Digital Amplifier

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my understanding is that the older digital amplifications schemes (1-5 years ago) sucked pretty bad. At best they were a DA converter on the same board as an amp, or at worst they were high effeciency class-D designs that were loud but had higher distortion than class-AB's. Thats assuming that it actually is a digital amp, and not just some strange marketing ploy. Some IC makers are making real digital amps now, some even say they sound good, but i've never heard any.
DIY class D amplifier

Hi !
I want to build a good amplifier, first i had think to build a class A Tube amplifier, but someone talk me about this forum and Class A Pass amplifier with Mos Fet (single end single stage zen.. or 2 stage Aleph) but these are not very efficient. A class D will be efficient but could we reach the quality of a pure class A with a class D amplifier ?
I'will be very interested in class D shematics, experiments, listening tests compared with other techniques such as Mos fet or

for an experiment of class D amplifier see :

best regards..
Pa, Why not just build a class AB amp? That's what most, actually almost all amp are. They are more efficient than class A, and sound better than class B or D amps. Class D amps are complicated and expensive to build and I will probably never build one, but I have no interest in class D. Class AB amps are simple.
Class A amps do sacrifice efficiency, but offer the most distortion-free sound possible. You can almost guarantee that a class D amplifier will never be sonically equivalent to a class A amplifier. Class AB is a good compromise between efficiency and distortion.

If you'd like further information regarding Pass Labs amps, I would suggest reading older or starting a new thread in the Pass Labs forums, or for more questions about class D amplifiers, a thread in the Solid State forum. You're likely to get more responses that way.

[Edited by Super on 11-18-2001 at 04:27 PM]
AB... Beuuurk :-(

Thank you, I have several "good" AB...
It's dirty compared to a single End Tube Class A, i just Had and there is a Big difference, i never want to ear another AB amp. Class A are so good..
And a Class D can be High quality see (e.g Tact millenium...) maybe a Pass...
7 or 8 in one case would be good for AV use. But then you will need a switch mode power supply, because a traditional one would be far too big. Actually you could get a couple of 1kw trannies in a 3u case, but then the amps and the smoothing caps will be a squeeze (don't want to compromise PS caps just because of lack of space)
But I really dont understand what is the usage for the onboard LCXO2 on the Zappulse? Anyone can explain?
Is it accept the digtial in or something?

Actrally I tried this amp at the office of their agency in Koren. The phototype which they testing havent the LCXO2 onboard. The sound compare with the Lcaudio poweramps "T.E.M" and the class A 50W. This Zappulse is lost! But when they tell me it just run-in about 24 hours only! Then I have supprise. Actrally the bass of Zappulse not heavy enough than the Class A and the T.E.M. But other just lost little only! It is terrble that it seems really powerful too! I think when it hae more time to run-in, maybe really great! And the price is attractive too!!!
pwm amplifiers


i have some news for those of you interested in pwm amplifiers.

we can now sell our demo boards as samples and the prices are reasonable (i think).

recent listening tests has shown that they actually sound better than other class-d amps involved in the tests (they may have better specs though , hehe)

we will be conducting a series of demos where we compare to other "digital" amplifiers and some cool a/b designs as well.

bye k madsen

(link to info :


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Digital Amp - Not Class D

I think the way to go is a true digital amplifier - not Class D.

A true digital amp accepts a digital input, converts it with a DSP or similar to a pulse stream which drives the output switches. There is no feedback and no low level analog. The volume is adjusted by changing the voltage level on the output stage supply rails.

I think Texas Instruments have come out with a true digital amp chip based on the tact audio amp. Has anyone tried it?
digital amplifier


there are many analog sources out there:)

i agree that a "true digital" amplifier , meaning a pcm to pwm chip and a pwm amplifier sounds interesting , we will take a closer look at it for sure.

i also think its fair to say that you can get quite good results with a good dac and an analog imput pwm amplifier.

the difference between the two schemes arent that big really.

we will perform a series of demos/listening tests with high quality pwm amplifiers (in copenhagen) if any of you have an interest in this or want to do the same please contact me/us and lets see what we can do.

regards - k madsen -
Hi there

Hatasa: As far as I can understand, the LCXO2 on the board is so you can sync the amp with the clock in your CD/DVD-player, which should eliminate jitter(??). The amp will not accept a digital input.
BTW, allows you to download the datasheet/whitepaper which I think is in english (havent bothered to DL'it, since I'm Danish ;-)

For those who wanted to know: The normal price for the Zappulse is app. 5000 DKK (~600USD/670 Euro). However, a stereo set of evaluation boards is now sold at the introductory price of 2500 DKK (~600USD). The kit includes two amp. boards (two channels) + 12 V gate supply. You need a 700 VA tranny and caps to build a functioning amp.

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