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Old 9th July 2005, 04:04 PM   #1
sachi is offline sachi  United States
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Default Newbie Transformer question

Helllo,

i received my 4780 and 3886 boards from Peter Daniel(Respect for the man)..awesome boards.

Now for the 3-way active system that i am planning, i want to use the 4780s in stereo mode..
so that is 4 channels driven by 2 4780s..
what is the transformer rating and secondary voltages that i will need
for the 4780s and how many transformers will i need...

is it possible to drive all the 4 channels of the 4780 with a single transformer..if so what should be the tranny rating and the secondary volatages..

Regarding the LM3886, is a single 160 VA with dual 18 v secondaries good enuf to power both the channels?

Thanks..
Cheers,
Sachi
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Old 10th July 2005, 09:13 AM   #2
Nuuk is offline Nuuk  United Kingdom
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Personally, for your application, I would power each speaker from a separate transformer, and preferably one for the bass and another for the upper frequencies.

Without knowing what you are drving with the amps, it's not possible to work out exactly what you need but if you use something in the region of 225VA for the bass units and 160VA for midrange and tweeters, you should have pleny of power.

If you want to use one transformer per channel, then go for 300-400VA.

Secondary voltages should be chosen to match the impedance of the drivers, ie for 8 ohm drivers 22-25 volts and for 4 ohm drivers 18 volts.
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Old 10th July 2005, 10:46 AM   #3
sachi is offline sachi  United States
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thanks for the start Nuuk..(awesome site btw)

Now the tweeter units are VIfa D27-tg-35 6 ohm drrivers
The midrange is the Vifa(Infinity replacement) 4.5 inch TC range 6ohm..
and the woofer is the Dayton 10 inch classic driver at 8 ohms..

From ur reply i gather that two trannies of 160VA with twin secondaries of 22V (22-0-22)i.e, 31 after rectification(is this also called rail voltage?) should be enough for the Midranges and the tweeter..

another tranny of 225 VA with twin secondaries of 22V for the woofer....is that okay.?


one further question i wanted to ask was ,

say u have two trannies , one rated 22-0-22 and the other rated 0-22 , 0-22.....is there a difference between them??

Volatage after rectification is the same as rail voltage right??

Cheers,
Sachi
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Old 10th July 2005, 04:17 PM   #4
homer09 is offline homer09  Canada
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Quote:
Originally posted by sachi

one further question i wanted to ask was ,

say u have two trannies , one rated 22-0-22 and the other rated 0-22 , 0-22.....is there a difference between them??

Volatage after rectification is the same as rail voltage right??

Cheers,
Sachi

22-0-22 is a center tapped transfo and 0-22 0-22 is a true dual secondary transfo. because of the boards you are using, i recommend the dual secondary variety.

and yes, rectified voltage is the same.
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Old 11th July 2005, 07:24 AM   #5
sachi is offline sachi  United States
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But if the two 0 volt wires are tied together in the dual secondary tranny it turns into a center tapped tranny..

Am i right in assuming that other than the differences in their application there is no significant difference between the two or am i missing something..
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Old 11th July 2005, 07:59 AM   #6
sachi is offline sachi  United States
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Oh!..i got it now..after looking thru Rod elliot's site i.e....Thanks for that homer..

Okay now what abt the values..
If they are okay then i will go ahead and order them..
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