Class D Amps - Anyone else having second thoughts?

[aborgman]

Seriously, all this talk about A/B ing two different amps to prove they can sound the "same" -what's the frick'n point? You dial an amp to produce a specific sound - not so it sounds like someone else's amp.

No - I dial a pre amp to produce a specific sound. I want my power amp to provide the effect of a "straight wire with gain"

Amp topology makes a difference. Just like the difference between acrylics, watercolors and oils make on a canvas.

Says someone who appears to have zero knowledge of amplifier design or the trade-offs involved in choosing a topology.

 

[tony_clifton]

Am I the only one thinking this topic was started by a troll?

 

[sawzalot]

+1 The 'next thing' IMO is what TC Electronics is doing with their amps..... true 'digital' preamps with software that can be used to 'tweak' the parameters of the amp to suite the user (lo and hi pass filters, frequency center/shelving start points and Q, built in boost and cut, tube emulation, compressor levels and attack, release, etc., etc., etc.).

+1

I've been following this thread since it's beginning without chiming in since I didn't feel I had anything to say that hadn't been said already--but this statement is a good one. I use a Crown Xti series power amp (class AB with a SMPS) and one of the reasons I like it is that I can program the Crown's built-in DSP parametric eq for different situations.

Basically, I want my preamp to give me my "sound"--that I can also send to the board. But I also want to tweak the power amp's EQ (in the DSP of the Xti amp) to make that sound translate onto a good stage sound.

One thing that I've always been frustrated with is that the eq settings that make my bass sound good through the cab/in the room are frequently in conflict with what the FOH engineer wants. But, if I give the FOH a pre-eq signal, then he loses everything from the preamp section: channel changes, bass boost, compressor changes, etc--all of which are part of my bass sound that I want to go to the board. I've always wanted sort of a post-preamp parametric eq--one that will let me correct for any shortcomings of the cabinet/room/etc. but that won't affect the sound going to the board. In my rig, my Eden Nav gives me my "sound" and I program the parametric eq in my Crown Xti's built-in digital signal processor to correct for the room. The unfortunate part of the rig is that it weighs more than I like--the Nav is about 11 pounds and the Xti is about 18, plus the rack.

I just recently auditioned a shuttlemax 6.0. I love the sound of the amp--but unfortunately I lose the ability to eq the on-stage power section independent of the signal I send to the board, which ultimately is why I'm going to stick with the Navigator/Xti-based rig right now.

 

[JackANSI]

Listening to agedhorse on here really makes me want to try out a GBSM... Just wish there was someone closer than 2 hours away that sold them...

 

[12bass]

The amps certainly don't need to get any lighter. I think there's room for improvement in the cabs though..... how about speaker cabs which use materials which are as stiff/strong as wood, but lighter! There's a few DIY composite cabs already floating around out there in gigland, nothing mass-produced though.......

Yep... there's little convenience to be gained with amps which are lighter than 2 kg. However, there is still progress to be made with new cabinet materials and rare earth drivers in reducing the weight of bass cabinets. Better covering materials would be nice too.

 

[Bob Lee (QSC)]

True enough but after awhile his reviews of audio equipment for Stereo Review became essentially useless. The standard joke regarding Mr Hirsch's reviews went something like--"Of all the amplifiers I've tested this is certainly one of them"...

I'll take J.Gordon Holt's subjective reviews anyday.

Indeed, many people still don't understand Hirsch's work.

 

[Bob Lee (QSC)]

Seriously, all this talk about A/B ing two different amps to prove they can sound the "same" -what's the frick'n point? You dial an amp to produce a specific sound - not so it sounds like someone else's amp.

For one thing, it would disprove assertions that one sounds inherently different from (or better than) the other.

Good grief, engineers and their test equipment! I know an oscilloscopes can display a eletronic trace of current and voltage - but can they hear? NO.

You might like AB/X testing. That relies on blind listening comparisons to see if the listener can identify them solely by sound. It often sounds easy.

Amp topology makes a difference. Just like the difference between acrylics, watercolors and oils make on a canvas.

Amp topology makes a difference, but certainly not in that way.

 

[sawzalot]

I'm surprised nobody's mentioned efficiency in this discussion--I personally love the idea of how efficient SMPS + class D is. No more blowing the circuit breakers just by powering up the amps.

Having just come off of an extended period of A/B-ing a Genz Shuttlemax vs. a component setup, I'm amazed at how cool that Genz runs. It never got even close to warm, and I was pushing it hard at times. I know my older power amps--I'm thinking of a Bryston 4B that I used to use some time ago--would heat the room even at idle.

Tom

 

[Implosion]

By day, I work with "instruments" of a different nature: Scientific instruments. When two instruments that purport to measure the same thing give different results, my instinct is to find out why. But I am also an engineering manager, so I understand that I shouldn't micro-manage. Thus a good compromise would be to ask the engineers for an assurance that they understand and have documented the root cause for the differences in sound between the different amplifiers, in case anything ever goes wrong or the design needs to be updated. Not knowing why something works is OK until it stops working.

Last week at work I was talking to a sales representative from a certain company. The sales pitch wasn't that great but I really liked their company slogan: The difference is measurable.

I think that a lot people would actually be amazed if they knew what sort of things can actually be measured.

 

[Joeykun]

I'm surprised nobody's mentioned efficiency in this discussion--I personally love the idea of how efficient SMPS + class D is. No more blowing the circuit breakers just by powering up the amps.

Having just come off of an extended period of A/B-ing a Genz Shuttlemax vs. a component setup, I'm amazed at how cool that Genz runs. It never got even close to warm, and I was pushing it hard at times. I know my older power amps--I'm thinking of a Bryston 4B that I used to use some time ago--would heat the room even at idle.

Tom

+1 I push two 4ohm cabs with my Genz-Benz Shuttle Max 12.0 using both class D amps built into it and have never once got that amp even warm. Fantastic stuff and well thought out for stage and studio use!

 

[Greevus]

I decided to rack up my GK800RB as a backup to my MB2-500. After lifting it, I realized that it even feels ridiculously heavy nowadays. Far from having second thoughts, am thinking of getting another micro D class. After GK tweaked my head, it's been flawless.
It's very powerful and if there is any trade-off for the thickness, the ease of moving and use has made up for it. I agree that Agedhorse makes me want to try a Shuttle. They seem like another company, like GK and RAG, that actually give a damn. Very cool and appreciated these days.

Down with big bulky amps. Keep tweaking those little heads!

 

[Joeykun]

I agree that Agedhorse makes me want to try a Shuttle. They seem like another company, like GK and RAG, that actually give a damn. Very cool and appreciated these days.

Down with big bulky amps. Keep tweaking those little heads!

a big +1 Seriously, Genz Benz has the best customer service in the business.

 

[seidler]

I traded my svt cl in on a fender 300t because it was unreliable and techs in my area could not fix it. After the fender smoking tubes twice in the 1st year (not under waranty) and never being playdd higher than 3 i traded it in on a markbass LMIII And a sans amp di. I already had a markbass LMII and sans amp i played out with and decided no more tubes for me. Maybe it is the newer asian amps quality control but the ampeg was 1997 made in the us so that blows that argument. Whatever the argument, save the weight, and get the sound you want. I get more compliments from my markbas rigs with the sans amp di with a markbass 210 and 15 traveler cabs from fans and musicians alike than i have with any other rig i have played. That is all i need to hear. Btq thisnis with fender american p and j passive basses and an active mm sterling. The 6lb head vs 90 is a no brainer.

 

[JimmyM]

The 6lb head vs 90 is a no brainer.

while i'm not immune to the lure of small and light stuff, it's not a no brainer for everyone.

 

[Eublet]

while i'm not immune to the lure of small and light stuff, it's not a no brainer for everyone.

Agreed. I'm not immune to heavy stuff, but a week ago I really tweaked my back pretty good such that it hurts to move around much. I could hardly lift a 6lb head much less a huge tube head. I've always thought that a lot of folks are just too weight sensitive, but if I had to endure back issues like this on a continual basis, I'd be going as light as possible myself. Thankfully, I don't, and I'll be back to moving whatever feels good at the moment. I don't have an SVT or anything like that, but I have been gigging with an IP310, which is an 86 lb cab. Most of the lightweight-only folks around here would gasp at the thought of that, but once it's on the gig, it just sounds so good that the weight is worth it.

Me and Jimmy will agree on this I'm sure, but trying to get the right tone is the no-brainer for me. I'll haul heavier gear to do that when required.

 

[KJung]

Agreed. I'm not immune to heavy stuff, but a week ago I really tweaked my back pretty good such that it hurts to move around much. I could hardly lift a 6lb head much less a huge tube head. I've always thought that a lot of folks are just too weight sensitive, but if I had to endure back issues like this on a continual basis, I'd be going as light as possible myself. Thankfully, I don't, and I'll be back to moving whatever feels good at the moment. I don't have an SVT or anything like that, but I have been gigging with an IP310, which is an 86 lb cab. Most of the lightweight-only folks around here would gasp at the thought of that, but once it's on the gig, it just sounds so good that the weight is worth it.

Me and Jimmy will agree on this I'm sure, but trying to get the right tone is the no-brainer for me. I'll haul heavier gear to do that when required.

Of course, you know your IP is a class D amp with a lightweight SMPS. It's only the box/speakers that makes it heavy.

 

[KJung]

As a side note, I sent my first and only 'letter to the editor' of Bass Player Magazine a couple of days ago. They have a little section about class D amps, and whether players think they are a 'compromise'.

That was a very poorly worded question, since it isn't the class D that defines micro amps (for example, the LMII is class A/B), but rather the power supply (SMPS). There are micro amps like the Puma350 and MB LMII/III that are class A/B, and there are relatively large and heavy amps like the iAmp800 and Epifani UL-502 that are class D with a relatively heavy toriodal power supply.

Class D is really not something that needs to be considered when making a purchase at this point, and the SMPS's are getting good enough these days to rival the heaviest of more traditional power supplies.

All tube amps are a different story... if that is your thing, you just need to deal with the weight.

IMO

 

[Eublet]

Of course, you know your IP is a class D amp with a lightweight SMPS. It's only the box/speakers that makes it heavy.

Oh yeah, no doubt. I'd LOVE to have the amp loaded into that AE212 I think. Get it under 65 lbs and it would be a really winner for me.