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Author Topic: Dissapointed with Mackie SRM450V2 and looking to upgrade  (Read 31236 times)

Bob Leonard

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #60 on: April 02, 2014, 11:35:51 PM »

Nick,
The entire point of having a sub woofer is to replicate the frequencies below the xover point set for the system. Think of the system as being the upper cabinets and lower cabinets (sub) working as one unit.

Full range cabinets of the type you are using will replicate frequencies in most cases down to about 65Hz. That doesn't always mean that the lower frequencies will sound great, but that is usually the spec.

Most subs will replicate frequencies down to 30-40Hz without a problem. The goal will be to find the crossover point where your upper cabinets stop reproducing sound and the lower cabinet (sub) takes over. Many people incorrectly assume that kick drum, bass, low register organs, should be heard coming from the sub. Wrong, totally wrong. Your upper cabinets are the source for all mid - mid/low range frequencies. This is why I am very partial to 15" drivers, in my case SRX725s, for use in a point source system.

If you want a bullet proof system put your signal through a DSP BEFORE the amplifiers. The DSP, once set correctly, will decide what frequencies goes to what cabinets. The DSP will determine high pass and low pass cutoff points, center frequency, correct levels for the cabinets and amplifiers, etc., and once set will seldom if ever need to be changed.

The magic number for your center frequency will be between 100Hz and about 80Hz and you'll be surprised by what you DON'T hear coming from your subs.

This is where you should start. No need for aux fed subs, special EQ settings or any other type shit. Just a properly tuned system and a smooth transition from top to bottom. I count my dbx 4800 as the second most important piece of hardware in my racks, right next to my board, but that's me and YMMV.
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nicklang

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #61 on: April 03, 2014, 05:19:00 AM »

Cheers Corey mate.....I bought the DSR's yesterday.......it'll be the first gig with them on Saturday :D

I really did try to follow your set-up procedure/arrangement I just couldn't quite understand how everything connected together :)
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Steve Garris

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #62 on: April 03, 2014, 01:21:38 PM »

Thanks guys....starting to get an idea.......

is there no issue with signal strength or such by sending different signals left and right pan to different speakers???.....then I guess you're saying daisy chain each subsequent top or sub......



Yes - you would just go out of the top on one side to the top on the other side.
Same with the bass bins.

I would certainly start with Scott's suggestion - just plug them in as recommended by Mackie using the 1801 internal crossover. Turn the 1801's all the way up, then bring the Yamaha's up to taste (you might not reach the 12 o'clock position or half way). Those Yamaha's are a great choice, I just bought 2 more yesterday as they make an excellent, loud monitor wedge.
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Mark McFarlane

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #63 on: April 03, 2014, 01:33:47 PM »

....ah okay.....I understand you now.....

One of my concerns ...... and from what I gleaned from earlier posts was that having bass guitar and pounding kick drum, floor toms.....as well as all the other instruments and vocals ........etc all going to the tops was causing me to wear out my tops......

Maybe I misunderstood.....but I thought that even with the high pass filter turned on.......it was damaging my tops having all the band going through them.......

I just assumed (maybe wrongly) that the point of the aux mix (or sub mix in my case) was to ONLY send the higher frequencies to the tops and the lower frequencies to the subwoofers? ???


oops, I missed a bunch of intermediate posts when I typed the reply below...

The drums and bass must go to your tops, they output frequencies well above the sub woofer range.  You'll completely lose the bass (upper scales and harmonics) if you don't sending it to the tops. 

When using a sub woofer, whether aux fed or not, you should filter off the low frequencies (the freqs that the subwoofer emits) from your main signal before sending the signal to your tops.

Summary: Bass, kick, toms, synths: both tops and subs
other instruments and vocal mics: to tops only.

You can actually cheat this without using an aux by, e.g., panning non-sub instruments and vocals far right and running tops off the right channel only. Pan sub-bound instruments to the center and run your subs off the left channel.  Poor mans aux-subs when you don't have an aux to spare.

If your subs have a built-in low pass filter, and your tops have an engagable high-pass filter, you may be able to 'get by' without a crossover, but those filters may overlap or leave a hole so a properly tuned crossover is a better choice.

Final note: The electric crossover numbers don't necessarily represent what the speakers will output (the acoustic crossover) so ideally you will have both a crossover and a way to measure what the combination of crossover and speakers is actually delivering.
« Last Edit: April 03, 2014, 01:37:07 PM by Mark McFarlane »
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Tim McCulloch

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #64 on: April 03, 2014, 02:11:47 PM »

Cheers Corey mate.....I bought the DSR's yesterday.......it'll be the first gig with them on Saturday :D

I really did try to follow your set-up procedure/arrangement I just couldn't quite understand how everything connected together :)

Hi Nick, here's a thought... post your city name (you can also change your profile so it will display, I think they call the data field "personal text".  http://forums.prosoundweb.com/index.php?action=profile;area=forumprofile;u=16  But put some kind of geographical reference there as there are forum users all over world, and one or two might be close enough that for a couple of pints and dinner, you can get some face to face advice and help.

Now for some more general explanation that, when taken with some of the advice already given, will help you get a better grip on the technical side of things....

I'm not familiar with your mixer and can't offer specific connection advice, but in general what you're doing with "aux fed subs" is creating a little mix that just goes to the subwoofers, much like you make a personal monitor mix where you'd only put in what the player wants/needs to hear.  As has been pointed out, there are different ways to do this and each has different levels of flexibility and control.

In the old days (before 2004 or so) that was usually done from an input channel's "Auxiliary Send" knob (auxiliary because they didn't directly affect the main mix the audience hears).  Yamaha began calling Aux mixes just "MIXes" and included a little switch that either made the MIX work like a traditional Aux send, or it would send the signal to a "Subgroup" or "Group", as had been done (and still is on some mixers) with a "bus assign" buttons and the Pan control.  Confused yet?  Believe me, at first it took some time to wrap my head around, so don't be alarmed if this doesn't seem perfectly clear the first time.

Anyway, "sub groups" and "submasters" are pretty much the same things with different names.  They provide another way for an input signal to reach the mixer outputs (note the plural) and offer a point to do things (what kinds of things?) with the inputs that are assigned to them.  Things?  Like using the group/submaster OUTPUT to send to your subwoofer.  In this case you would NOT assign the group/submaster output back to Left/Right, you want it to live in its own happy little world; and you'd assign the channel strip to both Left/Right and the submaster.  Another use of groups/submasters is to insert additional processing like a compressor on background vocals or a horn section, or an additional EQ for lavalier mics in a corporate presentation setting; in these cases the group or submaster output would be routed/assigned back to Left/Right and the group/submaster's physical OUTPUT would not be used; the INPUT channels would be assigned ONLY to the subgroup (no input routing to L/R).

By using a subwoofer and whatever 'crossover' filters are available in your speaker's processing (buttons and switches and knobs, oh my!) you help take the most extreme part of the low frequency duties and send them to the sub woofer; the top box will be much happier and the woofer or amp will live longer.  If you're blowing the high drivers, you're simply out of rig and nothing except turning down will save them.....  Using Aux fed subs allows you to keep from sending vocals, acoustic guitar, snare drum or cymbal mics, etc to the subwoofers and does so much better than any "low cut" switch on a mixer's input channels.

Hope this helps, Nick.
« Last Edit: April 03, 2014, 02:17:26 PM by Tim McCulloch »
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nicklang

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #65 on: April 04, 2014, 05:33:58 AM »

Thanks so much to everyone for all your help......You've helped me to get a better understanding of the way sound works within a PA as well as connectivity with the PA.......

:D
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John Rutirasiri

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #66 on: April 06, 2014, 02:54:27 AM »

The text in bold is the only thing completely correct in your post..

ALL Infinite Impulse Response filters (which is all of the various EQ and filters in a mixer) will cause phase shift, and the amount of phase shift is determined by the number of "poles" to the filter.  There is no way to change this by simply raising the component budget.

Tim, analog mixers (like what the OP has) do not employ IIR filters (which are a digital filters.) 

Yes, all analog filters and IIR filters cause phase shift, and all things being equal it is the number of poles and the topology the filter employs that affect phase shift.  But of course in the real world, analog filters are not created equally between mixer A to mixer B.  So it's not just the number of poles (X dB/octave) that affects phase shift and how it sounds.

Cheap mixers use cheap components, like caps and resistors with tolerance all over the place, or caps with high ESR.  The 80Hz low cut 12dB/octave on a Yamaha IM8-40 or APB (granted the cutoff freq is variable on the APB) sounds a lot better than one on a $99 mixer.  On an analog mixer, component budget/BOM and circuit topology most definitely affect phase shift, not just the number of poles.

Concerning doing aux-fed sub directly from mixer (without delay capability from a speaker processor): as I said, ideally you'd have a 3-input processor. If that's not available, the OP can still do aux-fed sub directly from mixer into his sub and use a 2-input processor for the tops.  Not ideal, but doable because his powered subs have built-in crossover.

Best,
JR
« Last Edit: April 06, 2014, 02:56:52 AM by John Rutirasiri »
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David Morison

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #67 on: April 06, 2014, 09:50:44 AM »

Tim, analog mixers (like what the OP has) do not employ IIR filters (which are a digital filters.) 


Oh boy, this is gonna be good....

Sits back...

Gets popcorn...


Decides to be less sarky and provide an actual answer instead.
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Tim McCulloch

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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #68 on: April 06, 2014, 01:05:44 PM »

Oh boy, this is gonna be good....

Sits back...

Gets popcorn...


Decides to be less sarky and provide an actual answer instead.

Nope.  I just added another name to the ignore list. I don't have time to correct every bullshit, patently wrong post.
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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #69 on: April 06, 2014, 01:50:15 PM »

Thanks so much to everyone for all your help......You've helped me to get a better understanding of the way sound works within a PA as well as connectivity with the PA.......

:D

Pay close attention to any responses from Tim McCulloch.  He is a top level working sound pro.

John R on the other hand is Way off the mark
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Re: Dissapointed with Mackie SRM450V2 and looking to upgrade
« Reply #69 on: April 06, 2014, 01:50:15 PM »


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