BobRiff Posted October 5, 2009 Share Posted October 5, 2009 Islander <snip>The other factor a really good engineer mentioned to me was that the mid and tweet of a khorn like any other speaker are not fixed resistors but will have varying impedance with amplitude. If used with a passive crossover the speaker may have a slight tendancy to sound brighter as amplitude increases. I'm certainly no expert and this discussion is over my head, but I though Impedance varied with frequency, not amplitude? Can you explain this further? Thanks. Quote Link to comment Share on other sites More sharing options...
Islander Posted October 5, 2009 Share Posted October 5, 2009 Islander The engineer's reccomendation was a sound one that works in practical terms --- the reason he does not like disimilar amps is because he wants to design the crossover points, slopes, amplitude, delays etc... without adjusting for the transfer function of amps with varying topolgies. Does that make sense? In fact it has nothing to do with power. Not to say this is what you are hearing but there are many who state as you do and as I thought that you are better off with running a Khorn with SS bass and tubes elsewhere but some of the roughness one hears in the mid and high's are not artifacts of the amps but artifacts of the crossovers. From a post last August:People often figure that when bi-amping, they need a big amp for the bass, but only a little amp, like maybe their favourite sweet-sounding tube amp, for the treble. If they're tri-amping, that may be the case, but when bi-amping, the mid/hi driver is carrying a lot of the load, depending on the crossover frequency, as shown in this chart found in the site provided by djk on a previous page ( http://sound.westhost.com/bi-amp.htm ): X-over Frequency (Hz) Power to Bass (%) Power to Mid+High (%) 250 40 60 350 50 50 500 60 40 1,200 65 35 3,000 85 15 5,000 90 10 With the Jubilee and JubScala crossing over a bit under 500Hz, you can see why it makes sense to use a pair of matching amps, one for bass and one for treble. To put it another way, when the crossover is at 500Hz or a bit below, the bass amp is powering the bottom 5 octaves of the audio range and the treble amp is powering the top 5 octaves. That means the load on both amps is comparable, so the treble amp should be roughly as powerful as the bass amp. Really bass-heavy music may change things a bit, but the chart should give good guidance in most cases.Using matching amps also simplifies level matching between the bass drivers and the treble drivers, plus you're likely to get a better timbre match between the bass and treble drivers, since it removes one element of dissimilarity, even if the drivers are two different types, typically a cone woofer and a compression mid/tweeter. As you can see, it would be wrong to say it has nothing to do with power. Power is not the only factor, but it is an important one. 1 Quote Link to comment Share on other sites More sharing options...
6l6gc Posted October 5, 2009 Share Posted October 5, 2009 6l6 Did I really read your response correctly? You tried a bunch of experiments none of which included actually triamping and running the speaker active yet you are convinced active would not sound better? From my first 2 days experimenting with bi-amping (not Tri Amping), there "may" have been some marginal (maybe wishfull thinking) improvment in coherency, solidity and definition, total independance of the lows and highs, eliminating FM distortion but then these 3 words that flash so brightly in a review far outweigh any real world improvement, just very slightly if at all, I cant point to any seemingly improvement and say wow it was worth it, its difficult todo an AB test due to the wiring and the ear getting used to the diffrence, we cant remember sound, we can remember what impression the sound had on us at a particular point in time, it wasn't an audio change worth the trouble, but it was worth pursuing as a quest for audio improvement , and to see what happens, and how such a system behaves, there is something to be had by delaying the highs vs the bass, but I don't think its worth the extra effort. You can look at the 1972 dope from hope article where they tried this with the technology of the time, and another article I found on the net http://www.hps4000.com/pages/spksamps/bi_amplification.pdf, The next thing I want to do is replace the high freq amp to a tubed one, that was my original plan. Quote Link to comment Share on other sites More sharing options...
6l6gc Posted October 5, 2009 Share Posted October 5, 2009 The DCX2496 has room for improvement, specifically the 17 $0.25 quality opamps and 15 polarized electrolytics in the signal path. Easy to see why you are not impressed. Most pro gear is little better, so I modify it. I'm open minded for any changes as long as I don't need to tackle SMD's or buy $50 caps, I need to open the unit up and see whats inside. Quote Link to comment Share on other sites More sharing options...
Islander Posted October 5, 2009 Share Posted October 5, 2009 there is something to be had by delaying the highs vs the bass, but I don't think its worth the extra effort. Time-aligning the drivers is a subtle improvement that's more audible with certain music and barely noticeable with other music, at least with La Scalas. The effect should be more pronounced with Khorns, with their longer bass horn. I see it as a bonus that comes with active crossovers, but not in itself sufficient reason to go through the expense of going active. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted October 5, 2009 Share Posted October 5, 2009 The trick to using the Behringer DCX or DEQ is: 1) Only use the digital input and avoid the A-D conversion (too many ways to do this wrong). 2) Replace the output section(s) immediately after the DACs with a transformer (and perhaps an RC anti-aliasing filter). This will remove the DC and can also drive the pre-amp with voltages that are "consumer level" The real trick is to not go overboard and use mega-dollar transformers. Check the threads out at DIYaudio and the Yahoo site devoted to the DCX. Plenty of good advice. Just remember to keep the mods within reason given the cost and reliability of the Behringer. good luck Quote Link to comment Share on other sites More sharing options...
Chris A Posted October 5, 2009 Share Posted October 5, 2009 The DCX2496 has room for improvement, specifically the 17 $0.25 quality opamps and 15 polarized electrolytics in the signal path. Easy to see why you are not impressed. Most pro gear is little better, so I modify it.I'm open minded for any changes as long as I don't need to tackle SMD's or buy $50 caps, I need to open the unit up and see whats inside.616gc,Maybe a more friendly and useful approach is to acknowledge that you may not hear much difference in much music that is played, and that's okay. Note that I have listened to conversations with one or two guys that have auditioned A-B some different active (digital) crossovers. The local consensus was that the EV Dx38 sounded the most musical (i.e., the best), but note that I did not participate in that test myself. I think that bi-amping a Khorn with active (digital) crossover AND correcting for the 8.4 ms (via Richard Heyser's Khorn article, but 6 ms via Greg Oshiro) delay between woofer and tweeter will make a difference in lower crossover region (~400 Hz +/- 1 octave) performance. You might hear a bit of tightening in the lower-midrange area (about the "middle-C octave" on the piano), with less "smearing". Also note that there are documented issues in phase alignment between the Khorn midrange and tweeter in the Heyser article, resulting in acoustic pianos and female voices sounding larger than life. You might find that correcting for the time misalignment of the tweeter and midrange to be more audible, so that is another area that you might consider for a potential test with the Behringer active crossover you mentioned. I think the that delay difference measured in the Heyser article is about 1.7 (1.6 ms as measured by Greg Oshiro) ms between midrange and tweeter. This should have have an audible effect on the aforementioned piano/female voice performance, I would think. But it may sound subtle at first. You might have to re-EQ a bit in the region of crossover after delaying the tweeter for this test. Chris Quote Link to comment Share on other sites More sharing options...
Chris A Posted October 5, 2009 Share Posted October 5, 2009 Link to thread on Heyser's article: http://forums.klipsch.com/forums/t/94684.aspx?PageIndex=1 Quote Link to comment Share on other sites More sharing options...
AltmanEars Posted October 5, 2009 Share Posted October 5, 2009 6l6 Did I really read your response correctly? You tried a bunch of experiments none of which included actually triamping and running the speaker active yet you are convinced active would not sound better? From my first 2 days experimenting with bi-amping (not Tri Amping), there "may" have been some marginal (maybe wishfull thinking) improvment in coherency, solidity and definition, total independance of the lows and highs, eliminating FM distortion but then these 3 words that flash so brightly in a review far outweigh any real world improvement, just very slightly if at all, I cant point to any seemingly improvement and say wow it was worth it, its difficult todo an AB test due to the wiring and the ear getting used to the diffrence, we cant remember sound, we can remember what impression the sound had on us at a particular point in time, it wasn't an audio change worth the trouble, but it was worth pursuing as a quest for audio improvement , and to see what happens, and how such a system behaves, there is something to be had by delaying the highs vs the bass, but I don't think its worth the extra effort. You can look at the 1972 dope from hope article where they tried this with the technology of the time, and another article I found on the net http://www.hps4000.com/pages/spksamps/bi_amplification.pdf, The next thing I want to do is replace the high freq amp to a tubed one, that was my original plan. I hear you --- we are coming from two different viewpoints --- I successfully used a number of active systems but --- BIG BUT --- a competent engineer setup the active crossovers and the crossovers didnt perform AD/DA conversions and they were extremely hgih quality. In one case the Levinson x-overs had separate power supplies and specialized connectors. The designers who developed the crossovers were good and had years of experience. I would not begin to think I could replicate their results without quality test equipment over even a period of a dozen weekends... Quote Link to comment Share on other sites More sharing options...
HeeHaw2 Posted October 5, 2009 Share Posted October 5, 2009 I have some speakers crossed over at about 500hz with some Mac amps with blue meters and going by the meter indication there is a 10 to 1 difference. When the LF is at 2.5 W the HF is at about .25. With all types of music. 1 Quote Link to comment Share on other sites More sharing options...
AltmanEars Posted October 5, 2009 Share Posted October 5, 2009 [quote user="Cask05"Link to thread on Heyser's article: http://forums.klipsch.com/forums/t/94684.aspx?PageIndex=1[/quote] Cask thanks a million for the article. Too bad that isnt a 2009 Khorn --- I'm sure Heyser is thinking the same thing in heaven... Quote Link to comment Share on other sites More sharing options...
AltmanEars Posted October 5, 2009 Share Posted October 5, 2009 Islander <snip>The other factor a really good engineer mentioned to me was that the mid and tweet of a khorn like any other speaker are not fixed resistors but will have varying impedance with amplitude. If used with a passive crossover the speaker may have a slight tendancy to sound brighter as amplitude increases. I'm certainly no expert and this discussion is over my head, but I though Impedance varied with frequency, not amplitude? Can you explain this further? Thanks. At some reference amplitude a driver's impedance will vary with frequency ---- This is also a factor for level as follows The results clearly show that the Q of the filter changes dynamically with signal level, increasing with increasing level. The figure show that a peak of 1.5 dB relative to the low level signal. This in itself would be audible. However it is important to recognize that related effects will occur in a 2nd order electrical high pass filter response. The combined effect is a significant bump in the response of the system in the crossover region that isn’t apparent in typical low level measurements. Additionally, this bump way introduce ringing in the response as well, making the system sound aggressive and harsh at higher play back levels while sounding fine at lower levels. Thanks John Kreskovsky Quote Link to comment Share on other sites More sharing options...
AltmanEars Posted October 5, 2009 Share Posted October 5, 2009 Islander The engineer's reccomendation was a sound one that works in practical terms --- the reason he does not like disimilar amps is because he wants to design the crossover points, slopes, amplitude, delays etc... without adjusting for the transfer function of amps with varying topolgies. Does that make sense? In fact it has nothing to do with power. Not to say this is what you are hearing but there are many who state as you do and as I thought that you are better off with running a Khorn with SS bass and tubes elsewhere but some of the roughness one hears in the mid and high's are not artifacts of the amps but artifacts of the crossovers. From a post last August:People often figure that when bi-amping, they need a big amp for the bass, but only a little amp, like maybe their favourite sweet-sounding tube amp, for the treble. If they're tri-amping, that may be the case, but when bi-amping, the mid/hi driver is carrying a lot of the load, depending on the crossover frequency, as shown in this chart found in the site provided by djk on a previous page ( http://sound.westhost.com/bi-amp.htm ): X-over Frequency (Hz) Power to Bass (%) Power to Mid+High (%) 250 40 60 350 50 50 500 60 40 1,200 65 35 3,000 85 15 5,000 90 10 With the Jubilee and JubScala crossing over a bit under 500Hz, you can see why it makes sense to use a pair of matching amps, one for bass and one for treble. To put it another way, when the crossover is at 500Hz or a bit below, the bass amp is powering the bottom 5 octaves of the audio range and the treble amp is powering the top 5 octaves. That means the load on both amps is comparable, so the treble amp should be roughly as powerful as the bass amp. Really bass-heavy music may change things a bit, but the chart should give good guidance in most cases.Using matching amps also simplifies level matching between the bass drivers and the treble drivers, plus you're likely to get a better timbre match between the bass and treble drivers, since it removes one element of dissimilarity, even if the drivers are two different types, typically a cone woofer and a compression mid/tweeter. As you can see, it would be wrong to say it has nothing to do with power. Power is not the only factor, but it is an important one. We are saying the same thing---you are saying power can be an issue--- I am saying since power can be an issue you should completely take it out of the equation by testing the crossover with amplifiers which are overspecified. Also I hate to tell you that simplistic chart is a bit misleading. Its just meant as a guideline. Under the dynamic conditions of a high end hifi system you need more power up top. Please understand my perspective --- Every time I have gotten active to work and work extremely well it has been with very similar amps where each amp was capable of running the entire system passively by itself. I think if you go to any of the better mastering studios where they run PMC BB5's you'll see that the tweets are running 300 watt plus monoblocks --- this is probably 10X overkill but it does produce marginally better sound and paradoxically your tweeters dont blow out... Quote Link to comment Share on other sites More sharing options...
Islander Posted October 5, 2009 Share Posted October 5, 2009 We are saying the same thing---you are saying power can be an issue--- I am saying since power can be an issue you should completely take it out of the equation by testing the crossover with amplifiers which are overspecified. Also I hate to tell you that simplistic chart is a bit misleading. Its just meant as a guideline. Under the dynamic conditions of a high end hifi system you need more power up top. Please understand my perspective --- Every time I have gotten active to work and work extremely well it has been with very similar amps where each amp was capable of running the entire system passively by itself. I think if you go to any of the better mastering studios where they run PMC BB5's you'll see that the tweets are running 300 watt plus monoblocks --- this is probably 10X overkill but it does produce marginally better sound and paradoxically your tweeters dont blow out... Then we're actually in agreement. I'm using identical 500Wpc amps for bass and treble, with woofers that are rated for 100 watts each and tweeters that are rated for 50 watts each, and I've had no problems in over a year of daily use, with occasional quite loud (but short) demonstrations of the system.The amps both barely get warm, with the treble amp sometimes getting a bit warmer than the bass amp, so the power demands for high and low seem similar, based on that admittedly inexact indication.Using the components listed in my sig line and Klipsch's lab-tested crossover settings gives really good and realistic sound with no fussing around. It's a recipe that's hard to beat, unless you want to spend an awful lot more money. Quote Link to comment Share on other sites More sharing options...
Arkytype Posted October 7, 2009 Share Posted October 7, 2009 djk wrote: The DCX2496 has room for improvement, specifically the 17 $0.25 quality opamps and 15 polarized electrolytics in the signal path. Easy to see why you are not impressed. Most pro gear is little better, so I modify it. The EV Dx 38 fairs little better. A quick count of those pesky polarized electrolytics shows at least 15 in one input/output channel. The EV Dx 38 uses 5532 op amps ($0.51) which are almost thirty years old and are getting long in the tooth. The use of the NJM4556s ($0.56) in the output stage is laughable. This device is in the family tree of the replacement for the LM741 which is a poor op amp for quality audio. Lee Quote Link to comment Share on other sites More sharing options...
babadono Posted March 22, 2016 Share Posted March 22, 2016 djk wrote: The DCX2496 has room for improvement, specifically the 17 $0.25 quality opamps and 15 polarized electrolytics in the signal path. Easy to see why you are not impressed. Most pro gear is little better, so I modify it. The EV Dx 38 fairs little better. A quick count of those pesky polarized electrolytics shows at least 15 in one input/output channel. The EV Dx 38 uses 5532 op amps ($0.51) which are almost thirty years old and are getting long in the tooth. The use of the NJM4556s ($0.56) in the output stage is laughable. This device is in the family tree of the replacement for the LM741 which is a poor op amp for quality audio. Lee And what I.C.Opamps do you favor/suggest? ---Sorry for opening this old thread Quote Link to comment Share on other sites More sharing options...
Chris A Posted March 22, 2016 Share Posted March 22, 2016 (edited) In the mean time until Dennis responds, you might find some answers here: http://www.diyaudio.com/forums/digital-line-level/237603-dcx2496-upgrade-board-objectively-tackling-improvement-stock-dcx2496.html "If it hasn't been mentioned earlier...the output opamps are 4580 dual opamps." 1. Replaced all the output stages with a single OPA1632 differential op-amp per output. Edited March 22, 2016 by Chris A Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted March 22, 2016 Share Posted March 22, 2016 I'd do what we do in live PA. Get a metronome app and play that through speakers, if you can find one where you can change the frequency to around 400-500 hz, you'll hear it equally through the woofer and mid horn. The one I have puts out 1kHz but you still get a lot of that through the woofer. Listen to the clicks and delay the top end until you hear a single CLICK from the metronome - voila you've found the perfect delay for that loudspeaker. PEQ wise, I'd do the same thing in your listening room, with pink noise (from a CD or other source). I have an app called RTA from Studio Six Digital - it outputs pink noise and gives you a 31 band real time analyzer so you can fine tune the frequency to nearly dead flat ( if that's what you're after). Similar to what modern receivers do with their YPAO or Audyssey. 2 Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted March 22, 2016 Share Posted March 22, 2016 Islander The engineer's reccomendation was a sound one that works in practical terms --- the reason he does not like disimilar amps is because he wants to design the crossover points, slopes, amplitude, delays etc... without adjusting for the transfer function of amps with varying topolgies. Does that make sense? In fact it has nothing to do with power. Not to say this is what you are hearing but there are many who state as you do and as I thought that you are better off with running a Khorn with SS bass and tubes elsewhere but some of the roughness one hears in the mid and high's are not artifacts of the amps but artifacts of the crossovers. From a post last August: People often figure that when bi-amping, they need a big amp for the bass, but only a little amp, like maybe their favourite sweet-sounding tube amp, for the treble. If they're tri-amping, that may be the case, but when bi-amping, the mid/hi driver is carrying a lot of the load, depending on the crossover frequency, as shown in this chart found in the site provided by djk on a previous page ( http://sound.westhost.com/bi-amp.htm ): X-over Frequency (Hz) Power to Bass (%) Power to Mid+High (%) 250 40 60 350 50 50 500 60 40 1,200 65 35 3,000 85 15 5,000 90 10 With the Jubilee and JubScala crossing over a bit under 500Hz, you can see why it makes sense to use a pair of matching amps, one for bass and one for treble. To put it another way, when the crossover is at 500Hz or a bit below, the bass amp is powering the bottom 5 octaves of the audio range and the treble amp is powering the top 5 octaves. That means the load on both amps is comparable, so the treble amp should be roughly as powerful as the bass amp. Really bass-heavy music may change things a bit, but the chart should give good guidance in most cases. Using matching amps also simplifies level matching between the bass drivers and the treble drivers, plus you're likely to get a better timbre match between the bass and treble drivers, since it removes one element of dissimilarity, even if the drivers are two different types, typically a cone woofer and a compression mid/tweeter. As you can see, it would be wrong to say it has nothing to do with power. Power is not the only factor, but it is an important one. We are saying the same thing---you are saying power can be an issue--- I am saying since power can be an issue you should completely take it out of the equation by testing the crossover with amplifiers which are overspecified. Also I hate to tell you that simplistic chart is a bit misleading. Its just meant as a guideline. Under the dynamic conditions of a high end hifi system you need more power up top. Please understand my perspective --- Every time I have gotten active to work and work extremely well it has been with very similar amps where each amp was capable of running the entire system passively by itself. I think if you go to any of the better mastering studios where they run PMC BB5's you'll see that the tweets are running 300 watt plus monoblocks --- this is probably 10X overkill but it does produce marginally better sound and paradoxically your tweeters dont blow out... If bi-amping, remember that the portions of the signal that pass through the internal Khorn crossover are being tapered off in terms of output so that nullifies the need for a smaller amp for the mid/high. If you are entirely bypassing the internal speaker crossover, it might reasonably be expected that you might want larger amp for LF, mid sized for MF, smaller yet for HF. It's all about balance. I can tell you stories of how much wattage is used in large PA installations that would blow your minds. 1 Quote Link to comment Share on other sites More sharing options...
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