Direct input into power amps

richhutch

Active member
Jan 20, 2023
10
1
25
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.
 
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

Active member
Jan 20, 2023
10
1
25
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

Well-known member
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

Active member
Jan 20, 2023
10
1
25
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

Well-known member
....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

Well-known member
May 18, 2015
247
90
18,870
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.SonyCrimson.jpg
 
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