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

Showing 8 responses by abalem

Again, I must thank you very much for this detailled answer. You are a person of great advice, and though I'm really new to the field of Hifi, I managed to understand all of what you said (at least I think so..)

Cable lengh won't be a problem, I have kept it between 6 and 10 feet actually.

I've emailed Scandyna about the input impedance of the sub, I'll see what they say about it.

Fortunately, the shanling and the primaluna don't seem to be a mismatch, at least !!

I understand now that I can't take the risk of not connecting speakers (or a resistance) to the Shanling. But the fact that there is a pre-out still leaves me wondering. How do normal people like me do, who have no knowledge of physics ?? I mean, I read the manual, and it was clearly specified that the pre-out was to welcome a power amp if needed. How should I know that it will fry the Shanling if I really do so ! It's mad.. There might be a built in systeme as you say, but who would want to take the risk ?!
Hello Almarg,

Thanks for the reply !

Gosh ! Though I knew tube amps should never be run without speakers, I must say I didn't even think about this issue !! Damn..

Is it not enough to run the sub or is it not considered as a speaker ? If that's the case, how do you normally use the preout then ?

I'm even more confused now..

Yes, my sub has separate left and right channel inputs.

I'll look into the non-inductive resistor you mentionned.
Resistor :

I googled your advice and I came upon a picture of the resistor. I would never thought it was that complicated just to give more punch to the Shanling...

How do you plug these things ? Do you need wire and does it fit in just like that ?

Sorry if my questions sound dumb, but it's getting way above my head !
Actually, Scandyna The Ball 2.1 input inpedance may be specified in this document : http://www.podspeakers.com/Files/Filer/specs/the_ball21.pdf

it reads :
L,R input sensitivity : Input @ 1kHz 450mVrms @ rate power output
Sub input sensitivity : Input @ 1kHz 270mVrms @ rate power output

Is it correct ?
Thanks Al, I'll come back to tell you how it goes, need to find these bloody resistances first ! :)

Just to make sure, 8 Ohms should do the trick or should I go higher like 12, 16 or so ?
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 ?
Thank Al, once again your explanation is crystal clear ! I'll keep you posted on how it all went..
Cheers,