Jump to content


Super Users
  • Posts

  • Joined

  • Last visited

  • Days Won


Everything posted by Shredhead

  1. Here is something interesting in the way that REW interprets input levels for folks who may not know... This is the highest clean level that a class A/B chipamp can produce @ 30Hz without clipping the waveform: Now here is the same amplifier pushed into clipping. Neither REW's or the soundcard's input was clipped, only the signal into them was. The peak voltage into REW's input does not go any higher when the amp was pushed into clipping because the amp had already reached it's output limit but REW still shows a 1.7-1.8dB increase in level because it senses an increase in RMS level. This is another example for why I think it is less confusing for most people to stick to peak values and not focus on RMS. After all, the amps are rated in peak power values anyway.
  2. Oh, I didn't know Josh started using Skrillex songs for driver data. My mistake, nevermind.
  3. I wrote this in the above post: "The only way to get a clear idea of what you're working with is by looking at the current and voltage at highest and lowest impedances of the reactive load with the amps at their maximum clean level." I didn't say that you should have used water heater elements. Your test was interesting because you were beating the utter fuck out of the amps with hardcore drivers as the load and we learned that they will both go into protection mode in certain conditions as opposed to melting. You are still left guessing when it comes to which amp put out an undistorted signal at a higher level, whether the amp's clip lights are accurate and where the mute limits are, or where their limits are at 10Hz and below. Voltage and current measurement tools can help to show a clear picture of amplifier limits. My comment about volts and current is there for folks that might not know anything about amp testing, it wasn't aimed at you. You post plenty of good data about drivers already, I wouldn't expect you to go all out for 1 amp comparison.
  4. I like to shoot for most power but if you wire too low in impedance then you chance destruction of most amps (or protection circuits turning on). Fortunately these amps have reliable protections in place so that too much current doesn't cause a catastrophic failure. All amps produce a maximum voltage and current before overheating or exploding. How much for both of these maximum values depends on the amp design and amplifiers like these are insanely fucking complicated in design. The only way to get a clear idea of what you're working with is by looking at the current and voltage at highest and lowest impedances of the reactive load with the amps at their maximum clean level. Bus pumping aside, the ultimate test for these and any sub amp is for how they behave driving a reactive load at 20Hz and under. This is hands down the most demanding scenario for an amp. When comparing amplifiers and looking at only this, you pretty much have to start by comparing their looped frequency response and then with that as your reference point, compare their maximum unclipped levels (verified by a scope) and see what the deal is from there. Don't take me the wrong way Josh, I appreciate the thread and I know what a pain in the ass it was.
  5. No need to get petty about this Luke, you've only been asked to verify your claim which is not out of the ordinary for these discussions. If you haven't measured your system's voltage and current while playing your demo track then all you have is a theory, which is also fine with us.
  6. Things go in cycles for everyone, things will pick up again. And what, that was like the ONLY time I've seen Mod action needed since I've been here and no one was put in the penalty box over it and it didn't turn into a big deal. This place is as laid back as it gets and I dig it. Avengers 2 had better bring it for real this time or I give up on Marvel.
  7. -DTS 7.1 -French 5.1 DD Here is what I get from the ship crash scene from the bluray using the DTS and then Dolby Digital mixes. There is a huge difference between Andy's and mine, I wonder if it is a disc region thing.
  8. Whoa! Never would've guessed TOS went that low!! It really gives the lame new movies that get high pass filtered at 30Hz NO EXCUSE.
  9. K nevermind I'm wrong, I had the wrong input on. Now Alien looks a lot closer to what Andy had. I thought I was losing my mind for a minute there. Ghostbusters Zuel scene from 5.1 DVD. Subwoofer out with Andy's settings. Pretty close. It appears Andy has a bit more under 20Hz which may be due to the Dolby SR unit.
  10. No, I didn't have the stereo track on the BR so this is downmixed to 2ch from surround. This is the LFE of the surround with a bit hotter of a level. It's a bit different than the stereo downmix I posted above but pretty much the same. Doesn't even resemble the laser disc mix here http://data-bass.ipbhost.com/index.php?/topic/12-the-low-frequency-content-thread-films-games-music-etc/?p=9102 I believe I saw Kval put up a Bass EQ page for this for anyone out there who wants to boost the low end on the bluray for this movie. http://data-bass.ipbhost.com/index.php?/topic/285-the-bass-eq-for-movies-thread/?p=5599 For folks that don't know, these are BEQ settings for the people with the HDMI nanoavr. Andy, you might be interested in this piece of gear so you can get the bluray track of the older flix up to par with the laser discs.
  11. This was a digital loop on PC, it isn't accurate. It's downmixed to 2 channel in software just so I could grab a quick screen cap.
  12. This is the stereo track of the bluray for the same scene. LAME. I've always thought that laser discs had better mixes of the old flix! I remember there was a part in the original ghost busters where Sigourny opens up the fridge and that dog thing said Zuel and it had powerful bass on the laser. The DVD has zip squat.
  13. Yo, I forgot to tell you that depending on your settings, that newer version of SL you just got may act buggy. If it is buggy it will show double what the frequency you input to it, or it will repeatedly show loud transients with no input. If it doesn't work right, download this version and load the settings into it: http://www.qsl.net/dl4yhf/spectra1.html#download -It's the top link zip file. Regarding the new color scheme -the spectrum basically has more colors. Like having more colors on your monitor screen increases the resolution, so does this. When you get used to the scale you will be able to see more detail in the sound design. Let's look at the ship crash at the end of Prometheus: Here is the warp jumps in Star Trek: Digging it.
  14. Hi Andy, welcome to databass! If you turn up the input level to speclab, you will see more resolution of the mix instead of just viewing the peaks of the content you feed it. Shoot for a strong looking waveform like this and you will get more colors to show up: Bossobass came up with a new color scheme for speclab with more resolution that I am really liking. If you want to download the settings file to load into SL, it is located here: http://data-bass.ipbhost.com/index.php?/topic/435-bossobass-mini-gtg-thread/?p=8831 This is the first I'm learning of the Dolby SR (spectral recording). It says on wiki that it boosts dynamic range by 25dB. That would be quite useful for analog recordings. Do you know any specifics on how it works?
  15. Hahaha, it's a "fun party speaker".
  16. The amp was probably out to lunch and oscillating. That sub's port tune is 25Hz so it was just howling at you guys. Absolutely annoying I bet. You'd have to be a real chode to run that place and not notice something like that.
  17. LOL! I do wish that there were more bands that got to record at the high levels of bands like Steely Dan. I remember a few years ago I picked up an album from the band Train that was mixed in surround. I was interested in hearing more of a modern band in the format and it was one of the harshest recordings my ears have ever had to deal with. It seems silly that we're in the two thousand and ten's and there are still bad sounding recordings being sold. I guess producing digital audio to sound pleasant isn't as easy as analog was. I know I've struggled at it.
  18. Hey man, sorry to hear about the medical stuff. A string of my family members have logged some ER time lately too and few things are less fun. As far as speclab goes, there is a bug that I know about for the latest version where if your system runs 24bit audio, you have to select 16bit in the settings on SL or it will give you all kinds of crazy noise and stuff. Maybe it's that? I don't know about audacity but you can loop your soundcard's out to in, use REW to generate different sine tones and see if they register at the same levels on the graph in Audacity.
  19. This was the DVD with a DTS ES soundtrack. The scroll speed was set to 2 minutes.
  20. ...And I guess my next question would be why are some mixes leaving so much headroom in the LFE/summed LCR channels? I wonder if they are taking into account that many consumer playback systems are not setup to leave headroom for a worst case hot mix on the sub out.
  21. Hey guys, I need some help understanding how the levels rating relates to sub out voltage. I compared 2 of the hottest scenes in Avatar http://data-bass.ipbhost.com/index.php?/topic/12-the-low-frequency-content-thread-films-games-music-etc/?p=2768 and Earth to Echo http://data-bass.ipbhost.com/index.php?/topic/12-the-low-frequency-content-thread-films-games-music-etc/?p=4883 and this is what the waveform looks like related to voltage levels on the grid which is 500mV per division: There should be a difference in levels of around 4dB going by the rating but I think the voltage out shows a bigger difference. I went to a voltage to voltage level calculator like this: http://www.sengpielaudio.com/calculator-db-volt.htm and when typing in the 2 peak voltages it shows a difference of almost 10dBV. I guess I have no idea what the composite levels in dB are related to. Will someone please help me understand this?
  22. http://data-bass.ipbhost.com/index.php?/topic/12-the-low-frequency-content-thread-films-games-music-etc/?p=3141
  23. Gotchya, good to hear nothing bad happened to it.
  • Create New...