Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

The Lounge A place to talk about almost anything but politics and religion.

John Curl's Blowtorch preamplifier part III
John Curl's Blowtorch preamplifier part III
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 Today, 05:47 AM   #25251
Terry Demol is offline Terry Demol  Australia
diyAudio Member
 
Terry Demol's Avatar
 
Join Date: Apr 2002
Location: *
Quote:
Originally Posted by chris719 View Post
See attached from AK4497 EVM datasheet. Looks like a serious problem...

I'm not sure why anyone takes Rob very seriously in terms of claims. He is marketing his product in that video. He mentions anecdotes like his kids heard changes watching cartoons. The old wife-in-the-kitchen thing.

Attachment 768693Attachment 768694Attachment 768695
My point was, I have always noticed this particular DAC artifact he refers to and newer DAC's appear to be improving. The 4499 is the best I've seen.

T
  Reply With Quote
Old Today, 06:11 AM   #25252
Joe Rasmussen is offline Joe Rasmussen  Australia
diyAudio Member
 
Joe Rasmussen's Avatar
 
Join Date: Jan 2003
Location: Sydney, Australia
Quote:
Originally Posted by PMA View Post
Such theories are on the same level as a Flat Earth theory, to me.
OK. You will never find unless you see. I suggest you tell Hans van Maanen that his amplifiers are rubbish, I will keep out of the firing line. Duck!
__________________
"Elsinore Project" DIY Speaker System
- "Don't take anything I say as an affirmation, but as a question." Niels Bohr [i.e. be humble]
  Reply With Quote
Old Today, 06:34 AM   #25253
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
Quote:
Originally Posted by Joe Rasmussen View Post
OK. You will never find unless you see. I suggest you tell Hans van Maanen that his amplifiers are rubbish, I will keep out of the firing line. Duck!
OK Joe, this is your "devil" - I am able to setup such measurement very quickly. This is a distortion of speaker current, speaker driven by a fine low distortion class AB amplifier. The output stage is in A to AB (B) transition zone. Idle current 100mA. 1 pair of output devices. See the distortion level. Any high orders?? I apologize for some mains spectral lines, the setup uses 2 x 10m cables from my lab room to the listening room, so the loops are unavoidable.

Yes I am stating that if there are high order distortions the amp is rubbish. However, Ohm's law is valid and if the impedance would have gross and strange non-linearities, they will reflect in speaker current, regardless it is class A or class B. It just must not be a rubbish.
Attached Images
File Type: png classAB speaker curr1.png (30.1 KB, 30 views)
  Reply With Quote
Old Today, 07:03 AM   #25254
KSTR is offline KSTR  Germany
diyAudio Member
 
KSTR's Avatar
 
Join Date: Jul 2007
Location: Central Berlin, Germany
Quote:
Originally Posted by mmerrill99 View Post
That is what I'm trying to find - a better test to expose NFM with the idea of a multitone test signal that varies but perhaps this is the totally wrong direction?
I managed to create a quasi-dynamic multitone by using two adjacent bins per frequency rather than one. This gives a beating of the frequency, its level drops to zero one time within a block of samples, the beat frequency is the bin width. I had to use a larger base multiplier (11 instead of 7) so that the IM components have enough space**) around them as they become wider, too. With some artificial 2nd and 3rd order added, the IM components can be up to 6 bins wide.

With phases all set to zero the waveform looks like a normal multitone which is amplitude modulated as a whole whereas with random phase each frequency has its individual zero amplitude point and it sounds like that, a detuned pipe organ chord which each note swelling up and down at a slow rate at different points in time.

**) For NFM we have to look at the spaces, not the IM components (which are there even if the distortion is fully static). And compare the noise floor in those spaces with the noise floor of a simpler signal, or silence. I tried to do this with my RME Adi-2 Pro in loopback, but alas, no difference found.

---------

I also tried to isolate that obscure "state variable settling" with a variety of time domain tests... again to no avail as of yet...

Last edited by KSTR; Today at 07:06 AM.
  Reply With Quote

Reply


John Curl's Blowtorch preamplifier part IIIHide 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

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 08:38 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki