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Lonman, you are most correct!...My memory failed me!....It was 4 ohm subs to avoid, not 8 ohms!....If you don't mind i will go back and edit that....but doing so will kinda make these two post look odd...I'll do it anyway just to keep the info in that post 100% valid.

Thanks for correcting me.

True fersure.

But even then there is room for improvement......As you get more expert and perhaps anal in you quest for improved sound quality, you will discover that bass freqs are the most expensive and difficult to get 'right'....but why let that stop you, cause after all, you seek the best, right?

Yep, bass is a beast to get right, but it really is worth the trouble and expense...you will agree once you hear a system with really tight and punchy bass...Perfect bass makes the rest sound better somehow.

So ok, you got bi-amped and now you are sending all the lows to your subs. It sounds better already...Let's take it a step farther....Let's just focus on the subs.

Subs are extremely sensitive to all kinds of quirks....They can suffer from something called subsonic feedback....feedback that you can't hear, but is very destructive and sucks up lots of amp power and robs you of tite punch...Subs can also experience cone overtravel and and cancellation and a few other nasty problems.

How to avoid subsonic feedback?....EQ your subs....Yep, go out and buy another expensive 31 band EQ and place it just on the subs...sounds like a waste cause you are only going to use the few sliders associated with bass freqs, but thats what ya gotta do....OR, you can look for a sub amp that has a 40 to 50 hz low-cut filter built in...OR, you can find an EQ with a 40hz low-cut like I use...you need to remember that even tho you are sending just the lows to your sub amp, it is going to amplify ALL the lows you send it....Don't allow it to amplify lows too low for the subs to use accurately...filter them out!....Subs able to use all the lowest freqs are super expensive and huge and require monster amps.

Good bass is centered around 65-to-85 hz, that's where your chest cavity resonates, so filter out freqs below that starting around 50 hz.....Doing so eliminates wasted freqs, helps prevent subsonic feedback, and saves lots of amp power for the bass you want to amplify....sub amps thrive on headroom, so give them extra headroom by not asking then to amplify freqs below 40-50 hz.

What's headroom?...just imagine a gal in a bikini on a trampboline.....pull the trampboline out from under low hanging objects so she can really bounce and you will get the idea of why headroom is GOOD!

Nah, if he sticks his eq in between the mixer & the crossover, all he would need to do is pull those extreme low frequencies out from the main eq, no need to get an entire eq just for the sub.  Most mixers have a low cut on the channels, I would definitely use the low cuts on all mics - that will also help reduce any low end feedback.



Works for me.

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So you too like girls in bikinis on trampbolines?...I figured you did.

I agree about using low cuts on mic channels if mixer offers them...mics generate tons of subsonic feedback!...and stage areas are nortorius for trapping subsonic waves.

Yes, fersure you can use your main EQ to filter your subs providing you place it correctly in the signal chain, as I described to Bigdog in a earlier post...some folks chose to use separatel EQs placed in each amp line, especially live bands....Careful sub amp selection makes this problem mute as amps designed for subs should offer low cuts.

My post was intended to cover things in a deep but general fashion....Hopefully when folks respond, we can get into the details of how to do it using what they got or what they need to buy based on what they got...also how to do it depending on how they run, mono-stereo.

In a live band situation, I agree that 1 may run an additional eq for each output from the crossover, however i've never found the need to yet - even in live situations.  I would run a separate eq for each individual monitor mix, but haven't yet found a need for the mains.  Your talking 12-20 (give or take with other factors such as amount of drums, guitar players, singers, etc...) open mics as opposed to 2-3.  If the 31 band eq is after the mixer but before the crossover, it will work just as well.  You have to figure anything cut in the sub frequencies (50 hz & lower) aren't going to affect the mains at all since the mains are already crossed over those frequencies.

I like your technical posts Keith, however sometimes you can get a little too technical  :D , Hell there's been times you've confused me......

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OK.     75% of my bar set ups are not ideal for stereo to be heard correctly.    

So now the stereo outs from the mixer will be left and right out to the crossover?   Or the one mono out to the crossover with a "Y" cord?    The mixer has 1 right out, 1 left out and 1 mono out.

The Yamaha amps have low frequency cut outs.   For the sonic boom cancellation, after the crossover.

I'll pull down the lows on the entire system EQ, before the crossover.

Out of the crossover is it, one cable to the high amp switched to parallel and one to the low amp switched to parallel?  

Well both of you did a job on me......

I would just use the mono out into one channel of the crossover.  The high out would go to the top speaker amp ran parallel input & each speaker would still have it's own channel.  No need to use a Y cord, this could actually do harm to your equipment.  
http://www.rane.com/note109.html




I thought you stated before you owned a Crown XS900???  Or do you plan on getting Yamaha amps?
http://www.karaoke-forum.com/viewtopic. ... n&start=25




Pull down everything in the extreme lows pretty much start the drop at 50 hz & slant downward before that.  The rest of the eq should remain almost flat except for harsh, muddy, piercing or feedback frequencies.  If everything sounds good flatlined, then leave it there - it's best to remain as flat as possible (yeah I know, then why bother having an eq).  If your system sounds good at a flatline, then you probably would never need the eq.  I have yet to experience a system that didn't require cuts in certain frequencies.  It's always better to cut frequencies than to boost.  If you find you are needing to boost alot to compensate for certain frequencies, you may want to consider an upgrade of components - ie amps & speakers would be the main consideration.  



High output to high amp switched to parallel, low output to low amp switched to 'bridge'.  Then you need to make sure how connect the speakers, the high amp would connect as it would normally with a speaker on each channel, the parallel input will take the 1 input & divide it for both outputs.  For the sub, some amps have a bridge output, some require a special connector/adapter.  Most common is the banana posts to 1/4" or banana posts to Speakon.  Many amps still use binding posts & the positive (red banana post) from channel 1 (or A) will be the positive speaker output of the bridge mode & the positive (red banana post) from channel 2 (or B) will be the negative speaker output of the bridge mode.  
When you get to this point, restate which amps (makes/models) you have & we can advise from there.

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Will aux fed sub be of an advantage in this situation? Alot of subsonic rumbles come from the mic channels and I can't see any advantage in feeding the mic to the sub, just the backing music. Has anyone try this in a karaoke set up?

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I can neither confirm nor deny ever having or knowing anything about nothing.... mrscott

Thinking about two Yamaha amps and new Yamaha speakers.     They have made some internal changes to the speaker componants and internal crossovers, etc, since I bought this set.    And they have matched the amps to the speakers for optimal performance.

Only problem would be it would be individual from the main fader, even if it was just on the music.  Kind of a pain overall to have to keep adjusting the Aux send.  In the mic channels, the low cut is used or back the bass (low) down a bit & it will work fine.

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Well if your speakers are working fine now, i'd opt for the amps crossover first before going all out.  
The Yamaha P series amps are pretty decent, however you may find the Crown XS series a little better still & you'd only need to get 1 on top of what you already have.  But if you go Yamaha, the P5000S would be the match for the tops & the P2500S bridged to both subs.  The new subs still don't have any internal crossovers.  The amps have a built in low pass filter adjustable from 25-150 (you'd want to guage anywhere from 75-100), they also have a built in low cut filter as well which would be for your top speakers.  Whatever you set your sub amp low pass filter (subwoofer switch) at frequency wise, make sure you match that in the top speaker amp.  Basically saying if you sub amp is set to sub, with the frequency at 90hz, then the top amp set on low cut also needs to be set on 90hz.  You don't want the amps overlapping frequencies.

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If you would stop chasing skirts and pay attention to the work at hand, we could breeze thru this lots quicker......Lonman, did you hear what I just said?....LONMAN!

You are correct, there is NO advantage in sending vocals to the subs because all mics are subsonic vacuums.....If you are lacking low cuts on you mixer mic strips, then one certain advantage of running auxfed subs is no subfreqs in the mics....Another advantage of auxfed subs is you have easy-to-reach and quick-to-adjust control of your bass....That's a nice thing to have when you are blending/alternating dance tracks with your karaoke.....Altho auxfed subs are a live stage band trick, it can be used very effectively in DJ/KJ work.

Jian, nice to see you hanging out...How did the Lexicon FX unit work out? You owe us an honest review.

Can the vocals be eliminated from the subs on the mixer?    Or where and how would you do that?     Or did I miss it in the Greek translation you two wrote.    LMAO



Dumb it down a notch or two.    :whistle:

Bigdog,

The Lonman gave you great advice on patching and EQing....(please note Lonman rates "THE" before his name  )

I'd like to add that once you have made those cuts and boosts he described, you really, really need to look closely at how they effect the gain coming out of the EQ.

If your EQ lacks output gain metering, then just eyeball all the sliders that are no longer midpoint.....and do a little quick math in your head....If you cut 10db at one freq, and 6 dB at another, and you boosted 3dB somewhere else and so on, then you can quickly/ruffly calculate how much those cuts/boost effected the total signal thru the EQ....If you see the total is more than +/- 3 dB then you need to restore gain before it enters the power amps or next device in line to the amps.

That's easy to do providing your EQ has that feature...A truely pro EQ may not offer metering, but it danged sure must have at least an output gain control and the sliders must be calibrated/labled in dB....Usually the output gain control is another slider located to the right of all the freq sliders....It might be a twisty knobby....It will be labled "output gain"....

So If you read and total all adjusted sliders and come up with a total of 10dB cut, then ease the output gain slider up from 0 to make up for all the cuts....Do the opposite if you end up with total minus cuts.

Yep, I said 'read' the freq sliders....you will notice that the sliders have little painted tick marks next to them and they are labled in dB. The midpoint for each is labled 0 and then up is + and down is -....And the higher/lower you slide each is higher/lower in dB....

dB is kinda different than inches or feet.....It's a logarithmic unit used to describe a ratio of power.....2 dB is NOT half of 4dB.....In fact, 3Db is actually twice the power of 0db, and 10 dB is ten times the power of 0dB, and 60dB is 1,000,000 times the power of 0dB...Wow!...Makes you look at them numbers with new respect, huh?

If after you have made all your cuts/boosts and you total them and you are looking at a whole lot of output gain adjustment, then back up and try to spread the adjustment out a little so the total falls within the adjustment range of the output gain slider.

Do you need input meters on every piece of gear in your signal chain like I stated earlier? Nah, not really....But you fersure want each piece to have an output meter or calibrated controls and an output gain control.

Why do you want either metering or at least calibrated controls?....That's because it is a 'signal chain'....the signal flows out one device into the next where each device is kinda like a link in a chain.....you need to know/be able to see, and be able to control the gain leaving each device...so if each piece has at least an output meter and output gain control, then by golly you can assume that "if my EQ reads 0 dB out, then the next device in line MUST have 0dB in."

Lacking an output meter, you want any adjustment  that effects gain to be calibrated to show in dB how much the signal has been effected so you can restore it with the output gain control....Don't be dismayed if a piece of your gear lacks metering and only has the calibration lables....some of the very best pro gear has no metering...They figure pros can add and subtract....some of the worst gear is overloaded with led meters, but they don't fool us, do they? Nope, not now that you can read calibration marks and do simple math.

If your mixer has low-cuts on the mic inputs, use them whenever a vocal mic is connected....Low-cuts are usually a simple push button located up near the input twisty gain knob at the top on the mic strip...don't use them if you are inputing full range stuff like a CD player output.....some mixer low-cuts are actually adjustable and include a twisty knobby, but most are a simple up/down push button where up is out, and down is in.....'in' means the low-cut is 'in' and the low-cut filtering is activated.

I refuse to "dumb it down" for you....Stop playing stupid, you don't fool me.
That Bigdumbdog stuff might work with the gals, but I know better. I ain't no gal and I ain't gonna be suckered into thinking you are big fluffy, loyal and cute....Nope, you the Bigdog and you got it hangin, and you just wanna pick my brains, and you figure I'll tell you all my secrets if you play dumb so you can then go out and impress the gals with your sound.

I got your number, man. Now roll over and let me scratch your belly and I will tell you a secret.

PSSST, Bigdog......Gals like bass....They friggin love it....but it's gotta be big n tite if you wanna get their big n tite butts jumpin and their skirts flippin.....So cut and filter anything that makes your bass muddy....Destroy anything that wastes bass amp power....Slap them hard in the butt with your subs while you yank them by the hair with your tops......Yeah, you get the idea....You'll know when you got it right, just watch the dance floor and wear loose fitting jeans.  :O  :dancin:

Without going out ot the truck and unloading half the equipment in the middle of the night, lets just say that most of the frequencies are boosted on the EQ from one to 5 notches above center.    The mid cuts are being used on the mike channels.    

There is an master output gain or reduction on the EQ.    I was told by the music store guy, that you never really want to use the EQ master gain as a volume control.   With the above EQ configuration the master gain is up 2-3 notches above center, at most.     Lead on master.

I can't figure out how to do it until I read this http://www.prosoundweb.com/install/tech ... subs.shtml
i will try it out as soon as I have the chance.

Keith; the lexicon works great, we now have a use 2 more efx on the top of onboard exf. ( The first time it was put to use, the stage hand blow up the power supply; he plug it in directly to a 240v socket and not thru the step down transformer). The Band had a pack crowd during the last gig over the week end; ended 4am.

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I can neither confirm nor deny ever having or knowing anything about nothing.... mrscott

I read the whole article and I understand about 3 lines.   Is this something we would want to do?   Keith translate it to simple english for us.  :worship:

Good link, Jian.  

I will try it out on a live band with 8 mic channels.

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I can neither confirm nor deny ever having or knowing anything about nothing.... mrscott