Ray Garrison Posted April 5, 2001 Share Posted April 5, 2001 Why the common ground between the high and low pass crossovers? Ray Quote Link to comment Share on other sites More sharing options...
jwgorman Posted April 5, 2001 Share Posted April 5, 2001 Mendeen, I have tried something similar to your set up (only taking it out of my pre's dual outs) running the high horns (on khorns) with the Wright 2A3s and the woofs with a mac MC162. I could never quite get it to gel. I certainly cannot explain the science but something was a miss. I preferred the sound of the Wrights or the Mac run full range. The electronic crossover's I've tried (bypassing the passive crossovers) were not particularly refined, certainly not transparent and thus unuseable. Running one tube amp and one ss amp on the khorns always seemed like a logical thing to do but I could never quite nail it down. I attributed my particular difficulties with my multi amp rig to the fact that I'm running a SET tube amp on top and a PP SS on bottom. I need to try this with a PP tube on top perhaps. Like the new Wright Sound Company 10watt PP 2A3 monoblocks...yeah, that's right...honey, I need another amp...My wife would probably just shoot me. jwgorman Quote Link to comment Share on other sites More sharing options...
gguy30 Posted April 7, 2001 Share Posted April 7, 2001 you guys keep talking about thing that has nothing to do with speaker wire. why is a speaker cable like Monster better then something like RCA? because the RCA is 18ga and the monster stuff is 12ga. that is it! the better the cable the more info gets into the speaker. The better cables will always give you better sound. But it will be a more noticeable difference if you have better equipment. If you guys want to know more about biwireing you can go to a web page like www.Monstercable.com I know they are trying to make it sound better then it really is but it makes some good points in the difference in the cables. i did try both and BiWire is better to me. Using. Yamaha RX-V800 Klipsch RF3 Monster Z2bi-10 (biwire cables) Quote Link to comment Share on other sites More sharing options...
djk Posted April 7, 2001 Share Posted April 7, 2001 >>Nelson Pass 10+ Posts Posts: 13 From:Foresthill CA USA Registered: Mar 2001 posted 04-03-2001 02:41 PM Unless you have any level adjustment circuitry before each power amp, the easiest way to go is identical amps. If you can adjust the level of each amp, then you can get away with dissimilar amps, but keep in mind that the less powerful amplifier tends to set the upper limit on how loud you can play. I'm not a big fan of bi-amping in this manner. While it arguably offers some improvement, my experience is that the improvement is small compared to the additional cost. Both amps have to swing the entire range of voltage driving both the top and bottom ends. I greatly prefer an actual crossover before the amplifiers, so that the high and low amplifiers only have to contend with the signal in their specific frequency band. When you do this you not only get the benefit accorded to "bi-amping" but the amplifiers will operate with significantly less distortion, deliver significantly more power, and have better control over the drivers through the elimination of the passive components between the amp and drivers. In my experience, it makes a big difference and is worth the effort.<< Here is Nelson Pass of Threshold fame saying virually the same thing I have been saying in response to a put o him about bi-ampng without benefit of an elecronic crossover.Note that the time is over 24hrs AFTER my first post to you.I have explained this twice and now Nelson Pass has explained it.I have suggesed you get an O-scope and measure it since you don't understand it.Maybe you should download a program like Electronics Workbench and simulate it.I am sorry if I seem short with you but this is really quite simple and it seems like you are pretending to be obtuse.As regards your drawing >>mdeneen Insane Poster Posts: 329 From:Healdsburg, CA, California Registered: Jan 2001 posted 04-05-2001 12:15 PM quote: Originally posted by djk: Without removing the passive crossover parts and using an electronic crossover ahead of the amplifiers the 5W amp will clip 13dB before the 100W amp. --------------------------------------------- Respectfully, This is what you described above.<< I see where some of your confusion lies.Your drawing shows an electronic crossover and then passive filters after the power amp.This is not bi-amping.The drawing at the bottom of your setup shows what I am calling a duo-amp set up.To paraphrase myself and quote Nelson Pass: bi-amping "In my experience, it makes a big difference and is worth the effort".duo-amping "I'm not a big fan of bi-amping in this manner. While it arguably offers some improvement, my experience is that the improvement is small compared to the additional cost. Both amps have to swing the entire range of voltage driving both the top and bottom ends. I greatly prefer an actual crossover before the amplifiers, so that the high and low amplifiers only have to contend with the signal in their specific frequency band".I hope this is of some help.Perhaps you could visit with someone at your local community college and have him show you on an o-scope if you don't own one. Quote Link to comment Share on other sites More sharing options...
djk Posted April 9, 2001 Share Posted April 9, 2001 This seems too much like work to me.I am going to try this one more time before I give up.Say you measure an amp with a 1Khz sine wave driving a load and you get 28.3V .Now you drive the load with a ten cycles of 1Khz (tone burst) once per second and get 40V .I am going to define this as dynamic headroom.In this case the dynamic headroom is 3dB.Amplifiers that have regulated supplies, choke input supplies (think tube amp), or huge unregulated supplies (think Krell,Roland,Levinson,etc) have no or very low headroom.The increase in actual power from duo-amping is limited to the dynamic headroom of the amplifier design.In other words it could be from nothing to say, 3dB.The worse the power supply regulation the higher the dynamic headroom will be.Removing the load current from part of the spectrum by duo-amping does not remove the voltage driving the input of the amplifier.Using an electronic crossover removes the voltage driving the amplifier above or below the crossover point.If you are doing a single sine wave analysis you will think these are equivalent.And they are for sine waves.But music has more than one frequency present at any given time.Assume a crossover of 500hz.Mix a 100hz 1V signal with a 1Khz 1V signal and parallel feed into two amplifiers with a voltage gain of ten.The signal coming out of each amplifier will be 20V.Now feed the same input signal into the electronic crossover and into two power amps with a voltage gain of ten.The amp driven by the high pass will have a 1Khz 10V output and the amp driven by the low pass will have a 100hz 10V output.Assume the amplifiers clip at 40V out.An increase in the input signal of more than 6dB will cause both of the parallel feed amplifiers to clip.The output signals from the amplifiers driven by the electronic crossovers will increase to 20V.Increase the input signal another 6dB.The parallel fed amplifiers will now be driven 6dB into clipping.The amplifiers fed by the electronic crossover will be just starting to clip.When I said >>Unless you are using an electronic crossover you are not increasing power in any meaningful way by adding two amps<< that is exactly what I meant.When I said >>The amp that sees no load in the bass will have a fraction of a dB more power reserve in the power supply assuming that the supply is not regulated(a reasonable assumption in mid-fi)<<that is exactly what I meant.I explained it the first time >>Even though there is no load as far as the current is concerned the amp still clips at the same point because the voltage is still there in the input signal.In a real bi-amp setup the electronic crossover removes the out of band input voltage so the amplifier does not have to amplify it<< and I gave you a clue here>>On a complex signal like music the voltages add<< and here>>You would be right if music consisted of single sine wave tones<<and I quoted Nelson Pass, someone most people would know and respect>>but keep in mind that the less powerful amplifier tends to set the upper limit on how loud you can play.I'm not a big fan of bi-amping in this manner. While it arguably offers some improvement, my experience is that the improvement is small compared to the additional cost. Both amps have to swing the entire range of voltage driving both the top and bottom ends. I greatly prefer an actual crossover before the amplifiers, so that the high and low amplifiers only have to contend with the signal in their specific frequency band<<who said basically the same thing I did and gave virtually the same explanation I did in response to virtually the same question elsewhere.You own an o- scope>>I have a scope, and a rack full of HP test gear<<.Hook it up to the speaker wired for uno-amp operation and run it up wih music until you see the amp start to clip.Mark that point on the volume control.Now unhook the low pass connection to the woofer.Now driving the high pass only run it up to the point where the amp starts to clip.Mark this point on the volume control.Unhook the amp and hook up a signal generator.With the volume control set to the second higher mark adjust the generator to get a 0dB output on a RMS voltmeter.Reduce the volume control to the first lower mark.The difference in dB is the increase in volume you get from duo-amping at the onset of clipping. Quote Link to comment Share on other sites More sharing options...
jwgorman Posted April 12, 2001 Share Posted April 12, 2001 DJK, To put this in chimp terms that I can understand, would it be correct to say that an amplifier receiving a full bandwidth signal is going to amplify a full bandwidth signal. Any crossover post amplifier will not allow the system to play "louder". I always assumed mdeneen's example was right. Upon reading your posts I believe I see what you're saying. How's that for simian engineering? jwgorman Quote Link to comment Share on other sites More sharing options...
Prana-Bindu Posted April 13, 2001 Share Posted April 13, 2001 But there is no crossover after the amp in a bi- or duo-amp situation.... Please excuse any ignorance I may be displaying (just a newbie to this technical nightmare that is audiophilia), but isn't the point of a bi-wireable speaker the removal of the crossover (read: its quantitative and qualitative effects) from the powering of the work being done by the speakers? If JWMORGAN's struggle with bi-amping and duo-amping was hosted by a pair of Klipsch RF-3's (the speakers I currently use), I would certainly understand why he could never quite get the sound right; and that he would prefer the sound of either the Wrights or the Mac driving the full range. The RF-3's crossover at 1975hz (I believe) -- that's at the upper end of the upper midrange!! The whole benefit of the low-powered SET (especially the 2A3's) is what it does to the midrange; it's the midrange people describe as magical and the extreme ends of the frequency range that are sometimes complained of as weak. This is where my ignorance shines through: Doesn't the division between the two sets of posts on a bi-wireable speaker provide a division, at the spec'd crossover frequency, that the amp driving either set cannot cross? So that when the Wright 2A3's are attached to the HF set of posts on the RF-3's, aren't those beautiful monoblocks driving significantly mostly the treble and the top octave? And the solid state would be driving the remainder of the frequency range.... Isn't the sweet 2A3 midrange robbed of it's work whether you use an active crossover prior to the amp or not? I am not familiar with the crossover spec' of JWMORGAN's khorns, but if they are anything like the RF-3's, I can understand the cycle of dissatisfaction with the two-amp set-ups he described. Following this line of reasoning, an electronic crossover prior to the LF amp that only allowed frequency below 1000hz to be amplified by the bottom amp would deprive the listener of the upper midrange of the music. Is this the source of JWMORGAN's struggle with the electronic crossover? It sounds absurd to me, but I've never had the opportunity to play with such distinct amps (or more than any singular amp, god help me) at the same time. And, I AM under the impression (the veracity of which I am entirely uncertain) that the crossover specified for a speaker is a hard drop between the two ranges in a bi-wireable configuration, or that only insufficiently constructive parts of the roll-off ranges are co-extensive between the two ranges. Are there any phase differences between the LF and the HF of each speaker that would encourage a very short crossover roll-of range? Am I misunderstanding the role of the bi-wirable configuration? I have learned very much from this thread, and I am very grateful to all it's participants. Now please help me figure out which bits of learnin' are right and which are wrong.... My limited vocabulary has lead me to the impression that there is yet one undecided issue of critical importance still on the table: Does a limitation of the frequency range being fed to an amplifier (electronic crossover before the amp) allow the amp to dedicate more work to the range supplied than it would if it had to dedicate some work to the remainder of the full range? Does that extra dedication subtract from the total work of the amplifier that can be allocated to any part of the frequency range? If it does, then what is so unnatural about the work that otherwise would be used to power one portion of the frequency range to be done at the other portion of the frequency range in addition to the work that it would otherwise do anyway? I'm vomiting diction.... I was always under the impression that certain frequencies demanded more power than others; this would explain why a SET 2A3 amp like the Wright monoblocks would be found to be a little weak in the bass, especially the deep bass. I certainly hope the weakness is not significant, because I have an eye on them to drive my RF-3's and, maybe by August, to drive the higher-efficiency RF-7's. By the way, if anyone is in the know about the expected impedence range of the RF-7's, I would be much obliged to learn. Someone please address the question of frequency range and its relation to power consumption. Please!! And don't forget the bi-wire crossover point issue as well.... Thank you. ------------------ May the bridges we burn light our way.... Quote Link to comment Share on other sites More sharing options...
jwgorman Posted April 14, 2001 Share Posted April 14, 2001 The crossover post amplifer would be the crossover in the speaks. Khorn crossover points are in fact much different than the newer model you mention. jwgorman Quote Link to comment Share on other sites More sharing options...
Prana-Bindu Posted April 14, 2001 Share Posted April 14, 2001 mdeneen: Thank you for your prompt help. Does the separation between amps when bi-amping occur at the crossover frequency specified for the speaker (1975hz for my RF-3's)? I ask because I'm planning on auditioning a pair of Wright 2A3 monoblocks, and I would love to be prepared to try to dedicate more power to the bass (for my RF-3's that would be 37hz-250hz) with a second, more powerful amp, without losing the Wright's dominion over the midrange (250hz-2khz) to the second amp. Just trying to be absolutely sure.... Thanks. ------------------ May the bridges we burn light our way.... Quote Link to comment Share on other sites More sharing options...
Prana-Bindu Posted April 16, 2001 Share Posted April 16, 2001 Indeed it does help. Thank you. Let's hope the Wright's won't disappoint too badly in the low end of the frequency range.... ------------------ May the bridges we burn light our way.... Quote Link to comment Share on other sites More sharing options...
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