750 mated to B&K Ref 30

If I use the control output trigger from the ref 30 to turn on my 750 on power up, there is somesort of backfeed that causes the ref 30 software to hang up. B&K said they have nevert heard of it. Has anyone had the problem? If so, is there a solution other than leaving the 750 on all the time?

You could try using the ref 30's trigger to power a switched power strip and plug the 750 into that. Or, if that doesn't work, you could turn off the 750 separately when you turn off your ref 30.

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Matthew J. Hill
matt@idsi.net

Thanks for your help. As it turns out my power is supplied by a PS600. It "grunts" under the load when the 750 is powered up. It either generates some noise or has a drop in voltage output. Either way, the B&K Ref 30 doesn't like it and the software seizes up. Changed the power source for the 750 and all is well.

Found a power strip made by Bits Ltd. It looks like a good product and can be found at www.bitsltd.net .

So I contacted PS AUDIO about my problem. The response follows. Does Outlaw have a design flaw in its amps?

...

Sounds like the Outlaw amp does not have an inrush limiter. We designed
the Power Plants to ride through an inrush surge even if the voltage
sags a bit in the process. This is the only circumstance where a Power
Plant will allow voltage to sag.

Best regards,


Jonathan Hart
Customer Service
PS Audio, Inc.
jonathan@psaudio.com

It's never a good idea to have a piece of equipment that has a high current draw such as a power amp on the same circuit as another that does not draw much current. The Ref 30 obviously has a low threshold where the power supply goes out of regulation. This is a design issue, and can be dealth with by having more filter capacitance to ride out momentary low voltage instances, or by having a higher voltage available on the secondary of the power transformer, or both. This increases the heat dissipation of the power supply however. These are all design tradeoffs, but ideally the power supply has sufficient capacitance and enough of a voltage buffer on the secondary that the AC dropout voltage is between 90 and 100 VAC. It's possible that your AC voltage is on the low side; it should be 120VAC. If your house has old, smaller gauge wiring, this will also drop excessive voltage as the demand for current increases, such as when a power amp is turned on, and it's filter capacitors charge.

Low voltage can also happen if you live in a rural area and demand has increased without scrutiny from the utility. In my case the first winter I was here I had voltage at the meter from 97-104 volts. This will cause a lot of things to not work quite right, but you'd be surprised how many household appliances still pretty much work.

The utility acted quickly in my case when they were notified. An easy way to check is to have an electrician measure the voltage on the incoming or 'line' side of your main breaker with the breaker on and then off. With the breaker off the current will be essentially zero, so there should be no voltage drop between you and the utility transformer. Whatever he sees in this state is what the utility is supplying.

The measurement in the 'on' state should be similar, but may sag a few volts. If it sags a lot the service to your house may need attention. If the voltages into the main are OK in both states then you need to look at your house wiring.