transformer

[KCC]

Well,I am trying to build two identical mono blocks out of two set of same identical parts - except the transformers. One of which is 370va and the other is 520va.Does this make a differences in the outcome - sound? One is louder than the other? Any opinions are wellcome.

[Bill Fitzpatrick]

IMHO the differences between channels wouldn't be worth talking about. Just consider the channel with the 520va to be a bonus. One channel won't be louder than the other.

[tool49]

The real question is whether the two transformers give out the same output voltage on their secondaries.

If they do give the same voltage, then the answer is no, you should have close to identical output from both amps. Where it will change something is when you stress your amps with a small load (ie <4ohm) and that your amp draw more current than what is available from the 370VA. Then at this moment the power supply will sag on this block and not on the other causing one channel to clip. But lets face it, unless you are building subwoofer amps (which I doubt since your transformers are quite small), chances are that you won't go into clipping even with the modest 370VA transformer.

However, if they don't give the same voltage, then one maybe able to go to higher volume befor clipping. This depends on your chosen topology and whether or not the power supply have sufficient current not to sag before this occurs.

I hope this helps!
Sébastien

[KCC]

Thanks Bill and Sebastien to clear things up.Yes,they are having the same secondary voltages.And ,no,these are not for subwoofer amp.One other question would be what if their current rating differs? I understand one rates 5 amp the other is unknown to me at this point.What if it is 6 amp.I imagine at max output one would provide more current than the other so is to be louder.Or is it?

[Bill Fitzpatrick]

They would be the same loudness. The supply with the 525va transformer has the "potential" to deliver more current with less voltage sag and transformer heating but if the input signal to both channels of the amp are the same the ouputs will be the same.

[sam9]

The only way I can see there would be a difference is if the one with a lower VA rating can't supply enough current so that the amp using that one sometimes clips from hitting the current limit before peak voltage is reached. But if it is adequate then all you have is one adequate transformer plus a more than adequate transformer.

As a rough approximation if the smaller's rated voltage 38-0-38 or less you have ample for nominal loads down to 4 ohms and would be ok under all but the most sever circumstances even if the rating was a few volts higher.

[KCC]

I haven't purchased the bigger one as yet. But both are rated
45 0 45 secondaries and providing rail voltages +65v / -65v. And I just found out that the bigger one has a 6 amp current rate as compare to the 5 amp smaller one. The smaller one is used in Hafler DH200(older and which I have) and the bigger one in later models. They look the same except the bigger one with better rating.I listen to music in a "listenable" manner so is unlikly to drive the amp to clipping state.

From what I read it's a go.Thanks everybody!