Direct input into power amps

[richhutch]

New to the forum so please be kind.

I have picked up a couple of pretty muscular power amps (Inter M R500s) and I am going to have a play about with them. I read somewhere that it is possible to send a signal straight from source to the power amps and I fancy trying this. Clearly it would not be a phono signal without a preamp being needed but was thinking of a CD player. I know that one stumbling block is that the volume would be at max at all times but the power amps have volume controls for each channel so I'm hoping that would deal with that problem. I even thought that I could use them as monoblocks and input one channel to each amp and on to each speaker. Is this possible or am I way off track? Thanks.

 

[Al ears]

Welcome to the forum.
No my area of expertise but I don't see how you can use them as monoblocks as you describe with the CD player. Even if it is possible I would be inclined to buy a cheap stereo pream to keep things simple as you're going to have problems synchronizing two pots.

 

[richhutch]

Thanks for that. I would still want to give it a try and adjust the volumes by ear. Failing that, can anyone recommend what you suggest, a cheap decent preamp?

 

[Gray]

Your best bet is to use a source with variable output.
(Quite a few CD players had remote controlled line outputs).

Or....a passive volume control between source and power amp would avoid the need to adjust two separate controls by ear.

Otherwise, say how much you'd want to spend on a preamp and you'll get some suggestions.
(I think there's a Tangent unit that might do you for around £200)

 

[richhutch]

I already have a preamp for my "own" system, a Hafler SE120 with 2 Hafler SE100 power amps. This is just for a bit of fun so not looking to spend a lot (that's Scottish for anything!!).

 

[Gray]

not looking to spend a lot (that's Scottish for anything!!).

The Scottish option - bung a dual gang 50k ohm log pot in a box with a knob and some sockets:

 

[Gray]

....even easier (and more Scottish):
Fit a single dual gang pot instead of the two in your power amp.
(Check / match the resistance value currently in there).
Not even any holes to be drilled, blank off the unused hole.

 

[treesey]

Old Sony CD players have variable line-out with a volume control on the front.

I have a 555 ESD but use analogue variable line output direct into the back of a 1980 Crimson 520. I have various other bits of kit, some quite modern, (including a well regarded Arcam stand-alone DAC ) but the Sony DAC into the Crimson sounds fantastic (to me) - I wouldn't change a thing.

Less is more.

 

[treesey]

I even thought that I could use them as monoblocks and input one channel to each amp and on to each speaker. Is this possible or am I way off track? Thanks.

Can't see why not?

 

[richhutch]

Evening all. I posted a while back about direct inputting from my CD player into a power amp. Well finally got round to doing it and it worked a treat. The source was my beloved 1986 Meridian 206 Delta Sigma CD player, the amp one of the Inter M 500s I got on Gumtree and the speakers an old pair of Kef Chorales I had lying about. The set up did sound great. The individual output controls of the power amp acted as dual volume controls with no balancing issue. Of course the amp has only 1 pair of inputs ( phone to 5mm jacks) and no controls whatsoever but is that not an amp should really be? I suppose it goes to show again the value of a really good source simply amplified. Next stop biamping!!