How long before they come out with a 2 ohm lightweight class D head?

AI have been doing it for a while

 

As mentioned, Acoustic Image does. The Focus is 1000watts at 2 ohms, around 5 lbs.

http://www.acousticimg.com/products/prod_focus.html

 

The Genz Benz Neo Pak 3.5 drives 2 ohms at 500 watts. I don't think it is a true class D though. It weighs 8.5 lbs.

 

Lot of amps can do it.
Their protection though is to shutdown (cut out) if they sense over-current situation.
Most people would probably want to hear lots of distortion so they could react and lighten up on playing instead of just having the amp cut out.

The makers of many OEM amp modules give instructions on how to configure them for low impedance loads. For example, many car amps are configured to run safely at 1 ohm.

 

Never IMO. Many players have different needs, different weight and size requirements, tuber, versus solid state, different price limitations, etc., etc.

Also, many, many players have no need for 2ohm operation.

Also, I think you are confounding 'class D' amps with SMPS amps. A few (Walter Woods, AI, some of the MB stuff, some of the Genz stuff) are class D power amps with switch mode power supplies. There are many hybrids out there also (i.e., heavier class D amps using toroidal power supplies like the Epi502 and iAmp800.. which does go to 2ohms with no problem), and some class A/B amps using SMPS, like most of the Markbass stuff and the Genz Neo Pak (which operates safely at 2ohms).

It's the SMPS that really makes an amp 'micro' and light, versus the class D power amp IMO.

Lot's of great sounding stuff out there, and quite a few 'moderate weight' heads that cruise along at 2ohms with no problem.

 

+1

And for many of us 2 ohm capability is arguably a negative in some senses. I strongly prefer that my amp makes the most possible power at the load I actually use. And I don't want to lug around an amp that's needlessly heavier due to extra heatsinking needed for 2 ohm operation.

 

Class D helps keep weight down a lot too. SMPS allows you to use a much smaller transformer, but class D allows a much smaller heatsink.

Really, class D is ideal for driving low impedance loads. Probably the main reason it's not too common is that there's not nearly as many people looking for it.

 

+1.. it all works together! Lot's of interesting combinations... class A/B with SMPS for most of the Markbass stuff, class D with toroidal for the larger EA stuff, class D/SMP for the Walter and AI stuff, etc., etc.

 

Class D amplification is also less accurate, and noisy....

I prefer Class A, or class a/b...

You may not notice it too much, but THD is more on a d than a or a/b. There are other reasons not to go Class D, but I'll stick with Cleaner power out of an A, or A/B.

 

That detail gets over my head, but I'm not sure as a rule it is true. The Walter Wood's amps are dead quiet, although the class D EA iAmps are very hissy for the most part. My Markbass SD800 was very quiet (class D), but my class D F1 has just a touch of a low level 'hiss' in idle... nothing you can hear on a gig but it's there. My LMII is very quiet... class A/B. My class D Epifani 502 is also very quiet, and about as clean as you can get (like the Walter).

Not sure you can attribute noise to type of amp... so much seems to do with the particular execution, the preamp, etc., etc.

Anyway, I'm a small amp fanatic, so I gravitate towards these types of threads. If you don't need 2ohm operation, there are just so many wonderful, reasonably small and light heads out there at this point.... clearn, grindy, warm, crisp, accurate, mid voiced, etc., etc. There seems to be something under 10 or 15 pounds for all but the tube-grind metal guys at this point.

 

I just bought an AI Focus 1 because I needed the "Micro/2ohm" thing.

They're expensive but make playing "legos" with cabinets very easy. You can also push 800 watts into 4ohms and 400 into 8ohms so you have lots of micro gigging options.

I've got 2 Epifani 110 UL's, and 1 Schroeder 4ohm 1212L... So before the 2ohm AI there was no way to link the Schroeder up with another cab.

I personally don't mind taking a couple trips to the car to carry in super light cabs... I just like being able to fit all of them including my amp into the trunk of a Honda Civic!

My favorite easy (good weather) transport rig for local gigs with great Monitor and FOH PA support is this:

Bass in gig bag on my back, Focus 1 in the gig bag pocket, Mountain Bike with a flat rack over the rear wheel with 1 Epifani UL 110 strapped to it! The soundman and Environment dig this rig

 

Cool! I was surprised a while back how many guys actually do use the 2ohm capability of amps. I've never had the need. It is a nice feature to have, and I guess it also makes you feel good about running the heck out of an amp in the more typical 4ohm configuration, since you wouldn't even be near the 'overheat point' of the amp.

I was always very impressed with the power sections of the AI stuff, but as an EB player who likes a very punchy tone with a little grind and sizzle, the pre's always sounded just a touch dark and 'lacking punch' to me.. that mid-range quickness.

That being said, I've NEVER heard my Rob Allen piezo loaded bass sound better through anythign than a Focus or Clarus with Acme cab rig... warm, fat and wonderful!

 

You're right on the $, KJung! with the right Guitar, and speakers you can't beat AI amps. Since the preamps are pretty flat, most of the tonal response really depends on what you're running into it... what you put in is what you get out

 

My EA Micro300 does 2 ohms. But the way it's designed you don't get an increase in wattage at 2 ohms like with most amps. IIRC it puts out 175W at 8 ohms, and 325 and 4/2 ohms.

 

Yeah, it seems like a broad generalization to say that all Class D amps are noisy. AI's entire marketing model is based on the pristine sound they produce. And I can attest to the fact that the moment I plugged into my Focus, I could tell it was time to clean my pots, something I couldn't hear on my A/B amp!

BTW, my Stingray/Aguilar OP-3 combo sounds great through the Focus. I can get real edgy if I pop up the treble on the OP-3, then the Focus smoothes it out!

 

I didn't mean noisy when you are not playing...

Class D amplifiers have problems with THD (total Harmonic Distortion). A class a, or A/B will be cleaner power, and more accurate...

Put it this way. If you are an articulate player, and want the subtlties of your playing to shine through, stay away from class D...

If you play rock, country, metal, or use a bunch of effects... You will never know the difference...

 

Holy cow... you just set the industry on its head. The executions of class D amps at this point are all about pure, clean, transparent tone. EA iAmp, Marbass F1, Epifani502, Bergantino IP's, Acoustic Image Focus/Clarus, and Walter Woods are considered the champions of clean, transparent, quick, accurate, low distortion sound.

Class A amps are usually in guitar amps.

I think you have it backwards! Most consider the Walter Woods and Acoustic Image amps to be as clear and clean as any amp made for DB or the bass guitar!!

 

I don't find this generalization to be true.

You can look at specs for Class-d amps and modules and see that they actually have lower average THD than Class-ab. (for example check the specs at hypex.nl, or the icepower modules) You can't get but a few watts using Class-a, and it's very inefficient so it's not practical for bass.

Still, with the major brand class-ab or class-d power amplifiers the THD is going to be so low in both that only those with golden ears would be able to hear a difference. Bass heads are a different story - they have built in preamps that are going to color the sound and affect overal THD, etc.

Class doesn't really matter. Accuracy, reliability, efficiency, and weight seem most important. It turns out class-d offers this.