Question about DSP in speakers and amps

[Snarl 12/8]

Hey Knowledgeable Knowers,

I'm finding myself desiring a few more channels of amplification, but something has always puzzled me with these newfangled gadgets that the kids are using these days.

If you get an amp or speakers that "have DSP" is the sound being converted to digital and back again before it is blasted out? Or, is a digital copy made, analyzed and use to control the analog signal path. I'm talking about DSP crossovers and eq, not things that add reverb or delay or whatever.

Sorry if this is a dumb question, but I can't find a straight answer on any of the gear descriptions I'm reading. I read something about how some piece of gear converts the analog to digital "because it needs both". Which got me wondering if some of this DSP gear actually has an "all analog" signal path.

Here's an example...
http://www.amazon.com/Crown-NXLS1500-0- ... =crossover

but I'm also thinking about the Tannoy (IIRC) "co-actual" speakers that use DSP to "align" the sound coming out of the woofer and tweeter. (if I'm not mistaken on what it's doing.)

Set me straight.

[hogfish]

Its a Class D amplifier. So it is indeed an analog system. Class D designs use a MOSFET that is configured to work as a binary switch. The switching circuits and and DSP used to control them are digital, but the power stages of the amp deal with voltage and current. The new MOSFET designs that are used in these type of amps can switch on and off so fast, there is virtually zero time between full on and full off. They are super light and pack a huge amount of power in a small package. I am a big fan of this type of amp design, it is especially great for bass players who gig regularly........

[Nick Sevilla]

Hi snarl,

If it helps, I use a pari of JBL 4328Ps.

They have digital input. I use the analog input.

Why? Because, dammit, I like my console's sound. Plus I get a nice level knob to boot.

I can never get used to controlling monitor levels inside my DAW or with software, I am just not in that "zone" of an extra step to change a listening level.

As to whether or not it has digital stuff controlling the crossover etc, yes it does and does it well.

Cheers

[The Scum]

Nope.

They're doing exactly what you're concerned about. Inside the speaker are AD and DA converters, with DSP sandwiched in between...or possibly all 3 components on a single chip.

[Snarl 12/8]

Nope.

They're doing exactly what you're concerned about. Inside the speaker are AD and DA converters, with DSP sandwiched in between...or possibly all 3 components on a single chip.

How come they never list the specs then? (At least not that I've seen.) Like, I'd think people would want to know whether it's 96kHz/32bit or 44.1/16 if their mix is going through it twice?!

[jhharvest]

How come they never list the specs then? (At least not that I've seen.) Like, I'd think people would want to know whether it's 96kHz/32bit or 44.1/16 if their mix is going through it twice?!

Because people don't generally notice the difference and the gear would be a lot harder to sell if you told the customers that your pristine analog signal is roundtripped to digital? But if the DSP speakers sound better than vanilla analog speakers, clearly the quality is good enough.

[Snarl 12/8]

An amp tech that built me an amp in the early 90's said that if there were such a thing as a digital amp it would be very efficient. But he said there could never be such a thing. I'm starting to think he was right and wrong.

The new MOSFET designs that are used in these type of amps can switch on and off so fast, there is virtually zero time between full on and full off.

Sounds like digital to me.

[The Scum]

How come they never list the specs then? (At least not that I've seen.) Like, I'd think people would want to know whether it's 96kHz/32bit or 44.1/16 if their mix is going through it twice?!

Sin of omission, or a dirty little white lie?

They have probably stated specs for the overall frequency response, THD, noise, etc of the system as a whole. If they meet those specs, does it matter how they're doing it?

In fact, with some of the processing schemes being used to squeeze performance output smaller drivers & enclosures, they might not be able to achieve the stated & desired specs without DSP.

Without lifting the hood, it's hard to know what's going on inside. One example might be the Hypex DSP crossover module:
http://www.hypex.nl/product/2012-11-23- ... dsp2w.html

It uses one of these:
http://www.analog.com/en/audiovideo-pro ... oduct.html

Which work at 24/96.

I know that this little TI guy:
http://www.ti.com/product/tlv320aic3256
is being used by at least one widely-known speaker manufacturer, precisely to get better performance out of small enclosures with extra filtering. It can do 24/192.

All of this is independent of the amplification technology. At this point, I think the class-D amplifier has been suitably tamed. All of those 500 W amps that weigh 5 pounds are class-D, with switch-mode power supplies. They're "digital" in the sense that the MOSFETs are either on or off, but not digital in the sense that they're doing computerized calculations. In fact, the basic scheme behind a simple class-D amp is decidedly analog looking.