Karaoke Forums

How important is a sub bass amplifier.
I have had to part with a DB 15" active
because I am not healthy enough to carry it very far.
I have just replaced it with a pair of Electro Voice SB122's,
although most of the time I would probably only use one of them.
My Mackie SRM 450's dont need that much help.
Venue's in the UK tend to be smaller than those in the US.
Question is...
Since the sound from sub bass is little more than a fart,
does it really deserve a quality amplifier.
I would like a Crown or C Audio 602 which would give me
380 Watts into 8 ohms.
For less money I could buy a cheepo 5 - 600 Watt Amp.
I love Crown amps, but would I actually notice the difference
on sub bass frequencies.
Also
Although the EV's include a passive 150Hz filter,
would the amplifier not be more efficient only
amplifying the sub bass frequencies.
I feel I might get better results using an active sound module
to send say 40-100 Hz to the EV's and 100Hz up to the Mackies.
I only use a mono signal that I want to split 2 way.
X-overs I have googled seem to insist on 3 or 4 way.
Other than using a stereo Graphic Eq... what are my options.

If you are using a sub a good 2 way crossover like a dbx 223XL would work. As far as an amp for the sub, I would run an amp that would double the main - ie if the mains put out say 500 watts i'd want the sub to push 1000 to really be effective. It wouldn't necessarily have to be the most top of the line amp (although preferred IMO), but if you are only running one sube at least match the bridged output to the program power of the sub!

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IMO, it's even more important to use a better amp for your subs than your mains. And they need to be matched together. Low end frequencies are much more demanding on an amp than mids and highs. An underpowered amp is a greater risk to frying subs than an overpowered one. I firmly believe you get what you pay for and stick with the better Crest and Crown amps only. You'll also get much more control with a good, clean active crossover, too.

Bass is the narrowest freq range but the most important.....It is also the hardest and most expensive to do right.

The best sounding rigs have the brightest highs and tightest bass.

Give your horns twice their program rating and 4 times that for your bass.....200 watt program bass cabs need 800 watts RMS amp power.......you will fry bass drivers quicker with too little power before you cook them with too much.

If your bass cabs have built in crossovers, then bypass them and connect using an active xover set at about 150 Hz, then attenuate sharply all freqs below 60 Hz.....also make certain to use low cuts on all mics when live.

In that case It looks like I have made a bad choice.
To power a single EV SB122 ... 400W @ 8 ohms,
I bought a KAM KXR1000
It is a cheep reliable Amplifier ??? Its also light. (Important)
500W x 2 into 4 ohm, 340W x 2 into 8 ohm.
Will run in bridged mode which is what I would use...
If I actually do use it.
I can not find any spec on bridged mode.
Should I use it... ???

Sorry, all specs I use are RMS.
I dont even know what program and peak are.

I see nothing referencing this amp to be bridgable in any fashion. I would not try to use it bridged - you could blow it up.
The EV sub would really need an amp to push 800 watts. The per channel rating on that amp is very low for that subs program requirements.
If you got one amp that you know could be bridged, that would be better. Even the Behringer EP1500 could be used bridged for that 1 sub. Then when & if you need to add another, the same amp could be used to bridge both subs in parallel.

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I have just pulled the following from

http://www.kam.co.uk/index.php?action=p ... uct_id=103

500W RMS power amplifier

Outstanding build quality and reliability
Thermally efficient central heat sink design
Vented front panel with forced fan cooling
Thermal protection relay
Peak signal protection
Balanced XLR audio inputs
Unbalanced 1/4 inch jack audio inputs
Speakon and binding post speaker outputs
Bridge mode operation
Earth lift switch

SPECIFICATIONS
Minimum impedance: 4 Ohms
500W RMS @ 4 Ohms per channel
340W RMS @ 8 Ohms per channel
S/N ratio: 84dB
THD: 0.1%
Dimensions: 341 x 88 x 481mm
Weight: 12Kg

Product code: 4768

Well it says it can be bridged, so I guess it's possible. Although not giving the bridged wattage is very odd but should be a little closer to the subs recommended power. But one thing it does state in their 'tuition' is that they don't accect anything lower than an 8 ohm load in bridge mode, so you would only be able to use that 1 sub, if you needed to add another later, you would need another amp.

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You need 800 watts at 8 ohms to properly power your speaker.

This is not an exact match but will do the job in bridge mono. And since you like crown, the price is very reasonable.

http://www.pssl.com/Crown-XTI-1000-Powe ... W-8-Ohms-s

I personally would us a QSC

http://www.pssl.com/QSC-PLX1802-Dual-Ch ... ifier-330W

Thanks for your input guy's.
Thing is I got the Amp off Ebay for $140. (£87) inc. shipping.
Yes I do like the Crown and the QSC.
Once I start earning, thats the direction I will be going.
I can't find much in the way of used DBX at the moment.
There is one on ebay ending in 2 days I'm watching.

Goto qscaudio.com and find the right choice for your speakers. Budget and weight are considerations.