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Ukko Kari

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Ukko Kari last won the day on November 16

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About Ukko Kari

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  1. Sound card and measurement mic upgrade

    From Ethan Winer: http://ethanwiner.com/myths.html Myth: Absolute microphone or speaker polarity makes an audible difference. Fact: While nobody would seriously argue that it is okay to reverse the polarity of one signal in a stereo pair, I've never been able to determine that reversing the polarity of one signal - or both if stereo - ever makes an audible difference. Admittedly, it would seem that absolute polarity might make a difference in some cases, for example, when listening to a bass drum. But in practice, changing the absolute polarity has never been audible to me. You can test this for yourself easily enough: If your console offers a polarity-reverse switch, listen to a steadily repeating bass drum hit and then flip the switch. It is not sufficient to have a drummer go into the studio and hit the drum while you listen in the control room, because every drum hit is slightly different. The only truly scientific way to compare absolute polarity is to audition a looped recording or drum sample, to guarantee that every hit is identical. Important Update: Mike Rivers from Recording magazine sent me a test Wave file that shows absolute polarity can be audible in some circumstances. The polarity.wav file (87k) is a 20 Hz sawtooth waveform that reverses polarity in the middle. Although you can indeed hear a slight increase in the low end fullness after the transition point, I'm still not 100 percent certain what this proves. I suspect what's really being shown is a nonlinearity in the playback speaker, because with a 50 Hz sawtooth waveform there is no change in timbre. However, as Mike explained to me, it really doesn't matter why the tone changes, just that it does. And I cannot disagree with that. More Update Info: After discussing this further with Mike in the rec.audio.pro newsgroup I created two test files you can download and audition yourself. The Kick Drum Wave file (324 KB) contains a kick drum pattern twice, with the second reversed. Play it in SoundForge or any audio editor that has a Loop mode, so you can play it continually to see if you hear a difference. The Voice Wave file (301 KB) is the same but with me speaking, because Mike says reversing polarity on a voice is surely audible. I don't hear any difference at all. However, I have very good loudspeakers in a room with proper acoustic treatment. As explained above, if your loudspeakers can't handle low frequencies properly that could account for any difference you might hear.
  2. Sound card and measurement mic upgrade

    Regarding reversed polarity, consider the example of simply using the device for playback: Instead of a forward motion on the speaker diaphragm, you will have a rearward movement. This will change our perception of the sound of a completed system if this is not corrected, especially in the bass, not so much in the region where wavelengths are short, and small head movements will cause many rotations of phase.
  3. Pushing a horn: how to measure (with an UMIK1).

    I concur, a boom mic stand is a solid investment when it comes to measurement gear. Here is an example from Amazon: https://www.amazon.com/AmazonBasics-Tripod-Boom-Microphone-Stand/dp/B019NY2PKG/ref=sr_1_3?s=musical-instruments&ie=UTF8&qid=1513464419&sr=1-3&keywords=boom+mic+stand I am sure you should be able to source one locally similar to the example. It does not need to be a heavy duty model, and the slimmer the better. ( you do not want reflections from the mic stand to reach the mic capsule )
  4. Pushing a horn: how to measure (with an UMIK1).

    Also of note, you must ensure that the settings in Windows ( I assume you are using Windows, not Mac or Linux ) match those set in REW ( 2 channel, 44.1 khz ) as these can be set differently, and your results can be wonky. Every time I use REW, I have to change the settings for Windows under the sound device.
  5. Pushing a horn: how to measure (with an UMIK1).

    Good question, with my duplex sound card, I use a loopback cable, in essence, returning the output of the sound card to the input. The software calculates the round trip latency and deducts that from the signal arriving from the microphone input, thus giving you your delay measurement. On one channel, the microphone is connected, on the other, the loopback cable. Alternately, REW can use a high frequency device to calculate delay. This requires the sweep to be set full range, and it will listen for the high frequency chirp before the measurement. ( Typically only used for full range loudspeakers ) Yes your Marantz has time delay functionality. I am not familiar with Audessey products, and if utilizing it will give you an appropriate delay. Someone more familiar may be able to help you out in this regard. Since the UMIK-1 is a USB device with no other input, you could add a second sound card with just a loop back cable in order to have REW calculate the time delay. In the drop down menus in REW, you have the option of telling the software what inputs and outputs you would like to use. Hope that helps you.
  6. Sound card and measurement mic upgrade

    I have done some more research on sound cards, and came up with some interesting information. The Behringer UCA-202 has reversed polarity on both the input and outputs, the only one in the test to exhibit this phenomenon, according to this website: http://www.daqarta.com/dw_gguu.htm Polarity: The Polarity tests were done using a separate scope. The Generator was set to produce a biphasic Pulse waveform, such that the positive phase preceded the negative phase, and there was a dwell time at zero before the next pulse. The output had normal polarity if the positive phase appeared first on the scope. A loopback cable was then used to feed the output back to the input, and if the Input waveform seen by Daqarta also showed the positive phase first, the input likewise had normal polarity. This was the case with all devices except the Behringer UCA202, which inverted both the output and input (which means that it could not have been detected with a loopback alone). Read this thread on DIY audio, might have second thoughts on the Focusrite Scarlett 2i2 sound card. http://www.diyaudio.com/forums/equipment-and-tools/301166-focusrite-scarlett-2i2-2nd-gen-measurements-whats.html This thread has me looking at another Behringer: http://www.diyaudio.com/forums/equipment-and-tools/312454-usb-audio-interface-measurement.html
  7. Pushing a horn: how to measure (with an UMIK1).

    Typically, horns with short path lengths are used in multiples, to extend the low frequency capability, when tightly packed. This appears to be a front loaded horn, which below the corner where the horn is effective, is still an 18" woofer in a small sealed box, so you can apply a modest bit of eq to boost the bottom end, but will have to keep in mind the short throw of the driver. I would only recommend doing so in a domestic environment like yours, not in a dance club or other pro use. With REW, you can play a sweep through the subwoofer from say 25 hz to 200 hz, and look at the response. I am not familiar with the UMIK-1 mic and interface, other than having read of the possibility of clipping the signal with high sound pressure level. This is dependent on the dip switch settings inside the mic on the preamp board. http://www.avsforum.com/forum/155-diy-speakers-subs/1797489-massively-clipped-umik-1-a.html People have received the UMIK-1 with different dip switch settings, both 12 db and 18 db. If you do not have a sound pressure level meter, you could likely use an application with a smartphone to set the level to calibrate the level with pink noise in REW before making a sweep. Start by measuring the time delay of the subwoofer, you will need that to tell the Marantz to delay all other channels with respect to the bass horn.
  8. Bulding the Room2 listening room

    In a low volume setting, I would agree. Once the levels get above where the typical domes run out of excursion, there may be some that can tell the difference.
  9. Sound card and measurement mic upgrade

    I can certainly wait a bit longer to grab something in that price range. Have a link?
  10. Eventually ( after the new year ) I will be looking at a new sound card and a measurement mic. Currently I have a Behringer ECM8000, and UCA-202 sound card. From this post on the HT Shack, it appears the self noise of the ECM8000 is higher than I would like to see: http://www.hometheatershack.com/forums/spl-meters-mic-s-calibration-sound-cards/10224-ecm8000-microphone-measuring-techniques-usage-discussion-10.html#post175019 I can pick up the Focusrite Scarlett 2i2 without breaking the budget, and from measurements that notnyt posted, looks like a great interface. http://www.avsforum.com/forum/155-diy-speakers-subs/1780914-measuring-amplifiers.html Any solid recommendations for mics that aren't stupid expensive, yet have decent response to at least 20khz? Low self noise and the ability to use common 48v phantom power would be great.
  11. Faital 15PR400, BMS 4594 MTM

    Life has been busy, second and third are partially finished, but not complete.
  12. Replacement AVR / processor

    Not sure why, but playing audio from computer > UCA-202 sound card > optical input of Denon DN-700 AVP results in a small 'thump' every time there is no sound output, IE: between songs, or between videos on YouTube. There were no issues previously with the same sound card to an old Marantz. Zero thump / pop noise. Using XLR from the BD player, it is dead silent between songs, no thump or pop noise at all. If that is the case, I may have to look into a new sound card as well, something with a lot better cross-talk performance between channels. I have been looking at acquiring a Focusrite Scarlet 2i2, based on what I have read. Any other suggestions?
  13. Replacement AVR / processor

    The lighting around the knobs is too bright for my taste, and too bright to use on the front wall with a projection screen. I may have to install some O-rings on the knobs like others have done on the iNukes to limit the direct viewing of the white ! LED's.
  14. Replacement AVR / processor

    Just inserted into the chain, and powered it on for the first time. The knobs are lit around the outside, with recessed lighting rings that make the knobs appear to float. They are bright, I haven't investigated whether or not they can be turned off yet.
  15. Bass system integration

    I concur that the time portion of the system response is what we must strive for correctness. Time of flight, processing delay needs to be accounted for. What I have done: in a multi-sub system, measure time of flight ( with no DSP engaged ) from each device in it's intended location to the main listening position, and compare that to the main L/C/R channels. I helped set up a system with subs that were radically different in distance, with a nearfield sub behind the MLP area. In that particular case, the closest subwoofer was set for level, and run at a bandwidth of <40 hz. Delay was set so it's time of flight was identical to the average of the main L/R speakers. The other 3 subwoofers in this large room were set so their time of flight was identical. The pair closest to the L/R were run <120hz ( main speakers were not on the level of some enthusiasts here ) The third subwoofer was run <60 hz. Subwoofers were not gain matched, the one behind the MLP was reduced considerably in level, it's 4kw amp was just idling barely with respect for the required levels. Processing added 1-1.5 msec of delay, so the main and subs required a bit of fine tuning. Once all 4 were playing 'nice' with respect to each other and the main L/R, Anthem room correction was run. Every situation is unique, and requires a customized solution. You may get better smoothing in the upper bass running all subs as full bandwidth, but may result in a softening of the attack across some of the listening positions, if there are many, due to the various complex phase relationships in different physical locations. Longer wavelengths ensure that you will have better success at integration. It's not hard to get sources within 1/4 wavelength at 20 hz, or even at 40.