Sub settings without a dedicated subwoofer output?

Boomzilla -- Tue, 04/12/2011 - 06:17

 I'm ditching my AVR and moving to a tube hybrid integrated amp (Jolida 1501).  My subwoofer, a Definitive Technology Supercube, has line-level inputs, but the integrated has no preamp outputs.  This means that I'll need to use the speaker-level inputs on the Def-Tech.  
 
My questions are as follows:
 
1.  It would seem to me that I will get the best sound by NOT using the crossover integrated into the Supercube.  I'd like to run the amp outputs directly to my speakers and cut in the sub when the speaker response rolls off.  The problem is that the Joilda is NOT happy with low impedances.  My speakers are 4-ohm and even if the Supercube has an 8-ohm input impedance, the amp will see a parallel impedance of less than four ohms.  This is a recipe for cooking my amp!  How do I get around this problem?
 
2.  If I do opt to use the internal Supercube crossover, it won't cross over my speakers at the expected frequency because its circuitry expects to see 8-ohm impedance speakers on the outputs.  I can't just buffer my speakers with additional 4-ohm series resistors, because then the internal speaker crossovers won't work properly.  Suggestions?

Steven Stone -- Tue, 04/12/2011 - 08:06

One quick and easy subwoofer output solution is often to take a feed out of the headphones out.
If the the headphones use the same volume control as the mains you're home free. If it has an independent output control you can easily find the right matching level for your usual volume settings.
Does the Supercube take speaker-level inputs? I've sometimes used the REL approach of running a second speaker cable run to the sub from the amp - most subs draw very little power from their speaker-level inputs UNLESS the speaker level output connections from the sub run to a set of speakers as well.

Steven Stone
Contributor to The Absolute Sound, EnjoytheMusic.com, Vintage Guitar Magazine, and other fine publications

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