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  1. dave alan

    Who is the reigning champ in the heavyweight DIY 15" subwoofer drivers???

    The champ is still the Tumult, which has new improvements in materials (cone, surround, glues, etc.) and shorting rings, which affords extremely low Le for an uber driver. Given your budget, size of HT and Earth shaking requirements, I would consider 2-15" Brahmas if I were you. Add a...
  2. dave alan

    New SVS Sealed Sub

    THAT'S irony, IMO. (An opinion, it would seem, that turns out to work for you, being there is a selectable steep HP filter at 32Hz on the SB-12). The shame here is that I posted a simple, positive post with 2 points of personal opinion that seemed to you to be negative toward your SB-12...
  3. dave alan

    New SVS Sealed Sub

    Of course, it depends on where the filter is as well as the filter Q, IMO. I'm not aware of any subjective evidence (unless you are pointing to people who buy a HP protected sub and say it's musical as evidence). As Ed said earlier, there are less than a handful of commercial subs that have...
  4. dave alan

    New SVS Sealed Sub

    "For anyone following along who is wondering how "bad" the sb12plus must sound because of these *evil* highpass filters(that are only bad when SVS uses them?)...please search through the threads that have dozens of people offering their listening impressions of the SB12plus in recent...
  5. dave alan

    New SVS Sealed Sub

    Hi Jack, You've mentioned this point several times at various places and the point is well taken, but not very well researched, IMO. Some of the 'gurus' you may be referring to have, in fact, had many conversations about this very fact. In response I would point out that Ed's review...
  6. dave alan

    New SVS Sealed Sub

    Hi Wayne, I appreciate the report. Help me to understand. The room compensation control switches between high pass filters at different frequencies. If we keep with the word 'filter' instead of 'choke', it may be easier to make my point. A filter does just that. It filters the signal to...
  7. dave alan

    New SVS Sealed Sub

    You know, Ron...the simplest way to understand my intent is to ask me. That way, my intent won't have to 'seem' like anything more or less than it is. Most people, in fact the vast majority of speaker manufacturers whose livlihood is tied to development and launch of new products don't hang...
  8. dave alan

    New SVS Sealed Sub

    Ron ("SVS-Ron"), "Given we're unaware of any OEM having a package in this price range, or size with flat and powerful output like we achieved,..." I didn't mention any other OEM and this is irrelevant. "You don't post a FR chart as we have on this sub, without sweating details for...
  9. dave alan

    New SVS Sealed Sub

    I thought the 12.3 was a new driver? How could SVS have been working on this sub for 2 years if the driver has just become available? Were they working on the size of the box? 2 years to develop a small sealed 1X12 that's choked by a HP filter. C'mon guys, I'm as excited as anyone that SVS...
  10. dave alan

    Preliminary IMD measurements for subwoofers

    This one looks the most interesting to me, also, FWIW. Dave
  11. dave alan

    Preliminary IMD measurements for subwoofers

    Cool... Now, in looking again at the speadsheet, there is f1+f2, which is OK, but later is 2f2+2f1, which would be the H2 of f1+f2, regardless of the fundamentals chosen. Example: 30 & 70Hz... (f1+f2) 30+ 70=100Hz (2f2+2f1) 60+140=200Hz 30+78Hz... (f1+f2) 30+ 78=108Hz (2f2+2f1)...
  12. dave alan

    Preliminary IMD measurements for subwoofers

    It's gonna be difficult to build a database if Ilkka doesn't name the subs:D Dave
  13. dave alan

    Preliminary IMD measurements for subwoofers

    From the def I use, '...Since it is NOT HARMONICS of the original signal...described as "harsh and grating"...' If the stimulus tones are harmonically related, then some resulting tones will also be harmonically related, so the device under test may show relatively high IMD but not sound as...
  14. dave alan

    Preliminary IMD measurements for subwoofers

    I think I'm clear now, after you have confused things with your geek speak.:D When you say 'fundamental' you mean the stimulus tone or tones. When you say 'harmonic', you mean integer multiples of the fundamental, or stimulus tone or tones. When you say 'non harmonic' you mean ALL...
  15. dave alan

    Preliminary IMD measurements for subwoofers

    No, we're not. We're trying to figure out what percentage of output of a given sub is inharmonic non linear distortion (vs harmonically related non linear distortion, which is less offensive and even preferred by some, and well covered by the test for THD). The tones should be deduced based...
  16. dave alan

    Preliminary IMD measurements for subwoofers

    This post is aggravating me and it needs to be deleted. Dave
  17. dave alan

    Preliminary IMD measurements for subwoofers

    Man, I'm gettin' old, but I swear I'd already done that. It was indeed a calc of sum/diff using 2 particular tones. I'll check my files. Possibly I didn't actually forward it to you, but I sure thought I did. At some point in this thread, a sample set of tones (or 2 or 3) will come up for...
  18. dave alan

    Preliminary IMD measurements for subwoofers

    Late night post...sorry for being so slow to get up to speed in this thread. Ed...thanks for the explanation. I am aware of the fact that there is no standard for IMD testing of a subwoofer and that you only need 2 (or more) tones, and that those tones may be arbitrarily selected, so your...
  19. dave alan

    Preliminary IMD measurements for subwoofers

    Ilkka, Some further thoughts after the rude interruption... In your report, you glossed over the reason(s) for the selection of 30 and 70 Hz. I wish you would expand on this. I am also a bit surprised that you and Ed didn't run it past a musician. I also wonder where you got the...
  20. dave alan

    Preliminary IMD measurements for subwoofers

    Ilkka, You mean the amp can't contribute to these distortions? Exactly what IS this thread about? Is it about you and Jakeman or Tom and Peter? I believe I'm the only person to ask you a pertinent question in this entire thread. Tom has chosen to pull his usual crapola and he's...
  21. dave alan

    Preliminary IMD measurements for subwoofers

    Tom, Post the price. Put up or shut up. Let's match my BS posts to yours. Shall I begin the search? If price is the LAST consideration for you, how is it you ended up with the Samson amp? Every worst case about your Company?? Are you insane? What are you basing this paranoia on? The...
  22. dave alan

    Preliminary IMD measurements for subwoofers

    Sorry, Mark. As I said above, I now see that this is something that has been previously discussed between SVS and HSU fans and reps, so it goes much deeper than appeared by Peter's first post in this thread.:b So, help me out here. What exactly is this thread about? Dave
  23. dave alan

    Preliminary IMD measurements for subwoofers

    Maybe you misunderstood my comment, so I'll be perfectly clear: First, I made no comments about any plate amplifier metting it's rating or not. I simply mean that ID companies use cheap plate amplifiers with cheap circuitry and they purchase them because they are low cost. Dirt cheapest...
  24. dave alan

    Preliminary IMD measurements for subwoofers

    Ilkka, Questions: "Used 30 Hz and 70 Hz fundamentals are therefore good, because neither one of them matches with the tuning frequency of these subwoofers. That means the place of the vent doesn't cause a large difference/error here." This is not confirmed by the test. For a...
  25. dave alan

    Preliminary IMD measurements for subwoofers

    Mark, I fail to see the vague point. I think it's painfully obvious that Peter means this: Given the same basket, motor and cone, a design with more Xmax will have less Sd due to the surround (generally speaking), and therefore more excursion for the same output as a design with less...
  26. dave alan

    Preliminary IMD measurements for subwoofers

    Please tell me what debate Peter entered into? What is in his post that you find in error or otherwise? In fact, Peter has very valid points and I wouldn't mind reading the 'debate' that might ensue if you would please butt out and find the 'how it sounds' thread to post in. This is just...
  27. dave alan

    Preliminary IMD measurements for subwoofers

    WOW!! Bott is an alien.:angry: I'm glad I checked here as I thought something like this may have happened. (Actually, I thought you retracted the posting to correct a mistake:D ) This is a lot of posting to digest. Good info for a start. The conclusion that high excursion woofers don't...
  28. dave alan

    Interesting sub calibration I did

    Patrick, It sounds like a simple case of running the sub hot vs running the sub closer to the level of the satellites. Many like the sub calibrated hot, but it results in a bloated low end relative to the higher frequencies. Some prefer the higher level of the subwoofer frequencies calling...
  29. dave alan

    A new look ....

    Outstanding work! Great design, great execution. Congrats on a job well done and a huge tip 'o the hat.:) Bosso
  30. dave alan

    Velodyne DD18

    OK...Ya got me. One of these days I'm gonna remember that a thread that's titled 'Velodyne DD18' really is about everything but a Velodyne DD18. :cool:
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