Will increasing PSU rails on OP amps give more headroom

I am modding a Yamaha mixer full of 4558's. They are being changed for 5532's. The rails are 15-0-15, if I up this to 18-0-18 (no problems with input voltage to the regs 25v) will I get more headroom.
Steve

Yes, but it's not much. 15 V gives around 21 dBu and 18 V 23 dBu.

Samuel

Don't do it.

You can get unpredictable heat problems, and it won't gain you much.

Are you sure you have the power needed for the 4558/5532 swap?

Jakob E.

Samuel-- Yes, that is in line with my thinking.

Jakob-- No problem with transformer etc. In fact the 15v regulators being fed with 25v generate a lot of heat, I think 18v regs could run cooler with the smaller voltage drop. I have checked carefully ALL other components are up to the extra voltage. I guess I could try it with one board connected and then plug the rest in one by one. There are three versions of this mixer 8,12 and 16 channel. They all use the same tranny and I have the 8 channel .
Steve

I think 18v regs could run cooler with the smaller voltage drop.

Click to expand...

Yes, but do the 5532 opamps draw more current than the 4558. The power being dissipated by the regulators is a function of the voltage dropped X the current being drawn through them.

P = IV

Yes the 5532's draw more current than the 4558's. There are three in each channel board, eight channels. The 5532 draws max 16ma, so 3 x 8 x 16 gives 384ma, no problem for a 78.. regulator. I have modded two channels already with 5532's and even driven to clipping with a 15v rail the draw less than the stated 16ma max. The rest of the mixer runs from separate rails to the channel boards.

Steve

What does output of the mixer run into?
Does 2dB increase in headroom really solve your problem?

The four sub outs (it's a 8-4-2) go to both a revox four track C274 and a four in/out delta sound card. The revox four out's come back to the mixer. This set up gives the most flexibility, four track analogue, four track digital, mixdown to stereo etc.
The whole thing works OK except that I have noticed that on close micing some things the mixer audibly clips. This is less on the modded channels with 5532's. I just figured that even a small improvement obtained so easily was worth it.
Steve