This is not a repair question, but I got flamed on the design forum and thought that I'd try here. I was labeled a kook and a troll and ... Boy, does that group have bunched up underwear!
I have three LCD tvs that work well, but the audio is thin. I know about amps and external speakers and surround sound and all of that. Please don't recommend external devices, as that is NOT what this post is about.
Is there a technology to build decent speakers into these skinny tv receivers? The industry has come up with 3-D, dynamic LED backlighting, and other nice features ... but no decent STAND ALONE SOUND.
There is a significant market for flat-panel tvs with decent stand-alone sound. Any ideas?
Well certainly the technology exists. My TV has decent sound especially the spatial. But I get some sympathetic vibration from the plastic chassis when I turn up the volume. Makes one wonder if more importance is given to the picture quality because of competition and because the trend is to mate these TVs up with external surround sound systems.
...which is a turnoff for people who want compactness, and are going to connect the set to their audio system, anyway.
Ergo, and QED, I don't think there /is/ much of a market for sets with really good sound.
My 60" KURO came with two large speakers intended to hang on the sides, but I didn't even listen to them. Instead, I attached two shoebox-sized KLH Audio 900B speakers from Best Buy, which I got for $15 the pair (due to a pricing screwup). They sound fine even on music. Unfortunately, KLH Audio is out of business.
Well good luck. If you have the resources you may wish to do a little footworks and visit some retailers and listen to the sound quality of the sets on display. I run everything via optical digital from my DVR and RF digital from my DVD to a 3.2.1 surround system. I've done this for 11 years even though my first large screen was a 51" rear projector with very good built in sound.
When you say "puny sound", what you really mean is a lack of loud, exaggerated bass. You can't get lots of bass at a high volume level cheaply.
Don't take this personally, but I really don't care. I have a decent pair of inexpensive speakers connected to the set, which provide much better sound than they have any right to. (I'm sometimes surprised at just how good it is.) And when I want to listen seriously, I have a sophisticated six-channel (plus cheap subwoofer) audiophile system. Really good sound /from the TV itself/, out of the box, is exactly what I /don't/ want, and don't want to pay for.
The audio drivers in those TVs probably cost all of $1 each in quantity, and they were probably selected for "it fits" much more than for their sound quality.
There are some fairly fundamental problems. As a rule of thumb, if you want to have loudspeakers with small total volume, decent low-frequency response, and decent efficiency... well, too bad... you can pick any two of these, but you won't get all three in a single device.
Most commercial TV-speaker designs choose small volume and good efficiency... and lose out on the low frequency response.
If you want to keep the small volume, and get better low frequency response... well, you lose out on efficiency (need a much bigger amplifier for a given SPL). You also have problems due to the small physical size of the driver... it simply can't displace enough air, when moving back and forth, to create an acceptable SPL at low frequencies, before it hits its mechanical excursion limits and begins to distort badly. Also, its voice coil is too small to dissipate much heat... push more than a very few watts into the driver to overcome the low efficiency and you'll burn up the voice coil.
One possibility might be to widen the panel by a few inches, and install multiple small drivers in a vertical line arrangement on each side... you might get enough driver area to allow for halfway-decent low frequency response. A similar widened-panel arrangement might be used with a single flat-panel driver on either side... something perhaps akin to one of Magnepan's "magneplanar" drivers.
A third possibility might be to conceal some sort of larger driver behind the panel, with a ported feed out to the side... perhaps something like a transmission-line loading or porting arrangement. This might not work for flat-on-the-wall mounting arrangements, but for articulated mounts there's probably enough space.
Quite simply, to get good low-frequency response at halfway decent efficiency and distortion levels, you need drivers with a good deal of frontal area... and you need some back space for them to work in (as a sealed enclosure, some sort of ported/vented enclosure, or enough back-wave space for a dipole-radiation arrangement that the low frequencies don't cancel out).
There are plenty of acoustic tricks one can play, to make a speaker system sound (subjectively) as if it has more low-bass response than it does (objectively), and many speaker systems do use these. A modest boost in the upper-bass "warmth" range can present an illusion of deep bass, for example.
You might find that your existing flat-panel TV systems can be made to sound halfway decent, within their physical limitations, by some careful re-equalization of the audio. You probably can't boost the low bass very far before the speakers begin to distort, but you could probably level out the frequency response and "warm it up" a bit, as long as you're willing to listen at modest volume levels.
It's even possible that some simple physical "tweaking" to the existing speaker drivers and their (miserable excuse for a real) enclosure, would clean up the sound somewhat. Sticking some damping materials on the inside of the plastic case of the TV to damp out resonances in the case, and maybe adding some wool or polyester batting to tame resonances within the enclosures, might tame the "peaky" sound a bit.
It might even be worth replacing the drivers with less-awful ones, if you can find some which fit the enclosure and mounting... probably won't help the bass much if any but they might be more pleasant to listen to.
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
No. I used to design marine radios. The problems are similar. The challenges (or more properly, the problems or nightmares):
Thin sound means no bass. To get decent bass, you need a big air space behind the speaker (bass reflex). Without the air space, you get a nasty resonance at some point in the speaker. If you like lots of boom, rattle, and buzz at some low frequency, that's fine. However, it does get irritating rather quickly. Look at the Bose folded labyrinth pretzel horn design as an example of how it can be done:
Good bass can be had with a single speaker. No need for two as the lower frequencies are not very directional. High frequency tweeters are very different. If you just aim two tweeters straight ahead, perpendicular to the LCD screen, you get great sound in front of the TV, and nothing to the sides. With perhaps a 120 degree viewing angle for the TV, it's difficult to get the same audio dispersion without using a big ugly horn or acoustic lens for the highs. Without one, you'll have wide variations in sound quality at different sitting positions. If you look inside the speakers in a typical LCD TV, you'll find that they're angled away from the perpendicular in order to cover the viewers to the sides.
Good speakers require a rather solidly built enclosure. If you're going to pump perhaps 15 watts RMS per speaker into the enclosure, it has to handle the power without falling apart, breaking solvent welds, rattling screws loose, breaking component wire bonds, or otherwise shaking the TV into premature failure. One radio I designed many years ago had only a 3 watt RMS audio amp and a single 4x6" oval speaker. In locations where the radio volume was run at full blast to overcome a high ambient noise level, there were plenty of strange mechanically induced failures. It was fascinating watching the PCB's flex at various acoustic resonances under a strobe light.
For LCD TV's, vendors are discovering that bigger isn't always better. You can sell the TV on the basis of a larger screen, but when the customer takes it home and finds that it doesn't fit in his entertainment center or whatever, there are problems. The smaller TV's may have speakers in the "ears" of the screen (on each side), but the larger TV's often opt for a less space greedy minimalist approach.
Plenty more, but I'm tired and want to give up for the evening.
One idea I had was to place the folder speaker horn behind the TV in a separate enclosure that is the same height and width as the TV. That leaves plenty of room for the labyrinth. By building the speaker into a separate enclosure, it can be mechanically isolated from the TV. At the top or sides of the enclosure are the exit points, which are directed at the listener with various bizarre shaped reflectors. I don't know if this will actually work, but it might be a tolerable way to solve the audio quality problem without resorting to a component system.
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
I read your other thread. Apparently you just want to whine about it. I agree the sound on most TVs sucks though what comes into them can be very good. I told you how I added a very simple stereo system onto the TV to make it decent and totally transparent to operate. That's the best I can do as I don't design TV sets.
There are laws of physics any speaker designer has to confront. The relationship among sensitivity, maximum output, and bass extension seems essentially unbreakable. * The smaller the cabinet, the greater the compromise required in any one of these to improve the other two. **
It is true that /drivers/ have drastically improved over the last 20 years. The muffled, boxy sound that used to come out of TVs is gone.
There's a recent design that claims to have fudged these factors, but based on what's been published, it seems to be unduly complex for the limited improvement it provides.
** One way to get around the cabinet-size problem is to stuff bags of sulfur hexafluoride in the cabinet. Only Dayton-Wright ever did this, but it really worked.
Yes. You don't have a clue about designing electronics. The last thing you want in a TV is a lot of bass to vibrate the electronics. There are already enough problems with cracked solder joints, and the sound you want would make things worse. The cases would vibrate and rattle at high volume, as well since the cases are large and thin. From an engineering standpoint it is a good way to put yourself out of business. You would need a very thick and heavy case design with damping to prevent problems. the case would be a lot larger and heavier, and could add several hundred dollars to the retail price just to please a very small percentage of customers. Go find a working '70s color console made when the cabinets were measured in cubic feet instead of today's that are measured in cubic inches. One of those eight foot wide Zenith monsters with a one inch thick slate top would do. Of course, Zenith warned you that you needed six people to move one of them.
For the last time: I am not a mad scientist, I'm just a very ticked off
This is true of the cheap LCD TVs you buy, but it doesn't have to be the case. There is no way to get good sound at appreciable volume out of an ultra-thin set. The solution is simple - larger speakers. Several Philips plasma sets took advantage of the relatively deeper chassis to incorporate sizeable speakers appropriately space to give decent sound. Sharp and other manufacturers incorporated a sound bar under the set. Obviously this adds to the cost, so it's not a solution found in the bottom of the line sets favored by some.
If you insist on using the built in speakers, perhaps enhancing what you have might be more useful. Just add a cardboard megaphone to each speaker. That will produce the equivalent of a public address speaker, which will certainly be loud.
There are different types, such as muffler exhaust ends:
oversized funnels, kids toys, police bullhorns, trucker air horns, and popcorn holders:
Methinks a pair of cheerleader horns would probably work best. Some consideration for supporting the cantilevered horn will need to be devised. I suspect a camera tripod support will suffice.
Please note that this is not a new idea:
Jeff Liebermann email@example.com
150 Felker St #D http://www.LearnByDestroying.com
Luke 6:42: Either how canst thou say to thy brother, Brother, let me pull out the mote that is in thine eye, when thou thyself beholdest not the beam that is in thine own eye? Thou hypocrite, cast out first the beam out of thine own eye, and then shalt thou see clearly to pull out the mote that is in thy brother's eye.
For the last time: I am not a mad scientist, I'm just a very ticked off