My "audiophile" LM3886 approach - Page 65 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 26th August 2005, 08:50 PM   #641
diyAudio Member
 
Join Date: Dec 2002
Location: Houston
Default I am sold

Quote:
Originally posted by Russ White


I couldn't agree more. It is one thing to theorize, and quite another to test. this amp (REV C) tests better than ANY amp I own, and I don't own any junk. Listen to it, and you will be sold at once.

Cheers!
Russ

Like my Rev A a lot. I just used a 470 ufd cap because it fit. It works fine. May try bypassing it with a stacked film Siemens cap.
Changing the operating points of the Rev C is the least of my projects. Need to find a low esr cap in 220 ufd 50v that will fit the small pad.
But I learned something new today. May try the series connected nonpolar caps next time a large value cap is needed for signal coupling. Wait a minute, feeddback loop components are signal coupling.

George
  Reply With Quote
Old 26th August 2005, 10:55 PM   #642
diyAudio Member
 
Join Date: Jul 2004
Location: .
Hi All

i have to admit. (once i have tested it) that I have to withdraw my suggestion of a 1m input and 470uf cap. it boomed like crazy and the output DC shocking were nowhere to acceptable

Mauro optimised this to the best values that would satify most and also the most stable

in the end i settled for a 330uf feedback (might still be to big, but the bass is deeper) and 220k input resitor with a 330pf input cap. now it is to my taste. bit more loose and laidback.

well i still wish i could get the correct vlaues for a NP configuration

cheers
Rudi
  Reply With Quote
Old 28th August 2005, 02:30 AM   #643
maf_au is offline maf_au  Australia
diyAudio Member
 
Join Date: Jun 2005
Location: Adelaide
Default Construction finished

Well, I have finally finished it!

I'll have to search what the best method is to test it, but I think the standard practice is to test mv with shorted inputs, and if that checks low, then let her rip?

Piccy for prosterity. I've used medium hookup for the signal cables and 1.25mm enamelled cu wire for the speaker connections.

I was not able to solder any of the fastons, they are just crimped. What do people normally do?

Happy with the result, my only concerns are:

Should I split the signal wiring and twist it?

Should the signal input lengths be the same? (one channel is a lot longer than the other here)

The speaker ground wires are about twice the length of the signal wire. Will that have any effect?
Attached Images
File Type: jpg maurofinished-sml.jpg (98.9 KB, 1460 views)
__________________
My AudioProjects Gallery
  Reply With Quote
Old 28th August 2005, 02:52 AM   #644
troystg is offline troystg  United States
diyAudio Member
 
troystg's Avatar
 
Join Date: Apr 2004
Location: In a dream... Please don't wake me.
Well that is a very neat layout. One concern is I don't see a fuse on the primaries. Is there one?


As for the ground leads being longer, that is nothing to worry about.

Edit: My suggestion if there is not an integrated fuse in the power receptacle is to replace the two terminal primary strip with a 3 or 4 and put a fuse inline there. You have plenty of room and it would be a simple mod.

But once again, EXCELLENT execution!... Please let us know how you like the sound.
__________________
Troy
Thinking positive doesn't make things better, it makes you a better person.
  Reply With Quote
Old 28th August 2005, 03:10 AM   #645
maf_au is offline maf_au  Australia
diyAudio Member
 
Join Date: Jun 2005
Location: Adelaide
Quote:
Originally posted by rabstg
Well that is a very neat layout. One concern is I don't see a fuse on the primaries. Is there one?

As for the ground leads being longer, that is nothing to worry about.

Edit: My suggestion if there is not an integrated fuse in the power receptacle is to replace the two terminal primary strip with a 3 or 4 and put a fuse inline there. You have plenty of room and it would be a simple mod.

But once again, EXCELLENT execution!... Please let us know how you like the sound.
Thanks for the feedback

Yes, the primaries are fused - the IEC socket has an integral fuseholder, and there's a 5A Slowblo about to go in. Having interested kids around means I do things like remove the fuse until everything is complete, just in case someone decides to plug it in when I'm not around...

Oh yes, I'll defintely let you know how it sounds

Michael
__________________
My AudioProjects Gallery
  Reply With Quote
Old 28th August 2005, 03:33 AM   #646
diyAudio Member
 
Join Date: Dec 2002
Location: Houston
Default Burn in

Will not take long. Took mine to another equipment lovers house with about 2 hours run in. He loved it. I am way too biased, most amps that new sound better after spending so many hours building. It takes time to hear the small warts.
This circuit is not sensitive to ground lengths. I have another amp the hums if the ground wires are not exactly the same length. It taught me a lot about layout.
Good luck! Hope you are happy with it.

George
  Reply With Quote
Old 28th August 2005, 03:59 AM   #647
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
Michael,

You are good to go. Very nicely done. The faston connectors are meant to be only crimped. Everything looks good from here. Fire it up!

Cheers!
Russ
__________________
Less pulp more juice Twisted Pear Audio.
  Reply With Quote
Old 28th August 2005, 04:02 AM   #648
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
Michael,

Forgot to mention, when you first look at DC offset it is good to do so with the inputs shorted to 0V. After that check it with a live source. Then connect your speakers.

Cheers!
Russ
__________________
Less pulp more juice Twisted Pear Audio.
  Reply With Quote
Old 28th August 2005, 04:13 AM   #649
maf_au is offline maf_au  Australia
diyAudio Member
 
Join Date: Jun 2005
Location: Adelaide
Quote:
Originally posted by Russ White
Michael,

Forgot to mention, when you first look at DC offset it is good to do so with the inputs shorted to 0V. After that check it with a live source. Then connect your speakers.

Cheers!
Russ
So that is the signal to PL3/4 OR signal + sigGND to PL3/4 ?

I'm being called to lunch, so after that, it's fire up time

Michael
__________________
My AudioProjects Gallery
  Reply With Quote
Old 28th August 2005, 05:36 AM   #650
maf_au is offline maf_au  Australia
diyAudio Member
 
Join Date: Jun 2005
Location: Adelaide
Powered up with shorted inputs.

No Smoke!

Speaker protection relay clicked in, and...

I have 11.5/6.5mv

Doesn't look like a speaker-wrecker to me... Time to take it downstairs

I'll let you all know how it goes.

Michael
__________________
My AudioProjects Gallery
  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 06:16 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