For normal amplifiers rated at 150 watts output cap[ability, I would suggest step-down transformers rated at for at least 250 watts ,because the amplifier is not nearly 100% efficient. 300 watts is a good rating because the frequency is lower and so the efficiency of the transformers will be a bit less. I also recommend checking the temperature of the transformers in the amplifiers frequently for the first few hours of operation.
I also recommend getting a service manual for the amplifiers so that you can show us the circuit of the amplifiers. If they have a switcher mode power supply then the 50 Hz instead of 60 hz will not matter much.

 

I also recommend getting a service manual for the amplifiers

Referenced in next to last sentence in Post #1.

It has a transformer supply.

 

Draws 135W.
300W transformer is plenty ok.

 

Have you looked inside the amplifier to see if the transformer has dual primaries?
If so, it’s just a simple rewiring task.

 

Do people go out of their way to complicate the questions here?



And if you're posting after 20 replies have already been made, are you so certain that no one may have made a crumulent reply, that you feel no need to even read the previous replies?

This place is worse than a FaceBook forum.

 

It may be worth having a look at the internal power supply, in particular the toroidal transformer that may have spare tappings for 220-240volts, I guess these are sold in other countries and it is possible. As for the frequency of the power supply, I wouldn't worry too much, at most you may have a slight hum and have to tweak any filtering but the power supply looks basic so I would suggest it will be fine.

 

It may be worth having a look at the internal power supply, in particular the toroidal transformer that may have spare tappings for 220-240volts, I guess these are sold in other countries and it is possible. As for the frequency of the power supply, I wouldn't worry too much, at most you may have a slight hum and have to tweak any filtering but the power supply looks basic so I would suggest it will be fine.

If it is a dual-primary transformer, it will have been designed to work at 50Hz.

 

Of course you could just replace the internal transformer? https://uk.rs-online.com/web/p/toroidal-transformers/1730073

 

I was going to suggest changing the transformer, BUT that will be a big expense indeed.
I did look at the link on post #1 and it did not tell me anything except that it does have a transformer power supply. That diagram is only a block diagram; which shows the different sections and explains the inputs quite well. It does show that the power supply uses a big transformer.
And I see that SMALL BLOCK in post #16 and I consider the 300 watt rating to be very optimistic indeed. It does not look big enough to contain a 300 watt transformer, at least, not one rated for 300 watts continuously.

 

Do people go out of their way to complicate the questions here?

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And if you're posting after 20 replies have already been made, are you so certain that no one may have made a crumulent reply, that you feel no need to even read the previous replies?

This place is worse than a FaceBook forum.

Hi Jon - thanks for your reply. I think what confused me was the 350 Watt Burst Power Output - I was worried that might mean I need at least a 700 Watt transformer. Also, the 60 vs 50 Hz - tbh I have little to no idea how this is impacted or if this is a concern in my case?

 

When and where are you using studio monitors?
Are you using these for personal listening?
Are you using these in a bar, pub, dance hall?
How much listening power do you really need?

I have 300W powered speakers. I doubt that they ever go above 50W.

 

In sound systems, for some folks, too much is never enough. I repaired a 500 watt amplifier that was one channel of a person's home listening system. 500 watts for each stereo channel, Of course that did allow headroom for the 100 watt peaks that happen in some music..
Some folks believe that music should also be felt, not just heard.
I am not one of those, although I do feel that music worth listening to should be forground, not background.

 

Some folks believe that music should also be felt, not just heard.

Maybe that's because they can no longer hear it. When you lose it, it wouldn't come back.

 

It may be worth having a look at the internal power supply, in particular the toroidal transformer that may have spare tappings for 220-240volts, I guess these are sold in other countries and it is possible. As for the frequency of the power supply, I wouldn't worry too much, at most you may have a slight hum and have to tweak any filtering but the power supply looks basic so I would suggest it will be fine.

It is worth noting however that a transformer designed for use at 50 Hz will be quite happy at 60Hz but vise-versa due to an increase of the flux density of the core, a transformer designed for 60Hz my get somewhat warmer at 50Hz. The chances are the transformer has been designed with the world's various supply voltages in mind because Makie, although not ubiqitous elsewhere in the world, do export from China to foreign lands other than the US.
If they were manufactured in the U.S. I would have said they were design for 60Hz considering how secular they seem to be. Anyway, enough Yankie bashing, personally I would replace the transformer.