My "audiophile" LM3886 approach - Page 413 - 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 28th December 2012, 09:12 AM   #4121
diyAudio Member
 
Robert Kesh's Avatar
 
Join Date: Oct 2012
Quote:
Originally Posted by bcmbob View Post
No Sir, My comment was serious. Please note that I used the word respect twice in my message. I am simply stating the fact I have participated in at least three threads in the last two years where the identical positions - both pro and con - dealing with whether one can give credibility to what is heard/perceived are expressed. They all have decayed into personal snipes and dogma, again pro and con, and nobody's position ever seems to budge.

It is a very interesting area to investigate (just watched another series on how the mind can trick us last night - Discovery CH.) but consumes enormous amounts of time that I believe could be put to better use. Please believe that my comments are not a personal swipe at you and/or your body of knowledge specifically. I respect and enjoy science, but attempt to keep it within a usable perspective in matters artistic. In the end the technology is there solely to support a valuable and loved form of art - Music.

My hope is simply to avoid the clutter.
I'd suggest that if there is an argument you don't think is worthwhile, you don't participate. It takes at least two to derail a thread.

And I have little interest in the subject beyond making the odd passing comment, because, although I believe it's an established fact that our ears can deceive, proselytising this fact isn't any fun, least of all among audiophiles.

I will, however, continue to post what I please, so long as it is within the forum rules, and 99.9% of this you will find completely uncontentious. If you ignore the other 0.1%, it probably won't go anywhere.

Anyway, my last word, as I don't want to derail things further.
  Reply With Quote
Old 28th December 2012, 10:15 AM   #4122
Reality first!
diyAudio Member
 
ClaveFremen's Avatar
 
Join Date: May 2005
Location: Milan, Italy
Quote:
Originally Posted by gootee View Post
What numbers were you using for the trace width and trace thickness, for the inductance calculator? The inductance figures seem quite low.
Hi Tom,

32 mils trace witdht, 70u thickness, lenght as indicated (1mm and 5.5mm)

Quote:
Originally Posted by gootee View Post
Also: Is this Mauro's original PCB layout? I think you mentioned whose it was, actually. I seem to remember Mauro allowing someone to produce and sell copies of his first layout. So maybe this is that one.
No, it's my variation: My_Ref Fremen Edition

Quote:
Originally Posted by gootee View Post
Please forgive me, but I am unfamiliar with what versions and "spin-off" versions of the MyRef are in existence.
Quote:
Originally Posted by gootee View Post
Can you or someone please post links to the relevant threads for each of the major MyRef versions and spin-off versions or closely-related circuits? I think that I am finally ready for another project to build.
There are several versions:
  • the original stereo layout by Mauro Penasa (see Mauro's website for schematic and gerbers)
  • the monoblock layout by Russ White of Twisted Pear Audio, it's the most used and out of production (released for personal use)
  • LinuxGuru monoblock layouts (somewhat an unofficial evolution from TP boards)
  • Nimo e-store unauthorized stereo clone
Variations:
  • XCalibre
  • My_Ref Fremen Edition (completely redesigned PCB, PS, groundplanes, different grounding, SMD parts, etc.)
  • LinuxGuru double pump variation (yet to be released)
For the FE (Fremen Edition) you can find all relevant info on these threads

My_Ref Fremen Edition - need help on PCB evaluation

My_Ref Fremen Edition - Beta build/Fine tuning

My_Ref Fremen Edition RC - Build thread

Quote:
Originally Posted by gootee View Post
If this one is "frozen" for no more development, or is out-dated, then I might not want to keep bothering you and Siva about it. It might be like stumbling in through the back door of a famous ancient cathedral and excitedly engaging the nearest priest in a discussion of changes to the architecture that I thought were needed.
The FE is in the final development phase (release candidate) but suggestions and (constructive) comments are always welcome and appreciated.

The ony currently developed versions/variations are the FE and Siva's ones
__________________
Dario
ClaveFremen "Bailando Salsa en el Sietch"

Last edited by ClaveFremen; 28th December 2012 at 10:28 AM.
  Reply With Quote
Old 28th December 2012, 08:35 PM   #4123
Reality first!
diyAudio Member
 
ClaveFremen's Avatar
 
Join Date: May 2005
Location: Milan, Italy
Quote:
Originally Posted by ClaveFremen View Post
XCalibre
X-Calibre : Hot Rodding Mauro Penasa's LM3886 design
__________________
Dario
ClaveFremen "Bailando Salsa en el Sietch"
  Reply With Quote
Old 29th December 2012, 03:48 AM   #4124
diyAudio Member
 
Join Date: Sep 2007
Send a message via Yahoo to linuxguru
I'll add that the last Twisted Pear Audio (v1.2) and my v1.3 and v1.4 PCBs are closely related, with nearly identical schematics and parts designators. My boards are physically larger, because one of the reasons for the respin was to allow physically larger components to fit comfortably, e.g. 35mm diameter PSU caps (C3,C8) vs. 30mm earlier, and 16mm diameter caps at C1,C2 vs. 12mm earlier. There are also numerous changes to allow component flexibility, while allowing components from earlier BoMs to be used interchangeably wherever possible. There are some routing improvements, most visible in V1.4 around C4, C7 and the PGND nets, and better shielding/ground plane for the small-signal nets.

The double-Howland MyRef-X2 is an ab-initio redesign and fresh layout, and it is still in the process of prototype validation. The only change in specs is that it can drive 4-ohm loads also, with the same nominal 32V rails for a power rating of 80 Wrms per channel. Specs for 8-ohm loads remain unchanged.
  Reply With Quote
Old 29th December 2012, 10:29 AM   #4125
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
Siva, does the "sharing" of the X2 amps work between two chips have any audible impact on the quality and/or character of the amp's sound. I would have suspected at least a small gain in headroom when pushing for higher SPL even with 8 ohm loads.
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 29th December 2012, 10:53 AM   #4126
diyAudio Member
 
Join Date: Sep 2007
Send a message via Yahoo to linuxguru
Quote:
Originally Posted by bcmbob View Post
... I would have suspected at least a small gain in headroom when pushing for higher SPL even with 8 ohm loads.
In simulation, with unofficial LM1875 models instead of LM3886, there is indeed a small improvement in THD20 into 8-ohm loads compared to the single-pump case. I'm not sure if it will be audible - the standard MyRef was already very good.

Last edited by linuxguru; 29th December 2012 at 10:54 AM. Reason: typo
  Reply With Quote
Old 29th December 2012, 11:24 AM   #4127
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
I want to be discrete and polite, but did you find any of DW's comments in this section of the discussion of "amp sweetness" applicable to the X2, or if implemented, an entirely new PCB (non-MyRef) would be required?
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 31st December 2012, 09:36 PM   #4128
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Nice little decoupling/bypassing capacitor animation:

Bypassing
  Reply With Quote
Old 31st December 2012, 09:48 PM   #4129
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
That's great gootee. Answers a lot at a level even I can comprehend

THANKS!
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."

Last edited by bcmbob; 31st December 2012 at 09:52 PM.
  Reply With Quote
Old 1st January 2013, 03:10 AM   #4130
soongsc is offline soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
Good link gootee. I have been pondering a lot about grounding. Different grounding schemes make quite a difference.
__________________
Hear the real thing!
  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 08:14 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