[Davey]

That's an interesting analogy.  

Tell me if you buy this comparison....

With a four wheel drive two of the wheels (load) are physically disconnected from the engine (source) when in two-wheel drive mode.  The engine doesn't "see" that load.  (However, you could make a case that there would be a concurrent increase in the load of the driven wheels assuming you're asking the vehicle to motivate the same conditions.....)  

Anyway...

With the setup we're talking about the driver (load) stays electrically connected to the amplifier (source) at all times.  The amplifier "sees" the same load, but (because of the high-pass crossover) it isn't asked to work as hard.

Do you buy my analogy?

I guess I can see how this discussion will quickly turn into semantics.....  I will stipulate to your definition of the situation.

Cheers,

Davey.

[drphoto]

I don't know if this is pertinent to the discussion of impedance (told you my electronics knowledge is limited) but the Merlins use an external RC (Zoebel) network. It's my understanding that this is used to stabilize the load seen by the amp.

[konut]

This is good.    To extend the analogy, the 2 nondriven wheels are just being dragged along. Its as if your hooking up to a second vehicle with another engine(powered subwoofer) to only be used when needed. By the same token, if your playing music with no frequency content near the woofers impedance peak, the woofer sees a less complex load. Your not asking the amp to address the rising impedance UNTIL you aproach those frequencies where the impedance actually rises.
       Yes, the Zoebel is used to make the impedance more stable. With the Merlins I do not know if the Zoebel is there to stabilize the passive xover or to tame the woofer's impedance peak. If its there for the woofer, then it might not be needed if you use a line level xover.

[Davey]

It's not uncommon to see an RCL conjugate network placed across the input of a crossover network to reduce the impedance peak created in the crossover range.  This is useful with higher output impedance amplifiers so the frequency response doesn't get skewed in that area.  However, you very rarely see a RCL conjugate used to address the impedance peak(s) of the woofer itself because it's not absolutely necessary and the component values become very large because of the low frequencies.

A Zobel network is usually just an RC network used to counter the rise in impedance created by the inductance of the driver.  I've also seen these used with smaller component values to terminate the far end of speaker wires so they don't act as antennas in RFI-rich environments.  I'm not sure what type the Merlin is......maybe it's some other kind of.....magic.  

Davey.

[suits_me]

>The goal of using a high-pass filter isn't necessarily to prevent the woofers from bottoming out or to increase SPL. The goal is to reduce distortion, thus improving sound quality.

These are Merlins we're talking about. Why would you put a Behringer in a system with Merlins? That would muck up the midrange and the high end you are trying to improve. You might as well get cheeeper speakers. Now, if you're talking these single driver speakers or, say, Ref 1's, then some of these solutions might make more sense to me.

I'm still confused why the Merlins are bottoming or whatever, if they are. Those are pretty robust speakers. Now, if you have the money then the Rives unit probably would be nice, and there are other higher end solutions depending if drphoto has an allegiance to analog or to digital.

As far as consumer literature goes, I believe Cizek was the first company to emphasize cleaning up the midrange as a reason to get a sub, but of course none of the components mentioned in this thread existed back then.

[Davey]

suits,

These are speakers we're talking about.....and very conventional ones at that.  They'll color or distort the sound way more than any line-level device (like a Behringer crossover used properly) would.  I hate to break this to you, but the Merlin TSM is just another two-way box design using off-the-shelf drivers.  There are about 6000 of them on the market.  (No offense, drphoto.)

I remember Cizek mentioning this in some of their sales material many years ago, but the concept of high-passing a driver to reduce cone excursion and thereby "clean-up" the frequency range farther up dates back well before that.  They were called "rumble filters."    Exactly the same concept as we're discussing here, just at a lower frequency range.

Cheers,

Davey.

[suits_me]

Most simply, I do not consider the Behringers to be high end equipment. I do consider the Merlin monitors high end equipment - although they're typical in that there are certainly lots of other good monitors. I'll stick with my opinion that adding a Behringer to a system with Merlins is not good system matching. It's degrading, in fact. Now, with Ref 1s or something, okay.

Rumble filters usually meant getting rid of tonearm resonance to ease low frequency demands on the amp. Of course you are correct that, say, Paul Klipsch's tech papers were talking about doppler distortion as it affects frequencies well above the lows from quite early on. The Cizek literature - remember I specified advertising material - highlighted the use of a sub to clean up the midrange. That's the first advertising material I can recall doing that, but my memory is almost as fried as Paul Klipsch himself. Perhaps you can name an ad talking about this aspect of a sub which I have forgotten from before the Cizek years, but remember that subs themselves (in the context of sats) are a relatively recent phenomenon, and they were and are usually sold as ways to add low end (even though most average subs are just woofers, not subwoofers.) We can argue whether Fried or M&K came first with the sub/sat aspect.

The good news is that there are better crossover options than the Behringers if that's an appropriate course. I never did get an answer as to how the Merlins are being used or why they're having problems from the owner. He did post back saying, you're probably right, a crossover probably would complicate things. I don't know the reasoning behind that decision in terms of his situation with the Merlins, like how big the room is and all the rest. For all I know, he's not having any problems with the Merlins...maybe he's having undiagnosed problems with the amp. Or maybe the room is huge. I just don't know.

The Merlins are fairly precise products.

[Davey]

suits,

Well, if you can determine the dividing line between "high-end" and not high end you're a better man than me.  I don't even know what "high-end" means anymore.  

Yes, I was referring to the days before "subwoofers" (M&K, Fried, whoever) made their appearance.  There were multiple problems that could be addressed with a rumble filter.....Mismatch between tonearm and cartridge, warped vinyl, vertical rumble actually recorded onto the vinyl, etc.

In any case, in this situation it appears the Merlins are either being driven too hard, there's some sort of a problem with the power amp, there's very low frequency (non-music) information in the program material or possibly something else.

Cheers,

Davey.

[Watson]

It doesn't sound like the Merlins are bottoming out or being overdriven.  It just sounds like the guy is looking for improved sound quality.  Highpassing the Merlins will do this.

As good as the Merlins are, they're not immune to physics.  Speaker distortion increases as excursion increases.  When you run speakers with full range signals, you significantly increase the drivers' excursion.

To see how this works, consider these graphs of a two-way bookshelf speaker.  Here's a graph showing excursion at various listening levels when run with a full range signal (each line represents a doubling of power, from 1 watt to 128 watts):
http://www.zaphaudio.com/audio-speaker19-excursion-1thru128watts.gif
Compare that to the same speaker run with a 100Hz LR4 crossover:
http://www.zaphaudio.com/audio-speaker19-excursion-1thru128watts-100hzLR4.gif

At equivalent listening and power levels, the speaker is driven to roughly 8 times the excursion when it's run full range!  That translates to at least 8 times more distortion, likely muddying the midrange and causing increased harshness.

Even if a person were to use a fairly cheap crossover, the amount of distortion the electronics introduces is almost certainly going to be an order of magnitude less than the 8 fold reduction in speaker distortion that it gives you.

[suits_me]

>Highpassing the Merlins will do this.

This is not a true statement in all cases. The ear is much less attuned to various orders of harmonic distortion at the low end than to anomalies where the ear-brain is more sensitive. This is why the REL idea of having a sub only fill in the low end makes sense for a lot of situations. Also, as we are discussing, the effect of highpassing will be affected by what is doing the signal splitting.

I don't consider the Behringers hi end because they ruin the sound of an audio system which is at a certain level. People pay hundreds and thousands for interconnects - and then you need all those Behringer connecting do dads on top of the cheep electronics to boot. Of course all this is subjective, but you don't have to look far to find comments that the Behringers add hash and glare to systems. Some people buy turntables to avoid stuff like that, you know....

This is why I am interested in three way speakers with low crossovers for the woofers which are capable of passive BI-amping, like the 2Ce's (although relatively high at 600 hz with 6 db slope....) Then you can put the Behringer on the amp(s) going to the woofer without screwing too much up while gaining what I want: EQ for the room peaks. OTOH, Vandie 2Ce's don't resolve like Merlin monitors anyway, imo, and so wouldn't be as damaged by the Behringer effect.

I guess we can conclude Cizek was the first company to advertize cleaning up the midrange as a reason to get a sub.

[drphoto]

Well, it seems like some of the problems I was having w/ bass distortion was due to a bad IC. Now that I've got that fixed and my Stratos Monos back in place, all is good.

I do have this rig in a very large room. I might give those ACI filters a go at some point and see whether it helps or hurts.

Yes the Merlin is a simple sealed two way, using off the shelf Morel drivers in an MDF box, but it is never the less a remarkable speaker. It's just incredibly musical. I dunno how Bobby does it.

[Davey]

suits,

You know, it's possible the music on that CD/LP you're listening to right now was passed through a number of Behringer gadgets during recording/mastering.  

I'm not concluding anything about Cizek.  My memory is fairly decent, but I can't remember every little detail from that long ago.  I do know Cizek hasn't been around (as a company) for ages.  

Cheers,

Davey.

[suits_me]

And most recordings stink. And everybody might as well toss the expensive cabling, then. It's actually for this reason that I don't buy truly high end equipment, although I have access to lots of systems and some simple test gear. I listen to lots of mass market and/or world music that sounds dreadful. But if I ever bother to get more than a really good mid fi system I will be sure not to then undo it by attaching things indiscriminately in the chain. Again, it's very subjective, but I like those Merlin products a lot.

And I still might try the Behringers in that application I described, or maybe just for fun.

I am sure about Cizek's ads being the first I can recall. I was working in the industry in that whole New England scene at that time, and I owned a pair of Cizeks. What I can't say for sure is whether Cizek's ads were the first to tout a sub for cleaning up the midrange. That would be like trying to prove a negative. ; >

[ctviggen]

Suits_me, you say:

This is why I am interested in three way speakers with low crossovers for the woofers which are capable of passive BI-amping, like the 2Ce's (although relatively high at 600 hz with 6 db slope....) Then you can put the Behringer on the amp(s) going to the woofer without screwing too much up while gaining what I want: EQ for the room peaks.

How do you do this?  This sounds as if you're going to split the signal to the Behringer and then run only the woofers with the Behringer. Is that it?  If so, then your woofers would still be subjected to distortion (according to Watson's graphs), although you would gain EQ.

As for Watson's graphs, those are nice, but are they applicable to every other speaker on the planet?   For instance, if a speaker is a three way design with woofers specially selected (xmax, Qts, etc.) for that frequency range, how much would that speaker benefit?  I ask because I have Linn 5140s (8 inch woofer) that I might put a simple high pass on to get rid of distortion on these particular speakers, but I also have RM40s (one 10 inch for low frequencies and one for upper low frequencies) that I run full range.  I'm currently using an active crossover (NHT), but I split the signal and run the RM40s full range and supplement with subs.  (This also works out very nicely for movies, as my system is HT too.)  I was thinking of sending a single output to the NHT then to the subs/RM40s, but now I'm rethinking this.  It'll depend, I guess, on what my room measurements say.

As for the "this is being used thousands of times during mastering, yet audiophiles don't like it", I'm currently reading two amplifier design books.  The authors think audiophiles are idiots.  I think I'm beginning to agree.  How many active crossovers, non-fancy cabling, and other stuff audiophiles hate were used during mastering?  I'd hazard a guess that many were, yet these "color the sound" according to audiophiles.

[Davey]

"And most recordings stink."

We agree on something!  However, we might not agree on the reasons for it.  
I think it's poor recording techniques and way too much "producing," but I think you probably believe that inferior equipment along the way has a significant effect.

A nice example is spinning in my CD player right now.  The new Sara Evans disk "A Real Fine Place."  A horrible recording, typical of many nowadays.  Everything miked with an in-your-face quality, highly panned, highly compressed.  The whole disk has a biting/grating quality that is pretty unlistenable.  Maybe it's even worse than I'm actually hearing because my ears aren't working that great because my eyes are working hard.  She's so beautiful, but I'd really like to hear her voice.    
Unfortunately this is the state of affairs with the mass-market music business nowadays.  It's all about marketing...

Sorry for the digression.  


Bob,

"Audiophiles" are not idiots...they've just lost their way, are in their own world, and can't see the forest for the trees.  (Not all of them of course.)

Cheers,

Davey.

[Watson]

How do you do this? This sounds as if you're going to split the signal to the Behringer and then run only the woofers with the Behringer. Is that it? If so, then your woofers would still be subjected to distortion (according to Watson's graphs), although you would gain EQ.

As for Watson's graphs, those are nice, but are they applicable to every other speaker on the planet? For instance, if a speaker is a three way design with woofers specially selected (xmax, Qts, etc.) for that frequency range, how much would that speaker benefit?

Highpassing the mains makes much less of a difference with typical three-way speakers, because the speaker designer has already done a highpass for you (dedicating a driver specifically to the lower bass).  I wouldn't bother with a highpass filter with typical three-ways unless the bass driver is 6 inches or smaller.

Incidentally, this is part of the reason why three-way speakers often have a cleaner midrange than comparable two-way speakers (all things being equal, e.g. MBOW1 3-way vs. MBOW1 2-way).  The midrange driver in a 3-way has been relieved of having to handle low bass duties.  This is the same rationale for highpassing 2-way mains.