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Grex > Agora41 > #143: Home Theatre System: speaker sensitivity question |  |
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| 23 new of 47 responses total. |
other
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response 25 of 47:
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May 9 23:27 UTC 2002 |
Funny we should be having this conversation now. Today I was trying to
fix a noise problem with a some powered computer speakers and concluded
that the office they were in was just flooded with RF noise. The little
stereo mini cord by means of which the computer audio was fed to the
speakers was acting like an antenna and doing it waaay too well. I
unplugged the cord from the computer and held it up and you could clearly
hear at least a couple of radio stations playing through the speakers. I
told the person whose office it was to try wrapping the cord in aluminum
foil. Or wallpapering in it...
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jmsaul
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response 26 of 47:
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May 10 04:00 UTC 2002 |
Re #23: It's possible. I'm a knowledgeable consumer of audio, but I'm not
a technical expert. However... if you believe that the job of the
pre-amp, amp, and speakers is to accurately reproduce your source,
it makes sense to upgrade the source first.
Re #24: Linn also makes very high-end CD players. Yes, you can hear the
difference (no, I don't know why, but I've a/b'd them, and you
can).
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scott
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response 27 of 47:
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May 10 12:41 UTC 2002 |
It's relatively easy and cheap to make a good amplifier instead of a cheesy
one. Transducers are much tougher, so speakers are usually the weakest link.
Back before CDs it was speakers and turntables. Now it's pretty much just
speakers, although there's plenty of arguments going around about CD players.
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jaklumen
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response 28 of 47:
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May 10 13:44 UTC 2002 |
resp:26 how much money we talking about for these Linn CD players?
resp:27 well, how do you do that? Most A/V receivers aren't modular.
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jaklumen
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response 29 of 47:
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May 10 13:45 UTC 2002 |
whoops-- btw, scott or krj-- could you link this to the music conf,
please?
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gull
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response 30 of 47:
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May 10 13:54 UTC 2002 |
Re #25: The best trick is to wrap the cord around a ferrite rod or through a
ferrite toroid, near the end the amplifier is on. Sometimes an iron nail or
a big steel washer works, too. The idea is to create a choke coil that will
have a high impedance to RF, but will let audio pass unaffected.
Re #26: I'm a little suspicious of informal A/B tests, because they're so
susceptible to the placebo effect unless they're done "blind". (People tend
to expect the more expensive equipment to sound better, and they hear what
they want to hear.) There are also a lot of subtle tricks...like if one
player's output level is slightly higher, it will sound 'clearer' in an A/B
test.
Re #28: My understanding is that audiophiles turn up their nose at A/V
receivers in general. They aren't big fans of any of the Dolby surround
sound systems.
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scott
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response 31 of 47:
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May 10 15:25 UTC 2002 |
OK, I'll link this to the Music conf. Good idea!
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jmsaul
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response 32 of 47:
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May 10 16:42 UTC 2002 |
Re #27: That's true, and it makes sense to upgrade the weakest link in
your chain. I was assuming all elements were of equal quality,
but if not then upgrade the worst one first.
Re #28: (Price of Linn CD players) I think they have models that retail
for ~$1300, ~$2200, and ~$10000 (not a typo).
(Separating amp and pre-amp) He wasn't suggesting that you build
your own amp stage for an existing receiver, he was just saying
that at a given price point / level of quality the amp is likely
to be empirically better than the speakers, because it's cheaper
to do amps right.
Re #30: (Informal a/b tests) I'm suspicious of them for the same
reasons. I had a friend switch the equipment out, I couldn't see
which one was running, and I know he didn't mess with the volume,
but it's always possible that other factors (e.g. output level)
confused the issue. On the other hand, how else do you decide
which you like better? There really isn't an objective measure.
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bdh3
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response 33 of 47:
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May 11 05:07 UTC 2002 |
What parts of your body do you use to listen to your stereo?
(got a tin ear? then buy shitty speakers)
Thus the speakers are the most important. The problem is
good speakers will make a shitty system sound even more
shitty than shitty speakers will. (is simple physics)
Second is the 'input'. A shitty media player will obviously
render the best speakers mute point. GIGO, and the best
speakers will obviously only more accurately reflect the G.
Thirdly is the 'middle ware'. This is the last place that
you should concentrate on. (Unless you are listening to
(c)rap in what case obviously it is the first place U should
spend yer $ - GIGO again).
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keesan
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response 34 of 47:
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May 11 12:37 UTC 2002 |
Without a good antenna I cannot even receive the three radio stations that
I listen to, no matter how good the speakers.
Toroid - magnet from a hard drive or a speaker?
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other
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response 35 of 47:
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May 11 13:55 UTC 2002 |
A toroid is an object circular in shape, with a circular cross section at
any point along its circumference.
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other
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response 36 of 47:
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May 11 13:56 UTC 2002 |
(A washer is like a flattened toroid.)
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jmsaul
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response 37 of 47:
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May 11 15:08 UTC 2002 |
Re #34: That counts as part of the source.
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i
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response 38 of 47:
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May 12 04:19 UTC 2002 |
Toroid = bagel with a carefully-centered hole.
CD player technology moves fairly fast. There are probably loads of not-
the-current-model Linn CD player available much cheaper on the used market.
I've got "fancy" twisted-pair speaker cables. I got 'em when living in a
ham radio operator's house.
Good speakers: there are two different ways for a speaker to be good -
it can have good bass response, or it can do a good job with whatever
(limited) part of the audio spectrum that it does reproduce. Both kinds
of good tend to cost money and the bass kind generally means physically
larger speakers, but there are plenty of crappy speakers out there, so
don't assume that big and/or expensive guarantee you anything. Think
about what kind of good you really want *before* spending money. I've
got poor bass (dinky & ported) but pretty-good sound speakers. This is
good for life in a quiet apartment building.
A/B testing: even if your awesome hearing notices that the $10,000
stereo system sounds better than the $8,000 stereo system, aren't there
loads of other things you spend money on (car, house, vacation, eating
out, computer, etc.) where A/B testing would reveal that an extra $2,000
would get you something better?
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keesan
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response 39 of 47:
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May 12 13:49 UTC 2002 |
You can spend a lot more on speakers if you want them to sound louder, or get
smaller cheaper ones and sit near them in a small room. Some speakers are
designed to overemphasize the bass, which seems to be important to people who
want to feel the music through their feet.
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jmsaul
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response 40 of 47:
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May 12 14:03 UTC 2002 |
Re #38: (Used Linn CD players): There sure are. I've gotten all but one
piece of my Linn gear (a CD player, ironically) used. Linn's
stuff is very reliable and durable, so buying it used isn't much
of a risk. (If you're going to, though, email me first. I know
where to look and can check serial numbers too.)
(Good speakers): Personally, I'd prefer to have smaller speakers
with excellent sound reproduction and minimal bass, rather than
big speakers with tons of bass but lousy sound reproduction. You
can obviously get speakers with great reproduction and lots of
bass, but that costs more. I finally did it, because we have a
big living room. You can get something very good for $1500 or
less.
(A/B testing): Yeah, you have to do a cost-benefit analysis on
that kind of thing. ;-) Probably the most cost-effective thing
I've ever done to improve sound quality in our house was to buy
curtains for the huge window behind the couch...
Re #39: Many speakers, including the majority of floor-standing speakers
you'll see in appliance stores, etc., are designed to overemphasize
the bass. It's cheaper to do that, and since the people who buy
them have crappy sources, it also helps hide that. Smaller speakers
aren't necessarily cheaper, though; there are some excellent small
speakers out there that simply reproduce the upper and mid range
very, very well. Price doesn't necessarily corrrelate with either
quality or loudness.
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keesan
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response 41 of 47:
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May 12 14:08 UTC 2002 |
Good speakers have a level response curve (they don't have peaks or valleys
at certain frequencies). It is probably more expensive to get the curve level
at higher volumes so you can get cheaper speakers that sound just as good if
they don't have to play as loudly. Consumer Reports published one review
showing all the curves, and they suggested adjusting the speakers to give less
bass for many models, if you wanted the music to sound more realistic instead
of more bassy. You can also adjust the receiver for more or less bass.
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eprom
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response 42 of 47:
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May 13 00:07 UTC 2002 |
I'm thinking about testing the whole system out. Tell me if this
sounds right.
1) Connect a sine-sweep generator to one of the audio inputs.
2) Set the (audio input) freq of the sine generator to 1KHz (reference
tone) at 1 Vpp (audio input) and adjust the speaker volume (output)
to say 60dB.
3) Take a SPL reading of the room without audio (noise floor).
4) Set the sine generator to sweep from 20 Hz to 30 KHz and take readings
on the SPL meter at various freqs?
The only thing i'm not sure of is the SPL meter, which seems a tad
subjective (such as where it's placed in the room).
I have access to a oscilloscope but how would I go about getting a way to
measure the audio from the speakers?
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i
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response 43 of 47:
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May 13 00:59 UTC 2002 |
Ironic? Since CD technology moves the fastest, it would be the reasonable
thing to get new in a all-but-one-piece-is-used system.
As keesan & jmsaul start to say, there are loads of things beyond generic
"bass response" and "sound quality" to picking speakers. (The same is
true of other stereo piece-parts to a somewhat lesser degree.) There is
no substitute for having someone who's familiar with both the products and
your *real* wants help you select parts for your system. Very-high-
efficiency speakers plus a huge amp are a money-wasting combination (well,
unless your goal is blowing out the windows); ditto low-efficiency speakers
and a nice low-power amp. A CD player & speakers which are both a bit
heavy on the tweeter end of the spectrum sound great in a room that eats
high frequencies, but crappy in another room. And so on....
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scott
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response 44 of 47:
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May 13 01:54 UTC 2002 |
Re 42: The problem with getting the signal into your oscilloscope is finding
an accurate-enough microphone. You might call around to audio places (and
car audio places) and see if they will rent you a spectrum analysis rig.
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jaklumen
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response 45 of 47:
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May 13 02:05 UTC 2002 |
oh, amen, brother.. acoustics of a room are a *big* deal, and it's
generally a good idea to consider them when you're really serious
about sound quality.
My understanding of bass is the speakers generally need a lot of air
for the frequencies to move, or something like that. More often than
not, that means relatively large speakers, and a fairly large
enclosure. I remember reading a Sound & Vision article where the
author strove for massive dB levels using 18" speakers with a
downstairs basement as an enclosure. To move all that air, you also
need some oomph behind it, which makes me doubt crappy sources.
Subwoofer speakers alone take up about 75% of your total power in a
system, and this is generally why powered (active) subs vs. passive
ones are popular.
My experience has been that vented ports are sometimes a good solution
for midbass, but I haven't seen many subs that soar down to 13-20 Hz
with one. They just can't produce enough sound pressure. But ports
can be wonderfully designed to allow for smaller bass speakers; hence
your "bass reflex" design, and the coiled tube design that is a part
of the Bose Wave radios.
Passive radiators also tend to help with bass sound. I'm not
completely sure how they work, but I know that they are generally
tuned to a particular frequency.. whatever low frequency you want
emphasized, which is usually 40, 33, or 20 Hz.
As far as bass and acoustics, well, they are important, too. Simply
putting a sub in a corner will generally emphasize lower frequencies,
as drywall needs to absorb frequencies above 40 Hz or so. Many people
have carpets in the room, but some have hard wood floors, so bass
reverb can be a problem in the latter case.
There are some subspeakers available that can be mounted in the floor
joists, or even inside furniture, but I think most people go with the
separate floor speaker type that was designed by Infinity in the 1960s.
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gull
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response 46 of 47:
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May 13 15:58 UTC 2002 |
Re #41: It depends too on what kind of music you're listening to. If you
listen to rock and you're trying to duplicate a concert sound, well, most
concert sounds systems are fairly bass heavy. Likewise, pipe organ music
often contains a lot of deep bass.
Of course, these days a lot of people go for obviously unrealistic levels of
bass just because they like to make stuff rattle, and that's obviously
rubbing off on the manufacturers of stereo equipment.
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jazz
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response 47 of 47:
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May 14 22:43 UTC 2002 |
Middleware can make some very noticeable differences if, for instance,
you switch to middleware that more easily supports Dolby Digital Surround
Sound. Some features really are worth investing in.
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