How to correctly match power amplifiers and passive loudspeakers

hello YouTube Bruno loose here with GLB productions thanks for joining us for this video now in April of 2015 I posted a video entitled how to connect a power amplifier to passive loudspeakers and since then I've had a whole bunch of questions from you my viewers usually along these lines the first type of question is I have these speakers what type of power amplifier do I need the other type of question is I have this power amplifier what kind of speakers do I need and so in this video I'm going to address both of these questions under the general heading of how do we mash speakers and power amplifiers in sound reinforcement context let's begin okay so let's begin with the first question I have these speakers what power amplifier should I buy now for my first example we're going to use the same speakers that we used in the earlier video and those would be the ECLA verso twelves you'll probably remember the specification sheet from that particular video so I've broken down this problem into three steps the first step is you need to determine the recommended amplifier power for your existing loudspeakers determine the recommended amplifier power for your existing speakers in order to work this out the first place that you should look is in the loudspeaker owner's manual or the datasheet in front of us we have the data sheet for the verso 12 and as you can see it gives a whole bunch of information here this particular data sheet is shared between three models the 8 10 and 12 and you can see that on the on this side here although it does have something called power rating it doesn't actually provide us with a recommended amplifier power however if we look in the preceding pages of the owner's manual we actually see that there is a section entitled recommended amplifier and it tells us that for the verso 12 you should use an amplifier between 350 and 700 watts so so far so good now the second step is to determine the impedance of the speaker in ohms determine the impedance of the speaker in owns the majority of sound reinforcement loudspeakers are eight ohms but you don't want to guess you want to make sure you know this for sure so if we go back to the specification sheet you can see here that under verso 12 it tells us that the impedance is in fact 8 ohms in fact the 8 10 and 12 are all a ohms so we know that we want a power amplifier of between 350 and 700 watts and we know that the enclosure is eight ohms impedance the third step is to look for a power amplifier that has that power rating into 8 ohms now this is really important ok most modern power amplifiers have two channels which are independent of one another and you need to look for the rating per channel into 8 ohms all right so let's say that you have these loudspeakers from ECLA and you decide to go with Eckler power amplifiers simply because they're both from the same company maybe you can get a discount or something along those lines so the next thing you should do is you should have a look at the power amplifiers from that company and make a choice based on what you have worked out so as you can see here Eckler happened to produce three power amplifiers the 500 the 1000 and the 1600 now again bear in mind we're looking for a power amplifier that delivers between 350 and 700 watts per channel into 8 ohms let's see I want a stereo okay and what that means is is a dome stereo is a way of saying power per channel into 8 ohms right you don't want 4 ohms and you don't want 8 ohms bridged Bridge is power from the amplifier in bridge mono so as you can see here the XL a 600 produces 450 watts into a ohms per channel this amplifier would be the best match because we're looking for something between 350 and 700 watts you can see the 1000 is too small it's 330 and the 500 is smaller still at 210 could I use a smaller amplifier and bridge it into that particular enclosure and the answer is yes you could conceivably use the XL a 500 and run it bridge mono into a single one of the enclosures it delivers 640 watts which is within our recommendation of 350 to 700 the problem with this is that you would need to buy one power amplifier per loudspeaker and this is not very efficient and it involves transporting more amplifiers and special types of cabling so I normally recommend that you try and get a larger power amplifier and run more speakers off of it rather than choosing a smaller one and then having to buy more power amplifiers as a result now let's say you didn't want to buy Eckler power amplifiers right let's say that you choose to go with another company and that company is crown okay so you ask your crown sales rep hey you know what what kind of amps can I use and he recommends you this which is the drive core series a very popular series of amps for portable PA so same thing you want power per channel into 8 ohms all right now crown calls it a ohm dual you can see they have 4 ohm dual 4-ohm bridged etc and you run your eye down this and you say okay I want 350 to 700 watts and you can see these two the two larger models would both be suitable alright the XL s2000 delivers 375 watts which is above 300 and the 2500 delivers 440 now between these two models you could choose either one if your budget covers it I would choose the larger of the 2 simply because it gives you more power reserve and with power amplifiers you always want more power as long as you are within the recommended amplifier specifications for your loudspeaker now let's use another set of loudspeakers as an example let's say that you have a pair of Mackie C 300 Z's alright these are the passive version of the SRM 450 they're very popular they're very widely used so you have this pair of C 300s and you need to choose a power amplifier again the first step is to determine the recommended amplifier power for that model loudspeaker you look at the c300 zi specification sheet and once again although it does have something that's entitled power handling RMS music peak and so on that doesn't appear to be a recommended power amplifier so having watched this video you know let's go and do a little bit of digging so you go into the loudspeaker manual and you find on page seven there is actually a section entitled amplifier power and within that section you find this that says we recommend that you use an amplifier that is rated at twice the continuous power rating this would be 300 watts so 600 watts per channel into 8 ohms so once again you may need to do a little bit of digging to find this information but it is almost always there at least from reputable loudspeaker manufacturers so we're now looking for a loudspeaker that delivers about 600 watts per channel into 8 ohms we go back and we look at the spec sheet for our crown series here and oh dear oh gosh even the largest amplifier here only delivers 414 to 8 ohms DME okay maybe maybe one of the hecklers will do so we go back and we look at the ECLA spec sheet here and we see to our dismay that even the largest of the hecklers the 1,600 tops out at 450 watts into 8 ohms so what are we going to do the good news is Mackie in this case of being quite conservative alright they're recommending the largest amplifier that could be safely used with these speakers let's go back to the specification sheet here now if in doubt and if the manufacturer does not provide a range of amplifier powers what you do is you need to look for this the rms power handling root mean square if amplifier manufacturers give nothing else they will almost always give an RMS rating okay if they don't give an RMS rating so you see something like music power or peak power or pmpo peak maximum power peak music power I would think twice about using those loudspeakers for sound reinforcement so if you look you'll see an RMS rating you want a power amplifier that has an output power of between rms and double the rms so in this case you want an amplifier that delivers between 300 and 600 watts okay doesn't have to be exactly 600 so you give a big sigh of relief and you go back to your specification sheet for your hecklers and you see okay I want between 300 and 600 aha the in this case the 1000 delivering 330 Watts will be suitable and the 1600 delivering 450 watts is also suitable let's look at our crowns crown drive core series in this case the top three models would all be suitable the 1500 doing 300 the 2,000 delivering 375 and the 2500 delivering 440 now once again if your budget allows it's always better to have more power so the 2500 would be the best choice I would probably not choose the 1500 simply because it's right at the bare minimum if you can avoid it you don't want an amplifier that delivers below the rms rating of your loudspeakers so now let's move on to the second question that I get a lot I have this amplifier what loudspeakers should I buy I think that after the previous two examples you should have a fairly good idea of how you answer this question basically step one is to determine the output of your amplifier per channel into a ohms not the total wattage of the amp manufacturers like to use the total wattage of the amp in their amplifier serial numbers because it makes everything look more impressive especially to men because we like things that are bigger okay so don't be fooled alright don't don't think that because my amplifier is the XLS 1000 I have a thousand watt amplifier yes you do but not per channel into 8 ohms okay which is the figure that you're interested in so let's say that we have a crown XLS amplifier and we have the 2500 okay so you want to work out what does this do per channel into 8 ohms 440 so with this figure what you want to do is you want to look for an 8 ohm loudspeaker that has a recommended amplifier power of about 440 watts okay now as we learn from the previous example some manufacturers will give a range of numbers okay so to use the verso 12 right the verso 12 350 to 700 watts so this one the 2500 would be suitable right because 440 is between 350 and 700 watts what about the C 300 we know that the C 300 C 300 we want an amplifier between 300 and 600 watts would that work yep it would okay so again determine output of your amplifier per channel into 8 ohms and then find a loudspeaker with a matching recommendation now the final question that I get when it comes to matching power amplifiers and loudspeakers is my amplifier is quote too small for my loud speaker can I still use it so the first thing is what do we mean by too small in general by too small we mean an amplifier whose output per channel is less than the rms rating of the loudspeaker in question so if we use the C 300 we know from the previous discussion that we want an amplifier that delivers between 300 and 600 watts so if the amplifier delivered less than 300 watts per channel into 8 ohms that would be too small right in other words it would be underrated for that particular loudspeaker can you still use it the answer is yes you'll still get sound ok you could use a 1 watt amplifier to drive this loudspeaker and you would still get sound is it a good idea not really because the tendency is with an underrated power amplifier you tend to push the amplifier and you tend to enter a situation that is called clipping okay clipping is where the clip light on the front of the amplifier comes on and usually the output sounds distorted visually clipping looks like this this is a normal sine wave this is a clipped sine wave basically the amplifier has reached the maximum output that it is capable of doing if you continue to increase the input signal the output level won't go any any further right but it becomes characterized by this sort of flattop squared-off waveform and if you send this type of signal to the loudspeaker you'll get Distortion and you will get overheating in the driver which will eventually result in driver failure so if you use a power amplifier that is underrated you need to be very very certain that you do not clip the input to your power amplifier in other words the clip indicator on the front panel should never never come on now what about if you clip a properly rated power amplifier if you clip a power amplifier that is rated properly it will also damage the loudspeaker however the tendency for you to do so is less because the power amplifier is bigger therefore it will give you more volume for a given input signal okay all right so I hope that this video has helped to clear up your doubts whether you have an existing power amplifier and need new speakers or an existing set of speakers and need a new power amplifier it should also help you to match speakers and power amplifiers if you have varieties of them floating around and I'm not sure which ones work together the best as always if you have questions or comments do leave them below you can also get in touch with me via YouTube messaging or on my Facebook page GLB productions so until the next video this has been Bruno Lewis with GL B productions thanks for watching and God bless you goodbye

Channel: GLB Productions

Views: 411,986

Keywords: Amplifier, Audio Power Amplifier, Sound, System, Audio Equipment, Ecler, Verso 12, Crown Amplifiers, XLS Drivecore series, Loudspeaker, ohms, impedance, power, wattage, matching, match

Id: l9L7uK7Xy0w

Length: 20min 4sec (1204 seconds)

Published: Thu Oct 08 2015