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WTB: F4 PCB boards

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#304
#307
If you cut the input voltage in half then the output voltage is half.

Volt amps is: Volts times Amps and are measured at the output of the amp for our purposes. So if half the voltage is coming out, then you need twice the amps to get the same Volt Amps. twice the amps is going to be a lot of strain on the output wiring, so the transformer won't work for a continuous output. The complicating factor is that we overspec the transformers we use. Partially because a lot of manufacturers exaggerate the capacity of their transformers, partially because it works better to a point because the current flows in pulses. Partially because "more is better" we think.

See:
http://www.diyaudio.com/forums/showthread.php?postid=1247229#post1247229

Also Class AB amps tend to only need max power for max output.
Class A amps have a more continuous power draw and the F4 is class A unfortunately.

So, the transformer is a little small used as you are proposing, but has certain characteristics of a larger transformer so will probably just work. BUT it would be a shame to buy a new component that is underspeced when in theory for the same money you could get one that is over specced. We tend to use your trick on surplus transformers or ones we have laying around....

AV is a big manufacturer and they may have more models that Amazon/Parts Express sells so you can contact them directly and buy from them. BUT I believe that the direct prices are higher.

Search the surplus places, Google, and you might find a deal!
 
#308
#312
Variac said:
You could get a pair of these


http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=122-610
or:
http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=122-615

for about $6 more. A Transformer for each channel is considered an upgrade.

Or a pair of these for $17 more:

http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=122-620

Of course dual transformers requires a dual power supply (Diode bridges, capacitors (can be half the size though) resistors (pretty cheap)
Click to expand...


OR you could buy exactly what im buying 2 of 🙂 one for my self one for a friend.

http://cgi.ebay.com/18-18V-400VA-To...12581336QQihZ017QQcategoryZ4660QQcmdZViewItem
 
#318
Dougie085 said:
But would 2 (1 per channel) be better?
Click to expand...


it will have/consume more power though 🙂

look at your room and speakers and decide if the extra cost is worth it

=============

I was thinking of building the parallel mono version. But I decided I would be wasting my money on such a project since the living room isn't that big. I decided to spend the extra money of better parts 🙂
 
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