what is the bit about not connecting the negative terminals? I was about to suggest that he run both channels in parallel to the subs in series.
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Topping PA5 Review (Amplifier)
- Thread starter amirm
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antcollinet
Grand Contributor
That would likely be a very bad idea.
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You're right, but it might be fun to watch!
why? I thought it was always safe to run stereo amp channels in parallel to double the available current.
Roland68
Major Contributor
Regardless of whether it's a PA5 or a PA5II, for a subwoofer it's really like throwing pearls before swine and wasting money.My subs are just 70 Wattso don't need that much power. Just wondering if the Topping PA5 would work with 2ohm speakers/subwoofers.
It's the wrong application for this amplifier anyway.
An amplifier designed for 2 ohms, such as the well-tested AIYIMA A70 MONO, is significantly cheaper and has a much higher output when needed.
And if that's not clear, too little power is a problem, too much is not.
You should definitely film that for the forum and for YouTube.
With many amplifiers, especially Class D, the loudspeaker minus connections must under no circumstances have contact with each other or with ground. This can lead to short circuits and smoke signals.
Talisman
Major Contributor
If I remember correctly it seems that many class Ds cannot be connected (for similar reasons) to the high level inputs of the subs, but I could be wrong or have got confused, those who know more feel free to correct me
Roland68
Major Contributor
That depends on the SUBs.
If the manual does not explicitly state that you can also connect Class D power amplifiers, or that the negative speaker poles are isolated from each other, you definitely have to check it.
gamerpaddy
Member
this class-d amp has 4 outputs, two for each channel,
the amplified signal and the amplified signal but inverted 180°
in addition... both outputs are floating at around half the supply voltage! but your speakers only see the difference not the absolute, so its fine.
but dont touch one wire to the amplifier case when the other one is connected and its turned on.
and for paralleling... class-d are low output impedance, any imbalance between the channels makes them fight with eachother.
you can parallel class-d amps if they are designed for it in the first place. the tpa3255 can be configued in PBTL (page 28 of the datasheet) but it isnt in this case.
the amplified signal and the amplified signal but inverted 180°
in addition... both outputs are floating at around half the supply voltage! but your speakers only see the difference not the absolute, so its fine.
but dont touch one wire to the amplifier case when the other one is connected and its turned on.
and for paralleling... class-d are low output impedance, any imbalance between the channels makes them fight with eachother.
you can parallel class-d amps if they are designed for it in the first place. the tpa3255 can be configued in PBTL (page 28 of the datasheet) but it isnt in this case.
antcollinet
Grand Contributor
Class D outputs are switching from + to - rails of the power supply. Unless they are perfectly synced, and locked together so they do that at exactly the same time all the time the amp will try to connect +Psu to -psu.
The output filter might save the amp - or it might not.
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