Power rating

[Viruz]

Hi,i have this mesa/boogie dual recto won at ebay,problem is the power rating is different.So any body know or who can rewired it to local voltage.sending it back to mesa cost $$$$ again.

 

[brundisium]

best to use step down transformer. To rewire is more than just changing wires. The transformers in the amp might not be suitable. And to change the transformer, might as well get a new amp..

 

[Viruz]

So can u recommend some?

 

[brundisium]

look around simlim tower. There are shops that should have it....

 

[JMguitars]

Sim Lim Tower or Sim Lim Square are your best bets.

However, for my US voltage amps, I've picked up step up/down transformers easily from the hardware stores in shopping centres.

Word of warning:

Ensure the end portion (to amp) of the transformer is marked Step-down.

If you plug it wrongly, and instead of stepping down the voltage from 220v to 110v .... you would be stepping up the voltage to 440v.

Thats one sure path to frying your internal amp transformer.

 

[Viruz]

thanks for the infos...any particular brand or make to recommend...how much this thing cost anyway?does it take a 'degree holder' to do it?

 

[JMguitars]

No particular brand to recommend. Its really very simple, just read which side is 220v and which side is 110v.

Just think logically when plugging in - input 220v thru to output 110v

 

[Viruz]

Oh somewhere in the internet said that if i were to use the u.s amp here using stepdown transformer,the tone will abit different cause of the current cycles.True?

 

[mikemann]

Theoratically, the tone will not be affected, because either case, the amp will still function on a fully DC supply current.

The difference could be in Tube rectifier kind of amp. Because a tube rectifier might give a supply output not as consistent as a diode based rectifier with accordance to the input condition.

Another possibility is that on different windings or stepped voltaged, the end supply voltage to the tubes could be slightly difference, thus could make a subtle difference.

But as long as your step down transformer is reputable and properly rated (always over rate), should sound similar. Tube amps requires heavy and big stepdown transformers, due to higher consumption.

 

[bongman]

elect engr

But as long as your step down transformer is reputable and properly rated (always over rate), should sound similar. Tube amps requires heavy and big stepdown transformers, due to higher consumption.

Hi Mikemann,
Wow! I'm impressed by your deep knowledge in electrical engr;
anyway what do you mean by 'properly rated (always over rate)' ???

Just happened recently I bought a 117V sound module and currently looking for a step-down transformer.

rdsg,
John.

 

[Hein]

Re: elect engr

But as long as your step down transformer is reputable and properly rated (always over rate), should sound similar. Tube amps requires heavy and big stepdown transformers, due to higher consumption.

Hi Mikemann,
Wow! I'm impressed by your deep knowledge in electrical engr;
anyway what do you mean by 'properly rated (always over rate)' ???

Just happened recently I bought a 117V sound module and currently looking for a step-down transformer.

rdsg,
John.

Well, if u have a 117V sound module, you can get a 240-120V transformer... You MUST look at the current rating of your module, and make sure you buy a transformer that can support AT LEAST that current load.... It's ALWAYS advisable to overrate the transformer; meaning that if you need 1A of current get a transformer that can provide AT LEAST 1A.. 2-3A will be good....

Also, make sure u buy an AC-AC transformer.....

Hope that helps...

 

[mikemann]

Re: elect engr

Hi Mikemann,
Wow! I'm impressed by your deep knowledge in electrical engr;
anyway what do you mean by 'properly rated (always over rate)' ???

Just happened recently I bought a 117V sound module and currently looking for a step-down transformer.

rdsg,
John.

Hi John,

Nah....just I started playing with electronics when I was about 14. It's more a feel and common sense knowledge, my theory is very bad. Almost flunk my diploma. heehee...

Over rate means, if the item behind states 0.5A comsumption at 110V, it means about 60watts of power needed at worst. So we kiasu abit more, and get a 100watt converter.
This is because transformer like to operate cool. If you operate at par value, some less reputable (chinese) trnasformer converter could have short life. And no way we can predict the outcome of a transformer overheating and shorting out. Could surge major, It could take your stuff along with it .

 

[Viruz]

Ok,ok.....wait for me guys...i'm lost.....let's say i have a 100 watt poweramp,wat transformer should i use?

 

[bongman]

Re: elect engr

Over rate means, if the item behind states 0.5A comsumption at 110V, it means about 60watts of power needed at worst. So we kiasu abit more, and get a 100watt converter.
This is because transformer like to operate cool. If you operate at par value, some less reputable (chinese) trnasformer converter could have short life. And no way we can predict the outcome of a transformer overheating and shorting out. Could surge major, It could take your stuff along with it .

Hi ALL,

Thank you for the advice.
I got one working from Sim Lim tower at S$13.00

 

[mikemann]

Ok,ok.....wait for me guys...i'm lost.....let's say i have a 100 watt poweramp,wat transformer should i use?

If lets say you have 100watts output amp, that is NOT the right power consumption rating. You have so see the rear normally have consumption in terms of amperes (like 2A, 3amp...etc) or like peavey ones will show in terms of watts.

WHY?? Because to convert to an output of 100watts, you need more power in practical sense, what we call efficiency. Typical a 100watts output may require between 200 to 300 watts of energy to produce (may be higher for tube amps as efficiency is lower). We can never have 100% efficiency in the real world.

Same as car, we mesure in conversion of joules(can be watt too) of energy to motion, normally about 55-60% effieciency in the physics books when we studied in young age, for internal combustion engines.

So be careful and not get a 100watts converter for a 100watts output amp. You may fry the converter very fast.

If not sure, always bring to a professional to evalute for you. May charge you some fee like 20 bucks. Better than blindly try, consequence could be painful.