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philipbarrett

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Everything posted by philipbarrett

  1. If you measured this with a sweep in an anechoic chamber stop reading right here. If not, then what you are seeing is either room node cancellation, phase cancellation between the K-Horns & sub or more likely a combination of the 2. I know I'm back on my hobby horse but if you search my user name for previous posts you can see my opinions (& data) on why subwoofers disapoint with Klipschorns. You cannot make accurate plots at these frequencies in the typical home environment the best you do is run prediction software. Here's a good place to start - http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html
  2. The code was a marketing ploy, the idea being that you would spend more on a DDD disc (DigitallyRecorded, Digitally Mixed, Digitally Mastered). Even today, a huge number of releases are delivered to the mastering house in an analog format (1/2" 2-track being the most popular high-end) and of course the last "D" was meaningless anyway, how else were you going to master a digital disc anyway? There are HUGE differences in the sound of CD players but $200 isn't going to buy you much, even used. If you can push your budget a little, the ever excellent NAD makes a nice entry single player the C-515BEE for around $300. http://www.audioadvisor.com/prodinfo.asp?number=NAC515BEE I've not heard it but the manufacturer is well known for packing a lot of sound into a simple package at low cost.
  3. I love my little 7140 int amp, but it isn't transparent... it's dark grey (which I suppose sorta looks transparent when the lights are off at night). So you want to go down that road eh, eh? Bring it on... I shall talk about how the NAD involves me in the music, about it's pace & timing, light & airy yet solid with a defined musicality and interlocking detail. How it's presentation invokes feelings of detachment in a lateral imaging kind of way and it rendered the inner detail in a complex soundstage. Finally, I'll mention the dimensional body and dynamic contrast. In fact it's so awesome I have to keep it in the garage with the propane tanks.
  4. I've had a 1020 since new, nice little piece, very transparent.
  5. Exactly, y'all are correct. The little Behringer will do a better job than DACs costing 10x as much (dare I say 20x?). As I mentioned before, there are better units out there but they cost substantially more. Mostly what you would be paying for are additional multitrack outputs, profesional mixing & processing capabilities that you wouldn't need anyway. You'll need 1/4" to RCA adaptors to hook into a home system, if you're on a PC then you'll install the FCA software, on a Mac it will be automaticaly recognized and If you buy from Muscian's Friend you get the option for a full refund if you don't like what you hear. http://pro-audio.musiciansfriend.com/product/Behringer-FCA202-F-Control-FireWire-Audio-Interface?sku=240108 For easy switching between and assignment of system sounds away from the DAC I highly recommend the free Soundsource program from Rogue Ameoba (Mac only) - http://rogueamoeba.com/freebies/ Please let me know how it works out.
  6. Your cousin's analogy is an excellent one. Just as a car engine uses a timing belt to synchronize the mechanical functions so digital audio needs a timing clock to synchronize the data. As discussed above, some digital audio signals contain this timing data which the receiving device can read and some signals require the receiving device to re-create the timing data. IMO this re-creation is where the most audible artifacts occur. To confuse issues, some DAC (digital to analog convertors) ignore the signals timing data and recreate their own. This is common in the USB world where low end, off the shelf chips are used to build interfaces. A fantastic guide to Adaptive & Asynchronous USB can be found here (although I wonder about the author's use of expensive solutions to an inherent problem when the FW alternative is available): http://www.computeraudiophile.com/content/Asynchronicity-USB-Audio-Primer In a nutshell, Firewire offers the best solution at the lowest price. The FW audio signal contains a clock and all FW chipsets use this clock to synchronize their workings to the incoming data stream. Signal coloration is minimized, mostly leaving the analog section to define the "sound" of the system. Of course there are better and worse FW systems (professionally we use interfaces costing many $1,000s) but I believe that the clock resolution gives even the most basic FW interfaces the edge over DACs costing much more.
  7. Bingo !! - I think you may have nailed it ! - I never thought of that, but it certainly was true of most old amplifers. No, I looked at the schematic, the 1st thing the Pat-4 power line hits is a transformer which has no opinion on the hot/neutral issue.
  8. Unless you physically added a ground wire on the IEC to the chassis of the Pat-4 then both should be floating which is what I believe the problem to be from the symptoms described (touching makes it better). The "ground wire" test mentioned in my last post should confirm or deny this.
  9. Take a regular (cheap) power cable and cut off the female (equipment) end. Strip back the insulation about 4" to expose the 3 wires inside & then cut back the black & white ones, leaving only the green. For safety, tape over the black/white ends. Now, strip back about 1" of insulation on the green wire & using a clip, physically connect the copper strands to the chassis of your preamp, a place without thick paint would be best. Plug your modified cable into an electrical oulet. Less hum? No hum? PB
  10. Bridging amps such as the Samson is going to give you more problems than it'll fix. You'll be running the amp so close to it's voltage rails that power supply sag will rob you of sonics and headroom. The only amps I've seen that can really handle a bridged load do not plug into a standard wall outlet. As Colin said "por que?" Are you running out of power?
  11. Ground noise can be caused by both "not enough" (equipment is floating & hunting for a ground) or "too many"(equipment is connected to ground in 2 or more places and their is a voltage potential between them) paths. I'm trying here to dissect your rather cryptic post. 1) you say "mainly on the phono" if that means there is also hum on other inputs I would suspect that the reason it's louder on the phono is the much higher gain from this input relative to the others - CLUE : if hum is present on all inputs then it's unlikely that the phono section is at fault or the caps or whatever you see back there 2) "if I touch the chassis it goes away" - CLUE : chassis is looking for a ground, you are providing one 3) "if I touch the postive wire it gets worse" - as it should, you're a great antenna & you've just connected yourself to a highly sensitive input 4)"I felt it necesary to replace the electrical cord and connected the ground to the chassie" if I presume this didn't fix anything then it totally contradicts statement #2 As mentioned above, without more information (the makes & models of your equipment would be a start) we can't go much further. Right now, basically all you've told us is that your car of undertermined age, model & make won't start!
  12. Its not that simple. Care to enlighten us why? What's not simple is the confusion around balanced interfaces & XLR connectors. The 2 are not the same. Search previous threads here for plenty of information on the subject & the reason why balanced lines make very little sense in domestic audio applications.
  13. You said what I wouldn't. 3 legs is the way to go, the bolts allow perfect leveling of the shelves once the rack is placed.
  14. I knew there was a reason for that, I think I did the math in mm too. I put the whole thing together in less than 3 hours from driving to Home Depot to gear wired, I just couldn't see spending big $ on a rack that could be spent on glowing toys! The floor is typical Texas, parquet floor on concrete slab, pretty solid stuff in other words, so no problems even once the dance party & air guitar wars start.
  15. 3/4" MDF & threaded rod, total cost >$30 at your local homestore. 3 legs is easier to balance & I recommend avoiding a leg at the rear as it makes connections more difficult Shelves are 16.75" x 23.25" which is either some kind of magic divisible number that gives low resonance or I forgot my meds that day!
  16. Pro audio runs at +4dB, home at -10dB, some amplifiers have an input sensitivity switch to compensate. If not the fix is simple & very cheap; turn up your preamp until the music's as loud as you want it to be. PB
  17. Not the pinnacle of pro audio amps but a decent piece of kit, if it's used it may well have seen a hard life. These amps don't get bought to be babied. As for pro amps sounding "better" than others, search some previous threads on the subject. PB
  18. This is the beautifully even coverage achieved by placing your low end in a corner, imagine that! The yellow lines are canceling nodes, there should be one but I probably had a sub an inch or so off in placement. In a perfect world it would be an infinitly narrow plane exactly between the speakers.
  19. ...and here's what PWK has been trying to tell everyone for years
  20. So here I told the MAPP software to estimate a plaster ceiling, painted brick walls & carpet on concrete floor. I think you can see how using the 2 sub configuration is really detrimental to the sound once you get into a real world situation.
  21. Not all, I assume by "variable gain tube amp" you mean a preamp? My only concern would be loading down the outputs of the preamp. As for the crossover frequency, your ears should be able to tell you that. Subs stop really being subs above 100Hz, for home I would look at a 12db/octave crossover at around 60Hz which should blend in nicely with Heritage speakers run full range. Live I tend towards an Linkus R at 24db/octave but then I'm also high pass filtering the mains. Happens at all frequencies but the wavelengths become so short that the time differences become minimalized. At 40Hz the wavefronts are at nearly 30 feet, by 1KHz they drop to around a foot and by 12KHz it's an inch or so. As you can see, mechanical time alignment becomes much trickier at higher frequencies. Old wives tale. Back in the days of vinyl, low end had to be controlled and mono'd in order for the cutter heads to create a groove that could be played back without the stylus jumping out of the groove (or the cutter burying itself in the acetate). There's plenty of low information on older records, either intentionally or unitentionally. If the subs make you happy leave them on, Bonham's 24" kick has all kinds of wacky stuff down there. Your hearing most of the directionality at higher frequencies. Put a 40Hz tone in there, eliminate the rattles (generally not possible of course) then try to locate. As for the cardiod subs; the MAPP predictions are not making this up, they really work if you have the room, processing & the $ to spend double the money (2 subs with 2 amps). I've set up big walls of subs in this fashion & watched stage hands walking in front & behind scratching their heads, it's that dramatic. Obviously room artifacts will come into play pretty significantly in the home but your area is pretty huge. Becuase his one sub is propagating per my 1st & 2nd predictions & yours are cancelling per the 3rd. It really is that simple. Further proof below.
  22. Now for the party tricks, or how to create directional LF with super-even coverage! 4) 2 subs stacked on the floor. The left (front) sub is placed 2 feet behind the right (rear) sub. The signal polarity is reversed to the front (sub is running "out of phase") and the front sub is delayed by 3.75ms (2 feet), combining it theoretically with the rear. I've never tried this at home (don't have subs) but the approach would seem to be very workable in a larger listening room. Obviously the spacing is not critical, the time alignment just has to match. If you want the pattern to face the other way, time align the rear sub not the front. edit : for clarity
  23. 3) 2 subs on the floor side by side. Now you start to see my objections to the stereo subwoofer set ups. Huge lobes & cancellations start to appear, these will change in amplitude & location with frequency.
  24. 2) Stacked pair of subwoofers on the floor. Notice that the amplitude throughout the roomhas increased but the coverage remains about the same.
  25. OK, here goes. Sorry Amy I'm taking up a lot of forum space here. I think I'll break this up into 4 posts so hang on to your horses for a mo' Using the Meyer MAPP prediction software, I built a 20' long, 12' high room and placed in it, various combinations of Meyer 700HP, front loaded, double 18s. The type of sub is not critical to the measurements, these are merely used to illustrate the points. All measurments are done at 63Hz with all room treatments turned OFF. 1) Single subwoofer on the floor. Notice the smooth, almost omnidirectional coverage, red is loudest, graduating down to blue for quietest.
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