good place for transformers

[zx3chris]

hello,
just wondering where everyone gets their transformers from?? Id prefer to buy new and not have to look around in surplus or ebay -- i dont have many electronic catalogs but the transfo's in jameco, for example, are too weak for what i plan ---
thank u

-chris

[ststone]

Chris, what kind (V/A/W) of transformers are you looking for ???
BTW. I know some good watering wholes in red bank.

[zx3chris]

i plan on making a bi-amping stereo amp, using 4 lm3876's. which are 56w each. supply range is listed from +-24v --> +-84 volts, so i assume i need around 200va and around 80vct transformer... this would be my first amp, so somene let me know what im doing wrong.

[ststone]

Chris is there a site where we can look up the specs of these
lm3876's

[zx3chris]

here are some specs;
http://www.national.com/pf/LM/LM3876.html


here is the full pdf
http://www.national.com/ds/LM/LM3876.pdf

thanx

[ststone]

Chris, my man...
Read some threads, don't go there.
If you want some music, hang on...
We will help you.

[JoeBob]

80vac is way off, read through the datasheets first, instead of 84V I think it may be +/- 48V, which is still really high for the LM style chips, get a 24vac transformer and you'll be good (or lower, like 18vac or 20vac).

[zx3chris]

i was thinking that a 80vct transfo would give me +-40v, which after rectifying would give me ~+/-35V .. would i be correct to assume that 4x56watts=224watts.. transformers are rated in volt amperes not watts, so would a 200 or 250va be correct??

then again, 40vac is ac... so 40/.7 = 57volts dc after smoothing it out...

??

[zx3chris]

ttt...

ive searched thru other threads and found some decent places for transformers, but what should i use to calculate what VA rating i should use ?? I found this formula;

VA = 1.4 x ( WATTS + 2 IDC* )

is this a good guideline to use??