Digitally controlled preamp/headphone amp - Page 72 - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems

Headphone Systems Everything to do with Headphones

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 11th November 2006, 09:52 PM   #711
diyAudio Member
 
Join Date: Feb 2006
Location: Atlanta
Motorized pot, right? I would doubt it's the code in the PIC.

Sounds like there is an issue with the POT/WIPER pin where it's somehow losing the ground reference while turning. Is there a away you can check that?

If the PIC were causing that... you'd have to see the POT Hunting wildly while it's being driven.
__________________
pw
  Reply With Quote
Old 11th November 2006, 09:54 PM   #712
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
Default Re: Strange problem when using v1.1 PIC

Quote:
Originally posted by arjscott
Hi there,

I recently purchased an assembled Kookaburra from a friend and have been having a lot of fun with it. I received a few extras with it including a PIC labelled v1.1 (the installed PIC was unlabelled).

I decided to connect a 50K log pot in place of the original. I know a logarithmic pot is not ideal, but it's motorized, and I'm too lazy to get up every time I want to change the volume :-)

So, I turned everything on, sat back on the couch and proceeded slowly turn up the volume. When the pot had travelled only a few degrees there was a sudden burst of full volume sound which triggered the amplifier protection circuit. Oh dear, I thought...

To cut a long story short, after some experimentation I found with the v1.1 PIC, when the 50K log pot is a few degrees from minimum, it causes very short bursts at full volume. These bursts are a fraction of a second, with about 1/2 second gap between them. Once the pot has passed this point, the volume level is low and increases gradually as expected. At least one burst will occur whenever the pot passes this point. With careful adjustment I get the continuous bursts.


This doesn't happen with the original unlabelled PIC, which I guess is v1.0.

If anyone (Russ?) has any ideas about what's causing this I'd be interested.

Best regards,

Andrew.
The "1.1" version was experimental, and should not be used.

It has a mathematical error which kicks in exactly as you say.

The unlabeled PIC most likely has the correct production firmware.

Cheers!
Russ
__________________
Less pulp more juice Twisted Pear Audio.
  Reply With Quote
Old 12th November 2006, 02:39 AM   #713
diyAudio Member
 
Join Date: Apr 2006
Location: NZ
Default Re: Re: Strange problem when using v1.1 PIC

Quote:
Originally posted by Russ White


The "1.1" version was experimental, and should not be used.

It has a mathematical error which kicks in exactly as you say.

The unlabeled PIC most likely has the correct production firmware.

Cheers!
Russ

Ok, thanks for letting me know. And just want to say thanks for putting the work into this product! I'm thinking of having a go at some of your new kits once they are available.


Quote:
Originally posted by pwillard

Sounds like there is an issue with the POT/WIPER pin where it's somehow losing the ground reference while turning. Is there a away you can check that?
That's exactly what I first thought. I really thought I'd see the error when measuring the pot. My guess at the v1.1 PIC was just by elimination.

Best regards,

Andrew.
  Reply With Quote
Old 17th November 2006, 02:18 AM   #714
diyAudio Member
 
TomWaits's Avatar
 
Join Date: Aug 2005
Default Kooky

I'm spreading myself thin into lots of projects these days. Here is what I just soldered together tonight. Took an hour to do it and I must say that the Pear Brothers make a fantastic kit! I still can't get over the attention to detail in the packaging method.

I'm off to see a cabinet maker tomorrow about putting some wood into the metal enclosure I purchased.

I have a funny feeling I'm really going to enjoy this kooky little thing. I'll be back when it is together with some more comments. I have all the parts to assemble it so I hope it won't be too long.

Thanks a bunch,

Shawn.
Attached Images
File Type: jpg kookaburrasmall.jpg (91.7 KB, 847 views)
  Reply With Quote
Old 17th November 2006, 02:23 AM   #715
diyAudio Member
 
TomWaits's Avatar
 
Join Date: Aug 2005
Default Bright Blue Cap

The 22uF 50V cap got torchured by someone during assembly. So I used one I had in stock as a stand in...more like a stand out! Should be fine either way?

Shawn.
  Reply With Quote
Old 17th November 2006, 03:39 AM   #716
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
Default Re: Bright Blue Cap

Quote:
Originally posted by TomWaits
The 22uF 50V cap got torchured by someone during assembly. So I used one I had in stock as a stand in...more like a stand out! Should be fine either way?

Shawn.

Brian does all the hard work, and yes he rocks.

As for that cap, it will be just fine. That particular cap acts as a reservoir for the relay. Just about anything would work.

I hope you really enjoy it!

Cheers!
Russ
__________________
Less pulp more juice Twisted Pear Audio.
  Reply With Quote
Old 26th November 2006, 06:43 AM   #717
D1GGY is offline D1GGY  New Zealand
diyAudio Member
 
D1GGY's Avatar
 
Join Date: Dec 2002
Location: Wellington, NZ
Hi guys, i built my Kook today, switched on and the LM7812 gets real hot (smells and you can't touch it) I have not tried to measure anything yet other than 2.2volts across the LED socket, Any pointers as to testing process going forward much appreciated....

Cheers mark
  Reply With Quote
Old 26th November 2006, 07:35 AM   #718
diyAudio Member
 
Join Date: Nov 2004
Location: Seattle
Make sure that you haven't mixed up the lm812 and the lm912. One is +12v and the other is -12v. It matters which side you install them.

(K)
  Reply With Quote
Old 26th November 2006, 08:25 AM   #719
D1GGY is offline D1GGY  New Zealand
diyAudio Member
 
D1GGY's Avatar
 
Join Date: Dec 2002
Location: Wellington, NZ
Thanks Bikedude,

Just checked again just to be sure, no mix up both are where they should be.

Mark
  Reply With Quote
Old 26th November 2006, 11:54 AM   #720
diyAudio Member
 
BrianDonegan's Avatar
 
Join Date: Dec 2004
Location: TPA HQ
What's your input voltage? Is the 7912 getting warm as well?
__________________
Twisted Pear Audio
  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



New To Site? Need Help?

All times are GMT. The time now is 05:57 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