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How to split pre out to connect power amp and sub

Hello !

I'm really getting confused about this one, so please help me !

I recently bought a Shanling MC-30 (2x3W tube amp/pre-amp, very nice btw), and I'm thinking about buying a Prima Luna Prologue Five (35W tube power amp) to give it more "punch" and soundstage.

I can simply hook it up the "pre-out" on the Shanling, but !! Right now, I have an active subwoofer connected to it (Scandyna The Ball 2.1 Stereo RCA input)...

So my question is : how to split the pre-out to connect both the power amp and the sub ??

I've looked on many threads, but didn't find the exact answer or didn't understand all the splitting story... Can you do a step by step (I'm a newbie, I know...)

First I understood I don't need a Y splitter to connect on both ends of the sub cables to connect the Shanling to the sub (but I still bought them before I found out !). So that makes that one of the pre-out input is used for the sub, and the other one is free... Do I need a Y splitter here to connect to the power amp ? Won't it deteriorate stereo or sound quality if it is hooked to only one pre-out input on the pre-amp ?

Maybe I got it all wrong.. so that's why I'm asking you pros in the end ! :lesson:
abalem
abalem OP
10 posts
 
Hello Almarg,

If you ever pass by this thread again.. I've emailed Charisma Audio about wether I would need resistances or not, or rather what kind of resistances they would advise, and they said I should put :

5 watts resistors with value between 20-30 Ohms

which seems to me much different than what we talked about here :

10 watt ceramic audio power resistors around 8 Ohms

Do you know why they would advise such a high impedance ? Does it actually change anything ?
almarg's avatar
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almarg
9,670 posts
 
Actually the one I suggested was 20 watts, 8 ohms.

The wattage rating is the MAXIMUM power that the resistor is rated to handle. A margin of at least 2 to 1, and preferably more, should be allowed between the wattage rating of the resistor and the maximum amount of power that would be put into it. You have a 3W amplifier, but into 20 or 30 ohms (rather than 8 ohms) the amplifier would only be able to deliver considerably less than 3W, which is why they are suggesting only a 5W resistor.

But the more important question is whether to choose 8 ohms or 20 to 30 ohms. If you have reason to have confidence in their statement, then perhaps 20 to 30 ohms is ok, but keep in mind (as indicated in the long writeup I quoted) that too high a resistance is what can be harmful, not too low a resistance.

The advantage of using the higher value 20 to 30 ohm resistor (and it is a minor advantage at most, in this situation) would be that it will draw less power from the amp, and everything will run a little cooler.

Regards,
-- Al
abalem OP
10 posts
 
Thank Al, once again your explanation is crystal clear ! I'll keep you posted on how it all went..
Cheers,
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