TV & Home Theater

[riky001]

im thinking of building my own home theater off of dif parts such as speakers,woofers,and receivers...and i have a few ?'s now does the amp have to be more than the total watage and should it be more than the peak ampage and wat does ohms have to do with it and are all speakers compatible with amps/receivers?....much appricaited

[paulmohr]

Your biggest concern will be the resistance of the speakers, the ohm rating. Most home audio systems are rated for eight ohms, car speakers are normally four ohms. Some high end home audio is six ohms. You want to make sure the speakers you use match the rating for the amplifier. The next issue will mininum wattage, you want to make sure the amp has enough power to drive the speakers you are using. Or make sure it doesn't have so much that it over drives them. You don't want to try and power big speakers with heavy magnets rated for 100 watts or more with a small amplifier rated at 30 watts peak or something. And on the side of things you don't want to try and drive small cheaper speakers rated for say 20 watts or so with a more powerful 100 watt amp or something.

If you told me what you had and what you were looking for I might be able to help you more.

Paul

[BBBob]

I think wattage is played up too much. Ohms is the impedence of the speakers and amplifier. It is important to have an amp that can run, say, between 6 to 16 ohms.  The real spec to pay attention to is one usually not published anymore unless you are into the medium or higher end amps. That would be the instantaneous amperage the amp is capable of producing. It deals with control of the drivers inside the speaker box. To give you an idea take the Onkyo or Yamaha receivers. They are high current amps and will give you alot of control over the drivers. It is relative to the higher up you go in model numbers. Like the Onkyo 507 is an entry level model with say a rating of 10 amps and the 807 model is middle of the road with a amperage rating of say 40 amps. The higher the rating the more control you will have over the drivers in the speaker box. It will result in cleaner, distortion free sound. Warmer sound, more true, without sounding like it is being pushed to max capacity all the time when you crank up the volume. Have you ever listened to a HK ( Harmon Kardon ) receiver? They are rated in less watts than any of the competitors and sound better and louder.  It is all in the design of the high current receivers. HK rated at 55 watts will sound better than a Pioneer rated at 100 watts. It will also play as loud but will have no noticable distortion. It is all in controlling the drivers. I hope I did not confuse anyone.

Bob

[paulmohr]

These receivers with the higher amp rating will also play stable into a lower impedence speaker. In reality if a speaker says its 8 ohms it really isn't 8 ohms. The resistance varies with the frequency so they are all over the place when the speaker is being used. The crossover will also effect this. Some of these higher end receivers will play stable into a 2 ohm load. The harmon kardon being one of them.

Eeach time you increase or decrease the resistance it doubles or halves the power needed to reach the same level. If you hook an 8 ohm speaker up to a 100 watt amp and turn it half way up it will draw 50 watts idealy. If you swap that speaker out for a 4 ohm speaker it will pull 100 watts instead of 50, which means your amp is working harder. If you hooked up a 16 ohm speaker it would put out 25 watts. So a speaker with less impedence will be louder than one with more, however it drives your amp harder as well.

And honestly if you have decent speakers and clean power you can run quit a bit of power into them without damaging them. Its distortion that destroys speakers. And you can under drive a speaker as well, like say drive a large speaker with a low powered amp. It just won't sound that great. The small amp won't have the current needed to drive the speaker accurately. Speakers are damped both magnetically and physically (encloser type) and if you don't have enough power to over come this dampening you will have very poor bass response.

Basically what I am trying to say is you don't want to take the speakers from one of these all in one combo home theatre systems thats rated for like 30 watts or something and try to drive them with a Denon 100 watt per channel amp. Or try to drive some large cerwin vega or Klipsch speakers with the small amplifier. It might work but its probably not going to sound real great.

In the world of amplifiers when everything is getting tiny and light I still look for something beefy. You want something with good strong terminals and something with some heft to it. Good clean power requires a good power supply and converters. When you listen to music on an amplifier it converts ac to dc, then back to ac again. A good amp is going to have some heft to it. If your looking at some little surround sound package that says its 60-100 watts a channel into 5 or 6 channels and it comes in this little box the size of a dvd player and weighs like 3-5 lbs there is no way it will perform that good. Your talking 600 watts of rms power! Something like that simply doesn't come in a small light box bundled with a dvd player.

Compare that with a harman Kardon, yamaha, denon or higher end pioneer. A 5 or 6 channel amp rated at 100 watts per channel is going to be three times the size and weigh between 10 and 20 lbs, maybe more. And these are the amps Bob is talking about that will put out the current you need for good dynamic sound. Going back to his harmon kardon example, some of them only run 40 watts, but they will drive a 4 or 6 ohm speaker, which means they can double their output with no damage. Some of these higher end amplifiers can darn near put out enough amperage to weld with (if it were DC).

If I had to pick between a 100 wat per channel amp that was in a small box and weighed a couple pounds and one that was 30 watts a channel and weighed 30 lbs I would take the larger amp hands down. Because I know it will truely push that kind of power into any speaker I hook up to it. And even though it will be less watts, it will be cleaner more stable power and sound better.

Your best bet is to tell us what you have and what you want to do with it. Then we can give you an idea of how well it work together.

[BBBob]

Like Paul and I are saying, if you get a decent receiver with decent speakers it will sound good. Most people would probably say that the speakers are the most important thing. I think a good receiver will make cheap speakers sound good. Good speakers will not sound good on a cheap receiver. It is all relative to what your ear can hear. If a HTIB sounds good to you then spending alot of money on seperates would be a watse of money. I can hear the differance between HTIB and seperates. That is why I have seperates in my house. If I want to get the sounds loud but not sound loud then I can. Crystal clear and no distortion at all. If you can hear the differance then start with a middle of the road receiver and some decent speakers. You should be able to get a receiver, front speakers, center speaker and a sub for around 800 to 1200, depending on how much you shop it. Buy one piece at a time. Decide what you want first and then add as you can afford it. If that is too much to start with a set  budget and stay within that. I think you will be surprised how much you can get and how good it will sound if you take the time to research and shop the products.

[paulmohr]

Yes I have heard some pretty nice HTIB systems as well, just don't expect a ton of power out of them. They are great for apartments, bedrooms and the like. There is really no point in buying a big powerful receiver, Klipsch floor standing speakers and a big powered subwoofer if you live in an apartment and can never turn it up.

But when mixing and matching old stuff with new stuff you do have to pay attention to what your doing to some degree. I doubt you are going to ruin anything though. Its unlikely using the wrong speakers with the wrong amp or vice versa is going to result in smoke rolling out of it or anything along those lines.

[riky001]

i asked bout ohms ands watts...no i know a lot of stuff bout computers im tech savy but not much bout this other stuff..so u were talkin bout teche stuff i didnt understand can u put it in english?

[Munatik]

What paul and Bob are saying, in a nutshell, is that you want to try to match the power of your receiver (i.e., your amplifier) to speakers that can handle what you are trying to accomplish with them.  TBH, I am myself by no means an audio guru, but the following is what I have come to understand.  

Why is matching these things important?  Because if your amplifier is underpowered for the speakers you want to use, then you may end up cranking the amplifier too high in order to get good performance from the speakers.  Doing this can cook your amp, plus the distortion can potentially ruin your speakers.   If I am not mistaken, it can actually be easier to blow your speakers this way with an underpowered amp than an overpowered one.

However, having an amp that is too powerful can also be harmful.  Most people associate too much power with the result of a blown speaker, and for correctly intuitive reasons.  Too much power can physically damage a speaker if said speaker is not built to handle it, especially when cranked to higher volumes.

How do you know if your speakers are designed to handle a great deal of power?  Ohms.  In general, the less ohms, the more power to takes to drive the speaker.  Luckily, 8 ohms is pretty standard and most speakers/receiver information will include power ratings based on 8 ohm speakers.

All of this, however, is also dependent on what your usage of your sound system will be like.  If you live in a huge house and have a huge room to put your sound system in, you're probably not going to want a puny amp tied to tiny bookshelves.  You're gonna want some umph to fill that room with good sound.

Alternatively, if you live in an apartment or otherwise have a small room you want to devote to your surround sound, then chances are you won't need to have a superbeefy monster of an amp feeding a couple of pulsing, earth-shaking skyscrapers.  Chances are you can fill that room with beautiful sound with modest amperage and fair quality speakers.

Sorry for the lack of specifics, but unfortunately, there is no definite formula for putting it all together (unless you buy a premade set of amps/speakers).   You may also need to decide between whether you want 5.1, 7.1, or even a nice set of  towers (Def Techs and Logans are superb IMO if you've got a great amp).   My advice is to post here (or ask an audiophile) some ideas that you have, starting with what receivers you are looking at.  If you are not sure where to start with receivers, I would suggest Pioneers, Onkyos, and/or Denons to start off with.

A tip for picking receivers/amps: you can often judge a good quality amp from a poorer quality one by picking it up and feeling its weight.  If I'm looking at two receivers, and I see one that totes a high amperage versus a lower one, but I feel that the lower amperage one if a lot heavier, I'm gonna think that the lower amperage one is the better amp.  Why?  Because I would trust it to be able to output cleaner, more consistent current to my speakers.  A beastly amp should feel beastly, if that makes sense.  

[paulmohr]

The easiest thing for you to do is tell us what you have, what you want to get and what you want out of it. Then we can tell you if we think it will work, sound like crap or possibly not work at all.

[bstarr1979]

Don't overthink it.  Amps, receivers, and speakers for the most part, adapt to eachother or at least are compatible.  Find out what a receiver puts out and match up some speakers than can handle it.  It's not rocket science.  Don't get an awesome heavy amp and some cheap light weight speakers.  It's all connected and you must consider the weakest link.  You would have to intentionally seek out componenents that don't match up, because manufacturers want their equipment to be relevant in order to mass market.