Amplifier current vrs watts; why is current more important?

As a Magnepan owner I will tell you I went through a couple amps trying to get the best out of them.  Maggie's are notorious for chewing up lesser quality amps and spitting them out.  They literally put one amp of high wattage into protection mode within 5 minutes and cooked the power supply.  I had a couple of monos built with about 220 watts but monster current and I finally heard all that the Maggie's had to offer.  Too much emphasis on watts.  

George - The " tone control" effect you speak of is due to output impedance of the amp. 
Man so much misinformation on here and the question was simple. The answers are going way off topic. 

I have the so called "easy to drive" Legacy Focus speakers because of their high 98 db efficiency.  But their low impedance (subsequent 20/20s were more difficult to drive) and 4 ohm preference make them difficult to drive.  Maybe it's their 3 12" woofers.  Anyway, an EAR 890 amp has great difficulty in driving them, lacking in bass and dynamics and just sounding pushed.  It's a Class A 70 watt design.  It sounds excellent on the Legacy Signature IIIs which have 3 10" woofers and slightly easier impedance curve.  

I can drive the Focus speakers with a highly modified 35 watt Dynaco 70 which has an electrolytic cap the size of the chassis underneath as opposed to the original.  Lots of power stored in that cap.  They're plenty the Sig. IIIs.  For the Focus speakers, I use a pair of 130 watt tube monoblocks, custom made, with 2 3" X 7" storage caps, huge compared to the tiny row of caps found in the EAR 890.   I  bet my big amps could drive most any speaker despite the limited wattage (although tube watts are 2 to 2.5 times more than SS watts generally, not including  Pass amps or other high current ones).

The " tone control" effect you speak of is due to output impedance of the amp.

Yes, this also as well on top of current starvation we’re talking about.

Any amp that has low damping factor, (output impedance is that high) should not be considered as well if one wants an amp that will not sound "coloured" and stays flat in frequency response.

Cheers George

Even though the OP’s title is
"Amplifier current vs watts; why is current more important?"

Just to take it off topic as oddio did, with his (excuse me) even grosser misinformation.
To show why output impedance (damping factor) is not the only cause for "tone control" behaviour, but also "available current" is just as if not more important.

Here is a typical case where "current" ability is the factor to making a flatter frequency response, more so than output impedance (damping factor)


Here are two very similar (save for their current ability) amps solid state linear each 60w into 8ohms, but their output impedance (damping factor) is more that 10 x different from each other, these are frequency response measurements (black trace) into exactly the same Kantor simulated speaker loads.
NB: Make sure you see what the graph graduation scale is for both.

1: This Budget Schiit is the one with lowish current , but the "best" lowest output impedance ( best highest Damping Factor) of DF=226 Output impedance=0.03ohm It’s FR is +- 2db
https://www.stereophile.com/images/416Schiitfig01.jpg

2: This Pass Labs one with high current but, worse 10 x higher output impedance and worse 10 x lower damping factor especially in the bass, and yet has far better control over the same simulated speaker load. It’s FR is only +- 0.025db!!!!
https://www.stereophile.com/images/1116Pint60fig01.jpg

As you can see the one, 1: with the "best" lowest output impedance (highest damping factor) is the one behaving like a "tone control" more that the other!!!!!!.
This is because the Schiit is current is limited into the low impedance loads of the simulated Kantor speaker load compared to the Pass labs.

Now back on topic, sorry hiendmmoe

Cheers George

Wow, what a rabbit hole you guys took this poor guy. His question was a simple one, one I try to answer from time to time, but within a couple of responses you guys were into slew rate, and it went down from there, with different people flexing their knowledge muscles. And I know you were trying but like a lot of forum questions it takes very little to take your eye off the ball. I thank you, for you enhanced my general knowledge but I'm not sure anyone answered his question. 

Yes, keep simple!
those 1, 2, 15 W watt amps are useless.

 Get a good amp w minimum 250-300W at 8ohm. Don’t look back, all this nonsense of if 1 watt is great, why have more......??

 Really?
jackalope!

 Power works, these flea watt,  moth,bunny, butterfly  fart amps w 1, to 15 watts amps are a joke.

done mess around.

get a good amp, and don’t look back.
silly stuff.

1 watt, HAHAHAHAH

The sound level of reproduced music is proportional to the voltage. Hence, voltage is most important.; A sagging voltage would ruin the experience.  How much current you need, depends on your speaker’s resistance to AC (a.k.a. impedance) in the audible range. Well-engineered cone loudspeakers like Tannoy, Lowther, Wilson, etc. have a high resistance to AC and require hardly any current to prevent the voltage from sagging. Electrostatic speakers, which have a low resistance to AC require a lot of current to prevent the voltage from sagging.

those 1, 2, 15 W watt amps are useless.

Really,... have a list to these 20w only into 80hm amps, and say that again.
https://img.canuckaudiomart.com/uploads/large/2097160-65b80b07-mark-levinson-ml2-class-a-mono-block-...

I'm currently planning an amplifier upgrade (current one is an Arcam PA240), and read through this thread with a lot of interest as my speakers (Focal Kanta 3) have some pretty large impedence dips in lower frequencies which has led me to look for an amp that has strong current capabilities.

I'm far from an electrical expert but I'm starting to understand the above. So far the criteria I've gathered from research is to look for:

• Amps that double wattage from 8-4-2ohms
• Amps that are 2ohm stable
• Larger power supplies

Is there anything I'm missing in terms of specs to look for that indicate good current output? Amp manufacturers don't make this easy as many list out spec sheets with varying degrees of information.

 

I'm far from an electrical expert but I'm starting to understand the above. So far the criteria I've gathered from research is to look for:

• Amps that double wattage from 8-4-2ohms
• Amps that are 2ohm stable
• Larger power supplies

Is there anything I'm missing in terms of specs to look for that indicate good current output? Amp manufacturers don't make this easy as many list out spec sheets with varying degrees of information.

i think you are on the right track, nothing substantive to add, good luck!

The challenge is the fact amplifier manufacturers don't always post that info. Then it's back to looking up reviews, forum posts, etc. 

Even the size of the power supply isn't listed often, much less current delivery ability!

@gs5556 

+1 … nailed it 

In other words…

Q.” …. I just don’t know how to read amplifier specs to identify whether an amp is high current. …”

A. Don’t look only at the headline power figure - see what happens when the impedance drops to four ohms. If the number nearly doubles, then your amplifier has good current delivery and will be capable of driving more demanding speakers.

E,g, My  integrated amp

A no compromise, super high performance, 162 W into 8 Ω (250 W, 4 Ω), dual mono amplifier.

I'm far from an electrical expert but I'm starting to understand the above. So far the criteria I've gathered from research is to look for:

• Amps that double wattage from 8-4-2ohms
• Amps that are 2ohm stable
• Larger power supplies

@christianb5s4 What is important is whether your amp can behave as a voltage source on your speaker. This does not mean it has to double power into 2 Ohms from 4 Ohms at full power even if your speaker does dip to 2 Ohms.

It will have to double power from 4 Ohms to 2 Ohms at less than full power. Do you see the distinction?

The only time there might be a problem is when you are pushing the amplifier hard, like really at full power as loud as the amp will play. All that will happen is if the amp isn't able to do the job at full power it will overload. So just make sure that the amp makes enough power to satisfy your requirements in your room.

IMO/IME its more important to get an amp that sounds like music, rather than to get one simply on its ability to double power as you cut impedance in half. That's a bit more challenging, since to get an amp to double power as impedance is halved will require (most of the time) that the amp also use feedback.

To use feedback properly without the feedback causing brightness and harshness, you really have to jump through some hoops on the design side and frankly, 99% of amps out there simply don't. What good does it do you to have an amp that can double power into 4 or 2 Ohms if it simply sounds harsh and no-one wants to hear it??

 

Thank you for the detailed response, I'm still learning about all the ins and outs of this topic but think I've gotten a decent grasp on it now. And I totally agree with your point on sound, I've never been a 'spec buyer' but like to balance good objective performance and subjective performance.

 

While my Arcam PA240 is ok at higher volumes, it lacks low-mid volume punch particularly in the bass department. And I want to get a better quality amp anyway as my system is at a much higher level than when I first got the Arcam.

 

For what it's worth, the amps I've shortlisted are Pass Labs x250.8, Parasound JC5, Coda 8, and Musical Fidelity M8 series. Also have Krell on the radar.

i have a mcintosh mc602 advertized as having 15o current per chanell! how doe's this stand??

@christianb5s4 

my personal opinion -- get a modern pass, coda or krell, you won't need to worry about the speakers being well driven, the parasound and musical fidelity are (slightly) lesser units