Help with unpowered sub

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I'm trying to get my 14 year old daughter interested in building a sound system. All she cares about is pounding base (this does not bode well for me).

I've seen 2.1 chip amp boards on ebay for $30. Each stereo channel is 18w, and the .1 is 2 chips for 36w. I want to build a couple of 2-way speakers, and a sub.

Conceptually, can I just mount a Dayton Audio SD270A-88 10" DVC Subwoofer in a box and run the .1 leads to it? I've only built a couple of pairs of speakers, and I've become accustomed to seeing powered subwoofers. I don't even know how to search for unpowered subwoofer designs (given 5 minutes of effort).

We're looking cheap, and not too powerful (turn that racket down!!!!)
 
Isn't that price amazing? I wonder if they're seconds that failed Quality Control. I meant to post an 8 ohm speaker.

I know the sub is 'powered' from the board, but it's not powered from a separate plate amp ON the sub. I'm just trying to validate my belief that this configuration just replaces the plate amp on the sub with the chip amp on the board. (and solicit other relavant observations - e.g., I wondered if 4 ohm would be easier or harder to drive)
 
Isn't that price amazing?
And the kit is <$17 including shipping! Don't know about the QC questions, nor would I call the TDA2030 a great chip, but it's good enough at this great price. Yes you can connect the amp right to your passive speakers; it seems likely the board contains a LP filter for the sub. The 4-ohm connection of the SD270A-88 ought to be fine. For all things subwoofer I'd recommend a look at Brian's Subwoofer DIY Page.
 
As far as I can tell this board has 3 inputs. You'll need to sum your stereo signal and low-pass filter it off-board to feed it to the '.1' input. The inputs and outputs visible on the board don't really follow this theory though so it's a bit of a mystery. I'd email for a schematic.

Also, it does state that 2 chips are used BTL, and hence for that '.1' output you can use an 8Ohm speaker minumum (effective 4Ohm load on each chip).
 
Hmmm... I thought that was the LGR input beside the pot at the lower right in the photo, with the terminal block outputs at the opposite end behind the caps. The speaker impedance is good advice. That Dayton DVC may not be the best choice here.
What I mean is I'm taking it that the summing is done on the board by the DIPs, and the pots are just volume control for each channel. I'd try to get a schematic in any case.
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.