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Post by unsound on Feb 15, 2015 16:20:34 GMT -5
The Revel material calls out 'high order' filters on seperate boards per 'way'. This means they are keeping the inductors (can't have high order filters without 'em!) apart. good idea. Somebody who has TESTED and MEASURED them will have more / better info. By high order? 12db per octave, 18 db per octave or perhaps 24 db per octave slopes. Alignment? Not stated. And that WOULD be a problem. But the speaker IS setup for easy biamping which is cool. And the book even has some good drawings and more importantly, some good setup tips. The level control part is also a little tougher to duplicate, but simply going passive biamp would be a worth experiment and use for a QUAD of the 1Ls. How much is Big D paying you in 1L commissions? It would be sweet, no doubt at all. For sure, I will end up with 3 more 1Ls over time, for my front 3 (F32, C32).
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Post by unsound on Feb 15, 2015 16:30:08 GMT -5
The XPA-1L has it all. An amp I would want if I was running a passive speaker system. Lonnie and Big Dan really made a special amp here. Anybody who loves their music, yeah wow. The XPA1-L is really, really good. Couldn't agree more! The music is so much more "tangible" - like every note can be touched. I might be sinking to audio reviewer lingo there, but it isn't easy to describe for sure. I'd probably leave it at saying the sounds are more filled in and distinct.
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Post by leonski on Feb 15, 2015 18:19:24 GMT -5
As it turns out, and this is just an EXAMPLE, I have a buddy with Magnepan MG20s. Not the .1 or .7 but the originals. They are also 3-way speakers which he has biamped and uses a Marchand ($$$) crossover between low and mid/high. This removes the EXTERNAL crossover box which Magnepan supplied. BUT, the Mid/Tweet crossover is STILL in the speaker and being used. The EMO mono bloc on the basss is impressive and he manages to get it to play VERY WELL INDEED with a tube amp on mids / highs. The Revels would work in a similar way. Bass amp to THOSE inputs and thru the low pass to the driver. The mid/tweet amp to THOSE inputs and thru what is now just a 2-way crossover to the appropriate driver.
And yes, getting all wrapped up in this stuff CAN be a pretty deep rabbit hole. (Think Alice in Wonderland) For the most advanced experimenter, each step is NOT forward, either, with missteps along the way. The best of these guys understand a lot about crossover theory and practice AND have measurement software and tone generators / software in order to evaluate the product of the experiments. That's why I'm not going to stray very far from the path and when I build my passive LL crossover, will duplicate the electrical characteristics of the STOCK crossover as closely as possible in a very simple circuit.
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Post by Gary Cook on Feb 15, 2015 19:17:39 GMT -5
will duplicate the electrical characteristics of the STOCK crossover as closely as possible in a very simple circuit. But if you are using power amplifiers that have different signatures those differences will particularly manifest themselves at the cross over points. Some years ago I tried to set up a muso friend of mine's bi amped system (he was a McIntosh nut) which consisted of a McIntosh tube amp (an MC275) for the mids/highs and a Crown Class D pro amp for the woofer (a real woofer not a sub woofer). The problem was around the cross over frequency the sound was mushy, indistinct, not at all clear and concise. Mid keyboard on a piano was particularly noticeable. Run one power amp on its own and it sounded fine, just rolled off nicely. Run the other power amp on its own and it also sounded fine, natural roll off. But the two together were not so good, the natural second harmonic of the tube amp just didn't jell with the close to zero harmonic of the Class D amp. So I tried a solid state transformer coupled McIntosh power amp (an MC501) for the woofers and bingo the sound was a lot better, homogenous. Keep in mind that's around $A20K worth of amplifiers. What I took away from that experience (aside from reinforcing my dislike for the McIntosh "house" sound) was that bi amping requires careful matching of the power amplifiers. Even a small mismatch can be a bad news, a large mismatch can be a disaster. Cheers Gary
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Post by lhracing on Feb 15, 2015 19:38:29 GMT -5
I think you are absolutely correct, the propagation delay for two amplifiers of different design will be different. The difference may be only milliseconds but depending how great the difference is it could be audible. I think that bi-amping would best be done with matching amplifiers.
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Post by Jim on Feb 15, 2015 19:58:11 GMT -5
I think you are absolutely correct, the propagation delay for two amplifiers of different design will be different. The difference may be only milliseconds but depending how great the difference is it could be audible. I think that bi-amping would best be done with matching amplifiers. . I'm inclined to say fractions of a ms. A ms is really a long time in terms of electronics. Unless you're talking about a DSP or some conversion, I would expect the delay to be very very low. For a solid state amp, anyway.
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Post by jjkessler on Feb 15, 2015 20:22:34 GMT -5
I'm am checking with Emo now about trading my XPA-2 Gen 2 and XPA-5 for 6 more XPA-1L for a true 7.2 mono block set up with my XMC-1, Oppo 105d and Axiom speaker set up. Would sure love to go all fully balanced mono
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Post by leonski on Feb 15, 2015 20:49:21 GMT -5
Just be sure to have an Electrician scheduled to get you a few extra circuits installed so everybody is happy, power-wise. And all from one side of the box is nice, too.
As for propogation delay among amps? Yes, i've been thru that with a bunch of people and never got much traction with that idea. However, I tend to agree that it is at least POSSIBLE for an amp to take a LOT longer or shorter time than another amp for a signal to pass thru. Get unlucky with a quick and slow amp? could be trouble.
And I'd blame, if that's the right word, Gary's friends problem not on the amps, but rather the crossover. Swapping the phase on one 'way' may have helped. My panels are 2-way. And the drivers are wired out of phase. The lowpass is 12db/octave and the highpass is 6db/octave. This means they are 90degrees OUT of phase right from the git-go. Think of this as kind of a time-delay.
Each order of crossover ADDS 90degrees of shift.
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Post by jjkessler on Feb 15, 2015 21:11:07 GMT -5
My theater and listening room will be in my unfinished basement that will soon be finished where "my space" will be a blank canvas from no studs to finished 25x25x9 tall. I can specify the electrical anyway needed and will bring at least 2 and possibly 3 dedicated 20 amp circuits into the space. I plan on using heavier gage wiring and will look for some sort of power conditioning as well to drive Axiom M100"s, vp180 center channel, and 4 qs8"s
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Post by jjkessler on Feb 16, 2015 11:43:04 GMT -5
Is anybody rack mounting their XPA-1L's? If so, where did you find the rack mount ears for this amp?
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Post by stlaudiofan1 on Feb 16, 2015 17:45:20 GMT -5
My theater and listening room will be in my unfinished basement that will soon be finished where "my space" will be a blank canvas from no studs to finished 25x25x9 tall. I can specify the electrical anyway needed and will bring at least 2 and possibly 3 dedicated 20 amp circuits into the space. I plan on using heavier gage wiring and will look for some sort of power conditioning as well to drive Axiom M100"s, vp180 center channel, and 4 qs8"s That awesome that you can start from scratch with the room. My home theater/listening room is 20x12x8. I have a projector for the home theater, so I needed a room that I could shut off with doors to get rid of ambient light. I wish my room was wider, I think I would be able to get a wider soundstage, but it's what I had to work with. I have a 20 amp circuit for the amps and the projector. The rest is on a 15 amp circuit. You will really enjoy the 1Ls. Mine got even better over the first month or so.
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Post by Deleted on Feb 16, 2015 18:05:25 GMT -5
My HT is roughly the size of yours. Just a tad smaller 18x11. I am starting the build now.
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Post by Gary Cook on Feb 16, 2015 20:14:14 GMT -5
And I'd blame, if that's the right word, Gary's friends problem not on the amps, but rather the crossover. A straight swap of the woofer amps to something closer to the design of the mid/high amps fixed it. Never touched anything else, even used the same speaker cables. Tried that, out of phase was obviously worse, but in phase was unlistenable. Cheers Gary
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geebo
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Post by geebo on Feb 16, 2015 20:39:37 GMT -5
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Post by jjkessler on Feb 16, 2015 21:50:28 GMT -5
Thank you
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Post by pop on Feb 16, 2015 22:17:48 GMT -5
I'll see your two XPA-1Ls and I'll raise you three more. Enjoy your new babies. Russ PS- novisnick is missing my setup; I'm still not a member of the monoblock club. Paperwork is slow this time of year. It's the Mardi Gras season down hear in Louisiana!! Shouldn't I be in the monoblock club with my stealths?
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novisnick
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Post by novisnick on Feb 16, 2015 23:14:54 GMT -5
Paperwork is slow this time of year. It's the Mardi Gras season down hear in Louisiana!! Shouldn't I be in the monoblock club with my stealths? That's a good question pop but it will have to go to committee for further research!!
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Post by leonski on Feb 20, 2015 15:15:11 GMT -5
Gary, I'm using a PAIR of Parasound A23 amps for my panels. I get it about different amps. And since the crossover of 600hz. is very near the 50:50 power point, I think matching amps will work fine. Also, I'm low-cutting the MAIN speakers, which is also in my favor. Getting rid of most of that overlap between sub and mains worked wonders for bass definition and imaging.
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Post by Gary Cook on Feb 21, 2015 15:55:09 GMT -5
Gary, I'm using a PAIR of Parasound A23 amps for my panels. I get it about different amps. And since the crossover of 600hz. is very near the 50:50 power point, I think matching amps will work fine. Also, I'm low-cutting the MAIN speakers, which is also in my favor. Getting rid of most of that overlap between sub and mains worked wonders for bass definition and imaging. No doubt it's possible, but I've seen a lot of bi amping (woofer V mid/highs) and even tri amping (woofer V mid V tweeters) attempts that achieve absolutely nothing. Then almost as many that are worse than a single amp. The success rate is very small and even then it has such a tiny effect that in most of those cases it's indistinguishable. A lot of time, money and effort expended for no real gain. Which is not to be confused with the benefits from taking sub woofer responsibilities away from the woofer, that's different ball game altogether. Cheers Gary
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Post by leonski on Feb 21, 2015 19:47:45 GMT -5
the Next Step will be a line level crossover to duplicate the transfer function of the stock crossover. This will 'net' me nearly 3db, the rough equal of buying 2x more powerful amps. And yes, 'unloading' the main speakers lowest bass TO a sub is all good. And since for most people who own box speakers, the bass part takes the MOST power and the MOST space, the tradeoff is pretty good. And as long as you keep the crossover LOW enough, from mains to sub, you will NEVER be able to localize the sub. The strain is taken off the usually marginal PS of the HT receiver which is also a big plus.
Properly done, and maybe a step-at-a-time, you CAN go forward. Ill considered combinations can leave you scratching your head and plugging your ears. Attention must be paid to a whole host of issues most people are not familiar with. Everything from amp gain to power ratio depending on crossover frequency(s) to, in original designs, driver sensitivity and driver frequency limits and MORE. And lots of DIY guys figure that if '12db/octave is good' than '24db/octave is GREAT'!
And Gary, Magnepan might agree with you more than you know. The current x.7 series speakers have deleted the biamp/wire provision ONE set of speaker power inputs is all you now get! I don't know about the tweeter resistor jumper which has been a feature of some models for 20 years. But now, if you want to biamp your panels, it'll require some serious mods and a rewire job.
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