about speakers...

[nero1985]

ok so i have a Marshall AVT150 combo but as far as i know it gives u 150watts only when u have a 4ohms cabinet or the internal (8ohm) with and external 8ohm cab otherwise with the internal speaker only its half the power (75w), now i found this at carvin...

http://www.carvin.com/products/single.php?ItemNumber=GS12-75-8&CID=GSPK

its for sale, its 75w but is that the Maximun power of it or thats the wattage that it works the best with? cuz i wanna buy this guy

http://cgi.ebay.com/New-1x12-Open-Guitar-Cabinet-empty-Purple-chrm_W0QQitemZ7352854742QQcategoryZ10171QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

and fit that speaker in it and add it to my marshall, since the speaker is 8ohms it should give me 4ohms if i use with my amp right?

i just wanna make sure this would work and that the speaker would blow up or the amp!

id appreciate and comments,, thanks!

[Dave_B]

ok so i have a Marshall AVT150 combo but as far as i know it gives u 150watts only when u have a 4ohms cabinet or the internal (8ohm) with and external 8ohm cab otherwise with the internal speaker only its half the power (75w), now i found this at carvin...
http://www.carvin.com/products/single.php?ItemNumber=GS12-75-8&CID=GSPK
its for sale, its 75w but is that the Maximun power of it or thats the wattage that it works the best with?

Those are the speakers I bought.  They're a really good deal, IMO.  The amp reportedly puts out 100 watts with the single 12". 

i wanna buy [a cabinet] and fit that speaker in it and add it to my marshall, since the speaker is 8ohms it should give me 4ohms if i use with my amp right?

According to the back panel, yes that's how they wired it.

i just wanna make sure this would work and that the speaker would blow up or the amp!
id appreciate and comments,, thanks!

Based on what I've read, it should work fine.  Just keep in mind that the amp is not going to be twice as loud, even though it's producing more wattage.  It will be louder, and you'll have better dispersion, but you may be disappointed if you're expecting it to suddenly peel paint if it doesn't already do that.  As far as the wattage rating on the speaker, the Celestion in there is a reportedly a 75 watter (in a 100watt amp, mind you).  Do you normally play the amp wide open? 

[brett]

Hi.
Bellyflop has the deal.  Don't expect too much from an extra speaker unless you are after tone and dispersion.

If you want loudness, the way to go is efficiency.  A 95dB/W speaker makes a 25 watt amp as loud as a 100 watt amp with an 89 dB/W speaker.  That's a heck of a difference, especially considering how much extra wattage costs, while extra efficiency often costs almost nothing (up to about 95 dB/W).

My latest (and greatest) amp is a little Marshall 18 watter, but with a 94dB/W Sammi it really does the job.
cheers

[Mike Burgundy]

That would touch 110dB, almost. Good volume, that!

Assuming you have a "perfect" voltage amp, hooking up two 8Ohm speakers in parallel will increase sensitivity (dB at 1W) with 6dB. 3dB is caused by parallelling two speakers, plus the amp's output power is doubled because the load is halved to 4 Ohm - this also increases output with 3 dB.

The problem is:
-the amp still has the same maximum output power. At max, you only get the 3dB increase caused by the two speakers, the increase in wattage is not supported by the amp anymore.
-an amplifier isn't "perfect" -  there's only so much current it can supply, so when you lower the load impedance, the voltage sags a bit and the amp cannot supply the perfect double of the original power output. Notice how datasheets often state something like 100W@8Ohm, 170W@4Ohm....
So, if you push the amp to it's maximum, you'll only get *less* than 3dB increase in loudness.


More spread of sound will often result in more *percieved* loudness, though.

[nero1985]

thanks guys! what ive been doing is using a little Vox Pathfinder and using it to amplify the Emulated Line Out from my amp, i put the Vox on top of the Marshall and use it as a monitor so im just going to keep doing that and maybe buy a 30watts little amp to amplify the line out even more!

thanks again!

[formerMember1]

not to highjack but hey Brett:

What speakers are you using in the MArshall 18watter?  Is it your own build or genuine Marshall?

I have been looking into those 18watt amps, but only because the 50watt super leads are too loud.  Way too loud!!  Does the 18watter sound like a minature super lead?

PS:I used to play a 5 watt KAY amp from '62, that was too loud for bedroom practice.

Hey i see our old smiles are back.   

[Dave_B]

Hey formerMember1, not to speak for Brett, but the 18-watt is still plenty loud.  If you're looking for tube sound in a lower volume checkout Doug Hammond's Firefly at AX84.com.  .5w and ferocious. 

[formerMember1]

If you're looking for tube sound in a lower volume checkout Doug Hammond's Firefly at AX84.com.  .5w and ferocious.

Cool thanks, I always read on the forum about some firefly amp, but never really got into it. Thanks.