Semir

[Pan]

If you want a two way loudspeaker you should choose a 5"-8" driver for bass and midrange frequencies, and a tweeter for the high frequencies. You will also need to use a crossover to filter out the part of the signal that should not go to that particular driver.

This is not very easy to do, designing a speaker from scratch. Maybe you should go with a design on the net?

You do not need to search for a "25W" driver. But depending on how loud you want to be able to play you need to a balance between the amps 25W (which may be a true or false number) and the sensitivity of the drivers chosen.

Good luck!

/Peter

[Bill Fitzpatrick]

Thanks for the tips.

[Pan]

Hardly news for you Bill..?

Maybe I should have picked another name for the thread. However Semir asked some OT questions in another thread so I suggested that those be answered here instead.

/Peter

[Semir]

Hi there!

Above all, thanks for the reply. But actually these were the things I was familiar with

My "white spot" is at the end. I meant I have an amplifier with 25w output power. For this (I can take for sure ) a speaker should be used that is capable to handle this 25w. But what happens if I connect two speakers as you ment it too, a bass-mid and a tweeter? Should both be 25w, and connected in paralell (and using a crossover), or what?

See my problem?

Thanks a lot!
Yours, Semir

P.S.: Sorry for the offtopic thing but somehow I felt that the message will be in a good place there In a way, my problem is connecting to that spl topic, too.

[Semir]

Oh, seems silly question even to me after some thinking )
Tell me if I wrong, but both are connected to the crossover circuit. So neither parallel nor serial...

But how does it affect the impedance of the speaker and the power that is needed to drive them (the two in one box)?

One other thing which was not clearly answered for me by anyone: how should a speaker designed with respect to the amplifier used? If I use a 25w amp, should the speaker be 25W, or its musical power should be 25w, or should it be designed to be greater, or smaller? (with respect to sonic performance and the lifetime of both the amp and the speakers)

Why is that I feel myself even dumber when I try to correct a misstaken question of mine?? ))

With regard,
Semir

P.S.: so after these basical problems, I would not want to go into the questioning of these slope, and dB and the other things ) But one! What is this sensitivity thing? The input sensitivity of the amp and the speakers and every kind )

[Pan]

Hi!

"I meant I have an amplifier with 25w output power. For this (I can take for sure )"

Marketing numbers and reality is two different things and the power you can get from your amp depends on the impedance of the load... which has a variation with frequency.


"a speaker should be used that is capable to handle this 25w."

It depends on the sensitivity of the speaker and how large room you have and how loud you want to play..

"But what happens if I connect two speakers as you ment it too, a bass-mid and a tweeter? Should both be 25w, and connected in paralell (and using a crossover), or what?"

Yes, a crossover will be needed. Normally the drivers are connected in paralell to the amp and have a x-over between each driver and amp output. There is no such thing as a "25W" speaker driver.


"But how does it affect the impedance of the speaker and the power that is needed to drive them (the two in one box)?"

The impedance in the high range is determined by the tweeter and the midbass makes up the impedance in the low range. They meet in the middle range and there the x-over usually makes the impedance higher. The power needed to driver them depends on the voltage sensitivity of each driver.

"One other thing which was not clearly answered for me by anyone: how should a speaker designed with respect to the amplifier used? If I use a 25w amp, should the speaker be 25W, or its musical power should be 25w, or should it be designed to be greater, or smaller? (with respect to sonic performance and the lifetime of both the amp and the speakers)"

See answers above.

The rating you sometimes can see on drivers, regarding power, is normally what peak power the driver can handle in short bursts. It can also be a thermal rating. In the end this depends very much on the application since the x-overs of use comes into play. This is something you should try not to think so much about. There are other things you need to worrie about to get things right.

"But one! What is this sensitivity thing? The input sensitivity of the amp and the speakers and every kind )"

The input sensitivity of the amps tell you how many volts (millivolts) you need at the input terminals to give the rated output power from the amps. Sensitivity of a driver tells you (normally) how loud a driver will play in its midband when a 2.83 volt signal is applied to the driver terminals (often specified on a IEC baffle).



/Peter

[Pan]

Follow some threads for a while and soon you´ll get the hang of all of this.



/Peter

[Semir]

Hi!


Woow! That sounds great! )

Now, I am getting pretty sure about that I have not got any idea about what a driver can be...

But! Surprise, surprise! ) I am familiar with the impedance things )

And one other thing: I am building the amplifier, so it can be taken almost for sure that it will make 25w into 8ohm. As it was written ) And hope so. I can understand that it will give 25w only if u use it on maximum volume etc... But still I believe I cannot understand something from this...

Oh, I would be greated to follow up with the treads, but time time time!! ( And Im following many other forums for the amp, and reading books, articles etc, for both. Its too much I must confess. And the exam period has just started But I desperately want to build these things, and listen to music through them. Do you see? eh.
Thx for all the help!

Have a georgeus day!

Bye!

[Semir]

Hi!

Just one more question What is the "rated power" and what are the "rated" things?

Thx!

Bye!

[Pan]

A driver is a speaker unit.. a tweeter is a driver.. a 10" woofer is a driver as well.

The "rating" is simply what the object can do. When you read the power rating of an amp, you need to know HOW they came up with that number. There are different standards and some follow them while others do not.

The rated power into a 8ohm load is usually different from a 4ohm load. A "perfect" voltage source amplifier wil give double power everytime the load impedance is 1/2. So if you have a amp that give 100W in 8ohm, then it will give 200W in 4ohm. IOW an amp can be a "25w amp" and at the same time a "50W amp" and a "100W amp" depending on the load it is supposed to drive... load = speaker.

Also the amount of distortion at that rating is interesting. Some manufacturers look at the distortion and (dist. normally increases with level) when the dist. is at a certain level they read the power and call the amp a "25W amp" from that reading.

Some makers may draw the line at 0.1% THD while other choose 3%. Most amps will sound like poop at 3% though and therefore those numbers are not really worth anything... only serve to fool uneducated customers.

The right way is to choose a speaker that have performance that suits your needs, then you pick an amp that can deliver the power you need for the specific use.

If you have a 8ohm speaker with 90dB/2.83V sensitivity then a 10W amp will give you 100dB and that may be enough for many people. If you want to push that speaker up to 110dB you need a 100W amp and so on..

A typical two way may have a 85dB sensitivity and a 25W amp will not get you to 100dB but if you have a 105dB horn speaker and a 8W tube amp (as an example) will give you 114dB or so.

So it´s all a question of balance between the gear and the situation it will be used in.