Adding an Active Sub to a Passive system?

I doubt you will find many PA subs with RCA connectors at all. Let alone through. And due to the inevitable longer cables needed when setting up a sub (unless you want your amp out there sitting on your sub), RCA cabling is not very good idea.

And if your amp only has wire post outputs and RCA inputs it’s most likely a home type of amp. And I would not recommend playing out with it. If you use it in your home only, then it could be feasible. In that case you could add something like the KRK 10″ sub. It has line in/out rca.

The main problem with that setup is that a through connector will give all the signal to your passive speakers, INCLUDING the bit that you want your sub to handle (say 40-125 Hz). What you really want is a sub that gives you only the top end signal on RCA’s. I am not sure the RCA’s on the KRK’s do.

For the same price as this sub, you can buy two brand new KRK RPG6 G3 speakers which have plenty of bass for most home use. And if not enough you can always add the sub later if you want. You won’t have an aging passive system anymore, but brand new, great-sounding active speakers.

So, personally I would not invest in something to add to my existing speakers, but go for the KRKs as an upgrade.

Greetinx.

Actually Carver was, in it’s hayday, a great amp. His Magnetic Field amps did something wonderful that nobody else did, only supply the power needed when needed. Not like all the others that had huge capacitors to store excess energy for when you needed a boost. Nowadays every class-D amp works that way, but at the time it meant you could have a (P)M1.5T amp that was like 2U high with only two small fans. Everything else in that power segment was at least double the size and, often more.

I think that Carver hit the big (pro) leagues when Michael Jackson took them on tour (couple of racks full of them). Not sure for what tour anymore.

Enough Carver history (there is way more, the man invented quite a few interesting things like the Time Lens for CD’s), back on topic.

It being an old Carver amp does explain only wire posts for speakers. I can’t seem to remember SpeakOn being available then. Our mobile rig had a few Carver amps in racks. I think we just ran wirepost to speakon in later times inside the rack and then SpeakOn to the speakers.

The whole issue is getting the right sound to the right amps. You can run full spectrum into the sub and it will only play the sub-low. No problems there.

Since you are playing out, the whole KRK issue is mute. Those are not to be used in a live environment.

However, having XLR out from the controller does facilitate things a bit better.
First don’t use both XLR and RCA outputs on the controller for this purpose. You’d still be missing the crossover.

1) Go dual XLR to a sub, using both Left and Right (often A and B) inputs on the sub
2) Go dual XLR from the subs High Pass (also called low filter, satellite or something) to your Carver. If you have a P(M)-series Carver it will have XLR as well. You said you only have RCA in, so you’ll need something to change XLR to RCA. See below link for an example.
http://www.bax-shop.nl/di-box/art-cleanboxpro-signaaltransformator/product-details.html
3) From the XLR-converter into your Carver.

You now have a sub that plays only sub-lows as intended and the Carver powering the passive speakers playing everything BUT the sub-lows.

My tip would be to make a multi-cable (4-core) yourself with two male/two female connectors on either end. You just have to roll out on cable and just connect everything up.

As to what sub you should get, personal taste really. Optimally you would want to listen to it together with your passive stuff.

So what you want is doable. You might still want to look into getting a complete sub/satellite system. There are a few reviews on the blog for the HK Lucas systems and the LD Systems. I’d be weary about adding too much stuff to your current setup. You clearly don’t have the Pro version of the Carver amp (it would have a PM instead of M productname and XLR inputs if it was) and I don’t know about your speakers. Assuming they are in the same age range or at least not very new.

Speakers go bad too. If the cones are connected to the frame with foam edges, those wear away after a longer period of time, which means you’d have to have that fixed. The amp is still working, but a timebomb. Could last another 5 years or 5 days. Not bad if you keep using it as is. But if you start spending money to expand your system and THEN having it go south would be a major bummer.

My advice would be to stick with what you have til it breaks down and then replace it with a matching and tuned sub/satellite system. Or look into buying a used sub that you are willing to toss out with the Carver/passive speakers if they die on you. Personally I’d go for new or keep using what you have as is. But that’s just my way of doing things.

Greetinx.

The things is, you’d have to know now what tops you’d be getting in order to have a good match when you have an all new system. And the sub for that system might not be best for what you were talking about doing.

You could go ahead and get the sub that goes with the new Thump series:
http://www.mackie.com/products/th-18s/

Follow the guidelines above and it will work as you want. Then you can add the Thumps as your passive speakers and/or amp go to that beautiful place up in electronics heaven.