Hehehe...

Discussing with Peter about technical issues is like pissing in the wind. Peter has en enourmus knowledge about amps and his job is to test electrical DD equipment to the max and its destruction to se what can be improved.

I would stick well with Peters explanations. What he says about DD amps and amps in general is correct. At least in all the posts he have written so far I believe.

I have education in electrotechnique, and I would agree in all of his statements when he explains how and why when it comes to amps

It's best to have a load on the output of an amp when turned on

In Class D amps, the output needs the reactance of the voicecoil to prevent the output from oscillating and damaging the output fets. This is with or without input signal. Most Class D amps factor this in the design, some dont or don't have it filtered enough.

Actually the MOST efficient is having as little filtering as possible on the output, but this means that the speaker MUST BE CONNECTED TO THE OUTPUT IF TURNED ON!!!! The Output filtering on Class D amps rely on the reactance of the speaker to dampen oscillation. THIS IS WHY you must connect the speaker to the output or damage may occur on Class D or any switching amps. It is NOT because of rail voltage, blah blah blah... It's oscillation of the output filtering without a load that will kill the amp.

Also, this is true with almost any switching circuit. Without a load it will become unstable & oscillate if not damped properly. This is why the older AT style & some cheap ATX power supplies wont turn on without a load even if you jumper wire it to be on constantly. It needs a load to properly regulate & without a load, the output will oscillate & then you have a blown power supply.

Also Class A/B amps (if designed within the Global Negative Feedback limits) can play all day long without a load attached even passed clipping to the point where it is a square wave being outputted. Class AB amps work on linear analog voltages. As long as the feedback loop is designed to be a safe margin below nyquist stability it will play all day & forever without a load.

There are LOTS of written documents & papers & technical articles & best practices datasheets, etc. coming from every semiconductor manufacturer offering a switching amp solution explaining why Switching circuits need a load or proper filtering designed to compensate the output. In laptops, often there is almost no output filtering on the onboard switching amp because the speakers will never ever be disconnected and it is more efficient to not filter the output. There are also TONS of published papers on this type of scheme also. Rail Voltages & all that hoopla is not a factor.

Case Closed


& also rail voltages in today's class D amps are not that high. I've engineered, designed, & built Pro Audio amps with rail voltages in the 170V Per rail range & required a 3 phase input which equals about 340 volts rail to rail (no transformer needed when running directly off the line coming in, but they are only meant for 4 ohm loads at the absolute lowest. These amps will KILL you if you touch the output in full swing. The design was never commercially produced or bought because UL & all those BS agencies dont like the idea of an amplifier that doesnt have a transformer buffering the lethal output of a device that is commonly connected & disconnected with bare hands by people who are not licensed electricians.

The ENITRE reason car audio has lower impedance speakers are to make it so amplifiers do not need to have such high rail voltages. 2400 RMS watts only needs about 75 volts rail to rail (35-40 volt rails) for a 1 ohm load after factoring in efficiency of the output.

Back in the day (before most of us were born) when the built in amplifiers of factory headunits relied directly on the 13.8 to 14.4 voltage from the alternator to produce rail voltage, lowering the impedance made it so you could get more power output from the low voltage. It wasnt until the late 70's early 80's when outboard amps started using DC-DC converters to boost rail voltage, but building an amp to produce meaningful power into 8 ohms cost a shit ton so the lower impedance standard stuck with car audio & has gotten pretty extreme now days. The components needed to push 2400 watts into an 8 ohm load would more than double the cost of car audio amps.

One of the absolute coolest amplifier designs I've seen in car audio were the old MMATS Dx00HC series. They used what's called an H-Bridge for the output topology. These amps only have one rail and are incredibly efficient design wise. H-Bridges are commonly found in motor control PCB's... Hmm, MMATS originally started out making motor controls for washing machines in LaundroMMATS. I wonder where they got the design from?

EDIT: The M3 has a semi regulated power supply for what it is worth, but kinda back asswards in operation. It wont let the rail voltages get too high as in it regulates the rail voltage when the battery input voltage reaches a certain point, but when voltage is lower (like the car off) the power supply unregulates & battery voltage directly effects rail voltage. This is why running the M3 on 16v in my car made no difference compared to 14.4v. If I remember right from my testing (almost a year ago), the point at which the power supply starts to limit the rail voltage is about 13.4 volts on my M3. The Z1 is different than the M3 though & I dont have any direct experience with a Z1.

It is so that ALL amps need a load so that the rail volt in the amp doesn’t go max out and more.

This is the problem with ALL amps.
But the big ones are more sensitive then the small.

If you read what I have written, you see it is the BIG amps that can/will have the problem, not the small ones.
Or do I need to writ it one more time
But just because the small ones can handle it YOU shouldn’t do it.
And on low budget amps, the power supply is not something to be happy with. So your friend is right on that test.
But that is not a High end amp. Let him test your Z1 and se if he makes the same statement.

Ats sa oled maailma parim, imestan et miks sa juba võimendeid ei ehita, sinust saaks kindlasti miljokas oma teadmistega
See on sulle personaalselt:
Sõimates DD võimendite loojat ja täiustajat madalamaks, kui firma sekretäriks, näitab kui tropp sa oled !
Ta ütles mulle konkreetselt, kui ma tema juttu ei usu vms, siis hõõru Atsiga kokku ja ole õnnelik ... Edaspidi ma nii tehnilis küsimusi siin ei esita, ega too ka tehnilisi lahendusi SPL vallas jne, sest teil on ATS selle jaoks !
Aga ega eesti foorumis polegi targemad vennad(või nende postid), kui Atsi omad oodatud, seega võib selle teema lõppenuks lugeda, minu poolt vähemalt !

Sry, et teema tegin

Ühes postis kirjutab:Teises postis kirjutab:Ja siis nüüd:

Et sind ennast Tõnis klouniks ei peeta see selleks....

Öelda sulle korra mingi lause ala. "Selles võimus peaks oleka K173A kivi, mis tunneb ära takistuse väljundite vahel ning üle 16 või 18 oomi (küsi tootjalt) ta käima minema ei peaks. " ja juba on error ja klots koos, et nagu wtf... ja kohe kirjutatakse DD meestele, et kuulge kutid, mis see K173A kivi teeb... selgub, et sellist pole olemas... hmm.. kes nüüd loll on? IRW

Palun vasta mu eelmises postis seisnud küsimusele võimendite kalibreerimise kohta. Kloun oled siin sina, sest sa hiilid mööda kõikidest küimustest ja asjadest millele su hammas peale ei hakka.

ps. ma arvan, et mul on rohkem SPL karikaid riiulis kui sul, nii, et ära soiu siin midagi, et see pole minu teema

Mis siin arusaamatuks jäi ?
Probleem on KÕIKIDE võimenditega, odav ja väiksem sodi kannatab kannatab lihtsalt rohkem, mida aga ei peaks tegema, sest ühelt maalt enam ei kannata.

Atsi koha pealt on see teema tore, ajada rahvale udu ja võimu parandajana tööd juurde saada ...

Sina tõnis aga, ise soovitasid mul esindusest küsida ja nüüd soiud nagu plika siin
Ehita aga oma 50hz-eid mõnusaid bassikaste klientidele ja ära topi oma nina sinna, millest ka sa ise aru ei saa !