2 amps with 1 set of speakers?

[webelo]

I know this probably isn't the right place for this... but you guys seem to know a lot.

my question: Is it possible to hook up two amps to one set of speakers (I'm not referring to bi-amping) and be able to select between the two of them?

My plan is to have a full set of surround sound speakers with a surround sound receiver for playing movies in 6.1 and have pair of monoblocs for playing music thru the floorstanders. All home theater components (dvd, cable, etc) will be hooked up to the receiver and the stereo components (phono, cd, etc) will be hooked up to a pre-amp, then the monoblocs.

I've done some searching on the net and have come across anything definitive.

[joshuahhhhhhh]

do a google search on a Niles DPS-1 think it handles 350 watts a channel
and can accept up to 14ga wire

[cbutterworth]

I asked a similar question on the AudioCircle site around six months ago.

The advice that I recieved was that it would be risky. The amps would see the other low impedence of the other amp as the load resulting in smoke and sadness.

I am sure that a switch could be used, but according to replies to my posting from Hugh Dean (Aspen Amplifiers) and Frank Van Alstine, it is not worth the risk of switch misuse causing catastophic failure of your amps.

I suppose, there may be solutions to your two amps / one pair speaker issue. Why do you want to use two amps? For me, it was easy as my second amp is a cheap Sherwood amp that I only wanted to use for TV, DVD, radio, etc, which would save me routing these sources through my Aikido preamp and AKSA power amp. In the end, I decided that tube life would be very long, and I have a second set of my desired tubes "on-ice." For this reason, I play everything through my main system.

When I finally get around (ie. have funds and space) to build and install a tube power-amp, then I expect that I'll have to do what most other folk probably do - that is to simply change amps via disconnecting and reconnecting speaker cables.

Charlie

[webelo]

two amps... a DIY stereo tube amp for music, because I'm pretty sure I can build a tube amp that'll sound better than my solid state receiver. However, I can't build a receiver that will decode 6.1 surround sound, dolby digital, pro-logic, etc.

So, I want one amp for music and one for movies.

However, my movie and music listening space is the same, so I only want to buy one set of decent speakers too save on space and money.

Could I simply build a switch box? Are there schematics for that?

[Nordic]

I would imagine another option is to use relays and a PIC processor to guard over the swithing sequence...

[webelo]

Originally posted by Nordic
I would imagine another option is to use relays and a PIC processor to guard over the swithing sequence...

I'm pretty much a newbie... could you decipher this?

[Renron]

Seems like a PHYSICAL quad pole double throw switch would be safe. No way to fail......(yeah, right)
BTW, I would also like to do the same. I hope you get an experts opinion. (not me)

Ron

[Dan2]

Originally posted by webelo


I'm pretty much a newbie... could you decipher this?

A PIC (Programmable Integrated Circuit) is a chip that you program on a computer, which you can then use to drive relays - or rather drive transistors to drive the relays.

i think what Nordic is saying is have 2 separate sets of relays, and program the PIC so that one amp output is completely disconnected from the speakers before the other amp outputs are connected.

[webelo]

it seems like there are at least a few people out there who want to do the same thing. I have a hard time believing that no one has made a solution to this problem yet.

[ErikdeBest]

What about a relay (4 pole) that selects either the output of the tube amplifier or the receiver? Than there is no way that both amplifiers will be connected in parallel. As Webelo is building the valve amplifier himself he can include this relay in the chassis, and activate it from a voltage derived from, for example, the filaments. An activated relay selects the valve amp output, an desactivated relay (ie, the relay in a turned off tube amp) reroutes the receivers signal to the speaker.

A large wattage 100R resistor across the secondary of the OPT would be a safety measure in case the speaker gets disconnected from the tube amp (either through a loose wire or through a faulty relay). Both should be very rare, but can happen.