to cross as high as 100, impossible ports to get as broad a band pass with the drivers I have modeled so far. Looked great for 60 Hz.
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