Class T(ea) with AMP-3 - 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 13th August 2005, 05:47 PM   #1
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
Default Class T(ea) with AMP-3

When using the 41Hz AMP-3 I get a strange whistling noise (like the sound of a kettle boiling) on at least one track of a CD. The CD in question is 'Natural Light' by Eric Bibb and the whistling is most obvious on track 1.

What is this and the whistling down to the amp, the CD, or both? I didn't notice it with the other class-T amps that I ahve here.
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 13th August 2005, 06:10 PM   #2
t. is offline t.  United Kingdom
diyAudio Member
 
t.'s Avatar
 
Join Date: May 2003
Location: notts
Hi NUUK

I sometimes get a high pitched whistle with my Amp3
It seems to be when I use either of my NOS dacs most noticeable if theres no cd in the transport or when I'm loading a disc, its only faint but there is a high pitched noise, I've also noticed a few strange whistling noises on HDCD recorded discs

Leo
  Reply With Quote
Old 13th August 2005, 07:01 PM   #3
diyAudio Member
 
Join Date: Jan 2003
Location: Quebec city area
Default Re: Class T(ea) with AMP-3

Quote:
Originally posted by Nuuk
When using the 41Hz AMP-3 I get a strange whistling noise (like the sound of a kettle boiling) on at least one track of a CD. The CD in question is 'Natural Light' by Eric Bibb and the whistling is most obvious on track 1.

What is this and the whistling down to the amp, the CD, or both? I didn't notice it with the other class-T amps that I ahve here.
Hi,

I'm not sure if an experience I previously had could be signifiant here, but just in case. A guy at work have a Maranz reveiver and he had some problem with a particulra CD of Nora Jone. At some specific place of the songs, the amp was delivering a suspect noise. I can't tell you exactly how it sounded as I never visited this person. Anyway, he ask me to listen to the CD to see if the CD was bad and I had no such problem. So, he went to his Hi-Fi store and they finally found that the amp was not able to take the load during the "peak" of this CD. I suppose that the CD was recorded to hight as the music was very soft.

Maybe you have some similar problem with the amp3. You have to listen to many CD and see if it always happen and when it happen.

Regards,
__________________
Daniel
  Reply With Quote
Old 13th August 2005, 07:01 PM   #4
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
Quote:
I sometimes get a high pitched whistle with my Amp3
Hi Leo, I was just going to email you! OK, so I am not alone here!

Now we need to know if anybody else has experienced 'the whistle'!
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 13th August 2005, 07:08 PM   #5
t. is offline t.  United Kingdom
diyAudio Member
 
t.'s Avatar
 
Join Date: May 2003
Location: notts
Quote:
Originally posted by Nuuk


Hi Leo, I was just going to email you! OK, so I am not alone here!

Now we need to know if anybody else has experienced 'the whistle'!
Well I've mailed you anyway

The sound of the actual music seems fine and the whistle seems its nothing to do with the actual recording, its like that feeling you get when a tv is on if you know what I mean
Strange
  Reply With Quote
Old 13th August 2005, 07:16 PM   #6
dnsey is offline dnsey  United Kingdom
diyAudio Member
 
Join Date: Mar 2004
Location: Shropshire, England
Years ago, when I was contemplating buying my first CD player, almost all the players I heard demonstrated produced a sound similar to a TV line whistle.
None of the dealers I asked about it claimed to be able to hear it, but it was quite audible to me, and made the music almost unlistenable, and put me off CDs for some time. Eventually I decided I'd have to put up with it in order to listen to any newly released music.
These days I don't hear it any more, whether from a good or a bad player, so either I've become 'immune' to it or (more likely) my old ears don't go that high any more.
  Reply With Quote
Old 13th August 2005, 07:24 PM   #7
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
But in my case, it is not continuous! It sounds exactly like my whistling kettle when it boils and I am upstairs with the hi-fi on.

And like I said only noticeable on two tracks of one CD (so far).
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 13th August 2005, 07:37 PM   #8
Account Disabled
 
Join Date: Feb 2004
Send a message via AIM to classd4sure Send a message via MSN to classd4sure
I'm betting it also sounds like a cheap AM radio does when you're tuning stations on it.

http://dictionary.reference.com/search?q=heterodyne

Those difference signals, are your whistle.

Distance and shielding between modules is a good help. Are your modules right next to each other? I don't even know if they're both built on the same PCB so forgive the ignorance.

Is there any kind of low pass on the inputs already?

You could also take measures to attempt to lower the modules EMI, I assume there's some sort of heatsink on it, is it bypassed to ground?

Regards
  Reply With Quote
Old 13th August 2005, 07:38 PM   #9
t. is offline t.  United Kingdom
diyAudio Member
 
t.'s Avatar
 
Join Date: May 2003
Location: notts
Quote:
Originally posted by dnsey
Years ago, when I was contemplating buying my first CD player, almost all the players I heard demonstrated produced a sound similar to a TV line whistle.
None of the dealers I asked about it claimed to be able to hear it, but it was quite audible to me, and made the music almost unlistenable, and put me off CDs for some time. Eventually I decided I'd have to put up with it in order to listen to any newly released music.
These days I don't hear it any more, whether from a good or a bad player, so either I've become 'immune' to it or (more likely) my old ears don't go that high any more.
Well I've always had very good hearing
Mine is doing similar to NUUK though in that its only noticeable on a few cd's at certain parts of a track and normally if there is no cd in the transport
  Reply With Quote
Old 13th August 2005, 07:44 PM   #10
t. is offline t.  United Kingdom
diyAudio Member
 
t.'s Avatar
 
Join Date: May 2003
Location: notts
Quote:
Originally posted by classd4sure
I'm betting it also sounds like a cheap AM radio does when you're tuning stations on it.

http://dictionary.reference.com/search?q=heterodyne

Those difference signals, are your whistle.

Distance and shielding between modules is a good help. Are your modules right next to each other? I don't even know if they're both built on the same PCB so forgive the ignorance.

Is there any kind of low pass on the inputs already?

You could also take measures to attempt to lower the modules EMI, I assume there's some sort of heatsink on it, is it bypassed to ground?

Regards
Thank you for the link
We both use an amp based on the TA2021 so its stereo on a single chip, my psu is in a seperate case.
There is a 100pf cap on the input and ground which I presume is used for the filtering.
It seems strange that its only mainly noticeable on some cd tracks
  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
1500W RMS Class D PCB - which Class D Driver Chip is it ? mosfetsound Class D 11 1st April 2011 11:17 AM
Can a Class AB PP amp be said to be operating in Class A at low signal levels? ray_moth Tubes / Valves 19 23rd January 2009 07:52 PM
How about a round-up of Class A kit power amps, or collectable vintage class A? Brisso57 Solid State 4 14th February 2007 10:30 AM


New To Site? Need Help?

All times are GMT. The time now is 10:43 PM.


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