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In Reply to: RE: voltage transformer for ss class A posted by m0reilly on September 27, 2015 at 15:37:54
A class A amplifier isn't going to show much variation (if any) during playback. You have 135x2, so 270 Watts. Looking a little more specifically at your amplifier, it has regulated power supplies, so efficiency might actually be considerably lower than I had initially imagined.
There isn't a lick of information on the web regarding power consumption, perhaps it might be worth the time to put a clamp meter on the power cord feeding this monster to determine the actual power consumption. In the absence of this information, ask the dealer or the manufacturer for power consumption.
You may actually need a 1000VA step-up.
Follow Ups:
here is a little bit more info, re (220? at 8ohm) output:
"The amp draws an idle current of 0.75 amperes, making ~173 watts, although my power meter tells 80-90 watts due to the voltage/current phase shift."
does this help? this was from a euro review:
http://www.troelsgravesen.dk/JungSon.htm
Edits: 09/27/15 09/27/15
Either the power ratings are incorrect, the amplifier is not class A, or the power consumption measurement was done improperly.
then we have these numbers, which look 'normal'?
then we have these numbers, which look 'normal'?
then we have these numbers, which look 'normal'?
there was a link on that page i posted where someone had tested the class a wattage...not sure what to make of it:
"I wonder about the class A power from the 30kg beast. Now that we have the schematics with component values, we can easily calculate how much power the amp really outputs in pure class A (and B if we want). Here are my findings.
PclassA = Irms x Irms x Rload.
There are two amps per channel in a bridged configuration, ie in total 4 amps - or amplifier stages if you like. Each of these stages has an idle current of (80mV to 100mV) / 0.25 Ohms x 2, as there are two pairs of output transistors per amp stage. Letīs use 100mV. Idle current aka
Ibias = 0.4x2=0.8A. This is the maximum current that a sine wave can have on the positive side. The negative side of course also can swing this much as we use a push pull design. So, Irms = 2 x Ibias / sqrt(2) = 1.13Arms.
Now we are ready to calculate the class A power that each of these four stages could deliver into a loudspeaker (Rload) :
P classA 8 Ohms = (1.13)^2 x 8 = 10.2 W
P classA 4 Ohms = (1.13)^2 x 4 = 5.1 W
P classA 2 Ohms = (1.13)^2 x 2 = 2.6 W
P classA 1 Ohms = (1.13)^2 x 1 = 1.3 W
Now, we do have two of these amps per channel in a bridged configuration. What does this mean for the class A power? Well, in bridged configuration, we have twice the voltage swing, so we get 4X the power, right? Yes, and no! We do get more class B power but do we really get more class A power? No, we do not.
Also note that in bridged mode, each amp "sees" half the Rload.
The power dissipation without music playing is high and that not only depends on the relatively high Irms but also because we have 4 amps."
Yeah, that would seem to agree strongly with the measured idle consumption, and indicates that the amp should really be called a class AB amplifier (IMO).
The step-up transformer you bought should be totally fine for this. When the amp crosses over into class B, it will draw more power, and the transformer will be OK with that.
darn, didn't see your post last night. the seller just canceled the transformer purchase lol.yeah, from an oz site it is head that some models had a high A bias, so that may explain some. would the 1000v transformer be too much? if so, i'll see if i can reorder the 750...
darn, didn't see your post last night. the seller just canceled the transformer purchase lol.yeah, from an oz site it is head that some models had a high A bias, so that may explain some. would the 1000v transformer be too much? if so, i'll see if i can reorder the 750...
lol, can't find a way to contact jungson, and the seller hasn't a clue...plus, to get my discount before it ended on the transformer, i purchased the 750watt...didn't want that hum you mentioned from getting too powerful step up transformer...so if i don't really need it, would the 1000watt unit be a humming along if all it offers isn't used? seeing as how long this amp has been on the market, you would think there would be at least a bit more info...
Edits: 09/27/15
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