My View: Multiwave implemented in wrong way, peak not RMS ought to be maintained

Nothing can deliver more power on the average than it can get from the wall. But anytime there’s less than average draw for a little, the extra power can be stored for use later. The length of time a unit can provide more than average power is set by it’s energy storage capacity (heck, it could use batteries, etc. for a lot of storage capacity) and by the average power available minus the actual power uses.

It’s hard to give unambiguous but accurate specs for these things, saying that the unit can store x Joules and has an impedance of y Ohms may be accurate but not useful to everyone.

If you ignore the issue of how long it can deliver twice the power, then that spec says that the unit has the equivalent of twice the current carrying capacity on it’s output than the outlet does: i.e. thick wires with low impedance energy storage.

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Seems pretty straight forward…you trade VOLTAGE for CURRENT. The total VA (volt amp) has to be equivalent or you are “creating” more power than is there…can’t be done. We can lose power, we can’t gain it. The sine wave is broader and with a lower PEAK voltage but higher current. Same amount of “work” has to be done, though.

The 3600 VA is a BRIEF max VA spike. The higher you run the re-generator steady state the lower and / or shorter that stored potential becomes. The storage caps aren’t magic, and like any power supply ripple increases as the load gets higher and higher. Light loads allow a good quick surge of “stored” energy, but once it is used, we need to store some more! At full load, there is no extra “work” to store as it is all put to use so no more “peak” VA over the walls max VA minus inefficiencies.

Disclaimer, I use a P20 at maybe 30% duty factor at 85 avg SPL running the entire system through it so I’m a light weight!

Best,
Galen Gareis

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well, if not operating the wall socket very close to maximum current, can just pull more power from there, which is how the power plan operate, to have a lower “virtual” impedance than wall socket.

And my point is that since powerplan reduce peak voltage, which is scaled down by the transformer and then load the capacitors in the amp, the amp will operate with lower than designed for internal voltage. In my case, idle power with multiwave is 300 W, with sine 330W.

Yes, you can have one or the other for any extended time, not both voltage and current. Peak you could get both very briefly, but the regenerator holds VOLTAGE for you so you get a peak current to get that 3600 VA rating.

Best,
Galen Gareis

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Hi,

With peak here I was meaning the peak of the sine wave, not peak power use.

an interesting thing with Multiwave is that it reduces peak voltage of the electric waveform. And as peak voltage largely determines the voltage rectifying capacitors is charged with and deliver to component circutry, Multiwave typically means undervolting components, which sounds strange that this should be beneficial.

I wonder why multiwave is not implemented in a way so that peak voltage remain the same as for sine, but then with the multiwave form.

Anyone given this any thought?

I am not sure this is correct so it’d be hard to answer properly. MultiWave does not reduce peak voltage but rathe extends peak charging time, providing lower ripple at the same voltage on the power supply, not lower.

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Multiwave doe s not reduce the peak it extend the time the waveform spends at or near the peak. My P-10 still puts out 120 volts AC when set to level 6 of multiwave. It gives the capacitors a longer charge period exactly as the designer intended. Yes the waveform looks wider at the top and bottom on the oscilloscope. To the untrained eye it does look like the peak is reduced.

You’re not interested in the peak voltage anyway - that could be 1000 volts with a very narrow spike, and still have less overall energy (spikes not recommended though!).

It’s the area under the curve that counts for increasing stored energy in the capacitors - the regulators take care of the final voltage anyway so no under-volting is going on :slight_smile:

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Multiwave does NOT reduce the peak voltage.

Instead multiwave adds in a third order harmonic to widen the waveform at the apogee and perigee, see below:

Hi,

Not thinking of some very short peak, but the peak of a somewhat round waveform.

As volt RMS out of the powerplant remain the same with multiwave turned on and off, and we know that mutiwave provide a wider waveform, this show that the peak is lower.

Also, many power amplifiers do not have what we typically consider to be voltage regulators.

Hi Paul,

You are obviously the person who know all details about this.

But if charge time longer i.e. the wave get “fatter”, and peak voltage remain constant at 310V for a 220 V unit, shouldn’t then volt RMS increase?

Reduction of peak of the wave further confirmed with my measurements, both with a multimeter that can measure both peak and true RMS and oscilloscope. Also by the fact that power usage on my amplifier is reduced when turning on multiwave.

Would be interesting to hear what your measurements conclude.

That said, there is of course the option of turning on multiwave and increase output voltage of the Powerplant (which is measured in RMS or something RMS like) to compensate for the drop in peak voltage, to both get the fatter multiwave wave form and to maintain peak voltage.

No intending to criticize your product, I really like the powerplan and it have clear benefit in my system. The title of this tread chosen for the intention to get the discussions going. Maybe these discussions even can help to make your products even better?

Or maybe my thinking and measurements are wrong altogether…

Much appreciate your videos and and products! Hope i get an opportunity to visit PS audio at some time.

Hi,

It really looks to me as if your illustration show that peak has been reduced, doesn’t it?

Try plot the second graph, but exclude the third order harmonic and see where you get the peak.

Hi,

Not thinking of some very short peak, but the peak of a somewhat round waveform, like sine or multiwave.

As volt RMS out of the powerplant remain the same with multiwave turned on and off, and we know that mutiwave provide a wider waveform, this show that the peak is lower.

Also, many power amplifiers do not have what we typically consider to be voltage regulators.

As I said previously, multiwave does not reduce the peak voltage but instead adds in a third order harmonic to widen the apogee and perigee of the waveform, see below:

This is then smoothed, again still keeping the apogee and perigee at 120volts they are now simply wider.

To prove this - In your PSA regenerator change the ‘MW Strength’ to 6 in the setup. Go to the oscilloscope and view the output waveform. Watch the output waveform in the oscilloscope when you change from ‘sine’ to ‘multi’ waveform. You will notice the apogee and perigee is wider when in the ‘multi’ waveform than when in the ‘sine’ waveform. You will also notice that the aptitude and wavelength is unchanged when changing from ‘sine’ to ‘multi’.

I’m not an electrical engineer…but this is how I understand it - someone please correct me if I’m wrong.

(Focus on the top drawing below) After the current travels through the full bridge rectifier(D1,D2,D5,D6) the current will now be flowing in one direction but the voltage will pulse on/off and needs to be smoothed. Smoothing will occur with a capacitor(C1). The wider the apogee and perigee of the original AC waveform the longer the capacitor(C1) has to charge(remember it still has the same discharge rate as before). This is a beneficial design I assure you.

With the capacitor having a longer charge time to due to the wider apogee and perigee of the original AC waveform this results in lower DC ripple effect(Lower DC ripple means more linear power) after the voltage exits the capacitor but before it reaches the voltage regulator/device rail.

Now, many power supplies in expensive amps will have an inductor and another capacitor after C1 resulting in even more linear DC power and you can continue this design…adding another inductor and another capacitor. My guess is this is why you see amps with banks and banks of capacitors they probably have extremely linear DC power even without an AC regenerator.

Hope this makes more sense.

Ryan

Hi,

Thanks for comments.

Well, actually, the peak for 120V is around 170V. The 120 V we usually talk about is a RMS measurement.

As you spoke about the scope on the powerplant, i just checked, and as you wrote, the wave is clearly “fatter” but its also easy to see that the peak is lower.

So so far, everything I have seen, tested or measured point in the direction that the powerplant actually reduces the peak voltage which is feed into components.

This was discussed 6 years ago.
The peak voltage is reduced.
From that thread:

“I measured the B+ on my mono block tube power amps.
With Multiwave off, I measure 424 volts on each amp.
With Multiwave on, I measure 406 volts on each amp.

Is what I am seeing normal? And if so, please explain the electronics involved.

An explanation from Bob Stadtherr:

You are correct that the peak voltage is about 5% lower in order to maintain the same RMS value. However the softer wave shape extends the amount of time that the rectifiers conduct and charge the filter capacitors. This means the peak current from the transformer is lower, and thus the IR drops in the tranformer are lower. This offsets the lower peak voltage, but only under load.
The wave shape was chosen so that in typical equipment (with a constant DC draw) the lower peak voltage and the improved transformer efficiency just cancel out and the dc is about the same.
In a power amplifier, usually we see a slightly lower DC voltage at idle, and about the same with typical loads. When the demand on the amp is high, we usually see much less sagging of the DC voltages than with a sine wave input.
Another benefit of the extended charging time is lower ripple current in the filter capacitors. This reduces the internal heating and extends the life of the parts.”

Ah the reduction in R loses in Transformer and Rectifiers is a good point too, but I still think the main advantage is not about the voltage - speakers require energy to move them, voltage without sufficient energy store is not enough, and with the capacitors storing more energy between peaks of the AC waveform (and I refer you to my previous comment regarding the area under the curve) then more short term high current demand can be satisfied.

Or - use whichever sounds best - trying to estimate what is best from first principles is risky, as there are always more variables than we can account for in our theoretical ruminations :slight_smile:

Very interesting! ,So this confirms that mutiwave indeed undervolt as I suspected and measured.

I now did some measurements on my amplifier and can conclude that it loose output power by turning on multiwave (clipping occur at lower power).

I would want to see or do some measurements on the argument with R-loss in transformers before I completely believe in that.

I think there may also be a marketing and communication challenge that the undervolting address. The benefit of the multiwave shape is easily to intuitively understand, but I think many clients would be nervous to see measured output voltage (which is measured in RMS) increase 10% when turning on multiwave, being affraid that they will fry their equipment.

In my case, I hear no difference with multiwave on or off (at normal listening levels), but can do (the mentioned) measurement that the amplifier loose some power. A “benefit” i see with multiwave is that power consumption of the power amp is reduced from 300 watt to 270 watt as living in the tropics, it already generate too much heat that need to be air-conditioned away…

So now when we have concluded that multiwave undervolt, it would be interesting to hear what listening experiences people have by running multiwave at standard undervolt VS compensating the undervolt by increasing output voltage with 10%.

I will do some tests on that.

I do not believe for one minute that multiwave reduces the voltage enough to affect the clipping point of an amplifier operating on it! I bet anyone measuring the DC rails off the amp will see there is no change at all!