Not exactly a DIY question, but I guess this is the best place to ask. I have seen 2 channel amp with a single transformer and the single transformer feeds the two channels, Dual mono amps where each channel has its own transformer, but how about a 5 channel amp with two transformers? How is the fifth channel powered? Can the two transformer power the fifth channel or one transformer powers 2 channels and the other powers 3 channels or the two transformers power is pooled into a single source and powers all 5 channels?
Ordinarily sub or bass channels consume a lot more current (watts) than treble or tops channels. So the engineers may have assigned 3 channels to one transformer and 2 to the other, or one transformer to the sub and 4 to the tops. Depends on what is the most inexpensive and fits in the case. Amps for movies tend to have a high powered single sub. Those home movie systems tend to have low power IC amps on the tops, anyway.
I have a stereo amp with 2 transformers for no good reason except it was cheapest that way. (PV-4c). Dual mono is IMHO a sales pitch, where crosstalk may be reduced from 70 db to 110, down in the "you couldn't hear it if you didn't read the brochure" realm. The acoustic bleedover from one channel to another in an actual room is much more than 70 db due to reflections from surfaces.
One barrier to sharing transformers, class AB that have a flying ground require a separate winding or separate trasformer for each channel. Two windings is done in PA to allow cheap high current, since many high power transformers are wound with two smaller wires instead of one big one. Less wasted space that way. My PV-1.3k has flying grounds if you want to look at the circuit details. Free schematic on eserviceinfo.com .
I have a stereo amp with 2 transformers for no good reason except it was cheapest that way. (PV-4c). Dual mono is IMHO a sales pitch, where crosstalk may be reduced from 70 db to 110, down in the "you couldn't hear it if you didn't read the brochure" realm. The acoustic bleedover from one channel to another in an actual room is much more than 70 db due to reflections from surfaces.
One barrier to sharing transformers, class AB that have a flying ground require a separate winding or separate trasformer for each channel. Two windings is done in PA to allow cheap high current, since many high power transformers are wound with two smaller wires instead of one big one. Less wasted space that way. My PV-1.3k has flying grounds if you want to look at the circuit details. Free schematic on eserviceinfo.com .
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It is a 5 channel power amp with 200 watts each for each channel, there is no distinction between channels, they are all equal in output...
Then the engineers determined they saved the most money by buying twice as many transformers of the same size and loaded 3 channels on one or 2 on the other. Or they bought two different transformers, because that saved them the most money. Look for the schematic on the internet to see how they did it. If you take the cover off you may find one toroid or EI frame is bigger than the other, which is an indicator that the transformers are a different size.
Actually nearly every product since ~2000 has had switcher supplies, not transformers. Because that is cheaper.
Actually nearly every product since ~2000 has had switcher supplies, not transformers. Because that is cheaper.
They are smaller, lighter, cheaper, more efficient, power factor corrected and
have much better Voltage regulation PARTICULARLY if the line Voltage wanders
around. Line Voltage change from 117 to 125 increases power output 14% with
a linear supply.
Those old class AB amps would actually double their power from 8 Ω to 4 Ω load
with SMPS. I measured an old Phase Linear 400 rail Voltage droop from +/- 80
to +/- 60 with 8 Ω loads, driven to clipping. Obviously it would be even worse at 4Ω.
That Phase Linear transformer was an EI core 117 Volt 10 Amp, essentially a 1:1
isolation transformer with a center tapped secondary.
At my house in southern California I have seen the line Voltage as low as 99 on
a really hot day. SoCal Edison has replaced all the pigs and the 16KV wire on the
poles recently. Today I measured 120.6 with our HVAC stopped and 117.8 with it
on. Fluke 8060 meter. Outside temp 95° F
G²
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It has two 1.2KVA transformers, so guessing 1 tranny is powering two channels and the other is powering 3 channels