AudioNervosa
Systemic Development => Speakers => Topic started by: richidoo on April 14, 2007, 12:05:48 PM
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Much thanks to Carl for making a housecall yesterday and bringing his bag of tricks to try to zap this little problem I have been fighting for a few months. After a day of experimenting with cables, sources, placement, we still were not able to remove the shouty sound in my listening room. Since everything above the speakers has been tweaked, upgraded or swapped with borrowed high end components of known shoutless pedigree, I have to face the music and start pointing at the speakers. In so many ways they really are ideal for the music I love to play, but this thing is bugging me.
The speakers are Legacy Audio Focus 20/20 (http://www.stereophile.com/floorloudspeakers/104legacy/index.html). They midrange drivers are twin "7 inch" yellow hexacone drivers on each speaker which are supposedly pretty exotic, or at least they were 8 years ago when designed! The moveable cone actually measures only 5" across. When I touch the mid drivers when they are not playing, the friction sound of rubbing or scratching the cone material is bright and resonant, it has that same sheen of the shout sound. Could the driver cone itself be resonating to color the sound?
The room is big, and is already treated to a big improvement with 15 pieces of 8th Nerve adapts. The overall improvement of that was very obvious, and yet the shoutiness became even more evident, localized to coming from the speakers and not an artifact of the room. Of course, at the time I could not conceive of the speakers as being the problem, so I blamed the Cary integrated which is a wonderful amp but not well matched to the Legacys. I got new Manley Snapper tube monoblock amps which better matched the speakers. Again the performance improvement was incredible, but with the amps' added dynamics, the shout is becoming even more evident than the old amp! Ahhhhhh!!!! "You mean I could have just stayed with my $14 boombox and remained blissfully ignorant?" :x
When I sit in front of left speaker and listen to it from a couple feet away, I can clearly hear the shouty tone coming straight from the speaker. I don't see what else it could be. Hoping for some good advice... Drivers, maybe crossover to blame? Ideas for a fix?
The new version, Focus HD is out now, with "silver graphite" mid drivers and all ribbons, no more silk dome and no more hexacone mids. I know that carbon fiber is extremely non-resonant, so I wonder if the shout was the reason for the swap to carbon based mid drivers? Not sure when/if the HD version may show up at my dealer to audition.
Thanks for any ideas!!
Rich
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Dunno.
My guess is it's a cap in the crossover. Does it come from both speakers, or just the left channel?
WEEZ
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Hi WEEZ,
Yeah it is coming from both, nice imaging!
I am trying to think about how to analyze the problem to really nail it down. I will do a close measurement of the mid driver in a freq sweep. That will show the driver's response with crossover and amps, minimizing room effect. My omni mic has no proximity effect so I can place it close to the driver to reduce room effect enough for this rough measurement. Hopefully I will see any freq response issues from the driver itself. Then I can move mic back and see how room adds.
I will connect the amp to only mid/tweet post speaker binding post thus defeating the bass drivers. But to further isolate the mid drivers can I run the mids with the tweeter driver wires disconnected (ends insulated) without hurting anything in the crossover, or should I put a resistor across the leads? Will the mid drivers' response be affected by removing the tweeter loads from the crossover? Theoretically, very little of this shout frequency should be in the tweeters' output anyway.
Aside from this problem, the system sounds very good now, so I am very motivated to remove this last pimple. If it is a frequency response aberration, and if I can identify the peak and bandwidth I can apply a filter before the amps to take it out. I can use Sonar and Firepod to identify the needed correction by trial and measurement. If it is cone distortion or bounce back from the box, then I don't think I can fix it as well with freq tweek.
ADAM makes great pro monitors and their high end monitors use the same Eton Hexacone drivers as my mids. They are supposed to be the bomb for low resonance, stiff, with no metallic edge. So I haven't given up yet!
Thanks for any thoughts.
Rich
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Is this noticeable at all listening levels or just at higher levels?
In talking with guys that are very knowledgeable about driver design I've found that Eton is well regarded for their cone materials, but are considered mediocre from a motor design standpoint. I know of one gentleman who has often said he would love to see an Eton cone mated to a Scan Speak motor.
Another possible issue could be the crossover itself. I noticed that the top end of the mids is crossed over at 2.8KHz. Do you have any idea how steep the filter is? Most of the exotic driver materials have their first cone resonance lower in frequency than your typical paper or poly cones. As such, they benefit from lower crossover points and steeper filter topologies. This helps to keep the first cone resonance way down in relation to the rest of the frequency range of the driver. For instance, my speakers use all Dayton Audio RS series aluminum cone drivers and an Dayton RS aluminum dome tweeter in an MTMWW 3-way design. The speakers have an 8th order acoustic slope with the crossover between the dual 7" mids and tweeter around 1.6KHz. The accurancy and presence are among the best I've heard and have even had one gentleman, who happens to own the same speakers as you, tell me that they sound very much like Krells.
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Mids cross to dome at 2.8kHz, and cross to woofers at 300Hz.
Here is link to the Eton specs (http://www.solen.ca/eto.htm). It is the 4-300 model, 12cm diam. cone. I searched hi and lo but could not find crossover slope for M/T. Not even JA mentioned it in the review. tsk, tsk!
As unlikely as it may seem, WEEZ hasn't steered me wrong yet, and his suggestion that something on the corssover is broken makes sense. I don't remember it sounding this far off when I first got them, but I was totally naive and didn't know what the hell I was listening to either so it could have. There was no room treatment then, and a underpowered amp, both of which conceal the shout. It must be possible to characterize and test check a crossover circuit if I sent them in for service? I wrote to Legacy, will hear back tomorrow with any luck. I hope they don't just say "Upgrade!" Supposed to have reputation for good service.
The speaker was a dealer demo, where it was "demoed" with some very large amps, which I guess could have overloaded it when they were "working late" with some beer and pizza. "All time greatest rock and roll speakers," someone once said. Yikes! Can a crossover rated for 600w peak be damaged by a 1000w SS amp? Seems possible, although I think the glass windowfront in the store would have shattered by then?! I would think driver coils/ribbon tweeter would poof before any crossover components? True?
Thanks guys!
Rich
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Rich, it's possible that the 'shout' was there all along...but I doubt it :?
Best thing is to see what Legacy says; but I'm betting on a crossover component (probably a cap) in the mid/tweet network that's failed..allowing the mid to play too high and causing the 'shout'.
Curious to hear what Legacy has to say. Keep us posted.
WEEZ
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Thanks Weez, I'll let you know.
Hey, I just thought of something else. Last spring, at my first listening session, a Fourier OTL "San Pareil" monoblocks tube amps came over here to play. They sounded fine, but there was a ground hum we couldn't find. "By accident" someone who should have known better disconnected the amp inputs to see if the hum was coming from them. One amp started to oscillate and did blow a ribbon tweeter before we could shut them off. The amp makes more power (200+ watts!) into higher impedences, and the oscillation was increasing in frequency beyond audible. Lightning sparks were coming out of the tweeter, so there was power going through that crossover to get there. Could it be that the crossover components could have been damaged in this incident?
I bought new matched tweeters and it seemed to work fine, but I still had not treated the room or upgraded the amps, so I wouldn't have noticed the difference anyway. I forgot all about that! What do you think? Can over power fry crossover parts? I that is a no brainer.
Rich
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Yup, that could do it alright.
I really doubt the driver itself is 'shouty'. A 2800hz crossover point from a mid to a tweet is perfectly reasonable.
Hate to say it, but you could have blown resistors too. Bummer.
WEEZ
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You hate to say it because resistors are expensive? What's a little carbon? hehe I hope not as much as new drivers or speakers. I agree with you about the driver design. There are too many reviews saying how neutral the midrange is, and same driver used across the whole product line for many years of fast company growth. Thanks for helping me get my head straight on this. We shall see.
I might try to get a look see at those crossovers tonight after I fix the damn DirecTV that can't seem to phone home and has shut us down cold!
I love technology.
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Yes, I think 2.8KHz is reasonable for a 12cm driver as well. And yes, I think the incident you describe could have done some damage. The resistors should be much less expensive than any cap in the crossover.
I would be very interested in hearing what Legacy has to say. I've never heard anything but great things about the company so I'd imagine you will get good service from them.
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I heard back from Bill Dudleston and Jeff Hernandez at Legacy by email today. They assured me not to worry, "they are here for me." That is good to hear.
Bill said if it is peaky then I can just send in both crossovers for a "rebuild," if it is buzzing or driver specific distortion then send in the driver. I am 99% sure it is the crossover, but not positive, I figure what the hell do I know about this? So I thought I would fall back on my engineering logic and experiment. The right speaker is fine. I can swap in the damaged crossover and if it sound shitty, I know why. If the good crossover goes into the left speaker and sounds fine, I know those drivers are OK. Smart, right? I thought so until...
Carl got wind of this and said forget about testing and listening, just pack up all MTTM drivers and their crossovers from both speakers and send it all to Legacy for repair and proper matching. Let them decide if it's good enough on a test bench. This makes sense to me, since I know I can't hear as well as a test bench can see. I told Dudleston I would mail it all in, just waiting for his go ahead.
It took a little while to find the crossovers, they were at the bottom under the LAST of the three 40 pound woofers that I removed, near the posts, duh! The crossovers are beautiful, all custom Legacy caps and very neat boards with huge traces!
On a good note, I have a set of little BG Z7 speakers lined up to fill in while mine are down. They are not Focus, but they are very sweet ribbon tweeter speakers good for music listening. Will work fine with the Cary.
I think I'll be able to send it off tomorrow, we'll see how long it takes, and how much $.
Rich
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One part of me probably would have tried swapping the crossovers and/or drivers. The lazy part of me would have done exactly what you're doing. I eagerly await the outcome!
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Brian, do you agree with Carl that sending in the whole 'satellite' package for both speakers is the preferred method to just sending the crossover itself? Or will they likely just rebuild the crossover, characterize it on the bench with resistor loads and ship it back with no need for my actual drivers? Seems more QC to have every crossover meet specific performance tolerances so they will work with any matched pair of drivers. What say you, oh wise speaker builder man?
Thanks :)
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Gee Rich...
I must have ears of MUD :? . I thought your Legacy's sounded awesome, when we were over there a few weeks ago. Did something change since then...or is it your intimate familiarity with your speakers, that allows you the 'hear' the defect (?)???
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I think sending in the whole sha-bang is the way to go. Let the designers do their thing. It'll give you better peace of mind. Drivers tested; crossovers tested....ta-da...fixed!
WEEZ
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Thanks Steve, they do still sound awesome, but there are times when there's just somethin not right. Today I was determined to put a finger on it. I put on Bartok Dance Suite for Orchestra and played only the right channel with all the battling loud dissonant splatty muted trombones alternately in each speaker. Left speaker sounded like kazoos, the other like real trombones. I repeated it back and forth a few times to make sure I wasn't imagining it, (or to practice imagining it?) There is definitely something wrong with something on the left side. Unless you listen to it all the time, you might not notice it. Flutes accents are the worst, they are like a bomb going off in your head. It shouldn't be like that. The trombone thing removed any doubt that may have been lingering about it. In previous post I wrote what happened with the blown tweeter.
Thanks WEEZ. I do feel better sending it all in. I just have the natural urge to fart around with it instead of just getting it finished like an errand. Also a little hesitant to send my good friend's body parts off in a cardboard box!! :shock: I started to swap the xovers tonight and said screw it, not my problem anymore. There's nothing I can do anyway. Thanks for putting me onto the xover. You're the MAN!
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I think I'll be able to send it off tomorrow, we'll see how long it takes, and how much $.
Rich
I have a Legacy Pace Maker sub and a few years ago I thought I had turned everything off when moving interconnects and oops there goes the plate amp. I don't think it was even in warranty (should not be covered anyhow), but they fixed it for free.
So hopefully you will be pleasantly surprised.
Lin
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So hopefully you will be pleasantly surprised.
Lin
Thanks Lin, I love pleasant surprises! :D
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Rich,
Yes, I think sending in the whole shebang is the best thing to do. That way they can test everything all at once.
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I heard back from Bill Dudleston today. He agreed that checking questionable drivers and xover is a good idea. He has a tight spec to which he tunes the crossovers, so he will check them both.
I got it all packed and ready to go. I hope I get it back reeeal soon. Thanks for the help guys.
Rich
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Legacy reports they will try to get to it this week. Parts have arrived safely. YAY!
Meantime, In keeping with the title of this thread, I am using a loaner pair of speakers and hearing THE SAME DAMN THING! Ringing, shouting sound in upper mids. I have this new CD of Liszt's Schubert transcriptions which is a very solo clear piano recording, very dynamic. It has become my new shouting sound demo disc. Those high piano notes are murder.
So now I realize it is not the Legacy speakers. They definitely needed repair as evident by the different tonality L to R, and I'm glad that is getting taken care of. Seems to be a couple things going on after all.
When I hooked up the loaners, smallish BG Z7 speakers I was not totally suprised to hear the ringy sound in the room, since we had pretty much exonerated the Legacys. Thanks! I put my receiver in place of the tube amps, to see if my tube amps had anything to do with it. The Onkyo 65wpc rx sounded awful! YUK! The funniest thing of all was using it as DAC for SB3. It sounded like a toy. Just a big plastic piece of junk. Switching to analog input and direct setting with no processing made a huge improvement, but beside the point. The sound was still very blurred, harsh, brittle, compressed, whatever. I could still hear the ringing but it was so blurred it was less pronounced than with the clear and dynamic tube amps. I was even using cheapo copper twisted wire because the Rx couldn't handle spades. So everything in the system was replaced and the ringing still remains. It's gotta be the room. Duh? I was afraid of that. But now there is nowhere to run, nowhere to hide. Face the music. I already asked my wife for a new house. She said sure, in about 12 years when my baby girl graduates from HS.
I will start a new thread over in Psycho Acoustics lair about the room. Or maybe just sell it all and get back into RC gliders. ](*,)
Rich
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Rich,
Any news on the Legacy's yet??
If not, hopefully you will get it back, SOON!
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Hi Stevo!
No word yet. A couple weeks ago I wrote to find out wassup, he was out town, but he said he would make it his top priority this week. I just wrote to him again. He has stayed in contact, so I am not too bent yet.
As much as I like these little BGs, they are starting to get on my nerves now, not because of what they're doing wrong, but only because I know what I am missing!! haha Actually they really are amazing with a little bass trapping. But I am anxious to get into tuning the new room but no point with the little speakers, they don't excite bass freqs strongly enough.
Can't wait to get the Focus back in action again. They look so sad sitting there silent with no guts. All the rest of the stereo has left them for dead and moved upstairs :cry:
:lol:
Seeya
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Hi Richidoo,
Can you get someone like Carlman to audition your system for you and possibly bring along some speakers? I hate to say it but sometimes we can get a little paranoid about the way our system sounds and really focus on the negatives all the time.
Good luck.
Rod
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Hi Rod!
Thanks for the good idea. Carl has been over to work on the shouty problem and helped me to work through the puzzle of what was wrong. Carl, Bryan, WEEZ and several others have kept me out of the funny farm and on the right track to getting things fixed, for which I am grateful. If you read AN you will see a shotgun blast of posts everywhere about what I thought was wrong at different points in the discovery process. Most of that was before I learned about the crossover being damaged. When I compared both speakers to each other while playing identicle signal it was obvious there was something very wrong in one. That combined with new amps that are much more dynamic and have the power to really excite resonances in both of my potential stereo rooms I was finding myself in a pickle with several "causes" working together to to confuse me. Thanks to everyone's advice I think I have a handle on it now. Time will tell..
I am relatively new to the hobby, only about 2 years, so I am still learning what to point a finger at when I hear a problem. This situation has taught me a lot. You're right though, I am very paranoid! That's why I stay here on AN where it's safe for me - haha!! :lol: When my system sounds great one day and then it doesn't anymore it makes me crazy trying to figure out what is wrong. The feeling you get from listening to a great system is extremely addictive. I feel strung out waiting for it to return. :wink:
Rich
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Xovers are fixed and shipping back. :D
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\:D/ I know you will be thrilled to get them back.
The offer to help move them upstairs, still stands.
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Thanks Steve. I'm gonna try to get my wife to carry them up there first.. hehe :wink: I'll let you know if we're going up with them.
I talked to Bill today, what a nice guy. He found nothing wrong with the xovers, they checked out perfectly. The left ribbon was destroyed from distortion due to Cary amp clipping while (trying to) play at high volume #-o It never sounded that bad to me, but he said it happens while trying to amp the bass signals that the clipping starts and the square wave is made. The ribbon is deft enough to try to play them and that is its undoing. Gotta be careful with ribbons on low powered amps. It all makes sense to me. I wish I understood that previously. :) Oh well, live and learn...
The right ribbon still sounds pretty good, but on closer inspection it has a few ripples in it too, so I will get that replaced also. The new amps should have no problem with bass and thus protect the tweets.
Rich
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Rich,
A blown ribbon? Hmmm. That's what I first thought before I mentioned the crossover. (if the crossover was malfunctioning..the sound would have been the same, i.e., no sound from the tweeter, thus the 'shout')
Just never thought you would have clipped a 80 wpc tubed amp. Damn, you must listen LOUD :shock:
Anyway, at least you're on your road to 'recovery' from a b-a-d nervosa.
Be careful...don't damage your hearing now...
WEEZ
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Hi Richidoo,
The speakers will now sound much more balanced and you should be able to determine the problem in your system. I use raven ribbon tweeters and they occasionally blow.
Regards
Rod
ps try not to listen to your system faults too much otherwise it will cost you a lot of money. I should know i've got 3 amps at home.
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Thanks guys. I appreciate the comments. I think the power is coming from trying to play into the very low impedence. It dips (http://www.stereophile.com/images/archivesart/LEG20FIG1.jpg) below 2 ohms in a couple places down low. Yup, I play it loud, cause I have a huge room and I like bass - who doesn't? Maybe it was that Madonna CD I got for Christmas. I did play that kinda loud, actually. :oops: In anycase the low notes at low impedence caused the distortion. The new amps are effortless playing the low stuff, so I would hope it would not recur. Rocket, good to know blowing tweeters isn't such a big deal. :twisted: I just hope they don't run out while I still have these speakers. haha
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Oh yeah - a low impedance at low frequencies coupled with a tube amp is a recipe for pretty hard clipping.
Good luck with the new setup.
Bryan
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Parts are back from Legacy. Haven't tried to play it yet. Judging from pic (http://parkwestlake.com/nopw/rich/hifi/ribbon/ribbon.jpg) of the old ribbon the new one will make a big difference. It feels good to have them back together.
Not thrilled with the turnaround time, packing job or tweeter driver/bezel assembly. Price was reasonable for what he did, and Bill answered my questions and anxiety like a pro.
Rich