looking for an economical way to get a +/-17 volt supply with 5 amps

Did some searching and didn't come up with much.
Basically I've got a project that I need a bi-polar supply for but it draws a decent amount of power.  I've looked at old console power supplies on ebay, but they can be pretty expensive to ship.

Is it a bad idea to take 4-5 single amp supplies and combine the outputs?
And would it make more sense to get a single big transformer to power the whole thing, or does that not really make a difference?
I would also guess that diodes would be a good idea in combining rails to avoid back flow.

Anyhow, good idea or bad?
Any other suggestions?

Find an old console power supply? 

Current draw is a little high for audio amp with those rail voltages but close if amp is stereo with 4 ohm drive capability.

JR

I'm not a power supply Guru, but my first thought would be to make a linear supply.

Toroidal into an opamp+pass transistor regulator.

you could scale the pass transistor to the current needed. I doubt you'll find a single chip regulator that could handle that kind of current.

Off the shelf we have from Mouser at $168:

597-DD15-5.0 

Specified for 12-15V, but I would bet it goes to 17V with derating of current.  That gets you approvals from all the safety agencies, and a new supply requiring an enclosure, connectors, and fuse. 

To the original question, not sure if the definition of economical can be met, outside of used surplus, which may have it's own hazards. 

While an old console PS may appear expensive to ship, unless you do something clever like a mains voltage switcher, it will cost a bunch to ship parts (like a conventional transformer).

I have noticed in recent years that shipping costs have increased a bunch, along with copper and iron.

For a one off a canned solution is not crazy, but guessing that your project amy be a console of some sort, an old console PS is not a bad starting point. transformers and rectifiers don't generally wear out, so maybe invest in new caps. 

JR

Knock something up with LT1083CK. It is 7.5A. I used it on robotics applications many times. No problems.

Edit. I also realised that Douglas Self has got an example circuit in his book Small Signal Audio design.

I have seen many large console power supplies made up of smaller supplies in parallel.  There is an established method, and it is used commercially. 

you can get 2 single  output amps and depending which side you wire to ground, V+ or V-, will give you your +17 or -17.  If you wish to buy off the shelf, then it is cheaper to go that route.

Thank you all-
lot's of good information and ideas.

I'll do some more research, but I feel like I've got a better grasp on a solution.

I'd go for a couple of Meanwell enclosed 100watt 15 volt SMPSUs. They have tweeking pots so 17 volts is no problem. Reliable as it gets and <$40 apiece.
M

I found an Acopian supply for $65 that comes close enough to what I need.

I have found that the dual rail supplies are sometimes more expensive than 2 "single" isolated switcher supplies tied together...  The caveat may be space/size... I have found some of the medical grade switchers to be the case for this... when searching on Mouser or Digikey, try looking at single isolated switcher supplies...

in my example, for I think 60W or so, two medical grade switchers were 2 x $35 versus $120+ or so for a dual supply... been a while since I looked at power supplies... prices have probably changed...

You may find two similar/same old laptop switchmode power supplies hanging around in cupboards of companies - typically 19V at 5A.  Strip off the plug and away you go.  I did this very quickly with two HP supplies to get a stereo TV audio amp going from a dead Loewe.