Home alone after my daughter went off to open gymnastics class so I cranked up the Fellowship of the Ring we were watching and I realized there's a problem: during some of the loud passages there is an electrical crackling coming mainly from the left M80 and perhaps also the VP150 that I realized is not part of the soundtrack because it is not there at lower volumes. Could this be cabling or the 663 crapping out? It is only hitting -11 db when this begins to be prominent so I would think it's not the preamp. Does any one know what I should investigate in terms of the usual suspects? Using banana plugs for the M80s and the connections seem hand wound tight and solid to the upper posts. Maybe I should start by plugging the banana plugs into the upper connections on the M80s and see if I can continue to reproduce?

The crackling seems to happen with loud LFEs, a popping sound. Is it possible that the left M80 isn't handling the output of the A1400-8 with the mains set to large? More likely I should think loose cabling somewhere.

I would first of all have your 80's set to "small" and 60 or 80hz crossover on your receiver. I don't think that is your problem, but for HT that is what you want to follow THX standards. Have you calibrated all your speakers to the same SPL. Also, have you verified you don't have your speaker wires crossed + and - wrong?

Not sure what is the problem? I would call or email Axiom CS tomororrow and go through there suggested troubleshooting.

I'm such a big help .

Try switching the L/R mains and see if it does the same thing.

I was thinking the same thing, that would rule out the speaker.

Thanks guys for the ideas, my wife and daughter are back in play so no way to troubleshoot at the moment, have to wait til tomorrow.

Well I finally had a chance to crank up the system again today and was able to reproduce the crackling sound on the Fellowship of the Ring where the trees are being torn down around Chapter 19, if memory serves. When you crank it up there is this loud popping sound that is just not there at lower volumes. Today during this section of the movie the Yamaha spontaneously shut down. I have been suspecting the 663 since last week and won't be able to prove anything until I upgrade to a better pre/pro but I felt compelled to share my suspicions, which relate to the XPA2 as well, because perhaps the emo amp was going into protect for a reason. I never heard the popping sound on the XPA2 with the M80s because the amp would shut down, but when I hooked up the Polk 10Bs (to the 663 and XPA2) there was a popping sound as well as the speakers began to fry (burning plastic smell); I assumed this was because the 6 ohm 10Bs are rated at 250w max and the XPA2 puts out more power than that. You may recall I was using the intro to Hulk to troubleshoot the problem, unfortunately this contains a lot of electrical explosions so when I hooked up the M80s and the A1400 I thought a couple of the pops sounded a bit harsh but thought it might be accurate just too loud. The Fellowship passage is less ambiguous and suggests something is wrong.

The fix for now is not to play movies that loud (not something I want to experiment with much to avoid speaker damage), between 80-90 dbs is no problem, later I plan to replace the 663, still somewhat dragging my heels to see if the Outlaw 997 comes out in a timely fashion and is well received.

Although this is preliminary and still makes little sense I wanted to put this out so any who might be considering the XPA2 or 663 would know that my experiences with this equipment remain inconclusive, i.e., the XPA2 might pair just fine with the M80s given the right processor, the 663 might have some inexplicable glitches relating to "the curse of the Yamaha."

You could also look at the latest from integra. I think we forget about them a little here, I suppose a number of others as well.

The DTR 9.9 receiver looks very good as well, certified for 4ohm.

I wonder if Integra's can update the FW via Internet.

Ok I'm confused. Do you have the XPA2 or the A1400... Or both? I can't imagine why you would have both unless you upgraded to the A1400 & just haven't returned the XPA2 yet so you're comparing them.

Also, someone here will have to explain to me why a pre-amp wouldn't be able to handle loud levels of volume if an outboard amp is handling all the power needs? I mean I thought that was the whole theory behind separates... push your speakers with an external amp so that all your reciever has to worry about is decoding, formating, upscaling & the like.

With an amp like the A1400 (or the XPA2 for that matter) I simply can't imagine why there would be any clipping/power issues at all?

Hi Micah,

There are matters of compatibility between a separate preamp and a power amp that don't occur in an AV receiver, where the engineer/designer knows in advance what the gain of the amplifier section will be and how much output (voltage) that the preamp section of the AV receiver will need to deliver to the amp section to allow it to reach full output.

When you run a separate preamp or the preamp section of an AV receiver, it's possible to run the volume control of the preamp too high, driving the preamp output into distortion before it reaches the separate power amplifier. Although preamp outputs should be standardized at about 1 volt, some preamps may greatly exceed that. I once measured a Sony device that put out 18 volts at maximum rotation of the volume control. That sort of output would drive the input of a power amplifier into distortion. The latter is not the same as the output of the amplifier clipping.
It's just overloading the input circuit of the power amplifier.

What is the setting of the volume control on the preamp or AV receiver when you are driving the power amplifier?

Regards,

Alan

Melvin - he has the A1400 now. XPA-2 was returned after it continuously shut down on him while driving the M80s. Read the saga here.

Melvin??? Baha ha ha haha ha!!! No no no my good friend, I am not Melvin. Melvin White (aka the Joker) is the guy I quoted in my signature box.

This sort of thing keeps happening! lmao

Whatever you say Melvin.

Hey, I remember that line!

Don't laugh or Calvin will come in here and knock you guys around!

What's this the Melvin and Calvin show

It's a surrealistic comedy.

Oh, didn't I tell you? That's my new thing, calling people by whatever name they put in their signature... if you've got a name in your signature, and it's not yours, you've been warned.

Jason

Uh oh.

Whatever you say, Epic.

The setting on the preamp was less than 0 db, maybe -4db maybe less.

The Yamaha has a 6 ohm setting (which manufacturer states is also suitable for 4 ohms for the front speakers), I have been advised before here on the forum to stick with the 8 ohm setting; however, I have switched to the 6 ohm setting for the moment and it seems to be working better, still can't really tell until I have a free moment without the fam around to experiment a bit.

Before when I had the XPA 2, running the 663 at the 6 ohm setting did not trigger the infamous protect circuit on the XPA 2, but it wasn't loud enough for those moments when you want to crank up the sound a bit. Now with the A1400-2 the system seems to have plenty of head room on the 6 ohm setting, and the overall experience seems more smooth, e.g., as if the volume control increments on the preamp are smaller, making the "volume dial" more spread out, so to speak.

I admit that I did not think that the pre out section of the 663 would overdrive the inputs of a power amp even on the 8 ohm setting with volume output of 0 db or less (and it seems it would be immaterial to the preamp what ohm speakers are downstream from the power amp), so I am a bit mystified, however I lack time and inclination to do a lot of troubleshooting that might damage the speakers.

In addition the kicker for me was when the 663 shut down spontaneously, that just shouldn't happen under normal circumstances when reproducing material at 0 db or less, and suggests there may have been an overload within the preamp itself before possibly overdriving the power amp input(s).

Charles, again the reason for strongly suggesting that manual directions to set a lower impedance number be disregarded is that this in no way "optimizes" the receiver for lower impedance speakers, as some imagine. It's a safety precaution to keep the UL happy by reducing the chance for overheating at high volume levels and it does this by reducing the maximum voltage that the power supply can output by something on the order of 25-30%. Since power is proportional to voltage squared(Ohm's Law again)this sort of reduction roughly cuts the maximum power capacity in half, as test labs such as S&V have reported. For example, if the maximum voltage output was 40 volts otherwise, setting the lower impedance switch or menu setting might reduce this to about 30 volts or a bit less and power capability would be roughly halved.

Whatever better results you may get from your experiments, there doesn't appear to be a reason that setting the impedance lower would be a positive factor.

So here are my latest observations and loose reasoning/weak hypothesis:

We watched a dvd tonight and the peaks were up to 107 db (volume setting was +4.5 db) before mild almost subtle popping sounds kicked in, keep in mind that loud, nasty popping sounds were evident at 90-100 db before with the 8 ohm setting, so this was a definite improvement, although clearly not a solution. Also I should point out that I would not have noticed these sounds currently if I had not been trained to do so by previous experience, they were mild rather than obnoxious by comparison.

All cases of "popping" sounds going back the past 2 months or more (?) have only occurred during HT LFEs, never during music playback, even at similar or even higher db levels.

It makes no immediate sense that an LFE would cause a high frequency pop like a gunshot (not really a close example but just for comparison sake).

I have no subwoofer (waiting for Godot) and it has been documented that the M80s are limited with regard to the LFE frequency range.

I suspect that with no subwoofer to receive deep LFE output the preamp has nowhere to discharge the power output and this may cause the popping distortion I am experiencing during LFEs.

Everything else besides LFEs sounds perfect, actually LFEs sound smoother, louder, and better since I set the 663 to a 6 ohm output setting; although I couldn't swear to this since I have obviously done no DBT, it seems unlikely to attribute a much softer almost negligible "pop" to listener artifact given a 10 db increase in SPLs.

Perhaps others know better but I have no way to check this out except to wait a few weeks until the sub comes; of course this could be massive wishful thinking on my part since I am hoping this problem goes away at that point, or that at least I achieve something closer to the peak volume I would like have in play without the sonic defect kicking in.

JohnK, I don't think this in any way contradicts the info you have shared, given that according to my understanding it is not a good idea to run an amplifier at high volumes without a resistor downstream to discharge the power output, because then the power has nowhere to go other than toward some form of implosion.

Perhaps my thought process is way old school or off base, perhaps they have error correction built in to correct such issues nowadays, if so I'm sure you will all let me know the error of my ways (of thinking), at any rate the system is working much better and I will have nothing to report until the sub arrives, I will let you all know if I achieve greater workability at that point.

Sat(still had Charles on my mind from a previous reply for some reason), no I can't even hazard a guess as to why the situation would be improved at the lower impedance setting(if after switching back-and-forth that still appears to be the case). The suggestion about the pre-amp output wouldn't appear to be part of the explanation either(the lower impedance setting affects only the internal amplifier in the 663 and has nothing to do with the pre-amp section). The mystery remains.

Hi SatKartr,

I just had a conversation with Tom Cumberland, our chief R&D engineer who designs all of our electronics, including the A1400.

First, he asked me if you are running a center channel and it seems you are. Do you have it set to "Small"? It should be, because if you have it set to Large, the center can't reproduce low bass and any deep bass routed to the center might cause the woofers in your center to hit the magnet structure, producing the popping noise.

Next, Tom told me that there are several points within the Yamaha where distortion may occur. If an especially "hot" (loud) digital signal hits the Yamaha's DSP processor and if it's so-so, it may not handle the hot signal, causing distortion, which would be fed through to the A1400 and reproduced by the M80s. Another possibility is that even if the Yamaha's processor handles the hot digital signal, the peak in the gain might cause the Yamaha's preamp section to clip, which would also feed through to the A1400/M80s.

Finally, he pointed out that if you don't have a subwoofer and you are listening at levels you quoted of 107 dB SPL, it's possible that the LFE deep bass, which should go to a subwoofer, is going to the M80s and overdriving the M80's woofers so they hit the magnet structure, causing the pop. By the way, that won't damage the M80 drivers--it just makes an unpleasant sound.

As to the Yamaha shutting down, it may well be a product of the DSP board clipping or the preamp section clipping as described above. As JohnK pointed out, the impedance setting should have no effect whatsoever because none of the Yamaha's internal power amplifiers are being used.

Regards,

Alan

I realize what you're saying makes theoretical sense except I remember without a doubt empirically that one of the reasons I sent the xpa2 back was that I couldn't get much sound out of it at the lower impedance setting, whereas the higher impedance setting caused it to go into protect; not sure what the 663 is up to with their settings, that should not be the case with preamp output yet it seems to be so.

That is one of the reasons I felt compelled to post, it seemed to me that the weak link, for whatever unknown reason, might be the 663 and it was unfair to persist with the assumption that the xpa2 was the weak link without better clarity.

Alternatively, as Alan has suggested, the lack of subwoofer may have been the culprit, which I will test later and report my findings.

Thank you so much for your post, Alan, that gives me a lot more things to consider.

The center is set to "small," although it's funny that you mention it, because before lowering the impedance setting, it seemed there might be a popping sound coming through the center as well.

Since the Yamaha shut down, I tend to favor the hypothesis that the Yamaha DSP may be having difficulty handling a "hot" digital signal, especially deep LFEs at high volume.

I'm glad to hear that the M80s will not be damaged!

I am getting a lot of LFE bass out of the M80s, it seems even more so with the lower impedance setting; however, with regard to the 107 db SPL, keep in mind that I am using a Radio Shack digital SPL meter, and I was getting a louder popping sound at 90-100 db SPL with the higher impedance setting than with the lower impedance setting at 107 dbls. This again would seem to point to the 663 as the possible weak link in my setup rather than the Axiom equipment.

Thanks guys for your input, I have a much better idea of the likely culprits, I'm looking forward to plugging in the sub when this may become a former "ghost in the machine" or if not, truly with the SPLs I am able to achieve without appreciable distortion at the lower impedance setting I will be quite satisfied until I can replace the 663, wherein lies the root source of the problem I feel quite confident, although only time will tell.

I wonder if it was that crackling/popping signal that was setting off the XPA-2? When you couldn't get much sound the signal was too low for the XPA to worry about, with a stronger signal it would sense the distortion and go into protect.

I'd blame those three little Rice Crispies guys!

Murph, I was just thinking something along the same lines. Were you eating breakfast when you posted that?

Nope, but I was inspired.
I learned this morning that unless I become more mindful in closing doors, that I need to put dry goods on a higher shelf in our little pantry closet beside the fridge. My dog, Cosmo, enjoyed a good bit of Rice Crispies this morning.

What's your dog's favorite cereal?

Peanut Butter.

That remains my exact impression, for that reason to this day I have no reason to fault the xpa2, how can I blame the amp for failing to amplify a system defect that could harm the speakers?

So today I had to live with the popping sound again on Dark Knight, very noticeable, especially for example at the beginning when the batmobile crashed through the parking garage, but always at time of LFE, measured dynamic range today of 70-110 dbls.

I have gotten spoiled with the M80s because they have such great bass that I almost don't miss not having a sub (OK of course I'm dying yet still happily awaiting the ep800 still convinced it will excel versus the ep600) except for the annoyance of a pristine dynamic HT moment devolving into snap, crackle, and pop that is clearly not realistic, not even cheesy.

BTW, what do people think/say about this: the sound of wind, people clapping, or cheering (upper HF?) does not sound realistic to me at all with the Epic 80 system (disclaimer: no sub, only tweaking = speaker level set by ear, 1 db trim off 6.5 Khz); I tend to wince/grimace, everything else sounds perfectly accurate . . .

I have never really noticed, will check back later.

Maybe I'll have to be closer attention to cheering and wind. However I hadn't noticed anything out of the ordinary, accept for that recent Rush Blu-Ray which was mixed way to heavily on the crowd sounds in the rears. Maybe I'll have to track down a good stage show dvd or brd and see if I can summon some crowd noise.

Or perhaps a movie set (fully or partially) on the ocean, or one in which the engineers are intentionally intending to sonically represent wind or applause, like a movie version of a wedding or an award presentation or something, please skip analysis of music video/audios that make no attempt to provide realism in said domain, thank you!

That would suggest speakers that play a little too bright, no? And this is a characteristic that from EVERYTHING I've ever read about them, the M80's don't have. So to me that would futher suggest your reciever being the weak link in your system.

I can't speak for Axiom yet, but I know on my old system (very mediocer speakers, but the Denon is brilliant!) those sounds were some of my favorite! Expecially applause... it made 'Dave Matthews : Live at Central Park' my favorite cd of all time!!!

I haven't followed this thread from the start, but is this for Blu-ray? Are you sure you're not seeing/hearing the DTS-MA bomb?

I'll have to go back, but I was pretty impressed by the sound in both the Master and Commander and the POTC Blu-Ray discs when it came to ocean sounds. I'll have to dig for wind and weddings when I get back.

The DTS-MA bomb?

The only time I noticed ugly sounding cheering was when I had Audyssey turned on before I bought the feature pack upgrade. Before the latest upgrade (and before I reran Audyssey calibration more carefully), listening with Audyssey turned on really made everything sound "bright." Applause made the problem more apparent.

I'm curious, what is the DTS-MA bomb? I haven't heard of that yet.

I think Hansang just wanted to bait us all with that unexplained comment...

Fortunately our chief joke-makers are still slumbering off their Christmas hangover... give it awhile and the jokes explaining the MA-Bomb will start pouring in.

Jason

Wake up, funny-makers!!!

Some AVRs and pre-pros with the capability to internally decode DTS-MA bitsream had a decoder chip that produced a very loud pop (like a bomb) on a certain code string. Some Onkyo/Integra as well as Yamaha units (? Denon and others as well) were known to be affected. Most have upgraded their firmware to address this bug. Since it can be damaging to your equipment, it is best to either avoid those movies that are known to have the potential bomb or, better yet, upgrade the firmware in order to be immune to it altogether.

Cool, thanks John. What a horrible bug to have.

Jason,
Are you planning on running your EP600 *and* EP800? Or are you trading in the 600? Man...EP800 must sound awesome. I can't even fully appreciate the EP500 at this point (living in a condo and all).

John already explained the MA bomb so there's nothing for me to add on that front.

Pretty sure that Jason is keeping both subs but he can confrim that.

Yep, keeping them both, at least for now. I may sell the 600 privately once the 800 arrives, but I've at least decided at this point not to do the trade-up program. (the owner's club discount was too good a deal to pass up)

Though of course, there's always the option of trading up the 600 to another 800.

Jason

Yeah, Sean; there's been some discussion of this "bomb"(probably a bit of the exaggeration typical in audio)on some of the boards for maybe 8 months. The previous replies have covered it pretty well, but as to whether this relates to Sat's issue, there appear to be three common factors necessary and it isn't clear at this point if they all apply to his case: Blu-ray; DTS-MA; player sending bitstream(not PCM)to receiver for decoding.

I haven't heard issues with clapping or ocean noises, I used U571 for ocean noises and parts of LOTR - FOTR for various clapping noises also listened more closely to Eagles Farewell tour in DTS and they sound great to me. I am suspecting you may have a bad 663, maybe time left for some warranty or exchange for another make?

So we re-ran Dark Knight last night (the girls just had to see it, I was the only interested party on Xmas) and it clearly was the left M80 (mostly) that had the popping sounds, I replaced the speaker cable and RCA interconnect to no avail. Switched the Yammie settings to "small" for the M80s and crossover to "40 Hz" ("60 Hz" sounded like crap without a sub) which resulted in an amazing improvement; lost the deep, teaser "wannabe" LFEs but also lost the major popping sounds on this program material and gained an incredible improvement in the integration of the center, M80s, and surrounds (no more cheesy "Oooo" wind or other formerly ridiculous e.g. HF "audience clapping" sound effects); no joke, the surround effects really sound great now, I suppose that's no surprise but it's news to me, whew the qs8s actually perform as advertised, still waiting for the 800 . . .

Sat - the saga continues! Do you have a laptop you can use to run test tones through the M80s? If so, you might want to run a signal sweep through the system using a free program like REW to see where (at what frequencies) the M80s start to crackle.

This might help you pinpoint where the problem occurs, test different surround modes on the receiver, test speakers individually, etc.

Jason

SatK, I really think you should be looking for another avr to use a pre when you get the EP800 or theA1400, I think you will still be having issues. All that popping/clipping(?) in the LFE can't be good for the subs amp either.

This is my first post....I apologize as I haven't read the entire post. I saw the post about crackling noise in the Dark Knight. I had the same exact noise at the exact same point in the movie, except I have the M60v2's (less than 30 days) being driven by a temporary Denon receiver. I was waiting on the Emotiva UMC-1 and MPS-2.

I have been looking to see if anybody else heard the same thing in the soundtrack. Different system, different speakers...maybe this is part of the soundtrack or an error in the decoding?

I may have to check out that part of the movie on my setup again. The first time I watched the movie I didn't notice anything, and I'm usually picky.

I listened to it again today and I think it may be part of the soundtrack. It is odd, because there are other events with much more low end thump and this sound is not present. I hear it coming more from the left speaker more than the right. It is also in the center channel (VP150) a little as well. It seems to be coming from the tweeters. It occurs toward the end of the wall crumbling and I think it may be the representation of the crumbled wall hitting the ground. If this is the case it is a poor representation as it sounds more like sizzle and cracking than debris hitting the ground.

Has anybody else experienced this sound in their Axioms while playing back the Dark Knight Blu-Ray?

I wasn't really listening to it "super" carefully, but I didn't notice any sizzling sound. I was watching it via Samsung 1400, bitstreamed audio to Denon 3808 (and M80/QS8/EP500)

I don't remember what I was watching when it has happened, but I have had what would probably be the same crackling/whatever sound. It happens so rarely that I never thought it was worth investigating, as it doesn't just seem to be a certain volume causing it.

It is not related to volume. I can hear it at both low and high volumes leading me to believe it is just part of the soundtrack. Don't remember if I stated this or not, but it sounded like it was coming from the tweeters. Either the speakers do a good job at revealing what is there or my setup is doing a bad job of representing the sound the engineers hoped to reproduce.

Neo, you have not described your setup, I assume your using surrounds? If not, is it possible the surround channel is being routed to your 80's? Are you using Dolby or DTS modes? etc... speakers set to small?

Thanks everyone for the feedback, sorry for the delinquency in my replies, serious time constraints nowadays, wish you all well.

Thanks for the observation, NeoE46 that helps, now I realize there is little point in testing the left speaker as on that particular passage I observed the same across approximately four listens, mostly left speaker with a moderate amount of center involvement.

Thanks Jason for the concept, when/if I get time to do formal testing I will plug my notebook in and “get real,” i.e., engage in formal observation. It’s nice to know how that would be accomplished.

Thanks Jay, I share the same conviction/plan re: the 663, steps would be: 1) obtain subwoofer, 2) hire electrician as/if necessary, 3) upgrade processor once I have some clue re: what features I desire beyond stability/HD audio.

I’m reluctant to admit, Jay given that I have such limited experience with HT and the ability to EQ systems by ear in general seems so deficient; however, the “wind/applause” issue I suspect is related to the lack of thunderousness in the LFs. To be more specific, the problem seemed to be that when the crossover was set to 80 HZ, the surrounds were way too shrill/prominent in the sense that they did not mesh with the M80s/VP150, which always merge together to an amazing degree regardless of crossover setting. At 40 hz crossover setting the qs8s seem to provide ambient sound without being obtrusive.

In the absence of a sub most of this seems silly conjecture, I’m trying to reproduce HT sound with just the M80s doing double duty, i.e., Mains/LFE, so I am waiting to “fix” my set up until the sub arrives; however, since this thread is still active, I submit the following observations for your review:

1) I noticed the bogus crackling sound again that I sincerely doubt is due to sloppy audio engineering in the last (?) episode of the Matrix, at the end before the swarm/baby face appears, the defect did not appear until then which made me suspect that newer videos (Iron Man, Hulk, Dark Knight) might emphasize heavy LFEs more (?) and make the problem more prominent.

2) My reference scene remains LOTR first episode where they are destroying the forest, that’s when I first became convinced there was just no way that the engineers were that lame, to use a distinctly electrical popping sound to represent trees falling.

3) On every occasion of hearing the sonic defect I have experimented briefly and was unable to clearly reproduce the crackling sound at low volumes, at least in any way that was obvious to me as the same sonic representation at a lower level of amplification (i.e., no distinct crackling sounds).

4) The 663 actually shut down during loud experimentation with one of the defective sounding passages (Iron Man?), yes my hand was on the middle of the remote but nowhere near the power off button (which is at the top of the Harmony One as well as the 663 remote).

5) Problem does not seem to exist when I do NOT send the LFEs to the M80s.

For the above reasons I:
1) Continue to suspect faulty LFE processing or reproduction, especially given that cheesy HF crackling sounds should not emerge when LFEs are engaged unless there is a processing/reproduction defect.

2) Find it difficult to plausibly attribute the crackling sounds to faulty recording or intrinsically faulty speaker design.

3) Am waiting for sub before any attempt to correct since if I do not send LFEs to M80s I most likely will no longer have a problem.

Well perhaps this has been less than a waste of time since others have experienced transient issues with same and perhaps we might learn something, on the other hand it remains a ghost in the machine until someone can explain at least the Dark Knight passage, is it a defect in the recording, processing, or reproduction?

Best all,
SK

I have the following eq.

(L/R)Axiom M60, (C)Axiom VP150, (S/R)Axiom QS8
(Media)PS3, (AVR) Temporary Denon 1609...waiting on Emotiva UMC-1

Speakers set to Large. Crossover @ 60hz. Dolby Digital with PLex for the rear. Setup with Audyssey(sp?)

I would recommend you set all your speakers to small, especially your center and Qs8's as your sending frequencies below what those speakers can handle effectively below the crossover. Also, you want to use 80hz, not 60hz. This may or may not be your problem.

From what I was reading I thought I would see this answer come up.

It`s the industry standard, you make adjustments according to individual tastes from there.

Clarification: Only the L/R are set to large or full range. There is not much difference in S/Q between the two settings. No difference in soundstage.

As I said, I was concerned at first, but I don't think this is a problem with the setup. I think I am hearing something in the material as this is the only time I have heard the noise. Plenty of other soundtracks with huge bass and punch. Only this soundtrack at this particular time.

I would also suggest trying the mains to small, you can play with a 60-80hz crossover if your receiver allows for independent settings for each speaker. Let the sub do the job it was intended, to move air with the larger driver. Double bass is not always a good thing.

Double bass is frowned upon in the world of PA systems. Many get a 2-15" with 1 horn cabinet. The lower 15" is considered a "quasi sub". Then they want to add a real sub and it causes problems and muddiness in the low frequencies.

As I stated, I hadn't noticed any S/Q differences with it swithced either way. Wouldn't the Bass Mgmt system (LFE) limit which speakers get which sounds regardless? How do you measure double bass?

What is the shape of a low-pass filter? Surely there has to be some overlap in order to blend the sounds. At what point do you start to send too much information to the sub and the sound becomes muddy anyway? For example, a war scene with explosions in front and behind. In a small configuration, the sub is being sent information from all speakers. In large and if the L/R speaker is rated for the lower frequency, wouldn't all of the explosions be more crisp and have more punch?

Sorry for all of the questions. Just trying to understand what the differences would or should be and why the recommendation is to set everything to small regardless.

Small and Large has nothing to do with the size of the speakers, but how well the speaker can handle the frequencies below the crossover point. THX and others recommend an 80hz crossover, because anything below that becomes non-directional and are frequencies best suited for the sub to produce. A 12" driver can move more air than 2 6" woofers. Yes the m60's and 80's can go below 80hz, that is why there is a gradual slope or hand-off to the sub, it does not just cutoff.

Yes, the bass mgmt controls the direction of the LFE for those speakers set to small, and sends those freq's below the crossover to the sub. If your using LFE+Main your mains are also receiving the full freq spectrum. If that is what you like, that is fine, I'm just going on the industry standard.

Neo, the standard bass management in HT receivers rolls off the sub above the selected crossover frequency at 24 dB/octave and rolls off the speakers below the selected crossover frequency at 12 dB/octave.

If explosions and other very low frequency material sound better on the mains than the sub it means that the sub isn't a good one. They're specifically designed to excel in those frequencies; that's the whole idea behind a sub and bass management.

I was hoping to report that the sub had eliminated the problem entirely, alas that does not appear to be the case.

Let me begin by confirming that I have reached 99.8% audio nirvana with the addition of the 800 and could not be happier in any universe that I can imagine at the moment.

Watched Titanic with my daughter this evening and the sonic veracity of the 7.1 dvd soundtrack absolutely blew my mind, I never would have believed it was possible for sound to be so lifelike and without reservation feel I could die happy having experienced this level of audio reproduction and nothing further.

There were a few electrical pops in the hitting-the-iceberg scene that I mostly noticed because I am attuned to the aforementioned defect I chose to label "crackling speakers" yet they were extremely brief, minimal, and interestingly they did not appear at time of deep LFEs but a bit higher in hz, and it was the dual M80s that expressed the defect.

BTW the 800 manual recommends 40 hz crossover with the M80s, and running no EQ, I couldn't agree more: 80hz and 60 hz sound too unnaturally bright in my room (muy trebly) whereas 40 hz crossover is absolute sonic heaven. I do have wood floors so that may play a role as well, however I am still very happy with the no EQ Axiom philosophy so will persist with that for a while yet. Perhaps if my system were calibrated different a higher crossover would work but the blend at the moment is so sweet, why bother tweaking (except of course for the occasional "pop")?

My one major regret with posting my experiences has been contributing to the nonutilization of the XPA2 since I suspect that the problems I had with the electrical popping issue that may have triggered the protect circuit were largely running the M80s at low hz, and it seems most do not set the crossover much lower than 80 hz and would probably be not have an issue. I would love to hear if others were successful with the XPA2/M80 combo, I would feel less foolish for having pursued that possibility and it is a nice amp.

The whole wind/applause thing I brought up is completely alleviated with the introduction of the 800, as I suspected it was a problem of unanchored HFEs sounding cheesy, accompanied by appropriate LFEs the HFEs are simply superlative.

As when I first purchased the M80s I have reached a watershed moment, although this time I feel it is the promised land, the grass is only greener here, not on the other side. I am so much more impressed with the Axiom system, before I was of the opinion that OK yes this is very good/extremely good, especially for the money and I couldn't think about spending more to increase my reach because how much more would that have to be to incrementally improve the sound in a meaningful sense (while secretly wondering what it would be like if I could afford better) whereas now I am in a state of perfect satisfaction and care not that in some hypothetical world of course things could always be even more superlative.

Better has no meaning once you reach best.

Thank you, Axiom,

Nice write up!

When are you going to spring for a new pre-amp?

FYI, Over on Emotiva's site there are many running the XPA series, including the XPA1 and 2, with M80s and are having no problems.