Class D popping up everywhere. Innovation?

[B-string]

You gents are having WAY to much fun!

 

[seamonkey]

I thought an on-off switch was enough grounds to call it digital?

You can pay me later...

Add yourself a little PWM modulation to that circuit and you've got yourself a "lamp dimmer", able to control 600w from a little 3x4" box, with very little heat loss.
Unfortunately, without proper filtering it too introduces RFI

 

[agedhorse]

Add yourself a little PWM modulation to that circuit and you've got yourself a "lamp dimmer", able to control 600w from a little 3x4" box, with very little heat loss.
Unfortunately, without proper filtering it too introduces RFI

Lots of it too!!!

 

[J.D.B.]

Thank you, gentlemen! This has been a MOST entertaining thread. Well worth the price of admission! Special thanks to you, Mr Tiers!

Josh

 

[Volume4]

Here's another more analog way of looking at a class D output signal. Each infinitesmal time slice represents a bit of energy per unit time. That would be units of power. The instantaneous power varies along the sine wave. Now integrate these instantaneous power slices with respect to time and you have energy.

So, the "area" of each of these discrete and finite time samples represents energy delivered for that time slice and if stacked edge to edge represents the area under the power curve. There's nothing digital about it... except that it looks digital because ofthe time slices and samples and reconstruction but that's the gray area between digital and analog IMO. It's neither yet both at the same time.

A D/A converter does much of the same thing, though with numbers or a mathamatical series of bits.

This could be an interesting AES or NAMM discussion for sure.

A famous quote:

"when I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck."

I'm just kidding of course. I've enjoyed this quite a bit and am grateful for these knowledgable posts and am thrilled gentlemen like agedhorse are taking the time to share their knowledge.

I'll still buy with my ears, don't worry and I've been assured enough that the technology is where it should be.....I admit though...I think I'd still prefer a heavy old school style SS or tube amp

Pretty much the amps I've been drooling over and want to try when I can afford them. I expect to have 2 of the following amps by summer.

Ampeg Micro SVT (switching power supply)
Orange Bass Terror (Class D)
Tech 21 Landmark 300 (I don't know what power supply this has yet but it's a very strong contender for my cash)
Ampeg B-15N or B-15R (all tube)
A used USA B100R (classic SS design and I foolishly sold one)
And now I've been looking over Genz Benz as well

 

[SpamBot]

Are there any SMPS available for DIY?

And is class D executable with tubes?

 

[bassbenj]

Pretty much the amps I've been drooling over and want to try when I can afford them. I expect to have 2 of the following amps by summer.

Ampeg Micro SVT (switching power supply)
Orange Bass Terror (Class D)
Tech 21 Landmark 300 (I don't know what power supply this has yet but it's a very strong contender for my cash)
Ampeg B-15N or B-15R (all tube)
A used USA B100R (classic SS design and I foolishly sold one)
And now I've been looking over Genz Benz as well

I was gassing over the Class D Markbass for some time, but after I had a chance to A-B the Markbass against the Gallien-Krueger MB2-500 I'm now seriously gassing for the latter. The Markbass sounded good but with the MB2 the closed sound of the Markbass just opened up with an amazing clarity. I REALLY liked it. YMMV.

 

[fdeck]

Are there any SMPS available for DIY?

If you can keep it to "standard" voltages, such as 24, 48, etc., then there are lots of SMPS available from outfits like Mouser Electronics. That would get you into "practice amp" territory. Check out www.41hz.com for some Class-D amplifiers in kit form. In addition, I think that Hypex sells a SMPS module specifically for their Class-D power amps.

Of course these options assume that you are qualified to construct mains powered gear. Also, there may be (i.e. there probably is) more to it than simply plugging any old Class-D power amp module into any old SMPS.

And is class D executable with tubes?

In principle yes, since you can implement both an integrator and a comparator with tubes. Whether it would be sane to do it this way is another question. Also, unlike MOSFETs, tubes have not evolved over the past 30 years to address new applications.

 

[SpamBot]

I'm not planning on building anything until I am positive I know everything I need to know, which won't be anytime soon. I won't have enough money for a while, anyway, iron is expensive.

 

[seamonkey]

Are there any SMPS available for DIY?

And is class D executable with tubes?

Tube schematic here:
http://www.talkbass.com/forum/showthread.php?p=8463017&highlight=#post8463017

But the first paragraph should explain why you wouldn't want to try to use tubes.

Check out the Milbert GaGa 50 for a better melding of tubes to new techology. But I doubt they ever do a "kit" form.

Just buy a prebuilt amp and concentrate your efforts on a preamp. The preamp is where you can get all the tone you want out of a clean amp. The best amp reproduces whatever is thrown at it. It scales to all volume levels.

 

[WingKL]

David Berning has an amp out that looks like it's a class D tube power amp.

 

[JR2M]

I prefer a healthy mix of digital and analog when recording, but for amplification it's tubes baby all the way.

 

[KJung]

Just to bring this back to the 'real world' a touch, I've been a fan of these small class D and/or SMPS amps for many, many years, since my first Walter Woods amp in the very early 90's.

They have improved a great deal since the Walters IMO, and I find virtually no 'class D' or 'SMPS' tone that exists, any more than any other type of amp. In other words, there is as much variance in the tone of these class D and/or SMPS executions as there is across amp types and brands. Hence, it should probably not be used as any sort of input to the buying decision (other than defining a weight category of amp).

For example, here is a brief layman's description of the Micro amps I've owned or spent significant time with, followed by a brief tone description (based on IMO and IME):

TecAmp Puma500.. class D - SMPS.... super warm but clean and crisp, as close to 'hi fi clean tube tone' as I've ever heard in a non tube amp

Markbass LMII... class A/B - SMPS... warm, a bit more gritty in the mids than the Puma, deep, loud, fat

Markbass F1/F500... class D - SMPS.... what most 'think' class D amps sound like... crisp, mid present, clean, quick, tight, 'modern'.

TC RH450... class D - SMPS (with what I understand is a true 'digital' front end)..... sounds like a darn SVT...warm, punchy, grindy when you push it... even has some of the 'give' feel of a tube amp...remarkable

Genz Shuttle 6 ..... class D (with tube pre) - SMPS.... bright, quick, more solid state sounding than the LMII or Puma, even though it has a tube... a bit gritty in the mids, tight low end

Walter Woods Ultra... class D/SMPS.... VERY clean, bright, articulate, quick, not particular warm, tight down low, a bit lacking in low mid punch to my ear

AI Focus/Clarus... class D / SMPS..... warm, smooth, organic... polite top end, fat through the mids, the opposite of 'sterile' or 'clinical' to my ear... a bit 'old school' sounding, but not particularly in a 'tube-like' way... more compressed around the midrange frequency spectrum (i.e., strong in the low mids and mid mids... no 'hi fi top end to my ear).

Epifani 502.... class D / Toroidal Transformer.... VERY warm and fat, HUGE low end, a bit mushy in the mids, hi fi top end (the newer line of Epi amps have gone to SMPS)

iAmp800.... class D / Toroidal Transformer..... deep, deep low end extension, clean to the point of sounding a bit 'clinical'... another example of the cliched tone of 'digital' amps... super clean, super wide... deep, sizzly (the newer line of EA amps have gone SMPS)


Anyway, the point is, all these amps have somewhat different designs, and all sound different, but not in the way you would think.. i.e., class D always sounding more solid state, tube in the pre always sounding 'warm', etc., etc., etc.

IMO!

 

[Handyman]

David Berning has an amp out that looks like it's a class D tube power amp.

Is that marketed to audiophiles? Much of that page reads like a snake oil brochure.

 

[WingKL]

Yes, the Berning amp is marketed towards audiophiles. It's also got an audiophile price, which is why it isn't listed. I wouldn't consider getting one unless I was swimming in hundred dollar bills. It was an example of a working, very likely, class D tube amp.

 

[bwoodman]

KJung: Nice post - that's a lot of info and a nice "at a glance" look at quite a few different amps. I was also a Walter Woods user from 1995 to around 2007 when it was stolen - and the lead time of over one year and the over $3,000 price tag kept me from buying another one. I currently use the GB 9.0 and am happy with it so far, although I just heard about the two new amps from Carvin - BX1500 and BX2000 - nice price tag and light weight. I'm waiting to see if there are any bugs in them before I buy either one of them.

 

[MilbertCom]

Berning's Quadrature Z amp is not class D. It, like other Berning amps and also the Milbert GAGA-50 guitar amp, uses patented ZOTL technology. http://davidberning.com/technology covers the patents/white papers, and http://milbert.com/gaga#newkind addresses some specific questions.

 

[seamonkey]

Nobody said it was.
But why don't you make a cheap high powered one for Bass Guitar
The technology scales - right?

 

[WingKL]

Perhaps it's not exactly class D, but if I understand it right, the audio signal is amplified and chopped up with an RF carrier and is modulated like an AM signal rather than PWM and is fed into a small transformer tuned to work at RF, which spits out the low impedance signal out the other side and probably filtered? Very similar ideas to class D.

 

[Bob Lee (QSC)]

Yes, the description reminds me of an AM radio modulator.