egggy

Sticky?


Credit goes to minivanman over on mobilesoundscience

I don't know if this falls in the low cost necessarily, but it is high value. Here is a complete module that operates as a line output converter (LOC), and a digital sound processor (DSP)

The goal of this project was to build a unit that could convert the speaker level outputs of my stock head unit and supply a line level signal to a miniDSP module.

http://www.minidsp.com/onlinestore/c...7/minidsp-kits

http://www.mobilesoundscience.com/f4...-work-you-257/

Typical car audio branded LOCs generally have a limited bandwidth, and even within that bandwidth, the signal isn't very flat. All an LOC is is a group of small transformers that step down the voltage to a line level, and provide ground isolation. Since consumer car audio LOCs utilize such small, and inexpensive transformers, you'll get the limited bandwidth I was talking about. For example, David Navone brags that his LOCs exhibit bandwidth extending down to 80 hz. Roll off after that occurs at 12 db/oct, so by 20 hz, you're 24 db down in output. Usable, but we can do better, albeit with a considerably higher cost.

Now in come the pro grade transformers. These are not cheap, but they exhibit a full audio bandwidth between 20-20khz, and the signal is flat. The most respected, and popular are made by a company called Jensen (not to be confused with Jensen Car Audio).

http://www.jensen-transformers.com/

I decided to use a JT-10KB-D transformer for this project based on a very simple schematic that Jensen provides on their website for a LOC. The schematic is listed under application AS068.

http://www.jensen-transformers.com/apps_sc.html

Since the power being supplied in this application is fairly small, it was very easy build. In fact, technically, you could just run this transformer without any additional resistors. I put some on the back purely for protection sake.



Here are the transformers. You can fit about 4 transformers from a car audio branded LOC into one of these.



Here's the input plug. Simply two runs of speaker wire, and a 12 volt power, and a ground wire.


Output side.


Total this project costs about $225.00. With another DSP module this could easily run a full 4-way setup for under $350.00.

Big Mack

iTrader: (1)

While I applaud the effort, there are plenty of aftermarket units that will do much more than what you're asking this to do, and for not much more money. Additionally, they don't require nearly as much work. You can get the AudioControl DQS for a street price of less than $500, and that unit has 8 channels, DSP, and EQ built in. If you add your pieces together, then add the EQ and crossover functionality, you're spending a lot more green and won't have it nearly as neat and tidy.

Like I said, the work and doing it yourself is admirable, but those who want far more than the typical LOC offers will be looking at pieces like the DQS.

Big Mack

egggy

I had the DQS and while it's an decent unit, the mini dsp offers so much more. Let's not forget that the dqs doesn't have time alignment which is crucial to any sq install...and you're stuck with 4th order slopes.

Here's a run down of the standard features of a minidsp

* Time Alignment in 0.02ms increments
* Phase Flip (0/180)
* Channel muting
* Linkwitz-Riley with slopes of 12, 24, and 48dB/octave slopes
* Butterworth with 6, 12, 18, 24, 30, 36, 42, and 48dB/octave crossovers
* Bessel crossover (fixed slope)
* Individual channel input/output gains with attenuation of up to -70dB
* Bypass: You can bypass the crossovers, or EQ to compare the changes you've made to what it sounds like without those changes
* Levels of Equalizer is ±16dB
* Equalizer Types can be standard (Peak) or High or Low shelf.

Check it out
http://www.diymobileaudio.com/forum/...ternative.html

Big Mack

iTrader: (1)

I actually meant the DQL-8. It has many of the features you've outlined, save for the TA. While I agree with you that it can be very helpful for an SQ install, I do not believe it is "crucial" as you put it. I've been building SQ cars for years, and there are plenty that didn't use DSP, even, much less TA. Yes, it can make tuning a lot easier by fooling the speakers into sounding further, the placement affects this. If you are not using new mounting locations, is TA really important, or "crucial" as you said? No, I do not believe it would be. Also, a minor attenuation in channels can work very much like a TA circuit would. Been using that for cars with no DSP's for quite some time, and it is amazing how you can still influence the sound with even basic equipment.

Big Mack