Jump to content

PrestonTom

Regulars
  • Posts

    4394
  • Joined

  • Last visited

Everything posted by PrestonTom

  1. Folks, I truly hope that a potential K-Horn user will not look at this discussion and conclude that anything less than a 25x40 ft room (or whatever) will be inadequate to enjoy a pair of K-Horns. Although overall room size is important, it is not the only issue (or solution) in room acoustics. My own experience is living in a 12 x 22 ft room that opens onto a kitchen, hallway and front entry (making it seem larger). I added a false corner (half of a corner, actually) and l placed them along the long wall so I am at a 45 deg angle from each. This has been fantastic. It became even better, when I added a center. I enjoy these speakers and I would never try and use anything else and then try to supplement with a sub. I use these to listen to music (well-recorded music and played at realistic levels). Perhaps I am happy because I am not trying to play sound (or movies) at killer levels or listen to stuff that is recorded with an exaggerated bass. Corners are important, the other features of the room are also helpful but not as important. If it is an issue, then install a false corner. K-Horns are wonderful speakers (yes, I am biased). Please don't shy away from them because of the comments being made. Good Luck, -Tom
  2. "You are not the only one confused about polarity! Not only is it different between networks but it's difficult even to say which way is correct" Al, you posed this question about determining the "correct" polarity when hooking up the crossover/drivers. You suggested many solutions. I believe you will do the best (as you mentioned) when you you look at the amplitude spectrum where the drivers overlap. Do this, then set the polarity to minimize the fluctuations across frequency. This, of course, will partially compensate for phase shifts introduced by the order of the filter (eg. invert if the filter has a 180 deg shift at the corner). Although, with a very high order filter (and little spectral overlap) then a consistent phase would be fine. I thought this was the standard thinking. I guess I don't understand your objection. Good luck, -Tom
  3. Chris, Be thankful that the problem did not result in a fire. Speakers can always be fixed..... I definitely agree with the freezing method. This should be done first. If that fails, telephone a dry cleaners, they have lots of tricks. Good Luck, -Tom
  4. Tid, I appreciate your dilemma; however, I there is another perspective. Many of the folks are looking somewhat blindly at the cutoff frequencies for the various cabinets. Let me caution that the speaker response is not simply the output of the speaker, rather it is the output of "speaker-room " when viewed as a system. This is understood by all for the case of the K-Horn which does best in sealed corner. However, it does not stop there. It will also be true for the La Scala, a sub, etc. The output you will get will also be a function of room geometry, room treatment, location of cabinets and listening chair etc. So the difficulties one might have in placing a K-Horn will also occur when placing a La Scala etc. One really needs to consider the cabinet as part of a system where the other half is room acoustics. Incidentally, regarding the use of a sub, in my view one of the remarkable things about a K-Horn is that the deep bass is very clean sounding. I have yet to hear that from a sub. Sure, you can get a sub to put out plenty of low frequency energy, but I have yet to hear a sub generate the wonderfully accurate sound that a K-Horn produces. This is my bias. Good Luck, -Tom
  5. Robert, Glad that you are enjoying the Proton tuner. You are right about the NAD-Proton link (although I understood it was the other way around). I have a NAD 4155 which I have been quite happy with. It is a strong tuner & great for pulling in campus stations (supplemented with a small Yagi on a rotator on the roof). My collegue brought his Proton into work one day and low and behold, except for the nametag it is an absolute look-alike to my NAD. Since they are not a well-known company, you can pick these up for a very good price on eBay. Good Luck, -Tom
  6. Folks, Just a bit of perspective here regarding low fequency sound. Please remember at 100 Hz the wavelength is 10 ft, at 50 Hz it is 20 ft, & at 25 Hz it is 40 ft. These are big numbers. Add to it that these large wavelengths are relatively unaffected by things like carpet, drapes, & furniture. So when you talk about the output of the speaker or sub, you really need to consider it as part of a system. That system is the "speaker-room" system. Even with an upper limit of 300-500 Hz, much of what you are listening to is simply room acoustics. There is no getting around this. Room treatments for low frequencies are difficult and expensive. Typically, foam will not do it. You really have to rely on room geometry, placement, and bass traps etc. Even these treatments are not simple nor entirely effective. In many cases they simply "move" the problems somewhere else (location or spectrally). It really is a sobering thought, since trying to correct the problems will require some heoric efforts and a great deal of compromise. Good Luck, -Tom
  7. DJK, There was a caveat on my comment that soldering would not improve the sound. The caveat was: if the contact is clean and not corroded and the contact was secure. Then there would be no improvement. Under those conditions how will the electrons "know" if they are going through a soldered connection or not? The possibility of screwing something up with a soldering gun is just too risky. Good Luck, -Tom
  8. Careful, careful, careful If the contacts are corroded or lose, then by all means clean and secure them. If this is done then soldering will NOT improve the sound. Good luck, -Tom
  9. Tom, Congratualtions! No need to upgrade the equipment right away. Listen and enjoy. However, I would encourage you to get a CD player. There is so much available on this format. No need to spend a lot of money on a CD player. For less than $200, I would recommend a Dennon or Harman Kardon, or even a SONY (however not their bottom line models). You can spend more money , but the benefits will become elusive (the technolgy has gotten quite good, so newer is frequently better) Once you have some well-recorded CDs, I would encourage you to spend some time on tweaking the placement of the speakers and listening chair. This can make a profound difference, more so than swapping amps etc. Enjoy, -Tom
  10. Shawn, Yes, these are interesting measures. Bench testing is to be commended. I am going to mention some things that I suspect you already know, but others may be confused about. Using a square wave (and I am not sure how it is being generated) is a nice visual depiction for a time-domain analysis. The biggest thing that will mess it up (and make it look "less square") is a bandwidth limitation. You have nicely pointed out this limitation and where the harmonics are in a square wave. However, what others may not be aware of is that this graphical depiction can also be "messed up" by two other problems. The first (and more trivial) is if the device produces a phase shift (it is still a linear device with plenty of bandwidth). The decompostion mentioned earlier needs to understood in that the harmonics comprising the square wave must be in cosine phase in order to generate the "square" edges on the waveform. However we are relatively (usually) insensitive to phase so this is not a terrible problem. However there is a second problem that will also "mess up" the "squareness" of the waveform. That is the slew rate. This is simply the rise time or slope expressed in volts per time (microseconds). The bigger the number the better. Although I wil let others argue about the perceptibility of more modest slew rates. The final comment gets into a tricky issue about amplifier measurement (and this was obviously beyond the scope of your measurements - so it is not a criticism of what you are accomplishing). The question is simply: Should the amplifier be measured as part of a system? By this I mean should one substitute an actual speaker to the output of the amp rather than using a power resistor. I am still referrring to measuring the electrical output of the amp (and not the SPL of a speaker in a room). But now the load is rather different. The impedance being driven is not constant across frequency and the demands on the current delievered by the amp can be rather different. Just think of an amp with limited current capability trying to drive low impedance electro-static speakers. That raises a whole other set of issues.... However, realistically, no one can measure every combination of amp/speaker. I guess what I am trying to say is that this is an essential component of describing an amplifier; however, there are some other important issues (eg., transient current capability, damping factor, slew rate, distortion levels while driving a complex load, etc). Most of these are never adequately addressed & measured anyway. Good Luck, -Tom
  11. Bismarck, The smartest thing you can do is put an in-line fuse on each speaker. lstari gave some good advice about the Radio Shack ones. They are inexpensive and simple to install. Good Luck, Tom
  12. Eric, Sorry to hear about the bad news. However, just about everything can always be fixed. I certainly agree with DM & Gil about the most likely problems. At the risk of sounding like a jerk, it is always a good idea to put an in-line fuse on your speaker cable. Thes are fairly cheap (20mm ones from Radio Shack are fine). What you have gone through is one of my worst fears when using older electronics or having someone bump into a volume knob etc. There are some naysayers who will recite the usual cable voodoo about the sound degradation that supposedly occurs when the electrons are forced to transverse 20 mm length of thin copper. But that is nonsense. The actual surface contact between mechanical connections between components or within a component are comparably small. The electrons do not know and I won't even mention how small the gauge is on a voice coil winding. Again, I am sorry to hear about the bad news. Statistically, it is most likely a diaphragm in the tweeter that was blown. That can be replaced and is not too costly. However, I certainly recommend to you and to others to install an in-line fuse on your speaker cable. Accidents do happpen. Good Luck, -Tom
  13. Yes, that does bring back memories of the Ohm F (walsh) drivers. As I remember, there was a big to-do over the sound field. Supposedly, the sweetspot was just about the entire room. They sounded pretty good when they were loud. At this time the Carver-designed Phase Linear amps were quite popular. That was the combination that I remember Ahh memories, -Tom
  14. Jim, Congratulations!. There is no hurry on this stuff. You already have a decent amp and the real trick in matching an amp to a high efficiency speaker is to find one that is quiet and clean at the low power levels. The speakers do not present a low impedance, so you need not worry about an amp that will deliver high current levels. At this point the biggest impact on your system will come from spending some time on locating the speakers/listening chair. This is not sexy but it is absolutely necessary. Next some room treatment is in order. This can range from simply moving/adding/removing drapes, carpets, pads & furniture to more exotic treatments such as foam and bass traps. Before you perform the latter (since it can be expensive) you need to get a clear idea about what it is that you like and dislike about the sound. Refreshing the crossover is certainly in order also. The isssues of amps & pre-amps are secondary to the set up & room tweaking. Good Luck, -Tom
  15. You are correct DrWho. When the signal is not split (as is sometimes the case in audio but not the other applications) you can still cancel the noise by subtracting the noise (picked up on the inverted, other wire). Signal-to-noise ratio is still improved. But the key elements still remain: noise cancellation via a phase inversion followed by a summation between the two wires. Good Luck, -Tom
  16. Gil, That was a thoughtful, and thought provoking, review. BTW a couple of the "pluses and minuses" are inverted - but the context clarifies your intent. It sparked something in my memory banks about a derived center channel. The summation version for a center is usually used to "anchor" the center of the image when the speakers (L & R) have a large separation. So this takes care of the "hole in the middle" problem. Not as frequently mentioned is that it will also enlarge the listening "sweet spot". What you sparked in my memory was when I first came across the Bell Lab's etc symposium. One of the frequently mentioned observations was that the third "channel" now gave a sense of depth to the sterophonic image. This has always been intriguing to me. A number of folks get a sense of spaciousnes when there is a bit of de-correlation produced by reverberation, but the reports from the symposium (and these were individuals who could knowlegable and could articulate some of the percepts) was that there was now a sense of depth to the audio-image. The intrigue comes from the fact that this is difficult to explain. The stereophonic image, including the phantom center etc, is well-described / predicted by "stereophony" (as conceptualized and described by Ben Bauer). However, the sense of depth remains elusive in its mechanism. Bottom line: I know it when I hear it, but I just can't explain it. Good Luck, -Tom
  17. dboxmeyer, This is all very simple. The problem is that your wife does not like having 5 speakers in the room that are all in a black finish. Consider replacing them with just two K-Horns. The logic is as follows. They have nice wood finish and fit nicely into the corners of the room. There are only two of them (you really don't need the other three), so you have already made a good-faith-effort to consolidate. Now if you can convince your wife with this logic (practice in front of the mirror first), let us know. Good luck, -Tom
  18. I really do not understand why there has been so much confusion throughout this thread. Lets look at it very simply, because it really is simple. I can sendsplit a signal in two and send it down a cable (one inverted in phase relative to the other). While the signal(s) is travelling down the cable it picks up noise. The noise for the most part is correlated / identical between the two wires. When the signal(s) have reached of the cable and they have picked up some noise - what to do. Well I can invert the signal (plus noise) on one side (that was originally inverted anyway) and add the the two wires together. Presto! The signals are back in phase and add up by +6dB (& yes, you may have attenuated them by -3 dB to begin with so there is no net gain). What about the noise that was picked up by the cable. Since the noise was common/correlated between the two channels, You have effectively subtacted the noise (inverted the phase & then followed this by a summation). Good news. Between the two wires, the signals add and the noise cancels. Now you have a very large signal-to noise ratio. Now for the other extreme. What if the noise was uncorrelated between the two wires (vey unlikely in this configuration) then the signals are correlated so the summation for the signal is +6dB. However the noises are uncorrelated so the summation is only +3dB. Net gain: an increase in signal-to-noise ratio of +3dB. So between these two limiting cases, the signal-to-noise ratio has either increased by a VERY large amount or in the other (less likely case) it has increased by +3dB. Why is there this red-herring about impedance. The phase inversion will not change the impedance. However for this trick to work the signal at each wire(one inverted in phase relative to the other) must be equal. Why not ensure this by sending the signals to a transformer on the other end. Now the sender only "sees" the transformer. So whatever else happens in the circuit downstream is effectively isolated and the signals being sent are "equal" between the two wires. Now when you have low level / high impedance signals, such as phono or a microphone (the more typical example) you can now send it great distances and although you will pick up a bunch of noise, it can then be cancelled. So splitting the signal, then inverting one leg then sending them down the cable (and picking up some noise), then re-inverting the one leg and then summing (adding the signal and subtracting the noise) does in fact work. Is this important in audio applications where you have line levels sources (CD, DAT, tape or tuner)? There it is probably not an issue. Does it matter when you have a phono source going a short distance (with decently shielded cable)? Again it is probably not an issue. Does it matter in a professional rig and going great distances or when your "source" is a microphone? Yes! It is an absolute must. As I said before, this is a standard & straight forward engineering issue/solution. This is not just an audio trick. It is also used in data communications with TTL pulses etc. Good Luck, -Tom
  19. Measure the resistance of your bi wired path and tell me just how much damping is your speaker wire providing you. Ah Ha.... A voice of reason! -Tom
  20. Many of us have tried this set up. The results are positive. A Heresy will work and the results will be quite noticeable. If you like that, then the next step would be horn loaded cabinet (LaScala or Belle). These are preferred since the distortion is comparably low re: your K-Horn. Personally, I use a Cornwall 2 and have been quite happy. Plenty of threads on the circuit (which can be fairly simple & cheap). You will need an exrta amp. The set up takes a bit of tweaking. The trick is not to turn up the center too much. This set up may also cover up some possible anomalies in the room's acoustics. Good luck, -Tom
  21. Max, Thanks for your reviews. I am especially interested in your thoughts on the Cain & Cain's. At one time I was energetic and considering building some single (possibly 2 driver) driver cabinets. There are a number of designs comparable to the C&C Abbeys. Although I am sure these guys have been through a number of headaches getting them right, so I do not want it to sound like it would be a trivial matter. These designs (and I am generalizing) are frequently criticized for their lack of a deep bass (although this is true for many cabinets) and for being able to play at a high volume (since you are asking for a small drived to deliver a great deal of throw). Also there are comments about an "in your face" voicing. However, these comments are second hand since I have not yet had the privelge to hear them myself. However, given these criticisms, the same folks typically have some other very, very positive comments about them. I guess the summaries I have heard are that they are not meant for rock music. I don't condider that to be a show-stopper. Please tell us more. Some of the home projects of a similar design look like they would be a blast to design & construct. Good Luck, Tom
  22. DrWho, Re: the +6 dB gain. You were a bit quick to reply on that one. No matter if the inputs are attenuated. My analysis (not mine actually since this is standard engineering) is in terms of signal to nose ratio. Obviously one would not want the signal to have a net gain when going thrugh a balanced cable. I was just clarifying that you MUST have the inversion/summation to get a gain in signal to noise ratio. My examples were meant to be helpful in that this exactly what you would expect if you simulated this with a signal generator and 1 or 2 noise generators and looked at the output on a scope/analyzer In terms of gain in S/N ratio, the two extremes are the cases where the noise is correlated or when it is not correlated. This is standard stuff and I was confused by why others were confused. Good Luck, -Tom
  23. Wait, Wait, Wait, When using a false corner you may want to use some pipe foam along the horizotals to ensure a tight fit into the corner. This, of course, would also be the case for real corners. Fiber fill and batting are not appropriate in this case. They are designed for other applications (i.e., inside a cabinet for dealing with reflections or more appropriately for making the cabinet "seem" larger by altering the sound velocity). Your cabinets were not designed to have the sound velocity altered during the final flare nor were they meant to have the waveftont dispersed during the final flare. By all means use the pipe foam to get a good corner seal. Good Luck, -Tom
  24. I agree with Bruce / Marvel (who has been quite correct throughout this entire thread). If the noise is correlated between the two channels, then the inversion/addition will sum the signals and cancel the noise. The signal-to-noise ratio will be be quite large. If the noise is uncorrelated between the two channels, the signal will sum (+6db) and the noise will sum (+3dB since it is uncorrelated). In this latter case the improvement will only be +3 dB in terms of signal-to-noise ratio. This latter case, would be unusual and would indicate the limiting noise is perhaps in the electronics and not pickup along the line. There is no magic here.This is the exact same strategy is also used in transmission of TTL pulses and has been around for sometime. Good Luck, -Tom
  25. Tommy, You're right the McIntosh is nice looking, but it is quite expensive. The first step is certianly to supplement the Heresys with a sub. I believe the second step is to spend some time and arranging the room and the speaker setup/location. There is no simple formula (although there are some good starting points). It does require some time, tweaking and careful listening. With success, then some room treatment is in order. This can range from fooling with carpet & drapes & furniture to more elaborate treatments such as foam & bass traps. This last step can be expensive so you need to have a clear path in what you like and do not like about the sound. Perhaps prior to this, you might even consider re-freshing you crossovers. If you get caught up in a more extensive upgrading of the crossover you need to be very clear what it is that you like & do not like about the sound (and realistically would a super-duper cross over mod accomplish this) Next would come the amp & pre-amp since these (compared to the other issues) will contribute the least impact (unless you have a very poor system). It would be hard to recommend McIntosh at this point for driving Heresys. I am not knocking the speakers, but bigger gains (cost wise) would be gained from going the next step up in the speaker chain. There are a great number of good amps and pre-amps out there that are a better value (where value is determined by BOTH both sound & price). Good luck, -Tom
×
×
  • Create New...