How Much Current Capacity do we Need from our Amplifiers?

[EJ3]

Holy Cow!! You took the "My wife can hear the difference in the kitchen" and stepped up to I listen to my music "in the yard"! Now that means speakers that can put out some serious spl and an amp than cane handle it all without massive clipping. You are what I like to call a 1 percenter. That rare individual who has an extreme use case. I have to tip my hat to you, I never thought of having a system designed for in home use but using for yard listening. I learn something here every day. Your system must have some serious balls as it would be referred to by audiophiles!! I guess the obvious question is, what do the neighbors say?

In room, windows and sliding glass door open: 112 Db. Obviously one cannot stay in the room at that volume level but it's fine for listening outside.
System 2.2: Each speaker gets its own bridged mono NAD 2200 and the subs get their own bridged PROTON D1200's (running at 4 OHM's).

 

[Spkrdctr]

In room, windows and sliding glass door open: 112 Db. Obviously one cannot stay in the room at that volume level but it's fine for listening outside.
System 2.2: Each speaker gets its own bridged mono NAD 2200 and the subs get their own bridged PROTON D1200's (running at 4 OHM's).

Fantastic home and yard. I am impressed.

 

[Ropeburn]

Why would I have a yard so small that I would bother the neighbors? That defeats the purpose of having a yard.
Not an issue here, though:
View attachment 540644
The last home on the electrical grid, nearest neighbor: 1/4 mile. Second home (40 miles away) back yard:
View attachment 540647
View attachment 540648

Ah yes, I forgot. You've shown these a while ago! A little paradise. Lovely

 

[CDMC]

Why would I have a yard so small that I would bother the neighbors? That defeats the purpose of having a yard.
Not an issue here, though:
View attachment 540644
The last home on the electrical grid, nearest neighbor: 1/4 mile. Second home (40 miles away) back yard:
View attachment 540647
View attachment 540648

Congratulations, you just self nominated to be our resident subwoofer tester.

 

[Ropeburn]

Congratulations, you just self nominated to be our resident subwoofer tester.

Petition to krautfund him a fat outdoor PA with wall of bass and line arrays. Plus power infrastructure like nice solar system and all. Perhaps 48V so there need not be AC inverter...

 

[EJ3]

Fantastic home and yard. I am impressed.

Thank you, the property with the small house facing the river was bought by my parents in my birth year (1957) and they designed and built the original home (with the assistance of family friends). As it is in a River/Estuary preserve, the original 800 sq. ft. cannot be changed. But, over the years family and friends have helped change the interior layout and deck. The other property was bought by my family in 1964, my parents designed and built the home with family friends. We moved in in 1962. My 92 year old mother still lives their full time.
A few pictures around the Edisto River home:

A few shots around the Simpson Creek home (and our clock that is on the TIDAL schedule, not the 24 hour schedule:

 

[Ropeburn]

 

[john61ct]

must be nice

 

[Imakeller]

The quote below from Amir’s ASR review of the Revel F328Be indicates a dip to 3 ohms:

Revel F328Be Speaker Review​

This is a review and detailed measurements of the Revel F328Be floor standing speaker. I purchased a single unit through our company (Madrona) with kind discount from Harman Sales (I asked for a review sample from the PR group but was told "don't call us, we will call you."). The retail cost...

www.audiosciencereview.com

“Finally, here is our impedance measurement:

That is a pretty low impedance so make sure you have a good, high-current amplifier to go with this speaker.”

Amir recommends a HIGH-CURRENT amplifier. Is there a correlation between high-current and high-wattage? My Buckeye Purifi 1ET9040BA monoblocks feature “a robust 40A output current”, so I’m sure they’d meet Amir’s recommendation, but it got me thinking about the importance of high-current?

 

[john61ct]

The quote below from Amir’s ASR review of the Revel F328Be indicates a dip to 3 ohms:

Revel F328Be Speaker Review​

This is a review and detailed measurements of the Revel F328Be floor standing speaker. I purchased a single unit through our company (Madrona) with kind discount from Harman Sales (I asked for a review sample from the PR group but was told "don't call us, we will call you."). The retail cost...

www.audiosciencereview.com

“Finally, here is our impedance measurement:

That is a pretty low impedance so make sure you have a good, high-current amplifier to go with this speaker.”

Amir recommends a HIGH-CURRENT amplifier. Is there a correlation between high-current and high-wattage? My Buckeye Purifi 1ET9040BA monoblocks feature “a robust 40A output current”, so I’m sure they’d meet Amir’s recommendation, but it got me thinking about the importance of high-current?

The point is, with difficult to drive speakers like this, is to look for, out of the pool of amplifiers with similar Wattage output

those that can continue to deliver higher current than the others.

Close to doubling of Watts as impedance is halved is a decent proxy if you cannot find the actual current spec in amperes.

 

[Mort]

Why would I have a yard so small that I would bother the neighbors? That defeats the purpose of having a yard.
Not an issue here, though:
View attachment 540644
The last home on the electrical grid, nearest neighbor: 1/4 mile. Second home (40 miles away) back yard:
View attachment 540647
View attachment 540648

You have posted this like 10 times.

 

[rjp]

The quote below from Amir’s ASR review of the Revel F328Be indicates a dip to 3 ohms:

Revel F328Be Speaker Review​

This is a review and detailed measurements of the Revel F328Be floor standing speaker. I purchased a single unit through our company (Madrona) with kind discount from Harman Sales (I asked for a review sample from the PR group but was told "don't call us, we will call you."). The retail cost...

www.audiosciencereview.com

“Finally, here is our impedance measurement:

That is a pretty low impedance so make sure you have a good, high-current amplifier to go with this speaker.”

Amir recommends a HIGH-CURRENT amplifier. Is there a correlation between high-current and high-wattage? My Buckeye Purifi 1ET9040BA monoblocks feature “a robust 40A output current”, so I’m sure they’d meet Amir’s recommendation, but it got me thinking about the importance of high-current?

The input signal is a voltage as a function of time, and the output (if there is no distortion) is just a scaled version of this input signal. It too is a voltage signal.

The only reason current comes into play is to allow the amp to maintain this output voltage while feeding a load (speakers).

If the speaker’s impedance is high, little current will be required, but if the impedance drops lower, than proportionally more current will need to flow in order to maintain the same output voltage. If your amp can’t supply the required current you can’t maintain the target voltage, so you get distortion.

To me it sees a disservice to talk about amps as high current vs not high current. It seems to have confused a lot of people. Voltage is what matters for fidelity. At any given point in time there is exactly one value the output voltage should be. At this point high power means high current. They are proportional.

 

[wwenze]

Amir recommends a HIGH-CURRENT amplifier. Is there a correlation between high-current and high-wattage? My Buckeye Purifi 1ET9040BA monoblocks feature “a robust 40A output current”, so I’m sure they’d meet Amir’s recommendation, but it got me thinking about the importance of high-current?

That number really means nothing.

As demonstrated a few times in this thread, it is typical for an amplifier to use transistors and etc parts with >2-3x the current capacity of the power it is rated to push into the specified load.

For example the Purifi says 750W into 4 ohm which implies 13.7A, and an output current of 40A. That's roughly 3 times. So, nothing special, nothing makes this amplifier suddenly "higher current compared to the competition"

 

[MaxwellsEq]

The frustrating thing about this thread is that @NTK set out to use a simulation to show that massive current capability is not required. Which he did.

Even if you do not try to simulate real world music (using M-Noise) and real world impedance (using the Stereophile simulated loudspeaker) and just use good old Ohms Law and resistance it is clear that massive current delivery is not required.

@NTK comes up with a useful ratio and a handy rule of thumb:

But it is not going to be some huge ungodly number, and it is not going to exceed the maximum anticipated amplifier output voltage (readily calculable from speaker sensitivity and listening SPL requirements) divide by the minimum speaker impedance, regardless of the phase angle.

 

[solderdude]

So in measuring their performance with a chip amp comparing to my GFA-555 can normal equipment + say REW document such differences?

What do you want documented and do you plan to do that using M-noise ?

It is simple ... distorted sound means dial the volume down.
Don't throw parties with these speakers.

For outdoor/parties use outdoor/party speakers.

 

[wwenze]

The rule of thumb has always been to take the manufacturer's provided impedance value. But because as humans we are always somehow smarter than companies.

 

[john61ct]

The rule of thumb has always been to take the manufacturer's provided impedance value. But because as humans we are always somehow smarter than companies.

In this case, and many others, accepting their "simplified" version could lead to a failure to get full balue out of their product.

Some manufacturers do exaggerate their specs.

TSPs with bare drivers, third party verification can be essential, or even verifying yourself - production runs can vary enough to affect enclosure design.

 

[john61ct]

What do you want documented and do you plan to do that using M-noise ?

It is simple ... distorted sound means dial the volume down.

I want to identify "the point" just before the speakers start to go non-linear, long before I would trust my ears to identify distortion.

Can that be done with

> normal equipment + say REW ?

comparing the GFA-555 to small DC amps

comparing with HPF and without, with DSP and without, etc

Should that point be according to acoustic SPL? Or measuring Watts (and Amperes?) at the binding posts?

Obviously a line level protection mechanism needs to be separately dialed in, once the amp is selected, but that is later on down the road.

> Don't throw parties with these speakers. For outdoor/parties use outdoor/party speakers.

Again, no, these ARE the speakers I will be using, they are the one GIVEN in my system (& various iterations, there is no space for bigger ones) and I don't want less performant ones wrt SQ - critical listening will be 90+% of their usage.

The point of this topic fo me is, how to protect them, and I accept that that protection will limit how loud they go when used outdoors and for occasional dance / parties.

 

[mhardy6647]

I appreciate the attempt but my poor old brain hurts just looking at all that. Maybe one day the fog will lift, meantime I'll set up to measure actual SPL.

V = I times R
P = V times I

The rest of the wheel is just algebra.

Pro tip: Ohm's Law also works for impedance (Z)! Just bear in mind that Z is generally frequency-dependent. E.g., there is virtually no such thing as an "8-ohm speaker" (or a "4 ohm speaker", for that matter).
The one exception is some "planar speakers", e.g., some of Magnepan's products (Magneplanars).

Here's an example, with a tip of the hat to @John Atkinson -- who has recently retired from such quantitative duties.

source: https://www.stereophile.com/content/magnepan-lrs-loudspeaker-measurements

 

[Chanur]

This is a great exercise to do yourself! If you do this simple mathematics yourself, you will be much more convinced of the answer and will understand the principles.

Start with Ohms Law wheel:

View attachment 540128
If you are confident that, say, the impedance at 100Hz is 3 ohms, you can calculate the current at say 27W by plugging it into the yellow square above just before 9 O'clock. The square root of 27 divided by 3 = 3 Amps. So at 27W (which will be loud!) you are drawing 3A. In practice, this is for a difficult sine wave, music is less challenging. Of course, the speaker may be very reactive in which case Volts and Amps will be higher but in a real speaker, not by much.

I've always been math tarded , how do I know which of the 3 pies in a color I should pick?