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4.158.0.123
In Reply to: What is a reasonable frequency response to shoot for? posted by Russ57 on February 15, 2007 at 06:16:55:
RussYou're not really flipping out over 3 dB dips and peaks are you? If so, a bad case of Audiophile Nervosa is diagnosed. Start your treatment by reading J. Gordon Holt's article: "Space...the Final Frontier" from the 3/94 issue of Stereophile. You can almost hear JGH yelling "Iceberg ahead, it's shaped like a giant TV!". The S.S. Stereophile did hit the iceberg, but it did'nt sink. Giant chainsaws were procured from the hold, and big chunks of ice were cut off and stored in the leaking compartments. Ice floats you know. They shoveled more money into the boilers and off she sailed, a little lower in the waterline. Warning: Don't read the next paragraph here untill you finish the article.
Now let's take a look at the receiving end of an ideal pair of perfectly flat speakers: the human ear. Let's subject it to the scrutiny we would apply to a piece of audio equipt. Look at the freq. response: http://members.aol.com/sbench/fm.gif. Turn the graph upside down. At low levels the bass rolls off at 700 Hz at more than 10 dB per octave, with the highs down nearly 10 dB at 10K Hz. There's an 8 dB peak centering around 3500 Hz that increases to over 10 dB at higher levels. The device only has it's most linear region at 100 dB, and some experts will tell you that operating it at this level for extended periods will damage it. This begs the test question: can you fix all this with digital EQ on your ideal flat speakers? I dunno.
Paul
Follow Ups:
please pardon my behavior Rev. Paulif circumstances permitted maybe a was of money, a nice whore, bottles of booze, good cigars and a long visits to beaches might be better than squinting at RTA and graphs?
Freddy
FreddyA man in your position should have it all. You can take a laptop with RTA ware to the beach, pack some H. Upman Especiales and a cooler full of Pilsner Urquel. If your companion lacks interest in the RTA graphs, try bribing her with the promise of a nice dinner later. Works for me!
Paul
P.S. Cool it with the Rev. stuff. There is rampant prejudice towards audio polygamy lurking.
Hi Paul:H Upman especiales!!! Brings back memories....as a kid my father used to take me hunting with the owner of that company...Nice guy with sun sensitive skin (discoid lupus). He was totally cleaned out by Fidel in Cuba. The military first took his 57 T bird then his Mercedes (me and the hunting dogs used to ride the backseat). My father ended up buying him a junkie car so they would not take it too. I am traveling now but have residence in Miami too.
ArtemiusPerhaps you can put a word in for me with the Upmans. If they would bring back the Director Royale (not seen for over 10 years), I would happily sit on a beach with Ann Coulter herself and keep my yap shut, with just that Royale in it. The best cigar ever! Just my opinion.
Paul
so easy enough to do the cuban cigars and the visit to the beach:) Still need the laptop with RTA and my tastes lean more towards Bass and Guinness.Perhaps I worded my question poorly? I am taking it for granted that most will measure and listen a number of times before they consider a speaker "finished". All I am trying to do is get a handle on how well the speakers should measure. From there, if someone wants to go into how to measure and what to use that would be great.
I have seen the measured stuff in the reviews and such. But I build tube amps and can easily better commercial amp specs simply because my goal isn't to get the most watts for the least bucks. I was hoping the same might be true with speakers. Namely that if I am not trying to get 20-20khz out of a 2-way with a 6" woofer I should be able to get a better looking graph and hopefully better sounding speakers.
I am worried about Berenek's law. Simply put, I don't trust my ears when it comes to speakers. I don't know what to listen for and how to relate the sound to changes that need to be made. So all I can do is lay my cards on the table and ask for advice of how to proceed.
If it matters I have the xt1086 with nd1090 (from 18sound) with audax pr170mo on an open baffle. Bass is, for the moment, 12" in a bass reflex (borrowed stuff so this will be changed). Crossover at 250 and 1,800. Room is all concrete and plaster, so call it lively.
Russ
RussIt helps to listen to a lot of stuff, and then you will begin to trust your ears more, after all they will be the final arbiter as Olson once said. I've been to quite a few hi-fi shows, and one thing that amazes me is how bad some of the stuff sounds. Sometimes things on the recommended component list too. You hear complaints about the lousy sound in the hotel rooms and even low voltage at the wall etc, but everybody's got these factors to deal with at the shows to one degree or another. Sometimes there's something obviously wrong with the electronics, and the demo guy has to brave it through. I always feel sorry for the guy. Sometimes the salesman is oblivious to how bad the system sounds and just proceeds to practice his craft anyway, with the Emperor's New Sound approach The measurements have to proceed to some aesthetic end, or they are just measurement for measurement's sake. Sometimes you can change something, and the result just sounds different, not necessarily better. In this case, measurements can help point you in the right direction. But notice the disagreement between JGH in the Stereophile article and John Atkinson. It came down to a point of aesthetic procedure. We can add JGH to list of American enterpreneurs who started a company, got burrned out and sold it, and came back into the business later. JGH now writes for the Absolute Sound. The best advice is to not get too hung up on the measurements, they're just a means to an end and not an end in themselves. This is a hard learned lesson from the THD amp wars, when the amps became so "perfect" that their flaws were considered inaudible. The imperfect human ear won in the end, but it looked like it was going the other way in the 80's. You should proceed by trying to identify what you don't like about your rig using measurments to focus in, and to then formulate a strategy for addressing this. Some solutions will work, many will not. It's a struggle, but fun too. There is a certain pleasure in a nice freq. response graph, but you won't be coming back to it aagain and again like your favorite piece of music.
Paul
P.S. Did you get the roof on the hospital? I coulda blue-tarped it right away ; )
Funny you should ask now:) They ended up torching down some stuff in a small section and recoating everything. We have to let it cure for 60 days and they put some granulated crap on it. The basic roof was sound, just hurricane scrubbed of gravel, so I guess it will be okay.With the speaker stuff...I guess I am just frustrated/overwhelmed. With an amp I can hear things and know what to do....a coupling cap here, a tube there. With the speakers....well I don't know how things interact yet. So it is not trusting my ears so much as not knowing what common speaker problems sound like and the solution.
But the bright news is I feel, and friends agree, that what I have managed so far is a lot better than the commercial stuff I could afford. But now I want to get a little more serious and incorporate measuring....and down the road modeling software. Economically it makes the most sense for me as I simply can't afford to buy a bunch of drivers (and especially crossover parts) and build a bunch of speakers.
But maybe that is flawed thinking and I'd be better served to simply follow some proven designs?
Russ
RussYou're on the correct path. The roof coulda turned out lots worse, I could tell you some Chicago roofing stories! And your audio path is illuminated by a dark lantern. A basic speaker test rig does not need to be expensive. John Sheerin recomended a PC RTA freeware program recently, and he uses the ubiquitous Panasonic mic capsule. I use the Mitey Mic variant of this test mic availble from audioxpress, along with the VU meter in a Teac R2R tape deck and some graph paper along with the warble test tones on the Stereophile Test Disc. Test the drivers up close, and compare these measurements with those at the listening position to get a handle on what the room is adding. Problem areas should be obvious. Just don't try to solve room issues with speaker solutions and vice versa. You're on the right path, and have a good handle on the situation with your amp experience. Kurt's your man for OB. He put together several awsome ones! One was a Fostex driver on a cardboard baffle with Kurt's own sub. This rig could have easily mopped the floor with a Spendor rig (over $1000 a pair with sub) I heard at an audiophile salon. His 8 X 18's and ribbons rig was amazing too. So don't forget, this is supposed to be fun!
Paul
ok - no more revs - I still think church of Olsonology is good vs the crutch of nothingology
FreddyThat vision of you on the beach lingered a bit in my mind. It drifted to a White Owl and a case of Lone Star (sorry), but here's the good part, I saw Daisy Mae Duke sit'n next to ya! The vision started oscillating between Cathy Bach and Jessica Simpson (could'nt tune in both) and to stop the oscillations I tried to focus on the Fletcher Munson curves from the Steve Bench link, but there she was again! Take a look at it, at 120 dB Daisy is laying flat on the beach, at 0 dB down she's really arching her back. Her feet are cut off in the graph, but check the link for comparison which is also footless. It's a great numonic to remember the frequencies of the F.M. curves.
Forward for science!
Paul
Some of my best friends are nothingologists!
those are interestinghere's a still that looks right for the beach
FreddyThe bass cuts off on the left chanel, but nice stereo pair midrange, nice high extension too. I'd like to see Aki polishing some Japanese heavy iron, an Ongoku say, to see how she stacks up against Jessica for Fletcher-Munson Girl of the Month.
Dynamical Analogous Circuits and beyond!
Paul
Paul - perhaps some might think those lower extremities "lean" and lower mids pinched & threadbare, but putting all into perspeotive, everything seems well balanced, no superfluous features, a voluminous & happy chest tone reproduction plus ultra-pretty technicolor top - - -might all this go with GOTO or Feastrex?would Olson approve?
Freddy
I dunno FreddyThe static Aki representation makes it hard to establish parity with the dynamical format representing Jessica/Daisy. I see high compliance and low Q in the amount of energy being released. We need to establish Qms and Qes to put together a Qts on Aki. Invite her to FreddyiLab for tests!
Paul
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