[drphoto]

I often see post that say something along the lines of 'the Kaboom speaker likes current". Well how the hell do you know this? Maybe mine are like me and they prefer a nice red wine instead.

Ok, I'm being a bit of a smartypants but are these statements determined by comparing a high current delivery amp to one less capable? How do you know what amps are high current capable? I'm sure it has something to do w/ the size of the PS tranny and the PS reserve caps. Is this something manufacturers post, or should? Is it part of that elusive 'system synergy'? Should speaker makers start stating whether you need the Lincoln Welder amp rather than one rated by watts? 

[Big Red Machine]

Many amplifier makers will note the current capability of their amps.  And many do not.  I had some Belles 150A Ref amps running in mono once on my Salk HT3's.  They are high current amps.  And you could tell by the way they acted and sounded.  They were quite touchy and had noisy on and off cycles just like there was a bunch of additional current needing to be handled.  I had to have Dave Belles remove their protection circuits to be able to drive the speakers w/o clipping.  The high current nature and low efficiency speaker were not a good match in this case.  Once revamped they did not clip any more but were still noisy in the on and off cycles with snaps, pops, etc.  Long gone now.

I'd bet those un-revamped amps would drive the 95 db efficient speakers I have now pretty well.  Not to say all high current amps don't have b@ll$, but it might be something to watch out for.  I think AVA amps have decent high current in the double versions and still retain the energy to drive a wide range of loads.

I believe electrostatics require lots of current to charge/move the panels and since they are not using longer excursion cones per say, can be the right match.

I like tube amps now but am not sure there are low or high current tube amps.

[Wind Chaser]

My understanding is current is the domain of solid state and voltage is the domain of tubes.

[richidoo]

You can estimate the current demand of a speaker by looking at the specs. Impedance, phase and sensitivity combined with your peak listening volume and room size. A speaker only needs what it needs. Once you provide enough power, adding more reserve will not change the sound further, but speakers require a surprisingly high power during musical peaks and transients. Without enough current these will sound compressed and distorted. Most of us use amps that do not completely satisfy the speaker. My 92dB speakers dip to 4 ohms minimum, but they prefer 500+ watts to stay perfectly clear during high volume peaks. Unfortunately I prefer tubes, which get expensive when you pass the 100W mark.

A high current amp does not have a pile of extra current that it doesn't know what to do with. Current is only drawn when the load demands it based on the voltage sent. If something is limiting current then the amp will clip or distort. Sounds like the protection circuit was limiting power on the Belles. I heard a new Belles 150A amp last weekend and it was clear and powerful and loud on 85dB speakers, a really fine amp, no sign of strain or noise. I guess he got it sorted.

[*Scotty*]

Big Red,the current capability of an amp does not make it flakey. David's amp had stability issues with your speakers and possibly others. An amplifiers current capability is governed in part by the number and power rating of its output devices and the size of its transformer and storage caps. As the transformer is the most expensive component in the power supply and its weight drives up the cost of shipping, it is the first thing to be downsized when an amp manufacturer goes cost cutting to hit a price point. A amp with high current capability doesn't necessarily sound good or bad. I like to see an amplifier be able to double it's current into 4 ohm loads, this indicates that it might be able to handle speakers with problematic impedance dips better.  It would be nice if amplifier manufacturers could use output devices that were robust enough to not need protection circuitry. The protection circuitry almost always has a adverse effect on the sound. Unfortunately it may not be possible to stop the protection circuitry from the altering the amplifiers transfer function in a negative way.
Scotty

[planet10]

Power is equal to voltage x current x the cos of the phase angle between the 2. If that phase angle gets to 90 degrees, power = 0.

Lower impedance requires more current. A more reactive speaker requires more current (assuming that it is a constant voltage amplifier)

An amplifier capable of delivering high current is often marked by a doubling of power as the impedance is halved. How low that impedance goes is a measure of current capability.

A hi current capable amp will usually have a REALLY big transformer. Because the case is bigger, more devices are needed etc, and loudness levels are logarithmic vrs power, cost is exponential -- lots of brute force. This is cheaper to do with solid state.

Also one of the reasons why there is growibng support behind the generalization that the potential quality of an amplifier is inversly proportional to its output power.

A speaker needing lots of current will typically have multiple woofers run in parallel, and a highly reative impedance (ie complex cross-overs or exotic construction -- an electrostat is essentially a capacitor)

dave

[markC]

Some hybrid amps will provide this necessary current, ( built with large transforfmers, case, etc.), and still provide the tube sound that so many of us have come to enjoy.

[ecramer]

there is no substitute for cubic horsepower current and voltage. if your getting by by getting buy get a bigger amp. I guess you can tell i don't own a set of 98db speakers and a set amp 

ED

[*Scotty*]

Something to watch for when you read loudspeaker reviews is comments about the speaker not really coming alive until it gets louder than 90 or 95dB. Most people do not listen at average SPLs this high and they certainly don't listen this loud late at night. What the reviewer is telling you is that the speaker sounds dynamically dead when it is played at lower SPLs and micro detail and micro dynamics will be reduced or missing in action. I would look for comments like the speaker came alive with the first watt put into it and handled large scale dynamic swings with ease.
Scotty