Can massive increase in watts cure resonance?

Hilbert

This is more an anti-troubleshooting question: a few months ago I bought a Polk 5.1 system (Monitor 50s, 30s, CS1 and PSW 110), wired to a Yamaha RXV 663, and liked it quite well in the value-for-money sense, but the speakers had a few fairly obvious shortcoming, including a tendency to boxiness or boominess at certain frequencies. I'm assuming this is an example of resonance. Resonance was particularly evident on a few tracks, never more so than on Martin Pearlman/Boston Baroque's recording of Air on a G String.

A week ago I bought an Emo XPA-5, great product, big improvement in sound, and this morning I played the MP/BB version of G String and found the resonance greatly reduced, very nearly gone. I've heard similar improvements on other formerly resonant tracks.

I thought resonances were a product of the frequency of the sound, and the shape and composition of the enclosure. My questions are:

Am I right in thinking boxiness = resonance?

Am I imagining the improvement? or

Is it possible for a big power boost (from 95 wpc via Yam to 275wpc X 2 with Emo) able to cure a resonance? If so, and if there's a simple explanation, then what happened?

What else canbe cured by application of 550 watts? Baldness?:p

These questions have to do with the Mon 50 fronts only; my music listening is mainly 2 channel. Also it's true I moved the speakers around to accomodate the Emo, but I moved them a few times before Emo too without eliminating boominess.

Thanks in advance for any info anyone can supply.

Face

It could be the better dampening factor(control of the woofers) of the Emo amp.

Hilbert

Ah, that makes sense, thank you.

Jim Shearer

Hilbert,

What was the freq of the resonance?

I doubt it has anything to do with power. Amps aren't truly flat in freq response, and they do have different sounds. There was a time I didn't believe this was possible, but experience has taught me otherwise.

Most impressive difference in amps I have ever heard was earlier this year when I gave our daughter and son-in-law a pair of Half Chang speakers (w/ single full range Fostex FE206e drivers) I built and one of those Radio Shack Accurian amps to drive them. I tuned the HCs on one of my systems--which includes a Sansui 4000 receiver (vintage 1974.) The HCs sounded fabulous! So I set them up for Kate & Peter w/ the Accurian. Some music sounded OK, but female vocals were unlistenable! The sibilance was horrid! I swapped the Accurian for a cheap RS AVR I had given them earlier, and the sibilance almost disappeared.

The moral of the story is that upstream electronics are critical to the final sound.

Cheers, Jim

Hilbert

Jim Shearer wrote: »

What was the freq of the resonance?

Thanks for replying.

I'm not techie enough to supply a frequency number---(considering the track, perhaps it was a "G"?:))---it was a note a baritone's upper vocal register, in roughly the middle of the speakers' range.

Upstream electronics critical --- so maybe it's as well, when possible, to use boxes from the same manufacturer.

Jim Shearer

Hilbert wrote: »

Thanks for replying.

Upstream electronics critical --- so maybe it's as well, when possible, to use boxes from the same manufacturer.

I think just sticking with quality products is probably good enough. But it's true that within a manufacturer's line, the separate units should have been designed for maximum compatibility.

Cheers, Jim

ben62670

Better amps control speakers better;)
Ben

Hilbert

FWIW:

EE guy at work suggests new amp has indeed eliminated the resonance, not by virtue of superior wattage, but rather because the Emo creates a short circuit, through which electricity can flow, and the flow in turn generates a magnetic field which dampens the motion of the speaker cone, or the magnet in the speaker cone, or somesuch. This was a hurried hallway conversation so I couldn't ask why current would flow more readily through the Emo than through the Yam.

Thanks to everyone who responded. My conclusion at this point is that an accurate explanation would be mostly gibberish to me and that a wiser course is simply to enjoy the music without worrying much about where it comes from.

reeltrouble1

well if an EE said it..............

If you enjoy 2 channel you should eliminate that Yammie from your music's signal path, its full of op amps, intergrated circuits, signal robbing volume control and so on, get something that is designed with thought given to sound quality. If you want to keep the 5.1 then get a pre with a HT bypass.

RT1

Hilbert

reeltrouble1 wrote: »

well if an EE said it..............

If you enjoy 2 channel you should eliminate that Yammie from your music's signal path, its full of op amps, intergrated circuits, signal robbing volume control and so on, get something that is designed with thought given to sound quality. If you want to keep the 5.1 then get a pre with a HT bypass.

RT1

I intend piecemeal upgrade of everything except the xpa-5. But emphasis on piecemeal; got where I am by buying everything at once which now plainly was mistake. Speakers first.

Anybody have any idea what fraction of the Yam's op amps ICs etc are operative in Pure Direct mode?

Hilbert

Googled "op amp" and found it's "basically a differential amplifier having a large voltage gain." This means very little to me except I recall

watts = volts * amps

which suggests that for fixed wattage the watts from an op amp are mostly volts and therefore inferior, less virtuous than watts from another source.

Am posting this only because I'm pleased my intuition re watts from Yamaha amp seems to be confirmed.

apphd

Hilbert wrote: »

I intend piecemeal upgrade of everything except the xpa-5. But emphasis on piecemeal; got where I am by buying everything at once which now plainly was mistake. Speakers first.

Anybody have any idea what fraction of the Yam's op amps ICs etc are operative in Pure Direct mode?

Hilbert, I'm kind of in the same boat as you. Currently in an upgrade cycle which started with an upgrade to 7 ch. from a Dennon AVR2000 Pro Logic.

I picked up a RX-V663 for the price/feature set then added an EMO LPA 1. Using Polk Mon 50's for mains until I have time to replace surrounds on my old faithfuls.:p I can't say what % of components are in use in pure direct but Yamaha says it is the most direct path and goes so far as to kill the circuit to the display except for a few seconds when a control is adjusted. In my environment I see a slight improvement to the sound IMO. Give it a try and it might hold you over until you reach the end (this time:D) of your build.

Hilbert

I've tried pure direct and like it, mostly because the single blue light which is the only thing showing on the display, is almost the same shade of blue as the lights on the XPA-5. I sense deep harmonic convergence when I see this. But I can't honestly say I hear any difference between PD, Straight, and 2 ch stereo modes, other than presence or absence of subwoofer. Maybe I don't know what to listen for.

Re upgrade cycle: pulled pin this afternoon on two LSi9s from Crutchfield. Scheduled to arrive Wednesday. WThF are my busy days so I probably wont get to hook them up till Saturday, but I'm pretty excited anyway---at last some speakers that will make the xpa5 work a little bit.

However my money-capacitor is now very near empty so this will have to tide me over for a while, like it or not.

xandra

pulled pin this afternoon on two LSi9s from Crutchfield

boy am I jealous - I'm trying to maintain the discipline to wait till LSI line is upgraded, and snarf current line while it's on fire sale. Please write of your bliss once they're burnt in so that we may enjoy vicariously.

Hilbert

xandra wrote: »

boy am I jealous - I'm trying to maintain the discipline to wait till LSI line is upgraded, and snarf current line while it's on fire sale. Please write of your bliss once they're burnt in so that we may enjoy vicariously.

Thank you that's reassuring. Am a bit nervous about this purchase b/c I've twice auditioned RTiAs and LSis, once at Fry's and once at Tweeter, and both times came away liking the RTiA7 best. But the LSis were powered by receivers, and now that I know what a difference a separate amp can make I decided to ignore my ears and go with the forum consensus.

Am hoping that when the LSis hit the remainder table I can pick up 3 more.