New to subs, plz help!

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Sounds To Go

Sounds To Go

DJ
Dec 22, 2008
2,473
12
52
Roseville, CA
www.sounds2go.com
I haven't run subs yet, and want to add one so I have some specific questions.

First some background on what I am using now:

My tops are molded plastic (the horror) actives:
400w RMS low (15")
100w RMS high

Frequency response = 58Hz - 24 kHz

My questions are these:

1) Is there a general rule of thumb or whatnot as to what wattage of sub (minimum) you should have given the power-rating/output of your tops? Is there a ratio to be maintained so the low frequency will "keep up with" the tops?

To provide some background for this question, I am a musician for decades now and I know that the rule of thumb for guitar vs. bass amplification is that the bass amp/system should have at least 3(x) the wattage of the guitar amp system. Because the lower end requires more power to output.

Would this same general rule be applied to this scenario as well?

2) What crossover point should be used? i.e.

a) should the crossover point be the low-end cut-off point of the tops?
b) or should it be the upper-freq limit of the sub?
c) Should there be a little bit of "overlap" between the tops and bottoms to make sure nothing "get's lost" in the middle? Would an overlap result in "mud" or cancellation? Or the last choice....
d) "You're thinking too hard about this dumba$$... just hook it up, play with the crossover freq. control and leave it where it sounds good!"

(For the record, I won't be offended if the answer is "d") :)

Any feedback experience would be appreciated.

Also I am open to suggestions for subs as well. Mid-level price range, prefer to go 18" single box, and wood - not plastic for the sub. Any recommendations and the "why's" would rock.

Thanks guys!
 
If I were you I would go with an active sub in the same make as your mains, since you are using active mains. As far as Xover points most of the actives have this built in, but regardless i would stay out of the mid bass range and keep the Xover point in the 90 to 120 range.

Most active Xovers are going to give you a slope of either 6 or 12 DB between the sub and the mains!
 
What Thunder said

Sounds To Go said:
1) Is there a general rule of thumb or whatnot as to what wattage of sub (minimum) you should have given the power-rating/output of your tops? Is there a ratio to be maintained so the low frequency will "keep up with" the tops?
Click to expand...

I like double or more power to the subs others may think different
 
Agreed with Steve (Thunder). If at all possible, match speaker sets with like brands. They're typically designed to complement each other.

Some active subs contain on-board crossovers and offer left and right XLR outputs for your powered tops. This would be a great way to go if you can manage it.

With the addition of a sub box your mains will become mid tops and won't have to work nearly as hard. You will notice a big improvement in your overall tone and wonder why you waited so long. :)
 
Nice, thanks guys.

The same manufacturer does make a 15" active with a stereo crossover for +/- $500, spec here:
___________________________________

Transducer: 15 in., heavy-duty driver, 3 in. voice coil, aluminum former

Amplifier: High-efficiency tracking converter

Power Rating: 500 Watts RMS

Frequency response: 30Hz- 300Hz+/-3 dB

Sensitivity: 94dB SPL @ 1 W/1m

Input Balanced
Connector: XLR - FEMALE
Output Balanced, high-passed tracking low frequency crossover point

Connector: XLR - MALE
Crossover Frequency: Variable 30Hz - 200Hz

Switch Functions Stereo/Mono: Selects stereo or mono low frequency operation

Enclosure
Construction: 3/4" plywood, carpet covered
Finish: Black carpet
Corners: Steel
Casters: 3 in. heavy-duty
Mounting: Integral 1-3/8" (35mm) Pole Mount Receptacle

Dimensions (H x W x D): 20 x 24 x 22.75 in. (508 x 610 x 578mm)

Weight: 71 lbs. (32.25 kg)
___________________________________

How many of you would tend to agree with Marcos that one of these added and run in mono miught not be sufficient. Of course two is ideal and the ultimate goal, but if I can start with just one, would it be worth it or produce a desireable/noticeable effect? I suppose its a case of "anything is an improvement?"

At that price, I wouldnt have to wait too long to add the second one as well, Im just wondering if one would help out much.
 
I don't see why not. 500 wrms into a plywood 15" bass cabinet will give you some serious thump. It'll give your sound some nice warmth as well. This scenario should serve for most indoor shows.

If you'll be doing outdoor shows or youth-related dances you might want to add a second sub cabinet for those. Them pups like lotsa bass thump.

By the way, subs should always be fed with or run in a mono signal. Bass frequencies are omni-directional anyhow. Some older stereo recordings panned the bass to one side. You want a summed sub feed to capture it all. The active sub cab fed with both L&R signals should do this for you.

When you get your new sub, set it up at home and experiment with it in your system. Get the tone set to your liking before taking on the road. :)
 
thatmusicguy said:
what kind are they?
Click to expand...

They are actually Samson db500a's

(http://www.samsontech.com/products/productpage.cfm?prodID=1644)

I usually leave out the brand because people who don't know any better (read "equipment snobs") like to go off on tangents and slam based on the name, but they rock. They're actually made with a lot of the same components (crossovers, processors, etc.) as the Mackie's (not a holy grail for me... sorry...) that are 3(x) the price, but they're more powerful, have more low end, and are pretty darned good for the money. They run HARD all night without even heating up... the whole back of the thing top to bottom is one big heatsink!
 
I've read some pretty decent reviews of the Samsons.. If they work for you; that's what's important....

Most of those that criticize likely don't even own any gear....

I'd stick with the Samson sub.....2 15" units would give you more than enough bottom end, I've never used more than one 15" RCF at any wedding I've done.

You'll see a big improvement in overall tone with the sub (s)
 
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