Is it possible to parallel transformers

[dyarker]

Surplus resellers are much cheaper. But, you say you're getting enough volume and want to clean-up distortion. So you don't need enough power to drive the LM3886 and speaker to full rated power. Parallel a second transformer (like you originally asked), use a rectifier rated 2 or more Amps, and two more 1000uF caps. In fact, try just adding the capacitors first; that may be sufficient to clear up the distortion.<p>A linear supply is what you've built. PCs have switching supplies. 110V 60Hz (or 220V 50Hz in other parts of the world) is rectified and moderately filtered to 155V (311V) DC. There may be a circuit between the rectifier and filter to roughly regulate to a lower voltage. This DC powers a high power, high frequency (500Hz - 100KHz) square wave oscillator. The square waves go to the primary of a toriod transformer (iron dust and epoxy pressed into a dounut shape). The secondary output(s) of the toriod are rectified by fast power diodes. Then to regulator(s) and filters.<p>***********************************************
WARNING:
ALL PARTS BEFORE THE TORIOD TRANSFORMER ARE NOT ISOLATED FROM THE POWER LINE. CONTACT WITH ANY PART DURING OPERATION CAN KILL!!!
ALWAYS KEEP THE POWER CORD REMOVED WHILE THE CASE IS OPEN.
ALWAYS USE A 3 CONDUCTOR POWER CORD, AND A GROUNDED OUTLET FOR OPERATION.
*************************************************
It makes more sense to buy switchers. DC-to-DC switching supplies (like car battery to +-15VDC) are okay for advanced hobbyists because there is no connection to the power line. (Dangerous currents still exist! In a safety briefing, I learned of a guy who lost his finger working on his car. By way of a wrench on the positive battery terminal, his wedding ring made a short circuit to the chassis and welded in place. The ring got HOT and cooked the finger to the bone.)<p>No guarrantee on the following 'cause I'm working on long unused memory.
68W is only 2.8 times louder to the ear than 4W.
68W / 4W = 17 (the Watts cancel)
Relative sound level = Natural Log of 17 = 2.833<p>The relative electrical power difference is:
(Log10 of 17) * 10 = 12.3dB<p>Cheers & C U L,
Dale

[Mike]

Would the second transformer be as effective as a 5A transformer?<p>My rectifier is a 4A, so that shouldn't be a problem. I have 9300uf 50V caps, so I will try those first. Can I build a switching power supply? I was given a broken Dell power supply from a PC, and after opening it, and cutting off the cables, and removing the fan, and removing the power input connector, noticed that it had a fuse that had blown. So, I assume the parts are OK. Can I remove them and use them on my supply? And will changing the supply really make that big of a difference in sound quality?<p>Thanks, Mike

[dyarker]

If you're getting enough volume, then a second transformer is effective for the job. The distortion should be cured, and you should get a little more volume before distortion reoccurs.<p>On the other hand, if the object is getting the max out, 2 Amps does not equal 5 Amps.<p>--------------------------<p>Some of the dell supply can be used. But I think building a line power switching supply is over my head. If you insist, remember those things are dangerous. The ONLY connection between input and output must be through the toriod transformer and opto-couplers.