So you wanna be a karaoke host? (Part 8: Watts and RMS and Ohms, oh my!)

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Matching amp and speakers
Years ago, when I was working my way through college working for Radio Shack, we made sure that the power handling capability of the speakers was bigger than the power output of the amp. This makes sense, right? Clearly if you feed 1000W into a tiny little 25W speaker, you will do some damage to the poor little speaker.

When I recently talked with Bob (my favorite sound guy), I got a totally different story. He told me that the important thing is that you make sure the amp is big enough to drive the speakers. Ideally, you want the amp to be able to deliver twice the power that the speakers are rated for.

This blew my mind. If I have speakers that will handle 250W, then I want to drive them with an that will amp will deliver at least 500W?

The folks at Musician's Friend agree with Bob. I quote from their PA System Buying Guide:

Make sure to buy an amp with plenty of power for your speakers plus enough headroom. Many speakers are damaged by getting too little power, causing clipped waveforms that will ruin your gear. You will probably want an amp with twice the wattage of your speaker's rated power handling to ensure clean power gets to them.

The buying guide is not clear on which watts are what. You have an amp, and it has wattage ratings in peak and RMS and it lists wattage for 8 ohms and 4 ohms and maybe two ohms. You have a speaker and it has peak and program and continuous and RMS... How to figger it all out?!?!?

Step 1: Determine the ohms for the speakers and how many speakers you will be plugging into one channel. Generally speaker, you will have one speaker per channel - one in the right channel and one in the left. And generally speaking, the speakers will be 8 ohms. But, just in case you have two speakers plugged into one channel, or just in case they are four ohm speakers, you need to figger out the ohms for the speaker combination. In case you forgot, I mentioned how to do this in the post on amps, under the heading "Ohms".

- Will your amp handle the ohms?  If your amp is only rated for 8 ohm speakers, then you can't plug in a pair of 8 ohm speakers, dude.

Step 2: Determine the RMS power rating of your speakers. I gave a very simple way to convert any of the plethora of speaker specs into RMS in the previous post on speakers:

If there is a spec for peak power, divide by four to get RMS power.
If there is a spec for program power, divide by two to get RMS power.
If there is a spec for continuous power, then multiply it by 1. Or divide by 1. Or add zero. The RMS power handling is the same as the continuous power handling.

Step 3: Find the RMS power per channel for the amp, using the ohms that you determined in step 1. The amp probably list different ohm values, 8, maybe 4, and maybe maybe 2. Pick the watts for that particular ohmage. If they happen to list a maximum power or a peak to peak power, ignore that inflated number.

Step 4: Compare the rating for the amp (from step 3) with the power handling for the speakers (from step 2). Ideally, the ratio will be 2.0. That is, the watts for the amp will be twice the watts for the speakers. Don't get anal about this... there is some leeway. To get a feel for how much leeway, let's look at some systems that were put together by the pros.

I turned to the Musician's Friend website and started looking for live sound systems. The first thing I found was an interesting tidbit. All their systems fell into one of two categories. Either the system included a powered mixer and passive speakers, or it included a mixer and a pair of active speakers. There were no systems that they offered that was all components, that is, an unpowered mixer, an amp, and passive speakers.

Hmmmm... that makes sense. I guess? Having all components, you are of course more flexible. But combining one way or the other means less stuff to carry around. For a KJ, this is important.

Musician's Friend had a long long list of systems to pick from. I picked three of these to compare. All were around the $700 mark.I picked different brands to keep it interesting. I also just looked at systems with a powered mixer and a set of passive speakers. I chose this not because I am partial to that type of system (I am, by the way, but only slightly). I chose this type because you need to match amp and speakers with this type of system. If the amp and speaker are in the same box, the matching has already been done for you. 

The Phonic system

The Phonic system includes their Powerpod 1860 Plus powered mixer, coupled with the Phonic S715 speakers.

Step 1:  The speakers are 8 ohms. We will plug one speaker into each channel of the amp, so each channel of the amp will see 8 ohms. The amp has a rating for 8 ohm operation, so we are cool.

Step 2: The speakers have the following power handing: Power handling: 600W (Peak), 400 W (Program), 200W (RMS). Which spec do we want? Yes, of course, the last one, the RMS power handling of 200W.

Step 3: The amp has the following ratings:

260W per side at 8 ohms
400W per side at 4 ohms
800W bridged mono

We first note that the amp does say "per side", so they aren't pulling anything funny like combining the power from both sides. Since we determined that our speakers are 8 ohms, we choose the 260W number. Note also that they did not specify whether these are peak watts or RMS, so we will assume that the numbers are RMS. If we were actually buying this piece of equipment, we might want to take a close look at the manual to verify this.

Step 4: Compare the two numbers. The output of the amp (260W) divided by the rating of the speakers (200W) is 1.3.

So, is this good? My opinion, the speakers are perhaps a bit underpowered, but nothing to really be concerned about.

If I am figgering how big a crowd I could handle, I would use the wattage of the amp (260W). Since the amp has two channels (right and left) I would multiply this number by 2 to get 520W. In the section on amps, I used the conservative number of 10 watts per person. Based on all this calculation, this system should be ok with crowds of 52. Get that 53rd person in and you need to run out for another bucket of watts.

Well, no... I'm just kidding. You can go ahead and have 53 people.

The Behringer system

The Behringer system includes the PMP1000 powered mixer and a pair of VP1220 speakers.

Step 1:  The speakers are 8 ohms. We will plug one speaker into each channel of the amp, so each channel of the amp will see 8 ohms. The amp has a rating for 8 ohm operation, so we are cool.(Gosh that sounds familiar.)

Step 2: The speakers are referred to as Behringer EUROLIVE VP1220 800W 12" PA Speaker, so they must be 800W, right? Tricky folks. You have to read further down to get the spec that we want: 200 Watts Continuous / 800 Watts Peak Power. Continuous power is the same as RMS power, so we will go withe the 200W number.

Step 3: The amp has the following spec: Ultra-compact 2 x 250-Watt stereo powered mixer (500 Watt bridged mode). I'm gonna call this a non-spec, since they don't tell you whether the spec is for driving 8 ohm speakers or 4 ohm or what. You would think that maybe, since this is all sold as a system, that they would pick the spec that is relevant to the set of speakers that are in the system?

But, no. They make you work a little to get at the number that is really important. When I click on the "Spec" tab, I find all kinds of numbers. In particular, the 250W is clearly much larger than the number we want. First, 250W is peak power, not RMS. Second (I reach for my blood pressure medication), this number is the power when driving 4 ohm speakers. 

Peak Power, both channels driven:
8 Ohms per channel: 135W
4 Ohms per channel: 250W

The relevant number is considerably less impressive: 8 Ohms per channel: 90W.

Step 4: Compare the two numbers. The output of the amp (90W) divided by the rating of the speakers (200W) is 0.45.

Ouch. The speakers are pretty seriously underpowered. Remember, this number is ideally around 2.0. I'm not gonna recommend this powered mixer with these speakers.

But, let's say you decided to go with this system. How big a crowd could you handle? Each channel is 90W, so the total wattage is 180W. Figgering 10W per person, I put the crowd size at 18. Maybe 20? Definitely a small gig.

The Yamaha system
Finally, let's do a little spec check on a Yamaha system, which pairs the Yamaha EMX212S powered mixer with a pair of Yamaha A12 speakers.

Step 1:  The speakers are 8 ohms. We will plug one speaker into each channel of the amp, so each channel of the amp will see 8 ohms. The amp has a rating for 8 ohm operation, so we are cool. (Gosh that sounds familiar. Most speakers are 8 ohms.)

Step 2:  We have the following spec for the power rating on the speakers: 300W program handling (600W peak). Hmmmm.... program handling is twice the RMS rating, so the number we want is 150W.

Step 3: The amp is rated rather sparsely: Dual 200W amps. We need to dig further, since we have learned the the numbers at the front are not necessarily the ones we want. Unfortunately, Musician's Friend does not have the spec that we want.

To get that spec, I had to go to the Yamaha website. On this page we see the important number 130W+130W, which means 130W in one channel and 130W in the other.

Step 4: Compare the two numbers. The output of the amp (130W) divided by the rating of the speakers (150W) is 0.87.

Gosh. This is better than the Behringer system, but it still falls short of the magic value of 2.0. If I were considering this system, I think I would lean toward using the Yamaha EMX312C powered mixer instead of the EMX212C. This amp is rated at 190W per channel, which is a little better suited to the speakers. But... it costs $110 more.

Let's say we bought this system. How big a crowd could we host? We have 130W per channel from the amp, so the total power is 260W. When we divide this by 10W person, we get a maximum crowd of 26 people.

I have looked at three systems. Of the three, the Phonic system comes off the best in terms of matching amps with speakers and in terms of total wattage output. (Time for the weasel words) These specs are only part of the story. I have equipment from all three manufacturers and I tend to think of the Phonic equipment as the best value for a low end system, and the Yamaha as the better value for a slightly higher end system.

Copyright (c) 2010, John Seymour

So you wanna be a karaoke host? ( Part 7: Speakers - getting those karaoke vibrations going)

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As a karaoke jockey, you are much more likely to get a two-way than a three-way. Maybe at home, you may have a three-way, but you probably have a two-way at your gigs.

I am talking, of course, about speakers. Specifically, the number of speakers per cabinet. A two-way speaker has a woofer (for the low notes) and a tweeter (for the high notes) in a single cabinet. A three-way speaker will add a midrange speaker to this. Almost all PA equipment will have a woofer and a tweeter in a single cabinet.

Woofer and tweeter

Active versus passive
In a previous section, I described various ways that the pieces of a karaoke system are combined. In particular, I spoke about integrating the amp into the speaker to form an active speaker, which is also known as a powered speaker. The standard speaker (with no internal amp) is referred to as a passive or unpowered speaker.

My examples in this section are largely aimed at the unpowered speakers, although most of the concepts apply whether there is an amplifier in the speaker cabinet or not. 

What do you get with a bigger woofer?
The bigger the woofer, the better the bass. To give an idea how this works, let's look at a series of speakers from Phonic. These low end speakers are sold in a 10", 12", and 15" versions. You can see in the table below that the 10" speaker goes down to 65 Hz, the 12" goes down to 60 Hz, and the 15" goes down to 50 Hz.

Phonic S710         10"    65 Hz to 20 kHz      $70 each
Phonic S712         12"    60 Hz to 20 hHz     $100 each
Phonic S715         15"    50 Hz to 20 kHz     $150 each

Unfortunately, the size of the woofer is really what dictates bass response, and ultimately, the size of the woofer drives the cost, the size, and the weight of a speaker. If you want a good thump coming out of your system, the speakers will be big, heavy, and expensive.

But my earbuds have excellent bass response, and they aren't anywhere near 15". What's up with that?

The difference has to do with the fact that bass notes just don't travel that well. If you put a tiny speaker (as in  earbuds) very close to your ear, the bass will be much louder than when you pull the earbuds away from your ear. If you hold the earbuds even a few inches from your ear, the sound becomes very tinny. 

Watts - peak, program, continuous, RMS
The wattage ratings on speakers are probably the most confusing and most abused spec.

The power handling spec is the number of watts that are safe for a speaker. It indicatives how much power you can pump through the speaker before you start damaging it.

Note that this is different than the wattage ratings that we put on light bulbs. If I compare a 60W bulb with a 100W bulb, I will see a change in brightness. If I replace a 60W speaker with a 600W speaker, there will not be a big increase in volume. But there will be a big difference in how loud I can turn the amp before the speakers self destruct.

Wattage for a speaker could be reported as "peak", "program", "continuous", or "RMS" wattage. How confusing.  The "peak" power handling is the highest of the numbers, indicating the hypothetical level of a quick "pop" that could blow out the speaker. "Program" power is generally about half of that number, and "continuous" or "RMS" numbers are generally half of that number.

So... if you want to compare the power handling of two speakers, you need to first make sure that the numbers are expressed in the same units. I'm not sure any of the units are better than any others, so I will just say that I am going to work with "continuous power".

If there is a spec for peak power, divide by four to get RMS power.
If there is a spec for program power, divide by two to get RMS power.
If there is a spec for continuous power, then multiply it by 1. Or divide by 1. Or add zero. The RMS power handling is the same as the continuous power handling.

Sound pressure level
I said that a higher wattage rating on a speaker doesn't necessarily make the speaker louder. It's not just the watts, but also what the speaker does with them. The "SPL" (sound pressure level) is a measure of how efficiently a speaker deals with those watts. The speaker is hooked up to an amp delivering a standard amount of power. A sound level is measured at a standard distance from the speaker. The result is called the SPL.

The SPL of a speaker is measured in dB, with typical numbers in the high 90's. SPL ratings can be a bit deceptive. The range for the SPL might be only a few dB, but a difference of 3 dB represents a doubling of the amount of sound. 

What the specs don't tell you
Power handling is only part of the story. Sometimes loud is all you really want. Like if you are trying to scare squirrels out of your attic. But usually, you want good and loud. Just because 100W does not damage a speaker, it doesn't mean that it sounds good. Unfortunately, there isn't a spec for how good a speaker sounds. Sorry.

I have gone through the immense trouble to compile a list of specs on a number of 12 inch speakers.

    Speaker                Freq. resp        Power hand.       SPL      Wt      Cost

Gemini GSM-1260  50 Hz-20 kHz     100W RMS       ??        24  lbs     $70
Phonic S712            60 Hz-20 kHz       75W RMS      95 dB    ?? lbs    $100
Behringer 212XL     65 Hz-18 kHz     200W RMS      95 dB    24 lbs    $150
Peavey PR 12          54 Hz-21 kHz     200W RMS      97 dB    33 lbs    $170
Yamaha BR12         65 Hz-20 kHz     125W RMS       97 dB    35 lbs    $250
JBL JRX112M        60 Hz-16 kHz     250W RMS       99 dB    43 lbs    $320

What to conclude?  It would seem from the specs listed that the Gemini speaker at $70 is just about the equivalent to the Yamaha at nearly four times the cost. Like I said, unfortunately, there isn't a spec for how good a speaker sounds. 

Copyright (c) 2010, John Seymour

So you wanna be a karaoke host? ( Part 6: Karaoke system amp)

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There is a big question when putting a karaoke system together. How big? How many watts do you need?

Naturally size matters. Especially if you are a guy. More horsepower... more terabytes in your iPod... more watts in your karaoke system. All that stuff. I think it's part of the natural selection process. Male peacocks with the biggest tail feathers are the most successful at attracting mates, and so it is with KJs and watts.

But how much do you really need?

Bad news
The bad news is that watts are expensive and that you probably need a lot of them.

In an earlier post on how bands got their names, I reported that Deep Purple once held the Guinness record for the loudest band. The record is currently held by KISS, with a performance that reached 136 decibels. For reference, hearing damage starts at around 120 decibels, and the "threshold of pain" is above 130. Unfortunately, I have not been able to find a reference to that wattage for that concert.

Just how expensive is an amp?  The chart below is a plot of dollars per watt for a series of amps that I trust from an online vendor that I trust. As a rule of thumb, divide the wattage in half and add thirty. If you figure you need 500W, then the amp will cost about $280. I made this chart, by the way. Did I mention that I am a mathematician?

 
In future generations, this rule of thumb will become known as Seymour's Rule of Amp Pricing. In future generations, this rule of thumb will be obsoleted by inflation, and eventually, by technology. This is in accordance of Seymour's Rule of the Obsolescence of Rules.

Enthusiasts of the history of science will recognize a similarity of this rule to Stigler's law of eponymy, which states that "No scientific discovery is named after its original discoverer." This law was first discovered by Robert Merton, so naturally, it was named after Stigler.

Enough digression. Here is an important corollary of Seymour's Rule of Amp Pricing. It is more cost effective to buy a single amp with twice the power than it is to buy two amps.

For example, the Crown XLS 202D sells for $200 and generates 300 watts. I could get 600 watts if I buy two of them, and it would cost me $400. Alternately, I could buy the Crown XLS 602D, which is rated at 600 watts, and it would cost me $300. Not only is the bigger amp cheaper, but it is less total weight and less to schlep around.


Watts and specs
Before we talk about how many watts a KJ needs, we need to set some ground rules about specing of amps. The problem is, it is confusing.

First, there is the issue of the units that one uses. Some manufacturers spec out their amps in terms of watts peak-to-peak and some use watts RMS. Peak to peak numbers are given when a manufacturer wants to artificially inflate their specs, since peak-to-peak numbers are almost six times as large as RMS numbers.

Another very helpful way that a manufacturer can confuse a prospective KJ is to speak in terms of total power rather than watts per channel. Another bad thing. Well... it's actually not all that terrible. If an amp has two channels (i.e. stereo), you just add the watts RMS. Just be careful when reading the specs.

The next confusing thing is exemplified in a spec on the Crown XLS 202D: "330W/ch @ 2 ohms, 300W/ch @ 4 ohms, 200W/ch @ 8 ohms, 660W bridged mono @ 4 ohms, 600W bridged mono @ 8 ohms." Depending on which number you look at, the amp could be rated at anywhere from 200 watts per channel to 660 watts per channel.

Isn't this deceptive advertising? Actually, not at all. The specs merely reflect the power output that you get with different configurations of speakers. You just have to know a bit about your speakers in order to properly read the specs. In particular, you need to know a bit about ohms.

Ohms
To clarify right off... I am not talking about the kind of oms involved in transcendental meditation.

Speakers are generally described in terms of their resistance, which is measured in ohms. What does that mean?  Well, I could explain it, but the simple explanation requires some explanation of electronics, and the correct explanation says that ohms are actually meaningless when you talk about speakers.

So, let's just say that a typical speaker is 8 ohms and forget the details. Generally speaking, if the speaker has one woofer, it will be 8 ohms. Not always, but usually. If you plug one speaker into each channel of the amp, then the spec from the amp that is relevant is the "watts per channel at 8 ohms" number. In the case of the Crown amplifier, this relevant number is 200W.

With this particular Crown amp (and with most decent amps, for that matter) you can plug two 8 ohm speakers into each channel without blowing up the amp. How can you tell if an amp will blow up with two sets of speakers?

When you plug two speakers in, the resistance (that is, the ohms) of the speakers gets cut in half. If you plug two 8 ohm speakers into each channel, the load for each channel becomes 4 ohms. And now the applicable spec on the amplifier is "300W/ch @ 4 ohms". Just by virtue of the fact that the amp has a power rating for 4 ohms, you know that you can plug in two 8 ohm speakers.

So... hmmmm.... we doubled the number of speakers and the power went from 200 watts per channel up to 300 watts per channel?  That doesn't seem fair! We didn't get twice the power.  :(

I agree that it's not fair, but it's reality. There is a certain amount of inefficiency when you plug two speakers into the same channel. And this leads to another important point: It is more cost effective to run a single set of speakers per channel.

These important points lead in the same direction. Buy a bigger amp, dude, and use a single set of speakers.

That said, I am going to make a case for plugging in multiple sets of speakers. You probably have noticed this, but the closer you get to a speaker, the louder it is. If I have one speaker, and try tomake it loud enough on the opposite side of the room, it will necessarily be too loud near the speaker. If I add a second speaker, with proper spacing, the overall sound levels are more consistent around the room. Each set of speakers that I scatter throughout the room makes the sound level more even.

In a larger room, I will run with two sets of speakers to get this evenness.

Caveats
For the more technically adept: I need to clear some stuff up. I have made a whole bunch of simplifications in describing this stuff above.

When I talked about the resistance for speakers plugged into the same channel, I was assuming that the speakers had the same resistance. The formula is more complicated if the speakers have different resistances.

Another simplification is thatI have assumed that the speakers are combined in parallel, rather than in series. If you go out of your way with a soldering iron you could combine speakers in series. But, if you use standard plugs and cables in the way they were intended, your speakers will be in parallel.

The third simplification was in my discussion of using multiple sets of speakers. I neglected to say that if the listening areas of the speakers overlap, you will get dead spots from phase cancellation. Analyzing this is very complicated. Don't go crazy with it.

Yet another simplification was that I completely avoided talking about the bridged mono mode for an amp. Let's agree to ignore this. Well... unless you get a passive subwoofer. Then I recommend bringing in a sound pro just to make sure.


How many watts do I need?
Boy... good question.

"It all depends" is a good answer, although probably not all that useful. But of course wattage requirements do depend on a lot of things. I should be honest, though. The real reason I say "depends" is to avoid having to accept any responsibility for my actions.

The first big question to ask is whether you want to do outdoor gigs. If a gig is outdoor, the PA is going to be a lot less efficient. A lot. I mean, a lot. There is nothing to contain the sound, so it will just get lost. Most importantly, the bass will get lost. My opinion... if you are playing a gig outside, you should look into adding a subwoofer. You only need one because the stereo effect is less pronounced at low frequencies. But you do need one.

Another important variable is the efficiency of the speakers. I will discuss this in the section about speakers.

(Now I will actually get down to giving some advice.)

The wattage requirement also depends on the size of the venue. Here is one advisor that gives a specific number: "If you intend using the machine at parties or small social events you will need at least 80 watts (2 speakers at 40 watts each)."  Sounds pretty cool. We can get off really cheap!

I am not so excited about 80 watts. The only gig that I have run where 80 watts is sufficient is my New Year's Eve party. This is maybe 20 people, in my living room. And we are generally somewhat older, so we don't need to have music quite so loud. And with 80 watts, the music doesn't interfere much with conversation.

Musician's Friend has a "PA System Buying Guide" that I recommend reading. They offer some advice on power requirements that I find more reasonable:

"The size of the venue you play in can help you determine the continuous power handling (wattage) your system will need. For example, smaller gigs, conferences, lectures, and outdoor meetings may need about 350-500 watts, while club bands, garage bands, and mobile DJs may need 500-1,000+ watts."

 
Here is a different expert who gives a number in terms of people. If we assume that karaoke fits into the category of "bands and average size venues", then 3 to 4 watts per person (in the audience) is recommended. So, if there are 50 people listening to karaoke, you need something like 150 to 200 watts.

The karaoke pundits put a slightly larger number on it. The number tossed about in this forum is around 10 watts per person. So, if you have a venue with 100 people, then they might recommend 1,000 watts.

The Crown amp that I mentioned above (the XLS 202D) puts out 200 watts per channel into a pair of 8 ohm speakers. So, with one set of speakers, you get a total of 400 watts. With two sets of speakers (the equivalent of one 4 ohm speaker per channel, the amp will put out 300 watts per channel, for a total of 600 watts.

I have this amp. I have run gigs where 400 watts (with one set of speakers) is fine. I have had other gigs where 600 watts (two sets of speakers) falls a bit short... I wind up pushing the amp a bit harder than I would like.

For larger gigs, I now bring one set of passive speakers (speakers that run from the amp) along with one set of active speakers (speakers with their own amps). My active speakers are the Behringer B212A speakers, that put out 250 watts each. Thus, I get a total of 400 watts from the passive speakers and 500 watts from the active, for a total of 900 watts. Still, I sometimes feel I would like to push a bit more. I have my eye on a Crown XLS 802D...

So, I am gonna agree with that range of 200 to 1,000 watts. To make most customers happy, I think a KJ should be set up to deliver something like that amount of power. o make the KJ happy, you need to push toward the other end.

Now for the weaselwords. If you are running outdoors, you should really consider getting a subwoofer. And more power. And if you are running a large club, then you will probably need a whole lot more power, but (my experience) large clubs usually have their own sound system. And they will usually allow you to hook into their system.

Copyright (c) 2010, John Seymour

So you wanna be a karaoke host? (Part 5: Mixing it up)

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A mixer, in it's simplest form, is just a box that combines the signals from one or more mics along with a music signal in order to create a single signal to send to your amp. That's all it really is, but somewhere along the way it got more complicated.

This article is orgamized in such a way as to start you off thinking it is all gonna be really cheap, then suggest that it will really be more, and then finally leave you at the point of "how can I afford not to go all out?"

Taking it simple (CHEAP) first
Let's have a look at the simplest (and cheapest) options for a mixer. Along the way, we will see the features that get added for a price.

One of the simplest mixers is exemplified by the Nady MM-141, which sells for $30.

This particular mixer will combine four mics into one, with a separate volume control for each mic, and then another overall volume control.

Wow. What else could someone possibly want?  Seems like this is all you would need for a mixer. Pipe this into a a set of active speakers, or into an amp and speakers and you are all set. Well, except for a few things. Most importantly, the music.

Let's say that you are running your karaoke show with a laptop. You have the karaoke music coming out of your laptop, but where is it going? Your laptop speaker output should go to the mixer. The job of any self-respecting mixer is to combine the music with the voices of the singers and allow you to balance one against the other.

It would seem at first glance that this cute little mixer has you covered. Four inputs? That sounds like three mics and one input for the music. Cool.... Except.

The inputs for this mixer are mic inputs. They are (go figger) designed for mic level inputs. Your computer puts out a different signal level, called "line level", which is suitable for headphones and amplifiers. I will discuss the difference between these two levels in another section of this tutorial ("Tying it all together"). Suffice it to say right now that to balance the music and the mics, you would need to turn the music all the way down and the mics all the way up. Once you get it balanced, you really don't have much breathing room left to adjust either music or mics during a show.

Oh yeah, and then there is the issue about stereo. The inputs to this simple mixer are mono. To connect stereo up to this, you need to take two of the inputs, one for each channel. And the output of the mixer is also mono, so you have lost the stereo effect. That might not be an awful thing. I would argue that while stereo is a nice thing to have, it is not crucial for karaoke.

But still, I do not recommend this mini mixer for karaoke. 

Bringing in the music
There is another cheap solution that will allow you to mix in a mic: your computer. Sound cards on computers often have a place to plug in a mic. Within the sound card, there is a mixer that will combine the mic input with the music that your are playing, and send this out the line out of the computer.

Which is pretty much what we want, right? Well... once again I intend to try to pop your "I can get my karaoke gear real cheap" bubble.

There is a lot of variability in the quality of mic inputs on a sound board, and this is especially true on  the sound card for a laptop. These inputs were designed for the speaking voice, not for singing. If your mic input is not good enough, you could go with an external sound card. This device (Sabrent USB 7.1 CH 3D) plugs into a USB port and provides two mic inputs. It sells for $24. 

I have one of these. Perhaps I am missing something, but there does not appear to be separate volume controls for the two mics. But in my opinion, a bigger problem is that the volume controls for this box are  software controls. To adjust the volume of the mic, you must first bring up the volume control window, and then adjust it with the mouse.

While this may seem pretty easy just talking about it, but you probably won't think so the first time someone screams into the mic. Why do people do that? I don't know. But they do, and when they do, you need to be right there on the volume control to assert your own dominance. You are in control. You are the alpha KJ.

The solution to both of these problems is to use the two boxes together. I should clarify. The solution to the problem of separate controls for the two mics and of mouse controls is to use the USB sound card and the mini-mixer. All your mics would plug into the mini-mixer and the mini-mixer would plug into the Sabrent sound card.

I don't have a solution to the problem of people screaming into the mics.


While this setup (mini-mixer and USB sound card) would (should) all work just hunky-dory, I'm not going to recommend it.

But before I move on, there is one cool thing you can do with a USB sound card. You can have two sound outputs going at the same time: one for KJ and the other for DJ. I will talk about this in a future blog. 

Mixing it up for under $100
I found five mixers for under $100 that I would call "adequate" for karaoke. True to my noncommittal ways, I am not going to recommend any of these mixers.

When I say adequate, I mean "don't come crying to me when you decide you want something bigger and better". When I say adequate, I mean "base level functionality". (Also, when I say adequate, it also brings back some bad memories of what she said after the first time I "did it". I mean, after the first time I did karaoke, of course.)

Behringer XENYX 1202

Mackie 402VLZ3

Nady SRM10X
Peavey PV6
Yamaha MG102C

What are the base level functionalities?
In my opinion, there needs to be at least two mics, so the mixer has to have at least two mic inputs. When  running with two mics, the KJ has one mic and the singer the other. When two people get up to sing, the KJ passes the mic to the second singer.

There must be at least one stereo, line level input to plug the computer sound output into.

There must be separate volume control for each input. It is imperative to have a volume control on each mic because of the huge variation in volume between people.

There must be a stereo main out (for the club speakers) and then a second output. This second output might be called monitor out or control room out. These outputs must each have a volume control. This second output will be used to run a monitor speaker or two. A monitor is a speaker that sits on the floor, pointing toward the singer. This speaker allows the singer to hear their own voice. In my opinion, a monitor speaker is absolutely essential.

In a pinch, you can use a headphone output to run the monitor speakers. A few of the mixers above have only this as a second output. This is not as good as a real output, but it allows us to achieve base level functionality.

Additional features
So, if I limit myself to spending $100 on a mixer, what great features might I miss?

More mic inputs - To me, it just seems a bit pedestrian for the KJ  to be exchanging the  mic back and forth with the singers, so I think you need a lot of mics, and hence a lot of mic inputs. I normally run with three mics just for the singers. If I am running the gig with another KJ, I will have two additional mics. I don't know if I mentioned this or not, but I am a fabulous karaoke host.

Second stereo line input - Hey, did you know you can hook your iPod into a mixer?  And that it will sound good?  I always bring some sort of mp3 player with me whenever I run a gig. It can provide background music between singers. Just leave the iPod running and bring the volume up on that channel between karaoke songs. Also, the iPod can provide music while you are setting up or tearing down. You can pack up the laptop while you still have tunes going. Finally, having the iPod always ready can help you avoid complete humiliation if the karaoke software crashes. To run an iPod like this, you need to have a second stereo line input.

Sliders - Sliders are just cool. I like sliders. It makes me feel like I am Scottie, running a transporter. I like a mixer where the main output volumes are all controlled via sliders rather than knobs that you turn.

Special effects - This feature is often written "Special FX". (If you are cool, or if you want people to think you are cool, you will also abbreviate effects  as FX.)  Special effects can make a mediocre singer sound great. In order to get that true American Idol sound, you really need to add a little reverb to a voice. Or that's the thought. On the other hand, reverb can make it more difficult to control feedback. It also will take some learnin' to go from "ewwww.... that's sounds like too much reverb" to "wow!  is that Dannie Gokey?"

Bass and treble on mic input - A bass and treble control on each mic input allows you tailor the sound to the person's voice. When I use these, it is most likely to turn down the treble on a shrill voice.

Bandpass equalizer on output - All rooms are different, all speakers are different, songs are different, quiet sound needs more bass. All these require that you have some control over the equalization of the final output. Having five channels is nice. Seven? Gee I dunno. Do you need it? Do you have time to tailor it for each gig, or will they always be set to whatever you used at the last gig?

Level set LED indicator - My mixers have little LEDs next to each mic input to tell me when the signal level is starting to get too high. I try to keep the signal level just below the point where this LED flashes.

More better mixers
Here are some examples of mixers that I would consider pretty darn good for karaoke. They all run from $200 to $300. Note that the basic price difference has to do with the number of inputs.

This is the Mackie ProFX8, selling for $230.

Here we have Yamaha's MG124CX, coming in at $290.

And here is the Peavey PV14, with a price tag of $300.

Which to buy?  I dunno. I have two Mackie mixers (one a little bigger than the ProFX8, and one a little smaller -- both older models), and I have one Yamaha powered mixer that is real old. I use the Yamaha mixer most often, simply because it has the built in amp. Convenience. I think I like the mixer functionality a bit better, but partly that's just my own familiarity.

Running a mixer
Mixers have a lot of buttons and switches. It will necessarily take a while to learn how to run the crazy thing. I will save that long discussion for another blog, but I will motivate the discussion a bit.

If the volume of a singer is too high, you could ask the singer to sing quieter. You could ask the singer to hold the mic further from their mouth. You could lower the gain knob right next to the input plug. You could lower the bass, midrange, and treble controls for that mic. You could lower the AUX or the Main for that mic. You could lower the main mix volume. Or, you could lower the volume on the amp. All of these will serve to lower the volume of the singer. Which is the correct one to adjust?

When I first started running a mixer I found that my knobs would run away by the end of the gig. Eventually, certain knobs would be pushed all the way one way. I didn't know how they got there, except that every time I adjusted a knob I was doing something that made sense. The thing is, I knew what each of the knobs did, but I did not have a coherent strategy for adjusting them.

There is some artistry to running a mixer and there is some science. I will go into that deeper in another blog. 

Copyright (c) 2010, John Seymour

So you wanna be a karaoke host? (Part 2a: Examples of all-in-one systems)

First part of karaoke system tutorial         Previous part            Next part

In the first part of this series ("a generic system"), I described the various pieces that you must have in a karaoke system. This part was kind of theoretical. In this post I will give some examples of what I call all-in-one systems - systems where all or most of the pieces come in one package. The next post will describe other ways to configure a karaoke system.

I mentioned some disclaimers in my previous post. I wish to repeat disclaimer #2, because it is especially relevant to this post:

2. This is not intended to be a buyers guide. I will mention specific products and reference specific websites that sell stuff. Please interpret these as examples and not as endorsements. When and if some manufacturer or retailer decides to give me some money, then I will be happy to state that their equipment is the best stuff around.

Combined systems versus components

Not only is there a bewildering assortment of products, features and prices, but it is made even more confusing by the fact that the components that I spoke of before (mixers, amps, speakers, etc.) are often combined into one package. When you buy a system, you have to decide whether to buy all the components separately, or to have A and B in one package, or to have B and C together.

Years and years ago, when I worked for Radio Shack (Ummm... t wasn't called Radio Shack at the time, since Marconi had not yet invented the radio.) Years and years ago, when I worked for Two-Campbells-Soup-Cans-With-A-Sting-Between-Them Shack, I would tell customers to buy all the components separately because that way you could gradually upgrade your system, one piece at a time. I liked to give that advice cuz people spent more money if they bought all the pieces separate. I was working on commission.

Since I am no longer working on commission, I can talk about combined systems.

All-in-one system, toy category

This first category is what I might recommend for a kid who loves to sing. All the pieces are packaged together in one compact and convenient package. Nothing else to buy.

Well, almost nothing else to buy. These systems generally come with a small selection of songs. You're going to want to buy some tunes. Hannah Montana and High School Musical are kind of a necessity.

Here are two examples of all-in-one toy systems.

Emerson GQ755, $70 from Amazon

 Another one, $160 from ToysRUs

 

If the kid you are buying for is 14 or older, I would suggest staying away from the toy category. At 14, kids become hearing impaired. That's why you need a bullhorn to ask them to clean their room or empty the dishwasher, and that's why they turn up their music so loud. The sort of system in the toy category just will not have the kind of power than a 14 year old desperately needs. And believe me, when they try to get that kind of volume out of the system, the system will provide you with 100 watts of pure distortion. Not only will it be karaoke, and be loud, but it will also sound bad. Is "bad karaoke" redundant?

But if the kid you are buying this for happens to be "your kid within", and that kid within wants to enter the lucrative profession of karaoke hosting, then I have another reason why you should avoid the toy category. The equipment is not road worthy. If you start lugging these toys around to bars, you will be laughed at. But more important, your toys will fall apart very quickly.

This exhortation goes for home stereo equipment in general. Home stereo equipment is just not designed to be hauled around every night. Exposed knobs will break off and speakers that do not have a cage over them will get poked out. If you want to be a KJ, buy KJ gear.

All-in-one system, low end pro category

Speaking of which, here is one example of an all-in-one system that was designed for KJ use.

This system, the Vocopro Gigstar, is available from Karaoke Warehouse for $380. (By the way, did I mention that I do not intend this to be a buyer's guide?) It comes with all the components, well, almost all the components. I don't see any listing for microphones, so I am guessing you would need to chat with the folks at Karaoke Warehouse about getting a set of mics. I am sure they will be glad to sell you a few.

Oh, and a TV. You need to get a TV to show the words. Actually, there are a lot of bars that have TVs these days and you could hook this system up to them. I will discuss this further in the post "Getting the word out".

The particular system comes with something over 300 karaoke songs. This may sound like a lot. It is probably enough songs if patrons are content to dig through to find something they can sing. This collection is definitely not a big enough collection for someone who comes in looking for a specific song.

Referring back to my rather clever component diagram in the previous blog, this all-in-one system combines all the pieces that are within the dotted line.

The system is attractive because it is pretty much all in one box. Less stuff to carry around. That's good. It's also pretty inexpensive. That's good. But please note that I am giving this system as an example, and not endorsing the equipment. I don't know if I mentioned that. In fact, I am gonna un-endorse this equipment. Well... not this particular piece of equipment, but just the idea of an all-in-one system.

First, there is the whole argument I used when I was at Radio Shack. The only way to upgrade an all-in-one system is to replace it. And trust me, if you decide to be a KJ, you will want to upgrade. At some point you will read the manual for this equipment (that is, unless your a guy) and find out that you can hook up external speakers. So you take some of the exorbitant money you are now making and buy a set of speakers. Now you are lugging around two sets of speakers - one set in the box and the other set in separate boxes.

Then you will find out that the amp in the all-in-one box just doesn't cut it. The Vocopro gives you a place to connect to an external amp, so you will buy a second amp to run the second set of speakers. And you go to your gigs carrying a 53 pound box with 47 pounds of stuff you don't use.

Components also make sense when equipment breaks. If something breaks in an all-in-one system, you are dead in the water. If something breaks in a component system, you can replace that particular piece.

Another issue that I have with all-in-one systems (in general), the audio quality of this system is probably not all that fabulous. Now I should say that I have not heard the Vocopro system, but... The manual says that the system is rated at "100W total power (peak to peak)". I will talk about the whole subject of power in a later post (Watts and RMS and Ohms, oh my!), but this equates to about 18W of power per channel RMS. If you are looking for a karaoke system for a living room, or one to take to a retirement center, then 18W per channel might be just fine. But for a bar where people listen to music to drown out the demons in their head? Not nearly enough.

Another comment I will make about the likely sound quality... the speakers just aren't in the right place. You probably don't want the speakers to be directly connected to the mixer. More about speaker placement in the post "Speakers - getting those karaoke vibrations going".

Ok, so I have come down pretty harsh on this system, but let me back off just a little bit. Let's say that you have a gig at a bar that has it's own sound system. And let's say that you can hook into their TVs. For that scenario, something like the Vocopro Gigstar is certainly cost-effective and pretty easy to schlep around. I know a karaoke host down in San Miguel, Mexico who uses a system like this.

Another point... I started out with some pretty inexpensive equipment. And lousy. Inexpensive and lousy. Did it make sense to start that way? Hmmm... good question. One argument would say that the $500 that I spent on the first equipment was wasted. Another argument would say that this relatively small investment allowed me to decide whether I liked the job. The real bad decision would have been if I had spent $5000 on equipment that sat in my basement.

In the next post "Working dog category", I will give some examples of karaoke systems more commonly used by the pros.

Copyright (c) 2010, John Seymour

So you wanna be a karaoke host? (Part 1, a generic karaoke system)

So... you wanna be a karaoke host?

First of all, let me say that, next to being an applied mathematician, being a KJ is one of the best jobs around. I mean... you get to listen to absolutely fabulous renditions of the most popular songs around. You get to be around people who are drunk, without having to get drunk yourself. Respect... tell me, who gets more respect than a KJ? Really. Who?

Well, ok. Most politicians get more respect than KJs. And politicians get to hang around with Sarah Palin. That's a perk.

Me?  I'm in it for the groupies. I was just talking about that with Jaggar the other night. Yeah. He's envious. He wishes he would have decided to become a KJ. I told him there is still time. Naturally, he asked about the kind of equipment he might need. This series of blogs is a summary of what I told him.

What equipment do I need in order to enter the prosperous and glamorous profession of karaoke hosting?
I have been asked this question more than a few times, so I thought it might be worthwhile to dedicate a series of blogs to answering the question. I hope to put this at a level where it can be easily understood by the layman or laywoman who needs a little background into putting a system together.

Disclaimers
1. This is not a series of blogs for the sound system engineer. I have chosen at times to sacrifice less critical details in favor or succinctness and clarity. If someone corrects me on pesky facts, I will reiterate this disclaimer so that I don't have to admit my ignorance.
2. This is not intended to be a buyers guide. I will mention specific products and reference specific websites that sell stuff. Please interpret these as examples and not as endorsements. If and when some manufacturer or retailer decides to give me some money, then I will be happy to state that their equipment is the best stuff around.
3. If you wanna hang out with Sarah Palin, that's your business. I would prefer to just listen to the media poke fun at the stupid things that she says.
4. If you are confused reading these posts, just imagine how confused I am!  Have a little compassion, ok?

System diagram
Below is a diagram of a generic karaoke system, indicating all the parts that must be present in a karaoke system. Karaoke systems will box these pieces into subunits in different ways, but all karaoke systems need to have these parts. In the next post, I will gives some examples of how manufacturers combine different parts together in order to confuse people and talk about how these pieces can be brought together to make a complete system.

Karaoke tunes
Just like every CD player needs CDs, and every DVD player needs DVDs, and every KJ groupie needs KJs, every karaoke system needs karaoke tunes. As a KJ, you need to decide whether a) you are gonna be a scumbag pirate who enjoys the idea of paying tens of thousands of dollars in fines when he/she is finally caught, and really doesn't mind stealing from the very people that allow them to make money,  or b) you are gonna run your karaoke as a real business and an ethical business. If you decide that you actually want to deserve the incredible respect that a KJ gets, then you should realistically figger on spending thousands of dollars on tunes.

In a subsequent post, I will discuss the various formats of karaoke songs: CDG disks, DVDs, midi, mp4, bin, and mp3+cdg files. The wonderful thing about standards is there are so many to choose from. I am sure you will find that post absolutely riveting.

Music player
You will need something to play the music. Well, duh. This is analogous to a CD player or WinAmp or an iPod. I will discuss the various options in yet another absolutely riveting post. Surprisingly, the options for karaoke look a lot like a CD player, WinAmp, and an iPod. 

Mics
If you want someone to sing, you probably oughta give them a microphone. Maybe this isn't essential? I suppose you could be running karaoke in someone's living room, or in a karaoke booth. Or in your shower? Maybe you won't need any mics then. But, if you are doing karaoke in the shower, you probably will need me. Give me a call, ok? Well... unless you are a guy. You probably won't need me if you are a guy.

In my post about karaoke mics, I will discuss wireless and wired mics,and also look at the trade offs between cheap, lousy mics and expensive, high quality mics. I don't wanna spoil the suspense, but cheap mics are less expensive than expensive mics. Lousy mics are not as good as expensive mics.

Mixer
My wife's mixer is a KitchenAid. She loves it. I just haven't had much luck doing karaoke with it. (Maybe I will ask her to make some karaoke bars some day. and maybe she will ask me to stop making stupid puns.)

A karaoke system needs to combine several sound sources - at least one vocal and one backup track. A mixer needs to have some way to adjust the volume on each of these. A mixer should also allow you to adjust the bass and treble kinda stuff for each sound source. A mixer should also give you the ability to separately adjust the volume to various speakers. Also, a mixer should allow you to add some special effects. I will go into each of these in, you guessed it, another post.

Amp
Microphones and iPods and CD players don't put out a lot of power, and a mixer does little to make the signal any more powerful. An amp takes the minuscule output from the mixer and converts it to a level that can actually drive the speakers.  I will talk about amps in another post. Fascinating stuff, really.

Speakers
Speakers are called transducers. A transducer turns power of one sort into power of another sort. In the case of a speaker, the electrical power coming out of the amp is turned into vibrations in the air, that is, into sound. Woofers, tweeters, subwoofers - all subjects for a subsequent post.

Another thing that I will add to this post is a discussion about the monitor speakers. Very important, and often forgotten.

Technical stuff
Unfortunately, you have to know a bit of technical stuff in order to get the amp and the speakers to play well together. And to get an idea just how much power you need for a gig. This post will help?  Maybe?

Lyrics generator
So far, it's all been about the sound. Lets not forget about the words. In order to get most people to sing, you need to put the words in front of their face. There needs to be a piece of software somewhere in the system that translates the words that are encrypted in one of the karaoke formats into a signal for some sort of display.

Video display
And finally, you need a display for the user to see the music. This could be a TV screen, or it could be a computer monitor. But it could be something else?  To find out, you will have to read the post on video displays for karaoke systems.

Tying it all together
Cables. Forgotten, maligned, disparaged, often abused, and generally misunderstood. It's no wonder so may cables wind up in therapy.

The post on cables will discuss the three basic types of signals that cables need to transmit, and the plethora of connectors that could be put on the ends of these cables. The wonderful thing about standards is there are so many to choose from.

Menu of subsequent posts
Part 2a: Examples of all-in-one systems
Part 2b: Examples of systems, working dog category
Part 3: Formats for karaoke tunes
Part 4: Microphony for karaoke
Part 5: Mixing it up
Part 6: Karaoke system amp
Part 7: Speakers - getting those karaoke vibrations going
Part 8: Watts and RMS and Ohms, oh my!
Part 9: Getting the word out
Part 10: Tying it all together

Copyright (c) 2010, John Seymour