Oh, I forgot to mention that Bob, I changed the setting ffrom 50 to 30 HZ as per Guys advice.

Are you suggesting I turn it off altogether?

Sorry Bob, just re-read your post and I think you used the exact words "turn off altogether"

Just 2 questions to summarise though,

1. Do different amps produce different tones?

2. Does everyone take those range figures seriously? Am I the only one cutting the frequencies so strigently.

OMG, I was assuming you had everything flat! No wonder! Anyway, just shows what testing will reveal. The head amp may well not be flat; may emphasise bass amongst other things, even when set flat.

There's no need to use more than one low cut filter, and not even that if you're careful, and use your meters on the kick, bass, keyboards, sampler ... anything that can make a lot of lows.

--------------------
PA stuff on FB

Quote Scatamonkey:

---

The Behringer crossover was the first thing I checked. The last thing I did was take it out of the loop altogether.

So it's just Desk (A&H ZED22FX) going to amp (Numark Dimension 4) and then to speakers!

This is the simplest setup I can have and still produce sound, the speakers are 2-way full range and have two 15" drivers and a horn. So SHOULD produce a full range signal with plenty of bass.

To clarify, there were NO crossovers present during the final setup!

---

Quote Scatamonkey:

---

Tonight I thought, "I wonder how much music is hiding down in those frequencies?" So I turned the Low Cut pot all the way off, and put all the sliders back in the middle...and low and behold, the speakers started to sound a lot bassier.

---

Which is it?

--------------------
Ohm's Law states, "Your PA isn't as powerful as you think it is".

Okay Guy, so if it were your system would you....Turn off the Low Cut facility on the amp altogether AND turn off the low cut facility on the Behringer ? And just pull down the first 2 sliders, I think they are 20 and 25HZ ?

I still think I am fundamentally misunderstanding the speaker spec sheet. It says it has a range of 50 - 20,000HZ.....but....when listening to say dance music I brought the 40 HZ up and then the 31.5 and there is quite a substantial bit of low bass goodness down there.

I turned the bins on and they sound a hell of a lot beefier with the extra low frequencies and with the crossover down around 100-120HZ! Although, the trade off being, the amp is having to work a lot harder to reproduce those low frequencies. Without touching the volume, simply pushing up those 2 sliders shows a significant increase on the signal meter on the amp.

I still think I need a bigger amp for those bins!

From what I can find, the spec sheet for those speakers gives 57Hz as the -3dB point and 44Hz as the -10 point.

So your 50Hz figure is probably somewhere like 6dB down. It does not mean that the speaker does nothing below this point - what is happening is that the speaker is much less efficient at these frequencies. If you feed it a signal with a boost of 6dB at 50Hz it will bring the volume at that frequency (range) back up. Similarly a 10dB boost at 44Hz.

However, that boost as asking a lot more from the amp, which will then start to run out of headroom, so it's not a particularly good way to run things. This is where you need your subs to take over.

So if it were me, with that equipment, I'd use the HPF of the amp for your top cabs. This will stop the amp from using power that the speakers are not making efficient use of. I'd decide between the 30Hz & 50Hz by listening (& watching the amp's clip lights), though I suspect I'd end up at 50Hz. Then the subs can be set up to take over where the tops give up.

Don't try to use the sliders on the graphic to turn it into some kind of crossover (something i've seen quite a few people do - it does not work), but I would use the HPF its got to avoid feeding the sub amp with anything below the useful range of your subs.

Thanks Mark, its all starting to make a lot more sense. I WAS using the sliders...and the Low and High pass filters on the Behringer AND the Low cut set to 50 on the top amp.

I realise now that using the sliders was also robbing the bins off those lower frequencies too.

When a speaker manufacturer gives you the power figures, do they take those lower frequencies into account. What I mean is, if I DID boost those lower frequencies by 6 and 10db on the bins to bring them out at the same SPL as the other frequencies - does that equate to the 500 watt program power on the spec sheet?

I imagine it would be a lot more and that those figures are calculated on a flat EQ!

Do all you sound men out there use much of those low frequencies for a normal band setup?

I mean below 50HZ?

Isn't it just sucking all the power from your amps?

Quote:

---

Isn't it just sucking all the power from your amps?

---

Not if you've got subs or full-ranges that can handle it. Or rather, it *is* sucking power, but that power is going into stuff that people can hear.

Exactly how low you go will depend on your subs. You'd be lucky to get anything significant at 35Hz from most subs that you can fit in a car. (Sure there's exceptions - but they're exceptional...)

Okay Grab, so would you concentrate on everything above,say, 40 HZ....I'm not sure if I'm explaning myself right. The power required to generate low frequencies seems to be almost exponential the lower you try to go.

So for my system, would you simply forgo those frequencies to give you more headroom for the higher frequencies - 40 - 120HZ.....this is just the bass bins I'm talking about!

You forego those frequencies because all they're doing is generating a little warmth in the speaker coil, not actually producing anything audible. It's wasted power. If you don't waste that power, there's more left for frequencies that you *can* hear.

Awesome advice from everyone - I think Ive absorbed all I can on this subject, I'm still a little shocked that an amp also comes with its own emphasis. It actually works really well in my setup. But If I tried to use my tops by themselves I would have to push the bottom end a bit.

I formally invite you all over to Derry for the Jazz festival which is at the end of April start of May - some of the best jazz bands you will ever hear from all parts of the world will be attending and it lasts for four days !!!!

Next project - shopping for an a new amp...a cheaper version of a Powersoft digital amp would be nice !!!!!

You might be surprised what you can find in that second hand shop on Shipquay St.

--------------------
Ohm's Law states, "Your PA isn't as powerful as you think it is".

Shufflebeat!!!! You know Derry better than some of the locals...leading me to believe your not a Mancunian by birth.

I lived over there for about 5 years laying in a band called 'Jist'

We played loads of venues over there, The Manchester Academy and The Roadhouse being 2 of my favourites. But one of the most enjoyable gigs was in The Revise in Chorlton. The night was run by a dude from Belfast. Our "P.A." consisted of 2 of the oldest and most knackered speakers you've ever seen running off an old guitar valve head!

Luckily the only thing it had to deal with was our lead singer and he had so much volume he didnt need a mic half the time!!! Ah good memories, I actually have a recording of that gig that was recorded through a tiny condenser lapel mic onto a Sony minidisc.

Considering the equipment used the recording turned out surprisingly listenable to!!!

Graphic eq bands always interact unless you are using very small cuts and boosts. If your graphic eq sliders are at full cut they could easily be affecting signals an octave or more either side of the centre frequency.

Amps can certainly sound slightly different although it could be a slight roll off of the top end on the cheaper amp that makes you think that it has more bass.

James.

--------------------
JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net

This next question is the sort that always gets you guys in a debate.

I'm planning to give those bass bins a Numark amp each - 1300 watts @ 8 ohms, I don't like always being at or near the point of clipping so that should give me loads of power and loads of headroom.

So now I need to buy an amp to run the full range tops, they are 500 watt program @ 4 ohms, so Im looking for an amp to provide at least 750 - 1000 watts per channel @ 4 ohms.

Suggestions please....the bestest cheapest amp to give me this power. Money is definitely tight as I wanna upgrade the monitors too....and my van!!!

There is a Crown XLS2500 on DV247.com for 583 quid. 775 watts per channel @ 4 ohms.

That seems like a pretty good benchmark, the equivalent QSC RMX2450 only puts out 650 watts per channel and is 16 quid dearer!

How are these companies working these figures out - my Numark is 1900 watts max, but claims 660 watts per channel @ 4 ohms. The QSC is 2400 watts but only puts out 650 ???

I just looked at another page quoting power figures for the QSC, it says 650 watts from 20HZ - 20KHZ and then 750 watts at 1KHZ.

Which figure do you guys work from???

Sorry another question, before you have even answered the last, are Samson amplifiers any good? What is a Class H amp? Better or worse that a Class D?

Samson SX3200 gives 1100 watts per channel @ 4 ohms and is only 434 quid !!!!

This could be my next purchase unless someone out there tells me Samson are rubbish!

I know the SOS Forum stands divided on this but....

How about a Behringer EPX3000 switch mode amp, 900 watts per channel @ 4 Ohms for 295 bucks!!!

Behringer and the Thomann T.Amp range seem to be recommended budget amps if you can't afford anything better. I've used the QSC RMX range for industrial applications and they seem to be more rugged than cheaper amps although they're heavy.

James.

--------------------
JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net

Just looking at the T.amp D3400, 2 X 1800 watts @ 4 ohms for 399 quid. Thats a lot more power than I need but headroom is what we're after isn't.

In an emergency that thing could just about power my whole rig!

I use QSC amps pretty much exclusively, but happen to have a Samson SX3200 and have had no issues with it. If this is a professional application, I wouldn't settle for anything less than Crown or QSC. Half my Behringer stuff failed, the other half had little resale value when I decided to quite that brand entirely. Of course a cheap brand MAY work, but MAY and PROFESSIONAL are words that do not mix!

I suggest you check out and read ( you haven't already) the very good tech notes articles from the old 'Performing Musician' mag which are available here: Performing Magazine

Bob

--------------------
www.bickerton.co.nz

Try your kit now it's sorted, with those 4x15s and 2x18s now working properly. Forget new amps. Remember the loudness vs. power equation.

--------------------
PA stuff on FB

I did a wedding at the weekend there, band plus DJing. Sound was much improved, with the extra low end the kick drum sounded a lot boomier. Not in a nice way but then it was a circular room which sounded very reverby anyway. With the whole band playing the sound was great. Weirdly, I noticed the bass amp didnt seem to run as hot as before. I had it rnning down to 31.5 HZ but I also brought the crossover down to around 100 - 120 HZ. Maybe running in a more concentrated band of frequencies is easier on the amp!

Guy, although I don't "need" new or different amps, buying a new one is more for peace of mind. I dont have a spare and have been gigging those Numarks flat out for about 3 and a half years.

I would rather be running 3 amps on half power than 2 at full power! Plus, with 3, if one fails I know I can still achieve a full sound with any of the remaining 2!

That's a very sensible argument about the new amp!

--------------------
PA stuff on FB

What do you think Guy, the Samson SX3200 or The T.amp D3400 ???

I'm not up on amps at the moment, but I'd go for a class D switch-mode job.

There will be people here who've bought amps much more recently, who'll know more, and you could check out the LAB lounge forum. They are helpful and more oriented to live sound, though it's American, so they won't have Thomann! And, they can be frosty at first...

Worth checking out the second-hand market, too.

And remember to get an amp with loads of power, and one with built-in limiting!

--------------------
PA stuff on FB

I thought I'd heard iffy reports about those Thomann digital amps, so I googled.

http://forum.speakerplans.com/tamp-d3400-review_topic11188.html

Hmm...

OTOH the Thomann TA2400 is pretty bulletproof. They've got an old-school power supply so it's heavy as hell, but it does means you can push it hard and it'll just keep on going. So long as you don't have a bad one anyway (always an issue with made-in-China), but if it lasts the first couple of months then it's probably going to run forever. Apparently most of the lower-end amps at this rating (this one, W-Audio, etc.) are all actually the same amp with different badges on, so might as well get the one with the best price tag.

The Thomann TSA2200 isn't as solid though - it's a lot lighter with the switch-mode power supply, but apparently this power supply isn't actually man enough for the power it's supposed to be putting out, so there have been reliability problems reported with it.