Musician Gear & Tech Discussion

Ready?

It was explained to me as since my chassis is:

Total load of 4 ohms
100 watts R.M.S.

And I have to use 2 - 10" speakers because;

1) the baffles are 2 @ 10"
2) I prefer the way a 10" sounds.

I would be best suited to use 2 speakers of 50 watts each.

With me so far?

I just looked at 2 different speakers within the same line.

1) Jensen C10R - which is 25 watts RMS/ 50 watts peak.
2) Jensen C10Q - which is 35 watts RMS/ 75 watts peak.

Am I looking for the C10R because at peak it would be 2 @ 50 watts peak for a total of 100 watts MAX?

or

Am I looking for the C10Q because it'll be fine at peak power of 100 watts
with the ability to handle a little more ?

It gets weird here. I have 2 Fender Blue Alnico 30W, 8 ohm I was going to drop into the cab, but I am getting static about it.

I get this crap about 30+30=60 and since the back of the combo cab isn't
fully closed, it may be 50%. (>??!?!?!?!>!!>?)

I just need the 2- 10" I use to be clean sounding and loud.

I thought the 2 Fender Blue Alnico 10", 8 ohm was going to be the answer.

Now I am just confused..

Do I need (2) 50 watt rms speakers>?

Should I use the (2) Fender Blue Alnico's I already have? (30W RMS per)

FYI I am really more interested in an answer that defines the mathematical end of this, as if you just shout out another speaker type I am still unsure WHY!!!!!

What amp model are you talking about?

Sorry this is an old thread.

It's a Fender Twin Reverb

You might want to consult some of these guys:


http://forum.fendertalk.com/forum.php

Hey Capt.,

Yeah, I don't think you'd wanna use any of the speakers you're contemplating.

If I'm following you correctly here, you need two 10" speakers with a combined load of 100 watts RMS at 4 ohms. Right?

OK, so the Fenders will give you 60 watts RMS at 4 ohms, the Jensen C10R's will give you 50 watts RMS at 4 ohms and the Jensen C10Q's will give you 70 watts RMS at 4 ohms. They all are below the 100 watt RMS rating you need and they'll probably blow on you sooner or later.

Now, you could use the Fender speakers you already have (or the Jensens), but only if you wired them in series as opposed to parallel, thus raising the ohmage to 16, but then your amp would only be pushing about 25 watts RMS....probably not desired.

You might want to look into the Jensen "MOD" series of speakers, they've got a pretty decent 10" 50 watt model, or even one of the 10" 75 watt speakers from Eminence. Either way, just make sure that your RMS wattage is 100 or greater.

Hope this helps and best of luck to you.

It's easy really. Don't worry. As long as you do nothing silly, you can't go wrong(?)

Always make sure that you work in RMS. Most decent gear is rated in RMS as it is the reliable measure. Kit just quoting "Watts" will usually be "Peak" (Twice RMS). American gear can be twice that! Always determine the RMS rating.

OK! Contradiction here. You need speakers that can handle more power than your amp can deliver. This is to preserve your speakers. You need a lot more power available than you need. This is to give you "Headroom" allowing you to have a nice clean, controllable sound.

Overall then, you need more Watts (power) and speaker than you will ever use and you will have a nice clean sounding amp that will last for ever!

(Fuzz/distortion was born by guitarists driving tiny amplifiers at their max through low rated, hi-fi based, paper edged speakers. This is why bands (Hendrix for example) had multiple stacks of 4x12's and several amps stood on top. It was the only way they could get really loud!)

So, with your 100Watt(RMS) amp, use whichever speakers you prefer the sound of. Don't turn it up loud enough to get amp distortion or speaker distortion and it should last for ever.

If you want max loudness from the amp then fit 2x 100Watt(RMS) speakers.

If you really want max loudness for that amp then bone up on speaker efficiency. Speakers vary enormously in efficiency. It is rated in Db or "Sensitivity". If it is important, go for sensitivity of 100. If not, a lower sensitivity will do, just turn the amp up a bit more.

Last - the impedance quoted is just a generalisation. The actual impedance of a speaker changes dramatically with frequency so the impedance (Ohms) quoted is just a guide. Don't get too wound up by impedance!

Final - Be very careful to get the wiring right. If you get the speakers out of phase you will sound terrible. Wire the speakers and put a 1.5V battery accross the cable and you can feel, or even see, that the speakers are moving in the same direction.

Last final - Power works on a logrithmic scale. Like lighting candles in the dark. To get twice as loud (in sound pressure level terms) as a 100Watt amp, you need to get 1000Watts.

To end - If you wire the same speakers in series rather than paralell, your amp will have to deliver four times as much power to reach the same SPL but, if you are interested, try wiring them both ways in turn. I think you will struggle to hear the difference.

HEY THANKS, that made it pretty easy.

I just got rid of the 2 fender alnico blue, all I have to do is find a better set of 2 10" speakers.

Try http://www.lean-business.co.uk/eshop/ Some awesome deals and Celestion is best quality gear.

Malc