Switched and Un-Switched Outlets in Preamps

Hey all, I've finally assembled some vintage tube gear together and am noticing for the first time that the preamp has four outlets in it: two switched, two un-switched. What would be the ramifications of plugging my two mono blocks into the preamp? I've never had a system like this before (I'm used to a single stereo receiver,) so forgive my ignorance. If this has been covered before I'm sorry but I didn't know which keywords would bring up threads pertaining to this topic. The hardware is as follows:

Preamp: Dynaco PAS Preamp

2X Heathkit W5 Amps

Looking forward to learning something about all this!

 

I recommend not using switched outlets in preamps except possibly for a turntable. The switches are not made for the starting impulse currents in many modern units and in any event the switches are old and usually hard or impossible to replace.

 

Yes, we always suggested that the switched outlets be used for low level signal sources like turntables and tuners so as to go easier on the main switch in the preamp.

 

Keep in mind that on anything that has a switchmode supply the initial turn on can be very low impedance and that will play hob on many of the older switches. I have a Sony CD player that if I plug it into a live outlet you will hear a pretty good pop from an arc at the outlet. Same with several other pieces of electronics such as the little trickle charger I use on my car.

 

I would never plug an amp into a switched or unswitched socket on a pre amp, receiver, etc. as they are only rated for low power use. In fact, I would never plug anything into them.

I just finished restoring/upgrading a vintage integrated amp and matching tuner. One of the first things I did was remove the wires going to the switched/unswitched sockets.

 

My late 1970s Audio Research SP-6 preamp has switched outlets. They were included to encourage and make it easy for users to turn on power amps after this preamp. The SP6 has to be on for a minute or two before it would be advisable to power up the main amplification.

Anyway, I appreciate the archaic gesture of convenience, but have never considered plugging anything into the preamp's outlets.

 

I wouldn't use a rear power outlet for anything more than a 40-60 W per channel amp. Many years ago I had a Dynaco PAT-4 and Dynaco 120 plugged into it, which wasn't a problem. But a preamp power cord may not be designed to handle amp loads and there can be measurable voltage drop. These days, a large amp may have a 3-wire (grounded) plug and you can't plug it into a 2-wire outlet on a rear panel anyway. I'd reserve those rear panel outlets for tuners, cassette decks, turntables, etc.

My solution...a couple of years ago, our local electric company sent a dozen CFL bulbs, some LED nightlights and an "intelligent" power strip surge protector as an incentive for completing a survey on electric usage at our home. I hadn't seen this exact power strip anywhere else. It is rated a full 15 amps and has a "sensing outlet" to control 3 others, with two outlets always on. I have my Emotiva preamp plugged into the sensing outlet and my Yamaha M-80 amp is in one of the switched outlets. Works like a charm. Of course, and not to start a power cable war here, if you are able to hear the difference between a $3 power cable and a $3000 cable, you won't want to do this. Probably need to run a dedicated line from the main panel then anyway!

 

Thanks for all of the responses; learning a lot - which was the original intent. I wasn't really planning on using those rear outlets, but I'm glad to know what they're all about!

 

The rear outlets were a workable idea in the days of small amps and two wire cords on everything. Prevented ground loops and allowed for sequencing. Now many units have a separate DC power control connector which works better.

 

My W5's don't have an on/off switch either. I have them plugged into a power strip though, which is kind of my defacto on/off switch. In this case would plugging them into a Switched outlet make any sense?

 

The McIntosh preamp power switches were a lot more serious than the Dynaco's, though. Actually the amp that was sold as a partner to the preamp from the company I worked at late 70s-early 80s didn't have a power switch, either, and it was meant to be powered on by the preamp switch. But that amp was relatively low power (100W/ch) and the preamp switch was made to take it. But these days everybody's putting like half a farad of caps in their 300W/ch pigs and they suck down the power grid when they come on.

 

When I had ARC stuff in the mid-70's- SP 3-a-1 and Dual 75 a (still have the amp!, I think i used the switched outlet to turn on an outboard power strip that drew its power from the wall- so I could switch on the amp from the preamp (after the preamp warmed up), but I wasn't relying on the switched outlet to provide power directly to the amp- it was, in effect, a trigger. Isn't that how these are supposed to be used?