2.5 Amp Questions: Digital and Classes

Two.Five Questions:

1. What are the options for digital input car amplifiers? I can't find any using a quick google search, and i figured you guys would know some offhand or at least where to look. I'm asking because i'm considering getting the digital output board from Eutronix for my empeg in hopes of never having to deal with groundloops and alternator whine. Do these even exist yet at consumer pricing levels?

1.5. Sub question: Is/can the digital output be sent through the docking connector? I saw Cristian's post where he rigged up his Mlord dock with a digital out through the dock... so i presume it can. But, will this work in car?

2. What's the deal with Class T amplifiers? I understand Class A, Class AB, and Class D amps, and how/why they each have their disadvantages, but Class T is new to me. According to the glossary at Crutchfield, the Class T amps:

provide the sort of sonic advantages of conventional Class AB designs, combined with the high power efficiency and low heat production of a Class D design. Class T amps are able to generate 2-4 times more power than a comparably-sized Class AB amp.

So what is their downside? They seem to do everything. They are tiny and even come in plastic in some cases since they don't heat up much, and are supposed to provide a ton of power. What gives?

To quote two quasi-famous wine cooler salesmen... "thanks for your support"

To quote two quasi-famous wine cooler salesmen

"Well, we went to school with Vernal and, frankly, we never thought he'd amount to much..."

(sorry, I know nothing about digital amps, so I had to tangent!)

I'd never heard of Class-T amps before, either, but some reasearch leads me to believe that they uses some advanced DSP to achieve more accurate waveforms than Class-D amps, while still remaining as firmly in the digital world. It looks like they've been used for a few years in low power applications, and are just now getting to car audio.

I think that there's no disadvantage against Class-D, but still might not be as mellow as a true analog amp, if potentially better than the Class-D. It sounds like if your choice is between a Class-D and a Class-T, that you're more likely to like the sound of the Class-T better.

Also note that the Class-T term is promoted by a single company, Tripath, that developed them, although many other companies seem to be using their technology. The reason I point this out is that it seems to have not (yet?) gotten to the point where multiple companies are making them, which may mean that there might be some infancy to work through before they become truly robust. But I don't know for sure.

Digital out should be fine in-car --> Christian and others seem to be using the mic lines for this purpose, so you've already got the cable / connector on your sled for it!

Cheers

<bitt-->

yeah, the only one Crutchfield carries that i could find are these Blaupunkts. The specs look a little impressive for the price/size...

150 watts x 2 at 4 ohms
200 watts x 2 at 2 ohms
400 watts x 1 in bridged mode
stereo or bridged mono output
Tri-Way capable
Class "T" amplifier technology
MOSFET power supplies
speaker-level input adapters
50-250 Hz variable high- and low-pass crossovers, 12 dB/octave
selectable subsonic filter at 10 Hz
remote gain control
10"W x 2-5/8"H x 9"D

it's tiny and supposedly gives off little heat. Also says you can take the case off for tight installs... which is very appealing. I'm still not convinced though. Anyone else wanna weigh in on this?

<mark-->

Thanks... now if i can only find a digital amp...

Here's my thought:

It's fairly cheap ($200) and it's Blaupunkt. While Blau might not be the best in the world, they're certainly not going to put something out that's embarrasing. In addition, Crutchfield will accept returns up to 30 days after purchase and pay the return shipping costs.

It looks like it's a good deal, and if it turns out not to work for you, then return it and get something else. Since all the real parts of the Class-T are made by one company, then if you don't like one, you're probably not going to like another, either. In that case, Crutchfield's lack of further Class-T amps is probably not relevant.

I say go for it and then let us know. I might get some of them when I get my new car. I really like the small size and high power efficiency.

I was looking and Crutchfield has more than just that one model:

Blaupunkt PA275 (75W x 2) $120
Blaupunkt PA2100 (100W x 2) $150

yeah, i only linked to one.

So after more research, it looks like the Alpine MRD-F752 is another Class-T amp (5 Channel, 75x4+250W mono) and seems to have a few good reviews out there. Why the hell is there so little info on Class-T stuff?! I can't even find record of it on their site however, and it looks like they don't have any class-T's in their current lineup. Hm.

that alpine is pretty expensive.. $637

Oh, and with a little URL hacking, I got their info page...

The Rio Receiver uses a Tripath 1011 Class T amplifier too. They're very efficient, so run relatively cool, and seem to sound pretty good too.

They don't seem to have caught on in a big way though. Kinda strange that all their amp chips (last time I looked) were analogue input but digital inside. Wierd.

Hugo

Hmm... verrry interesting. Thanks for the info. Do you think they haven't caught on because of licensing from Tripath?

I don't think they license them at all. Class T is just a digital amp method, there are plenty of people making digital amps which probably use similar methods - eg Apogee were doing small digital chips too.

When I last looked, Tripath weren't trying very hard to get into automotive - they appeared more interested in the home cinema market (the early sony 5.1 DVD player and amp-in-a-box used tripath chips). That may well have changed now though.

Hugo

When I last looked, Tripath weren't trying very hard to get into automotive - they appeared more interested in the home cinema market (the early sony 5.1 DVD player and amp-in-a-box used tripath chips). That may well have changed now though.

I dug around their site yesterday, and their only obviously automotive product has a non-inspiring power output (intended for OEM headunit integration, I guess).