What is better for running subs, Class A/B, or Class D?

[stipud]

At 250 watts, my sub stage overpowers my front stage (75x2), so I have to turn it down. With only 250 watts max, I am not concerned with efficiency and would rather have A/B power, which I find sounds less boomy, and blends better with my front stage.

If my front stage had 300 watts x 2, then I would run 1000w or so on the subwoofer, in which case I would probably start looking at a class D amp. Anything under 1kw, efficiency is less of an issue and I prefer A/B.

[lopezi]

From what I have read a large portion of the audio quality of a Class D amp is the quality of the filter used to bring its PWM (pulse width modulation) output back to analog music land.

Also, the tantrum 1200.1 is kind of "primitive" by today's standards. It uses "tripath" what ever that means (never really looked into it myself). I am guessing it is somewhat hybrid like Rockford's Class BD technology. But, none of this means you would have any better luck with a Xenon 1200.1 for example.

I have some "TriPath" based amps (Blaupunkt PA series), amongst some PG and other amps. In any event, TriPath was one of the few that tried to tackle the issue of full-range Class-D.

From all of my travels I was always under the belief that Class-D was targetted towards sub amp duty because of the switch frequency used. The circuits at the time could be developed resonably cost-effective but the switch frequency confined them to sub duty. TriPath supposedly created chip circuitry that allowed for the higher switching frequency to be achieved to accomodate the full range audio spectrum. I believe one of the additional challenges was that the switching frequency could/would bleed into the RF spectrum and cause interference.

ICEPower is supposed to be another chip circuit that allows for full-range Class-D and I believe Eclipse and other use this in their products.

I wonder what chip circuit JL has employed?

One the things I like about Class-D is that you can run them hard and they remain relatively cool instead of the heat generators that A/Bs are. During the warmer months this is a nice side-benefit.

[shawn k]

A little bit off topic since the title is about driving subs, but it's about class
D after all. Hope you don't mind Eric!?

Yes, TriPath is used for full range class D and is still used in a lot of home class T amplifiers (not sure who are still using them in car audio). The Tripath chip allows for very high swithing freq and error correction to allow so called "audiophile" otuput. The one thing I can't figure out is why did PG use it in the Tantrum 1200.1? OK, cool it does full bandwidth, but does it really matter on a 1200w monoblock??? LOL. I have yet to see an install utilizing a slew of 1200.1's running a full system whether it would be active/bi-amping or whater! (now there's a project for someone!!) PG should have left the chip out and lowered the pricing IMO. Not to mention it could be repairable!!

It is possible for the high switching to effect RF, as you had stated lopezi. Actually I've seen a few instances where the new JL HD amps are causing some problems. I even remember having a couple of the 500/1's causings some RF interference to!

ICEPower is supposed to be another chip circuit that allows for full-range Class-D and I believe Eclipse and other use this in their products.

I think ICEPower is probably going to be the mainstream in the future. It's already the "new wave" and is gaining popularity by the minute. Yep, Eclipse had a line that was based on ICEPower topology. Alpine PDX, and Some Pioneer Utilize the topology. There may be others, not sure.

I wonder what chip circuit JL has employed?

I'm not sure either, but from what little info I've found I guess they're using their very own design (not TriPath or ICE) Whatever it is, it must be something special since it seems everyong is going GAGA over the HD's!

On a side note: With all of the new hype over full-range class d I think it's interesting that car adio has had these amps as far back as the mid 90's! If I'm not mistaken, Inifinity had the first full bandwidth class D car audio amps with their Beta series. Cool amps back in the day

[Bfowler]

fyi^ blaupunkt, rockford and alpine all use the same ice chip too

[rscecil007]

I wonder what chip circuit JL has employed?

This is what JL uses: http://mobile.jlaudio.com/products_amps ... age_id=251

It's some patented design they are using via a license.

I have no idea how that compares or differs to the ICE method and Alpine PDX, etc.

Shawnk, what RF issues have you seen with HD amps? Just curious.

[shawn k]

I've seen a couple instances where when listening to FM static (not from poor reception) was present. I had nothing to do with the installs, but I was present to see the issues. One installer was showing me how he could take a 900/5 HD a few feet out of the truck (from extending leads) and the static would go away. I'm speculating here, but JL prbably has ultra high switching in their design, which would improve SQ but cause these problems?

[rscecil007]

I've seen a couple instances where when listening to FM static (not from poor reception) was present. I had nothing to do with the installs, but I was present to see the issues. One installer was showing me how he could take a 900/5 HD a few feet out of the truck (from extending leads) and the static would go away. I'm speculating here, but JL prbably has ultra high switching in their design, which would improve SQ but cause these problems?

Hmmm, interesting. Thanks for the info. Can't say I've had any issues like that with mine, like I mentioned, mine is dead silent.

[shawn k]

Yep.. no surprise really. From what I've been hearing it's an issue, but not a major cotastophe by any means. Must be a certain few vehicles are more sensitive than others. Who cares anyway.. it's FM right?? LOL

[rscecil007]

Yep.. no surprise really. From what I've been hearing it's an issue, but not a major cotastophe by any means. Must be a certain few vehicles are more sensitive than others. Who cares anyway.. it's FM right?? LOL

Hahaha, that's a good point. I've only listened to the radio probably a total of 40 minutes since I got my system installed in January.

[dako]

After running a Tantrum 1200.1 for quite some time, and several other D amps in the past, I decided to switch things up last year and drop in a Tantrum 500.2 to a single RSDc 12". I can tell a huge difference in clarity compared to just the 1200.1 alone. Everything just sounds more realistic and more balanced as far as forward blend goes.

I have to agree with a previous post in here regarding the 1200.1's somewhat muddy sound. I listen to a lot of rock (think kick, double-kick drum) and A/B completely does it for me at this point. The 1200.1 used to be good for tones (rap, etc.) Of course the only drawback with something like the 500.2 is power consumption, but since I'm not cranking it up like I used to, this doesn't come into play too much.

[stipud]

Yeah Dako, that's been my exact experience too! Surprised you are noticing it with a class-T as well! Perhaps the difference goes beyond being able to play harmonic frequencies...

[kg1961]

so I have tried some other mucis with both the A/B jl slash and class d jl slash
Yes on rap it sounds 100% the same but on jazz and other music i can here a differnce the best way to discride it is muddy not as clean
I have to agree with you two above me