5 channel transformer rating for LM4780/LM4781

wjp007 · 5th June 2007, 07:05 PM

Hi,
Noob here. Great forum. I need some advice on a budget 5 channel systems I'm designing for use with a PC. I'm planning on using a seperate powered subwoofer so I only need something for the other speakers. I'm looking at an LM4780 for the front and LM4781 for the rear. The speakers I'm planning to use are 4ohms and won't be asked to drive anything below 100Hz. I'm thinking of getting single transformer and run the LM4780 at +/- 18V unregulated and use some linear regs at +/- 12V for the Lm4781. Do you think this setup would work, and what rating transformer should I use (I'm thinking 160VA should be more than enough)?

Any advice would be greatly appreciated.

Thanks.

YFW · 6th June 2007, 08:35 AM

160VA could work but not work at the best condition.
Do you need full output of the 5 chanels?If yes,300VA is much better.

wjp007 · 6th June 2007, 01:11 PM

YFW,
Thanks for the note. I would think I do need the full output. I'll go with the higher rating.

AndrewT · 6th June 2007, 05:28 PM

Quote:

I need some advice

use stereo amplifiers.
one to the front pair, another to the rear pair, and a third to the centre channel and the sub. That allows long interconnects and much shorter speaker cables to at least some of the speakers.

YFW · 7th June 2007, 02:52 AM

The sound quality depends greatly on the power supply.
If you could feed good power supply to the amplifiers,you will get a very good sound.You will benefits more compared to hign end parts.

Of course,you should choose better transformers and capacitors.

Ponz · 10th June 2007, 12:12 PM

the spec of transformer for 5 channel's +-18V unreg. and +-12V reg. voltage should be 14-0 5A x 2 and 12-0 1A x 2 or more power rating.

besides enough power of transformer, the filter capacitor needs
exceeds 2 x 10000uF, than get good sound quality.

5th June 2007, 07:05 PM	#1
wjp007 diyAudio Member Join Date: May 2007	5 channel transformer rating for LM4780/LM4781 Hi, Noob here. Great forum. I need some advice on a budget 5 channel systems I'm designing for use with a PC. I'm planning on using a seperate powered subwoofer so I only need something for the other speakers. I'm looking at an LM4780 for the front and LM4781 for the rear. The speakers I'm planning to use are 4ohms and won't be asked to drive anything below 100Hz. I'm thinking of getting single transformer and run the LM4780 at +/- 18V unregulated and use some linear regs at +/- 12V for the Lm4781. Do you think this setup would work, and what rating transformer should I use (I'm thinking 160VA should be more than enough)? Any advice would be greatly appreciated. Thanks.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Quick LM4780 Heatsink Thermal Rating Q	rhysh	Chip Amps	23	26th March 2009 03:15 PM
Voltage rating of p-channel MOSFET	Tahmid	Power Supplies	7	3rd July 2008 08:10 AM
6 channel LM4780 question	Wynand	Chip Amps	18	24th November 2005 01:58 PM
My new LM4781 6-channel project	microJean	Chip Amps	12	29th October 2004 02:40 AM
Transformer VA Rating vs. Current Rating	JhonDoe	Chip Amps	45	5th June 2004 01:11 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

6th June 2007, 08:35 AM	#2
YFW Account Disabled Join Date: Jun 2007	160VA could work but not work at the best condition. Do you need full output of the 5 chanels?If yes,300VA is much better.

6th June 2007, 01:11 PM	#3
wjp007 diyAudio Member Join Date: May 2007	YFW, Thanks for the note. I would think I do need the full output. I'll go with the higher rating.

7th June 2007, 02:52 AM	#5
YFW Account Disabled Join Date: Jun 2007	The sound quality depends greatly on the power supply. If you could feed good power supply to the amplifiers,you will get a very good sound.You will benefits more compared to hign end parts. Of course,you should choose better transformers and capacitors.

10th June 2007, 12:12 PM	#6
Ponz diyAudio Member Join Date: Jun 2007	the spec of transformer for 5 channel's +-18V unreg. and +-12V reg. voltage should be 14-0 5A x 2 and 12-0 1A x 2 or more power rating. besides enough power of transformer, the filter capacitor needs exceeds 2 x 10000uF, than get good sound quality.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)