2. amps-preamps
  3. 1097010033

how much current is enough?

I know that to gain 3db of additional headroom from your speakers you need to double the power from your amp...given that, its easy enough to calculate how many watts will be suficient to reach your speakers rated max volume level before compression...or to see if your amp will play loud enough for your particular listening habits...
and i know know that watt/sq.rt of resistance = current ...so i can calculate how many amps my amplifier will put out into various loads, but i dont know how many amps are enough for a given speaker...or if the difference between say 10 amps and 12 amps is a lot?

with regards to a specific difficult to drive speaker the Totem Mani 2 how much current is enough??

its specs are
4 ohm nominal...it drops down to 2 ohms, all resistive
81 db sensitivity at 1w/1m

and it uses an isobaric configuration which i gather makes it require more current than normal..but again i dont know why or how to calculate it...

so from a mathematical point of view how do i figure this out...

and in terms of the ability of am amp to put out lots of current what specs are the most important to look at?

thanks
mbacinello
jeffreybehr's avatar
jeffreybehr
805 posts
 
IMO you don't need to know that detailed current output.

Amp selection is controlled most importantly by the sensitivity of your speakers and your highest normal listening levels in YOUR room. Because your speakers are VERY insensitive AND low-impedance, you should look for a very-high-power amp that doubles its output power into 4 ohms. I'd say 250WPC into 8 ohms and 500WPC into 4 would be a good starting point.

If you love tubed amps, I recommend 2 stereo amps of at least around 75 + 75 watts. An amp like the (discontinued and hence 'affordable') conrad-johnson Premier Eleven is 70WPC into 8 or 4 ohms; with the 2 channels paralleled that turns into 140 watts into 4 or 2 ohms. In this case, using a stereo amp with channels paralleled is superior to using a mono amp of the same (combined) power rating, because the stereo amp will deliver that same combined power into half the impedance. If 140 'tubed' watts doesn't sound like enough to you, start with a higher-power stereo amp. For instance, an older c-j Premier Four will deliver 200 watts into 2 or 4 ohms from its combined 100-watt channels. Of course for stereo, you'll need 2.

I'm sure there are many more-current tubed amps that will do similar things and that you'll soon read about them from fellow 'Goners.
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yioryos's avatar
yioryos
723 posts
 
Hi I always thought that running a stereo power amp in mono configuration(even if it was designed with that in mind)degrades the sound to a degree.My Levinson 27.5 is capable of turning into a monoblock but reading it's manual clearly indicates that is not advisable.That,s why there are separate monoblocks to begin with.
My two and a half cents.
jeffreybehr's avatar
jeffreybehr
805 posts
 
Well, your Levinson is solidstate and those I mentioned are vacuumtubed. GENERALLY, when SS amps are 'monod', the channels are bridged so that the maximum power quadruples, not doubles. However, each channel drives only half the single impedance, so bridged SS amps are NOT high-current amps. The channels of tubed amps are paralled so they're generally able to increase current output enough to combine the output of the 2 channels. BTW, I understand that SS amp channels can be combined this way, but the only manufacturer I know of to recommend it is B&K.

For Mbacinello's VERY insensitive and low-impedance speakers, I am NOT recommending a bridged SS amp.
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