Sub wolfer advice


Hey guys I need some advise on a power sub. Here is my set up. Krell FPB 400CX & Krell KCT pre-amp with BMW speakers. I have never run a power sub before. I will be running my transparent cables from the amp to the power sub. Then another set of cables out of the sub into my BMW's. The sub will be 2ft away from my right speaker. Do I need to keep both lengths of speaker wire coming out of the sub into my BMW's the same length or can I run a short speaker lead from the sub to my BMW speaker that is sitting next to the sub or am I splitting hairs?

Next question should the speaker wirer coming out of my amp going into the powered sub need to be the same quality of wire going into the speakers?

Thanks guys for all your help in advance. Hope this makes sense. Any help you can give will be greatly appreciated.

Thanks
Chip
dancer
Here’s a different approach you can try ... your Krell KCT has a number of premium low level MAIN outputs you can put to good use

You can run a XLR balanced cable from KCT MAIN OUT (#22 in the manual) to the INPUT of 400CX amp ... then run speaker wires from the 400CX to B&W’s ... this keeps the Sub out of Premium Krell/B&W loop

As your powered Sub most likely has a low level RCA IN ... run a normal single ended RCA (#22 in the manual) from KCT MAIN OUT to the SUB INPUT RCA input on powered SUB

Now the 400CX and B&W don’t see the Subs lower quality electronics and the 400CX isn’t trying to drive the B&W’s and the SUB at the same time

Each is running exclusively of each other ... but when you turn the volume up or down on the KCT Pre amp it will turn the volume up or down equally on both the SUB and 400CX amp

You can also use the special CAST Output (#23 in the manual) to drive the CAST Inputs on the 400CX also and still use the RCA MAIN OUT to drive the SUB’s input

CAST connection requires special Krell CAST Cabling ...

Possibly you can tell us what brand and model the Sub is and how you connect the KCT to the 400CX
Get a REL, run it line level from the power amp.. Don't know what I mean? Google REL and read about the Speakon connection that is the preferred method of hooking up a REL
The sub I am looking at is a GoldenEar Forcefield-4 1200watt sub. I run XLR to my 400CX.
Dancer,
I'd take Krell's advice and run rca out of your pre-amp to your sub. I have my rig set with the same signal routing and it works fine. Simple is better.

Good luck!
NO! NO! NO! A lot of well intentioned suggestions have been made, that in many cases would be good advice, but which evidently have been made without looking at the specifics of the equipment that is involved.

1)It appears that your power amp has balanced outputs, meaning that both the + and - terminals have signals on them (as opposed to the - terminal being grounded). If so, you cannot connect the sub's negative speaker-level input to the power amp's negative output terminal, or you risk shorting that output signal to ground (if the sub and the amp both have 3-prong power plugs, and depending on their internal grounding configuration). Instead, the negative speaker-level input of the sub should be connected to a ground point on the amp.

A chassis screw is PROBABLY such a point. You can verify that by using a multimeter to check for continuity between a chassis screw and pin 1 on one of the XLR connectors, or else by asking Krell.

2)The RCA input on the sub you are considering is designed to only work with an input signal that has already been low pass filtered and summed to mono, such as an "LFE" signal. Your preamp does not provide that kind of output, and so your only choice would be to connect that sub to the power amp outputs (the + outputs and a ground point).

Also, Magfan has made an excellent point about the fact that you don't need heavy gauge high quality speaker wire to connect the sub to the amp.

Regards,
-- Al