Can I run a 5.1 amp as a quadrophonic amp?

[The Tasmanian]

Hi TRock gents -
Ive never done the home theatre 5.1 stuff.
Not starting now either. (Ive done 5.1 film mixing through a console w/ speakers).

But I do want to set up a quadrophonic system - with 4 speakers, and was wondering if these 5.1 amps can do a quad setup, or are they all doing dolby decoding type stuff?

All I want to do is :
use Front L + R ins - Rear L + R ins as a quad amp, so - input 4 signals into an amp, and get 4 outs without any movie/dolby/surround encoding/ decoding stuff.

Is this possible on most generic 5.1 hi fi amps?
Anyone got any advice here?

[audioio]

Is this possible on most generic 5.1 hi fi amps?

If you're referring to receivers (multichannel preamp/multichannel power amp/AM-FM tuner), then you'd need one with a 5.1 analog input. Cheaper ones don't have it; more expensive ones often do.

[The Tasmanian]

thanks for the info David,
Ive never looked at the rear of one of these amps before.
I somehow thought these amps had a audio input that related to an output = wrong.
Sorted that question out.

[Alastair Reynolds]

Hi Chris,
is this for an installation rather than a studio / listening room ?

The alternative I've done a while back because I don't like cheap surround amps was to use 2 good stereo Amps and feed them via a 4 Gang volume pot. You can get high quality multigang pots from RS or Element 14 components or if you want a really nice one buy a P+G RF 15 rotary fader (Available up to 8 gang and matched within 0.5dB) but they're expensive.
Alternatively you can do a control using more conventional Pots and a quad VCA.

Could be a good thing to talk to Rob Squire about and get a custom build.
Most domestic amps that do 5.1 analog inputs (pioneer and Sony certainly used to do some for around $400) use IC module power amps and are not the greatest sounding things.But can probably be picked up on (FL)EaBAY pretty cheap.

[ChrisW]

I know nothing on this subject, other than vintage Quad (the brand) amps still sound great and can be found on Ebay and through vintage hi-fi dealers (there are a couple in Sydney). Not sure if any specific Quad amp offers Quadraphonic. My brother had a system in the 70's. Sounded awesome.

[Drumstruck]

As a real world example I have a Marantz SR4600 that offers "up to 7.1" - it has analog and digital inputs and 7.1 outputs with the sub output designed to drive a powered sub.

Output config is selectable to whatever flavour you want between stereo and 7.1 - I assume most in this price bracket would offer similar options. I'm using mine as stereo mostly as "aurotones" (but I also have matching rear, centre and sub in case I want to do 5.1 mixes).

....paid $300 for this one, but it was new/old stock. A good unit if you don't mind the "marantz" sound......

[Chris H]

Many manufacturers make 4 ch power amps. Yamaha, Crown, and Australian Monitor has a 4 x 80 watt amp.
You should be able to pick one up 2nd hand pretty cheap. I see them all the time.
I have done some 4 ch stuff for theatre using my two Sansui AU555 amps. For some reason ie well built etc they sound clearer and louder than many 100 watt rms pa amps even though they are rated at around 50 watts. I just bypass the preamp section and use the power amp inputs.

[The Tasmanian]

I'm just trying to find a simple way to monitor 4 speakers set up as quad, quality is not that important.
Set up a section of my studio that is a multichannel monitoring environment.

Price - can be as low as poss, as I can make sure everything sounds good through my various studio speakers before monitoring in quad. As long as there is ok detail - no harsh annoying crap

Even if I have to buy 2 old stereo amps that are not related, and run 4 speakers from these.

Or even better, 4 powered low end studio monitors. 5 inch speakers would be fine.

Anyone know of low priced actives that are not too horrible / fatiguing ?

[The Tasmanian]

On further thoughts - 4 of these powered Mackie Mr5 Mk II's will make life very simple.
$350 a pair - is pretty good.
Also - Tannoy Reveal 501A's are a similar price - and probably better sounding.

Can have them wired to my patchbay, so straight out of HD into the speakers.
Powered speakers will solve many future problems I'm thinking.

Thanks for the info guys - much appreciated

[Drumstruck]

the Fostex PM0.5s are pretty good for the $s too - around $450 per pair - I have a pair (+ sub) connected to my televish

[mylesgm]

have the tannoy 5inchers here at home and the Maudio bx5 in the studio and I have to say I pretty impressed with how they sound for budget active monitors. Build or buy a 4 channel volume pot and you are set for 4ch surround with either of these.

As stated earlier in the thread you could use pretty much any stereo amp (and vintage amps are cheap on ebay) paired with any other amp for four channel with passive speakers especially if it is really only for monitoring spatialisation after you've done critical listening on studio monitors. This is how I've done heaps of multichannel installation mixes. Getting similar speakers is far more important than similar amps and usually the older amps will kill the new all-in-one home theatre amps for less money.
Another possibility is getting a purpose built amp made up from from JLM amp modules (they are pretty cheap, powerful and seem pretty foolproof), you could have a master volume control and individual trims per channel and then actually use this amp for the installation itself. I expect it would be far more reliable (and easier to repair) than many other off the shelf options and would deliver day in day out as you would need for a sound installation.

[The Tasmanian]

Thanks Myles - all good info.
It makes life easier if I do a set of actives.

Tannoy's I'm leaning towards as I can get 2 pairs delivered for $800.
And Ive owned 4 pairs of Tannoys over the years, and they have all sounded very useable.
These 5 inch versions also have volume controls on the rear, so I can set them all at the volume I want.

These are not to go onsite though, just part of my Frankenstein sound laboratory.
Ive ordered a black cape too!

Have to have a beer when you get back..
Enjoy the Warthog!

[Sammas]

New home hifi systems can also have protection systems in place. I have an old 1970's Akia power amplifier that seems to happily run with no load on it... While a much more recent Sony 5.1 amplifier would switch itself into protect mode and power itself down with no load present (no speakers attached). Just an observation from my brief experimentation with the two... Perhaps there could be some difficulties running a 5.1 amp without a centre or lfe speaker or load attached?

[The Tasmanian]

That's a very good point Nath - glad I've decided not to go down that path, i would have been wasting my money - and blowing up amps.

[Milo]

If you're not too concerned about using a cinema amp instead of hifi, QSC do a range of 4-channel and 8-channel amps

Milo

[The Tasmanian]

Bit pricey though Milo, then I need 4 passive speakers on top...
But very handy to know for the future.
Thanks