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Everything posted by SME

  1. Thanks for the compliment and for the clarification. That looks like an amazing setup!
  2. That's a major understatement with those numbers. I'd imagine your system gets exercised a bit more with movie content? Just for clarification, are both sets of numbers measured in "slow" mode? Or "fast" mode? Or are they peaks? Is it the same for both? Your words "I'll run" along with "and hit" make me curious. I've found 79 dBA to be about right for a "reference level" for most music, and from there, C-weighted levels vary quite a bit depending on how much bass the system and the program have. The program alone can be a huge variable. I can easily go much higher while staying
  3. I'll just add that subwoofer responses are mostly minimum phase (MP). What this is implies is that the magnitude frequency response (FR) essentially *determines*, the phase and group delay response. They are mathematically interchangeable. If you have a MP system and you have perfectly flat FR, then the group delay (GD) will be perfect *by definition*. Real subs always have at least a low-end roll-off somewhere, and you will usually see group delay rise and peak in the area of the roll-off transition. The most notable exceptions to "mostly minimum phase", where subs alone are concerne
  4. How did the testing go?
  5. I see. Does he work with impedance data and measurements for the particular drivers? That's necessary to get a high quality result, and then said crossover won't deliver equivalent results with different drivers. I have no idea, sorry. See my last post: "The problem with the CH201 apart from the steep drop above 10 kHz is the horn termination being too short, which messes up frequency response between 3-6 kHz." I personally wouldn't choose it for any of my designs, but I may have different priorities than you.
  6. Peaks at 30 and 60 Hz are harmonically related, which means they likely potentiate each other perceptually. And I wouldn't be surprised if those movie scenes happened to have peakiness at those same frequencies. I suspect this is a trick used on some live sound stages---EQ boost at the kick drum fundamental and a few of its harmonics, tweaking the relative levels by ear as needed---to get a very powerful slam effect, albeit at the cost of lost clarity of content elsewhere in the spectrum. This may be the "easy" way to get slam, but the result is very much conditioned upon the content, which
  7. Good to see you back on the forum! See my above post. I would have agreed with all of this like three years ago. Now I'm a heretic. I believe this kind of analysis is seriously flawed. Equal Loudness Contour data is interesting, and I think it describes real trends in apparent loudness vs. frequency. However, it is a big mistake to generalize about complex music signals from data obtained using pure tone sine waves. I'd argue this is *especially important* when trying to reason about audibility thresholds. Pure tone sine waves are very unusual in nature, and our brain's reaction to
  8. No, but not because of the different impedances. The biggest issue is that the high frequency section is a lot more efficient than the low frequency section and needs attenuation to play at the right level. Another issue is that you really need a high low pass filter for the mid or else it will make a mess of your upper mid response. And you probably want to cross closer to 1500 Hz. More generally to get good sound quality you really need a crossover that's custom designed for the combination of drivers, which for your case is actually 3 different drivers. In your first post, you said
  9. I've always regarded MDF to be heavier than BB plywood, so I decided to try looking it up: https://www.inchcalculator com/how-much-does-plywood-weigh/ Different products will vary a bit, but the chart there suggests BB is only about 70% as heavy as MDF. I do agree that BB plywood is stronger and more durable than MDF. There are other pros and cons. MDF is more messy and toxic to work with (dust) but also a but more forgiving. MDF has more adhesives which may improve its damping properties. Many speaker makers argue that the damping properties of MDF make it superior to BB despit
  10. I think you need to clarify, to us as well as maybe yourself, what your design priorities are here. Do you care about sound quality at all? Or are you trying to go as loud as possible as cheap as possible? Or are you willing to give up some output for better sound quality? Or save up more money for better components? You also haven't said anything about the intended application except "monitors". Usually accuracy and sound quality are prized in monitor design, and often the monitors are used at pretty short distances and so don't necessarily need a lot of output. How close will you
  11. Stiffness is most important, and Baltic Birch plywood tends to be stiffer than most other varieties, not just because birch is a hardwood but because the boards are assembled from a greater number of thinner plies compared to most plywoods. Higher mass also helps with blocking sound transmission, more for high than low frequencies, but it also lowers the fundamental resonant frequency of the panels at which disproportionately more sound is able to pass through. Hence, most speaker and sub construction tends to favor higher stiffness and lower mass.
  12. Welcome @RCAguy ! Frequency response specs for a sub, even if done "honestly", often don't tell you much about its real capabilities. A DSP (including the one built-in to most powered subs) can re-shape the frequency response, and a lot of commercial subs rely on DSP bass boost to achieve their specs. Of course EQ can't compensate for the physical limitations of the driver and available amp power, but in practice it is often very beneficial to design a sub whose innate response starts rolling off much higher than its intended bandwidth and then compensate for this as needed using DSP/EQ.
  13. Hmm, I can't seem to edit my post above. Anyway, I see that that coax is probably out of your price range. Another caveat is that the crossover design between mid and top might be tricky. Still, you'll be hard-pressed to find a better performing combo for 400 Hz+ in a 10" circular format. Another option would to be to install a couple small mids (like those 4") together with a small WG or even a dome tweeter, crossed at like 1500 Hz. Though obviously you're going to have to give up some mid output for that. I'm wondering though, why do you think you need 12 mm Xmax from a mid dri
  14. Why two? Are you trying to get super loud treble? Realize that FR measurements for drivers are usually done on a very large baffle. A driver with good looking measurements on a large baffle likely won't look or sound as good on a smaller baffle and no waveguide, especially with three other adjacent drivers to interfere with it. Panels radiating through the same rough area won't be much better in this regard. How committed are you to your design? Can you make it taller and/or go 3-way? It's very hard to find a good driver to cover 400 Hz+ unless you're going to use a coaxial of some
  15. That depends on the impedance at that frequencies of interest, which depends on the cabinet design. Also, long-term is a very loaded word. How long is long-term One second? One minute? One hour? One full day? Those are all likely to have different answers, and the longer durations will also depend on the cabinet ventilation and ambient air characteristics. To echo @peniku8, pure voltage limiting is not ideal. The driver can probably take 3-4X as much or more voltage (meaning at least 9-16X power!) in the very short term than it can take in the very long-term. A "fool-proof" voltage l
  16. I'm not using any Hypex amps. I'm just reporting on others' experiences. If the inputs can be modified to accommodate the Motu 16A and related products, that's good news for those willing to go through the trouble. I'm not aware of other amps that had this problem with the 16A thus far.
  17. Perhaps those are Aussie dollars which are 1 : 0.76 USD (currently). Even still! @h3idrun: Tthat driver should do pretty well. Dayton also has a new 21" with similar motor and price, albeit 8 ohm vs. 4 ohm impedance. I don't see it listed at your store, but you might contact them and ask if they are planning to stock it soon: https://www.parts-express.com/Dayton-Audio-PSS555-8-21-Pro-Subwoofer-with-4.5-Voice-Coil-8-Ohm-295-050
  18. SME


    What @Ricci said, but also how is the oak floor constructed? Is it suspended over another floor or above the slab? Or is it right on the slab? The difference in that regard isn't huge, but it's there. Much more important is the room geometry (including adjoining spaces that are normally open to the main space) and specific placements within the room.
  19. Or a floor resonance. And for that matter, I believe that audibility thresholds for content at the frequency extremes within typical audio program can be much lower than audibility thresholds for pure sine waves. Pure sine waves are actually extremely unnatural sounds and may be one of the worst possible "test signals" for assessing human hearing. Real sounds almost always have lots of THD, and audio programs almost always have additional THD---because it sounds better (in moderation). The tricky thing is that the audibility of ULF is probably very dependent on the quality of the r
  20. SME


    Room dimensions and rough floor plan would also be helpful information.
  21. Thanks! Hopefully the "burn-in" phenomenon is normal and is something that's usually done at the factory.
  22. I can't recall where, but I have read that many brand new electronic components (capacitors among some things) do have a break-in process, but it is very rapid, essentially done after the component has been charged for a few seconds. Distortion of 0.1% isn't exactly high---*it* might be slightly audible in an amp depending on the particular nature of it---but if the problem vanishes after pushing it briefly, it doesn't seem like anything of much practical concern. However, this does suggest that Hypex is not testing the finished components at their specifications before shipping them. I
  23. Thanks for doing this! Those CVR amps definitely look attractive from a value perspective. It's nice to know your doesn't run like a furnace. Amps typically sound very similar when operating within their performance capabilities. However, differences are still possible for a few reasons: Amps typically use a high-pass filter to protect them and/or the speaker(s) from inaudible DC signals, and they vary a lot with regard to where the HPF kicks in. However, most amps don't start rolling off until 20 Hz if not much lower. This is something that should show up in the REW measurements if
  24. I don't know if the size and/or dimensions work, but this looks like the design you want: https://www.avsforum.com/threads/reed-exodus-anarchy-25hz-tapped-horn.1238398/ Edit to add: A caveat is that it requires a high-order (DSP) crossover. You really need the crossover to cut the output above 80-100 Hz or else it won't sound very good.
  25. Wow. Nice looking setup! Just so you know, the frequency response / sound quality of these designs depends quite a lot on the drivers that are installed. Using drivers with weak motor strength like the cheap car audio drivers you used probably won't sound nearly as good or give you nearly as much output as using driver(s) with a strong motor like the ones recommended. If building new SKRAMs, I suggest going through the trouble of finding/buying nicer drivers for them, and if there's any possibility of modifying the old cabinets to accept better drivers, definitely consider doing th
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