Digital Amplifier Company? - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th August 2008, 05:14 PM   #1
diyAudio Member
 
Join Date: Jan 2002
Default Digital Amplifier Company?

Anyone familiar with this company?

http://www.digitalamp.com/

They make some interesting claims, such as this one:

"Does the DAC4800A wrap feedback around the output filter?

No. Wrapping feedback around the output filter doesn't provide significant improvement in output impedance. We keep the output filter outside the loop, which lowers distortion and provides a superior listening experience. We also use super heavy duty components to insure the lowest natural filter impedance (practically zero)."

And this:

"Why feedback around the filter is bad news...

Well, let me start by saying that the filter's reactance destroys phase margin so the feedback then needs to go through more stages to compensate. The compensation causes delay, and the loop becomes sloppy. Looking at it in the time domain, you never recover from delay.

The difference in THD+N can be quite large, especially when driving a speaker (not just a load resistor as is done for most testing). There's no magic in control theory. I have seen (and tried) modulation methods that actually use the filter to control the modulation, and they suffer from an even worse problem --- the speaker reactance and output current can swing the modulation frequency into the audio band during peaks. There are ways to protect against this effect or minimize it, but that just adds more circuitry. I prefer keeping simple things simple and just doing them right from the start. A properly designed output filter is invisible audio wise.

The bottom line is that I've tried both methods and even spent a few years on this issue! Compensation networks can get complicated, and when you start piling filter on top of filter the effect on the sound can be quite noticeable...

Amps with feedback around the filter just don't sound as accurate. I'll explain later why most Class-D designs on the market aren't all that good, and feedback topology is on the list."


Any comments?
  Reply With Quote
Old 16th August 2008, 08:36 PM   #2
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
See the PCB layout: Thin power tracks subject to high di/dt and no ground plane. For sure he had a bad time implementing UcD (doesn't tolerate ringing) and gave up. $6000, anyone?

Edit:

http://findarticles.com/p/articles/m...7/ai_n11851528

Ouch... $100000
__________________
I use to feel like the small child in The Emperor's New Clothes tale
  Reply With Quote
Old 17th August 2008, 04:31 PM   #3
diyAudio Member
 
Join Date: Jul 2004
Location: Seattle USA
Try out NewClassD.com and you can wire them either way.

Search this forum for feedback discussions ad nauseam
  Reply With Quote
Old 17th August 2008, 05:46 PM   #4
diyAudio Member
 
Workhorse's Avatar
 
Join Date: Dec 2004
Can someone tell me what is this so called "Nano Alignment" found on NCD's?? or its simply a deadtime tuning, but with new marketing name??
  Reply With Quote
Old 17th August 2008, 08:00 PM   #5
diyAudio Member
 
Join Date: Jan 2002
Quote:
Originally posted by raintalk
Try out NewClassD.com and you can wire them either way.

Search this forum for feedback discussions ad nauseam

Quote:
Originally posted by Workhorse
Can someone tell me what is this so called "Nano Alignment" found on NCD's?? or its simply a deadtime tuning, but with new marketing name??

What do these posts have to do with the original question about the Digital Amplifier Company???
  Reply With Quote
Old 17th August 2008, 09:23 PM   #6
diyAudio Member
 
Join Date: Jul 2004
Location: Seattle USA
Quote:
Originally posted by kuribo


What do these posts have to do with the original question about the Digital Amplifier Company???
What does Digital Amplifier Company have to do with DIYaudio?
  Reply With Quote
Old 17th August 2008, 11:48 PM   #7
diyAudio Member
 
Join Date: Jan 2002
Quote:
Originally posted by raintalk


What does Digital Amplifier Company have to do with DIYaudio?

Well, it is just possible that their approach to feedback/filtering may be of interest to the DIY community wishing to adapt or implement it for their own projects, just like people have discussed the UCD from hypex and their own homebrew version here....Hope that answers your question.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Digital Preamp for 5.1 amplifier elnec Digital Line Level 1 2nd September 2008 05:01 PM
A high-end digital amplifier for everyone DAXgroup Digital Source 82 30th June 2007 03:16 PM
CS44L10 digital amplifier Prune Digital Source 1 19th April 2003 02:14 PM
Digital Amplifier for ESL kelseywest Digital Source 6 6th February 2002 09:55 AM
Digital Amplifier Xavier Digital Source 21 5th January 2002 05:57 PM


New To Site? Need Help?

All times are GMT. The time now is 04:42 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2