What does it mean digital amp?

[twangman]

I currently have an Acoustic B100 bass combo... Ive been checking out the GK MB112 and MB115. I noticed it says they are "digital" amps. What exactly does that mean and how does it affect sound / volume ? The mb amps are 200 watts, my b100 is 100 watts , would it be wise to stay with the b100? Is the mb112 or mb115 and upgrade?

[KJung]

'Digital' is a technically not accurate description of amplifiers that use class D power amps (small and lightweight) and/or switch mode power supplies (SMPS... REALLY small and light weight). I think the 'digital' description came from the 'D' in class D, but the class D amps are still analog. I guess from the EE's who post on the site, there is a 'digital' type 'on/off' thing going on with the SMPS, but again, not a very good or useful descriptor. Just think of 'digital' as representing 'small, light and efficient (i.e., they don't waste a lot of power generating heat like older designed amps).

These days, it is a zero issue. Any amp that is really small and light like the Markbass, GK micro's etc., uses the switch mode power supply design... eliminating big, heavy power transformers. Watt for watt, they sound identical to the heavy iron these days.

The type of power amp is also a moot point, since most of an amp's voicing and character comes from the pre. EBS uses class H power amps, the popular Markbass LMII/III uses a classic class A/B power amp, and most of the other micro's use class D. There is no way to pick 'the type of power amp used' in a blind test anymore.

Interestingly, one of the 'warmest, most vintage sounding' micro amps out there right now is also the one that has the most 'modern' components. The TC RH450 has a class D power amp, and SMPS, AND a true 'digital' preamp!

So, regarding what is inside the box, ignore it and use your ears.... all these small, lightweight executions have their own tone profile, from the bright, modern voicing of the Genz Shuttles, to the super wide, aggressive voicing of the GK heads, to the warm and clean and relaxed voicing of the Markbass heads, etc., etc., etc.

[thudfromafar]

in the MB115 specs it actually says "digital power amp"

[billfitzmaurice]

Originally Posted by twangman

I noticed it says they are "digital" amps. What exactly does that mean

In most cases it means very little to nothing at all. More often than not it refers to a switching power supply, or a Class D amp, and neither have anything to do with digital per se.
30 odd years ago when the CD was introduced suddenly stickers appeared on everything from speakers to receivers to amps to cables saying 'Digital Ready!' The only thing that made those products different from those without said stickers was the stickers. Caveat Emptor.

[DJS]

Great explanation, KJung. I'll throw in a few more thoughts. Years ago, these amps weren't considered clean enough for high quality audio applications. But they found a great application in car audio, an ultimately gained some respect and were improved dramatically.

An astute home audiophile would still probably keep his 90 pound amp with large transformer, D-battery sized capacitors, and massive heat sink, and could likely detect differences in a lightweight class D amp over more traditional amp designs. Likewise, it might be difficult to separate a seasoned bass player from his all tube Ampeg head without a real fight.

For the rest of us everyday combo amp people, these lightweight Class D models are for all practical purposes, going to sound very similar to their heavier, traditional ancestors. I'd head into GC, play through Acoustic, play through a GK 112 or 115 and decide for yourself if there are appreciable differences. My guess is you'll prefer one over the other. I ended up getting a GK 210 last year, and love it.

[lomo]

Originally Posted by DJS

and could likely detect differences in a lightweight class D amp over more traditional amp designs. .

I'll believe this when someone shows it can be done blindly.

[billfitzmaurice]

Originally Posted by lomo

I'll believe this when someone shows it can be done blindly.

It can and has. The problem doesn't lie with the Class D, it lies in the power supply reserve capacity. It's why car audio uses 1 Farad stiffening caps that are larger than the amp.

[KJung]

Originally Posted by thudfromafar

in the MB115 specs it actually says "digital power amp"

+1 Again, not so accurate marketing speak for either class D or SMPS or both.

[lomo]

Originally Posted by billfitzmaurice

It can and has. The problem doesn't lie with the Class D, it lies in the power supply reserve capacity. It's why car audio uses 1 Farad stiffening caps that are larger than the amp.

Can you provide a ref for me to check out?
Thx

[RCCollins]

Hard to believe now, but there was a time when "Digital" was a hot buzzword and selling point - that was before the "tube revival" and "analog only" fads emerged. A buddy of mine has an oldish Peavey bass head that says "digital" on the front!

[Morning Beer]

Originally Posted by lomo

I'll believe this when someone shows it can be done blindly.

I don't agree or disagree. I will say that 3 class D heads I've had didn't really sound different then my A/B heads, but they have a different feel to the sound. If that makes any sense? I currently use class D as my primary head, on stage it doesn't make difference to anyone.

[lomo]

Originally Posted by Morning Beer

I don't agree or disagree. I will say that 3 class D heads I've had didn't really sound different then my A/B heads, but they have a different feel to the sound. If that makes any sense? I currently use class D as my primary head, on stage it doesn't make difference to anyone.

Agree-I'm not saying they aren't different, simply that it's close enough that for me to believe it's real I need to see a blinded evaluation.

[Morning Beer]

Originally Posted by lomo

Agree-I'm not saying they aren't different, simply that it's close enough that for me to believe it's real I need to see a blinded evaluation.

Gotcha.

[recnsci]

Originally Posted by lomo

Can you provide a ref for me to check out?
Thx

Class D inherently does have lower PSRR compared to high NFB linear amps (at least on paper; and PSRR in AB vs D is a bit apple vs orange). However, properly designed class D power amps can be as flat as any linear amp (if not even flatter).

Average class-A-single-ended-triode audiophool will most certanly notice difference. 'cus tube amps are crap from point of meaningfull numbers (like THD and damping). And same thing goes with big&heavy Ampeg bass heads

[agedhorse]

Originally Posted by billfitzmaurice

It can and has. The problem doesn't lie with the Class D, it lies in the power supply reserve capacity. It's why car audio uses 1 Farad stiffening caps that are larger than the amp.

Car audio uses large caps at the point of load to overcome the output impedance of the battery and supply wiring. Otherwise, some amps will oscillate (generally motorboating) from voltage sag under a step or heavy dynamic load. The reserve capacity of a typical lead-acid battery is plenty high, the caps just serve to improve the delivery of the power AT the point of load. If the cap was put at the battery termonals, the negative effect of the wiring losses would still be a problem.

[billfitzmaurice]

Originally Posted by agedhorse

If the cap was put at the battery termonals, the negative effect of the wiring losses would still be a problem.

Of course, and autosound dB fanatics are well aware of that. They also tend to favor 4 gauge cables and high capacity alternators.

[seamonkey]

And inside the car amps are SMPS's to raise the rail voltage to allow the amps to generate the power they claim.

[Kahooli]

Originally Posted by seamonkey

And inside the car amps are SMPS's to raise the rail voltage to allow the amps to generate the power they claim.

And there is nothing wrong with this either.

SMPS are used in nearly every modern product from consumer range devices to commercial television and radio transmitters. It is a mature field now and the reliability of an SMPS is comparable to a bulk transformer/rectifier/filter.

[seamonkey]

Originally Posted by Kahooli

And there is nothing wrong with this either.

SMPS are used in nearly every modern product from consumer range devices to commercial television and radio transmitters. It is a mature field now and the reliability of an SMPS is comparable to a bulk transformer/rectifier/filter.

Agreed - smaller, less heat, higher reliability, but more so as they can also be easier to regulate and make universal power supplies.

[CrUiSeR]

Digital is a buzz word for companies to sell their crappy amps and other products

http://m.youtube.com/index?desktop_u...89qLpT2I&bmb=1