General Questions

[Rich newby]

hi

thanks for that paul, I had not realised. its 700w per ch at 4ohm

rich

 

and the speakers are 8ohms each

[PDD]

In that case you won't have any problems but do be aware that your amp is capable of vastly over-powering your speakers. Keep the level right down! You won't be able to add any more speakers (in parallel), as with two speakers per channel you're already down to the 4 ohm rating, however you could easily use larger speakers with that amp if you need more power.

[Rich newby]

hi

so dose this mean that the amp is matching the speakers? as the speakers will be 900w per side if I have added that up in 8ohms(I belive that that is what the mesurment is on the back of the speakers). so running the amp at 700w the speakers will be around that at 4 ohms as well?

[PDD]

so dose this mean that the amp is matching the speakers? as the speakers will be 900w per side if I have added that up in 8ohms(I belive that that is what the mesurment is on the back of the speakers). so running the amp at 700w the speakers will be around that at 4 ohms as well?

<{POST_SNAPBACK}>

 

How many speakers do you have? If only 2 speakers per side, 150W + 300W only equals 450W per side in my book <_<

 

Each speaker is 8 ohms = 4 ohms per side, as "seen" by the amp. (It makes no difference to the speakers, except the amount of power they get).

 

The speakers are still 450W per side (if I've understood you correctly), being driven at 700W per side by your amp. Hence, over-powered, but not necessarily disasterous as long as you're careful.

[Rich newby]

sorry your right its my maths ok(and on my last post in our other convo)

the speakers are 450w per side and 900w total.( its with the 1.4kw amp being bridged and not per channel )

 

sorry and thanks paul

rich

[James]

In that case you won't have any problems but do be aware that your amp is capable of vastly over-powering your speakers. Keep the level right down!

<{POST_SNAPBACK}>

 

This can be miss understood.

 

with a video signal (0.7v) if you fade it half way down you get 0.35v

 

With a dimmer (240v) if you run it at 50% you get 120v

 

With a 700W Amplifier, if you turn the gain down to 50% of the maximum you can still get 700W out of the amp. An amp clipping will still be putting out its maximum power weather it is at "number 1 or number 11" on the gain dial.

 

BEWARE

 

It depends on the input signal you give it, and your gain stage. Get a piece of paper, a calculator and work out your gain structure.

 

so dose this mean that the amp is matching the speakers? as the speakers will be 900w per side if I have added that up in 8ohms(I belive that that is what the mesurment is on the back of the speakers). so running the amp at 700w the speakers will be around that at 4 ohms as well?

<{POST_SNAPBACK}>

 

How many speakers do you have? If only 2 speakers per side, 150W + 300W only equals 450W per side in my book <_<

 

Each speaker is 8 ohms = 4 ohms per side, as "seen" by the amp. (It makes no difference to the speakers, except the amount of power they get).

 

The speakers are still 450W per side (if I've understood you correctly), being driven at 700W per side by your amp. Hence, over-powered, but not necessarily disasterous as long as you're careful.

<{POST_SNAPBACK}>

 

 

Careful

 

If you have two cabinets presenting a 4 ohm impedance to the amplifier then they are going to have the same voltage across them (beccause of the laws of physics) and they will draw the same current.

 

"150W + 300W only equals 450W per side in my book" doesn't work in this case

 

BE CAREFUL

 

you can easily damage your 150W cabinets before you are properly driving the 300W ones,

 

not generaly a good idea to mix cabinets like this.

 

James

 

Moderation: Two posts merged.

[PDD]

I was trying to keep things simple for the OP. <_<

 

 

It depends on the input signal you give it, and your gain stage.

 

I meant watch the level at the desk, rather than referring to the amp, but I agree that wasn't clear.

 

not generaly a good idea to mix cabinets like this.

 

I agree, but let's just say these speakers are all the OP currently has available. Not a lot he can do about that, until he gets some cash for new gear. Making the best of a bad situation in this case, but a situation I can sympathise with, as when I was the OP's age, I was having to use a similar mix-match of kit.

[James]

I was trying to keep things simple for the OP.  <_<

 

 

It depends on the input signal you give it, and your gain stage.

 

I meant watch the level at the desk, rather than referring to the amp, but I agree that wasn't clear.

 

not generaly a good idea to mix cabinets like this.

 

I agree, but let's just say these speakers are all the OP currently has available. Not a lot he can do about that, until he gets some cash for new gear. Making the best of a bad situation in this case, but a situation I can sympathise with, as when I was the OP's age, I was having to use a similar mix-match of kit.

<{POST_SNAPBACK}>

 

If that is all the OP has then that is fine but you said

 

How many speakers do you have? If only 2 speakers per side, 150W + 300W only equals 450W per side in my book 

 

Each speaker is 8 ohms = 4 ohms per side, as "seen" by the amp. (It makes no difference to the speakers, except the amount of power they get).

 

which I would take issue with,

 

150W + 300W equals 300W per side in my book. Yes you can get 3dB more power out of the 300W speakers but that would be overloading the 150W speakers with twice as much current as they are rated to handle.

 

I would advise the OP to run 150W + 150W on one side of an amplifier and 300W + 300W on the other running the rig in mono. That would give 450W per side. But it is a lot of effot for only 1.7 dB extra gain.

 

James

[Rich newby]

hi guys

just thought of this one!

whats a reverb unit?

and wot is gain, and why would 2 mics effect it?

 

cheers for all your help

rich

[paulears]

Rich - are you serious?

 

Assuming you are, and are not taking the p*ss, then:

 

Reverb unit. a device that has audio applied to it. Reverberation and often echo, phasing and other weird sounds are then added to it in amounts you can adjust. this then gets fed back to the mixer, or guitar amp or whatever and makes the sound, well.... effected.

 

If you need a definition of reverb. Imagine echo, as in "echo, echo, echo...." Replace the word "echo" with say a hand clap. reduce the gao between the echos until instead of separate claps, it is just one longer one - echo has become reverb. This is a bit simplistic, but essentially correct. real reverb, as in a church is the result of large numbers of individual reflections from the hard wall, floor and roof surfaces. These arrive at many different times and create that great sound. Bigger rooms don't have many early reflections as the surfaces are all a long way away. Your ears and brain together can tell how large a space you are in. electronic gadgets try to recreate this and offer loads of different programs designed to recreate it. Cheap ones tend to have a 'grainy' kind of sound, while expensive ones sometimes even include the parameters of real buildings to make the sound more realistic.

 

In practice, revern helps vocals sound better. Some singers have to have it in the monitors or they say they can't sing properly. Saxes always sound dreadful without a little reverb to soften the sound up.

 

Gain and two mics? you need to put this into context? Gain is amplification - as in the gain control on a mixer strip, or the gain knob on a guitar amp. You need gain to bring a mic level signal up to line level and you need gain to get line level up to something that your speakers will respond to.

 

Two mics - more info please. I suspect a visit to the local library for real books to read may be a good thing. Basics are not best picked up from the net forums.

[fredfish]

Very useful thread.

I have another newbie sort of question: Starquad mic cable, looks very complicated for a cable which is terminated in a three pin connector. for a start, why the extra core, and why put them in pairs? was it origionally designed for stereo signals? also is the foil connected to anything? (sorry if this is hijacking someone else's thread!!)

[paulears]

it's ok.

starquad is a brand name, but gets applied to cables that have 4 conductors. Actually, there are two 'pairs'. I assume you understand the concept of balanced interconnections - starquad is even better at getting rid of, or reducing unwanted noise on the wanted signal. The two pairs are twisted pairs, as usual, but have different 'lays' - that is they have different amounts of twist. At each end, you take the 'A' leg of each pair and join them together, the same with the 'B' leg. This means it still carries just one circuit - but the two different spiral enable it to reject noise even more - really good for on stage use where there are loads of nasty dimmer circuits radiating rubbish all over the place. Broadcasters love starquad - anything to reduce noise and interference. It could be used for stereo - but as there is nothing separating the cores from each other, crosstalk might be a problem.

[Rob_Beech]

Clicking here for a topic that Talks a little about it. its generally accepted that there are advantages and disadvantages to using different types of cable. Cost is one thing but more importantly, noise rejection, capacitance and impedance.

 

Rob

 

........Thanks paul :)