"Save Target As..."

Heh...

HEY GENIXIA!!!!!!

Yeah Baby. Groooovey.

Excuse me a while. I'm going to disappear with a good read.

Hmmm the stuff about a subwoofer output is interesting, even though it would be impossible to do it. Are any of the pins on the dsp unused?

Sean

Yeah, we knew the subwoofer output was THERE on the DSP, just unused.

Would be interesting to see if some minor rewiring plus a kernel hack could convert the Aux plugs to Subwoofer plugs!!!!

Nah it would take more than minor rewiring, you would need a preamp for another output, right?

I dunno, would you? And how tough would that be?

Don't suppose you can get the equalier utility off them as well? It will make it much easier since it will be able to calculate the equaliser settings automatically

- Trevor

Nice work. We don't try the simple, obvious things sometimes just because somebody said it wouldn't work.

Anyways, me quits working for money today and goes home to read.

The subwoofer support in the DSP is all digital. The SAA7705H can mix and
filter the left and right channels in various ways and emit the resulting
stereo bit-stream on pin IIS_OUT2. That pin can be used in at least two
modes: digital audio output or second I2S bus---I think this bus is used
only if there is a slave DSP, which the empeg doesn't (or does it?), so
the pin is probably free. The data sheet recommends tying down unused
pins, so there is a good chance that IIS_OUT2 goes to a resistor.

Even assuming there is an accessible track going to this pin, you would
still need to connect it to an external DAC, so there's no way this
could be done with the existing empeg circuits.

Someone said it wouldn't work because it DIDN'T work previously. We had to sign our souls away to get the documentation three years ago.

Rob

Well, now. Thank you for this incredibly valuable contribution to the group!

Now.. what to do with it? Here are the VERY OBVIOUS ones:

1.Proper Bass/Treble tone controls for Hijack.

2.Tone Generator controls, possibly useful for tweaking the equalizer response curves.

3. White noise generation using the tone generator (dunno if possible).

cheers

Also, It might be nice to provide config.ini adjustments to the "source scaling" block on a per-mixer-input basis, for use in getting the Tuner/Aux volume levels to match the MP3 levels (without having to tweak the volume control, either manually or within Hijack).

-ml

And also, we now have the info needed for adjusting the "bass booster" on a per-input basis.. a Hijack control for that would also be nice.


I can implement the controls, but we need somebody to step forth and provide the core functions for adjusting the various equalizer modes.

??

One more.. maybe provide control for the noise filtering capabilities for the AUX input (not sure if they apply to that signal, but something is definitely needed on AUX-in .. seems to pick up noise really easy).

-ml

Aw cool! We never even got a computer readable copy (mind you, I suspect it was classified at the time). I had to take the bindings apart and make photocopies so we'd have a security backup

Hugo

Maybe it is a suggestion to start a new topic, since now it gets interesting having the full documentation. Fiddling through this long thread feels a bit uncomfortable.

I've also taken a look... I'm impressed in what Philips has stuffed together in that DSP and making it, at the same time, quite easy to program too.

Lets take the new possibilities to higher level (EQ and also mentioned the unused pin for sub-woofer output->requires also an extra DAC !!).

Cheers,
EiSl

Yes, the subwoofer/centre channel output (mixed L+R) is ideal for use with the digital out board...

Hugo

If someone could modify the kernel to provide subwoofer out, we could take a crack at a dedicated sub out board.

Stu

Looking at the datasheet, it is implied that this DSP can turn into a full tuner by adding an RF and IF front end. 2 Philips chips are suggested (TEA6824 & TEA6811), but they are both discontinued. Nontheless, an FM receiver front-end should be cheapo. Integrating in to the DSP might be more complicated.

Are these the chips currently in the tuner add-on?

-Ted

No, it doesn't do demod, it's probably a badly written bit of datasheet. The two-chip TEA set are basically (well, later revisions of the same type of chip) what is within the metal cased tuner block in the tuner module.

The DSP only has FM-MPX, AM-AF and signal level inputs. It can't tune broadband signals - it only has ADC capabilities sufficient to get to the 38kHz (pilot is 19kHz, RDS is 38kHz ISTR, L+R is 0-19 and L-R is 19-38) FM encoded signal.

Hugo

To print this properly, you will need to get hold of the (obsolete) MS Line Draw TTF font, which may not be around on recent versions of Windoze/Word. It has been replaced with New Courier.

Yes a copy was posted here by smu

I wish I'd known that *before* my first attempt to print it.

I notice that the DSP also provides support for dynamic signal compression (boosting low level signals and attenuating high level signals) which kinda sounds like the Auto volume adjust feature of Hijack. but a little more sophisticated. The DSP seems to have quite a sophisticated 'quasi peak level' detection thingy which might prevent having to manually tweak the current auto volume adjustment for different types of music.

There's also mention of three different modes for the Loudness control - the static mode sounds like the way the empeg works currently, but dynamic bass boost (adjusted according to the amount of bass in the input signal) sounds very cool. I guess this sort of thing detracts from the audiophile purity of the empeg, but most mid-market head units seem to encorporate something like this to add warmth to the sound. Several people have commented that the empeg can sound a bit 'thin' without loudness applied, however the current loudness control reduces the amount of boost applied at higher listening volumes. Perhaps dynamic bass boost would be a better solution?

Good work on this everbody!

The empeg uses dynamic loudness. It's set up in empeg_mixer.c