Looking for advice on a (mostly) DIY 2.1 rig

Justin Ward · 03-16-2005, 09:04 PM

I'm looking at setting up a new 2.1 rig for two reasons:
1) I'm moving out and don't have the space for my big 5.1 rig.

2) I find myself listening to much more music than watching movies.

Anyway, I'm looking at building a 75L sealed DPL 12, and matching it with either Adire 10.1s or GR AV-3.

Anyway, the thing that has me confused is the crossover/amp section of a 2.1 rig. Most people running 2 channel rigs seem to run a 2 channel pre-amp/amp combo. What's the best way to tie a sub into the whole system?

I'm studying to become an electrical engineer and would feel comfortable making my own crossover. However, I'd be worried about running a passive crossoever between the sub and mains due to the differences in efficiencies (especcially with the 10.1s). I'd feel more comfortable running an active sub. What is the best way to accomplish this? Should I maybe split the pre-amps output and put a high pass inline with the mains and a low-pass inline with the sub amp? That way I could take care of the crossover there and then adjust the sub volume to the right volume?

Let me know what you guys think.

-Justin

James W. Johnson · 03-16-2005, 09:46 PM

IMO for 2 channel id just build a good full range speaker, forget a dedicated subwoofer. And if you insist on a subwoofer then just go active. No point in complicating it.

Justin Ward · 03-16-2005, 09:51 PM

I would go full-range. But I have space constraints, and I love my subwoofers. I'm not a bass-head but I appreciate the extension alot.

gabeG · 03-16-2005, 11:19 PM

Justin, there are pro's and con's to this issue (just like any other topic!) and unfortunatley, you are the only one with the answers!

A minor point: I have no idea what some of the acronyms being used are (75L: is this a 75 litre cabinet or a brand?) so if I misunderstand one, please forgive me!

Active subs offer essentially plug 'n play capability to a system, generally performing well in a given system. Not every active unit offers the transparency that the mains provide.

Passive subs, assuming that the crossover is designed correctly and the amplification is adequate, can be quite exceptional in performance. My personal favourite is a package made by an older client (retiree into woodworking). The subs look amazing and sound the same: seamless transition to the mains etc. These are incredibly dynamic and extended.

Have fun with it. Gabe

Brian Fellmeth · 03-16-2005, 11:42 PM

Cheapest option is to just use a HT receiver and leave out the center and surrounds. The HT receiver has a built in sub crossover.

Second option is to use a line level crossover like the paradyme x-30 or you could build something from Marchand or ESP. A 3 good channel amp like tha anthem MCA-III could power R/L and sub from one chassis.

There are sub amps that will take speaker level in and supply a high pass speaker level out for your mains, convert a lowpassed signal to line level then amplify that for the sub. I wouldn't want to put my main signal throgh anything like that.

**HTF Ads**

Joey Skinner · 03-17-2005, 12:15 AM

Have you seen the GR Research AV-4? It's not on the GR website yet but here is a link to a sneak peek. Look to be great for music with the low extension you are looking for.

Jason Dalton · 03-17-2005, 09:24 AM

Quote:

Posted by Justin Ward
Anyway, the thing that has me confused is the crossover/amp section of a 2.1 rig. Most people running 2 channel rigs seem to run a 2 channel pre-amp/amp combo. What's the best way to tie a sub into the whole system?

Most two channel preamps/recievers have internal subwoofer crossovers nowadays. Shouldn't be much of an issue. Have you looked into any specific units?

Justin Ward · 03-17-2005, 10:14 AM

Jason,
I haven't really looked much into specific units yet. I have a reciver I can temporarilty power them with, for now. I don't imagine I'll need much power. I'm thinking maybe a clean 20 watts would work for the efficient 10.1s. Maybe 100-150 watts for the sub. Sound quality is more important that overall muscle, but I don't want to spend too much. I'd prefer to keep the cost of amplification under $500 total, not sure if this will let me get anything good or not.

Jason Dalton · 03-17-2005, 11:11 AM

$500 should be plenty for amplification, just make sure whatever unit you get has a subwoofer crossover.

TimForman · 03-19-2005, 04:19 PM

Would the Keiga 2.1 amp help you out?
http://www.madisound.com/kgamps.html

Nat Ward · 03-19-2005, 06:23 PM

Good catch Tim, that's a neat little amp - I bookmarked it for future reference. I wish I knew this was around a few months ago.
Nat