Marsh headphone amp from Linear Audio - Page 48 - 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 1st October 2012, 01:52 AM   #471
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
So many things going on and very little real meat to report, but here goes:

I found someone selling some LT1963A regs for half normal price on ebay and I got 8 pieces on the way. A really nice find!

I also placed an order to Digi-Key to get some transformers. I bought a pair of Triad Magnetics dual bobbin types so each channel gets its own xformer. I also will keep them in a separate box on a floor and not in an all-in-one configuration. But I will have the regs right up against the amp circuit, as you recommended.

This weekend was way too hectic to do anything useful as my 5 year old celebrated her birthday and that was a real adventure! But I want that board etched and drilled ASAP because I have all the other parts available now to build the amp circuit. It really is time to get the show on the road!
  Reply With Quote
Old 16th October 2012, 05:43 PM   #472
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
No major updates other than fine tuning my board layouts, including changing the layout a bit for the voltage regs. I wanted the LT1963A thru hole part but found the great deal on the DD package.

Work has been hell but in 2 weeks we're done with our major project. So I'm taking several days off in November and December and get this all done! I'm tired of sitting there just looking at the parts.
  Reply With Quote
Old 16th October 2012, 09:14 PM   #473
diyAudio Member
 
Join Date: Oct 2011
Location: North West, UK
Blog Entries: 7
Hi everyone, I'm quite intrested in putting one of these together and understand that the build & schematic etc. is covered in issue 3 of Linear Audio magazine. Until I'm ready to start I'll leave the technical questions to one side...

PCB's .... are any available to purchase, or like Sonidos is doing, does the layout and making of the boards need to be done one's self?

Paul.
__________________
Listening with Gusto!
  Reply With Quote
Old 17th October 2012, 03:53 AM   #474
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Default PCB sources

Quote:
Originally Posted by BuildMeSomething View Post
PCB's .... are any available to purchase, or like Sonidos is doing, does the layout and making of the boards need to be done one's self?

Paul.
See #21 for a source.
  Reply With Quote
Old 17th October 2012, 09:43 AM   #475
diyAudio Member
 
Join Date: Oct 2011
Location: North West, UK
Blog Entries: 7
Thank you, I promise that I have read the entire thread and had seen jackinnj's kind offer. With what appears to be little shown public intrest in his offer, I wasn't sure if it was still open... Should have asked jackinnj first

Paul.
__________________
Listening with Gusto!
  Reply With Quote
Old 17th October 2012, 12:02 PM   #476
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
This site/forum is just to answer questions and offer advice on building. The design is not here, either. The design is shown and described in Linear Audio publication. The pcb have been available for quit awhile thru the publisher. The design offers superiour performance with minimal parts cost. This site here is more about DIY designing and modifying and collaborating on design and on the construction et al. This one is all done. Nothing to do but built it and listen to music. Thx for your interest - Richard Marsh

Last edited by RNMarsh; 17th October 2012 at 12:09 PM.
  Reply With Quote
Old 17th October 2012, 04:37 PM   #477
diyAudio Member
 
Join Date: Oct 2011
Location: North West, UK
Blog Entries: 7
Once again, thanks. A copy of LA #3 has been purchased, are the pcb's only available to order directly through the publication and not the web site? [not including jackinnj's offer]

Without having yet read the article, is there scope for changing the gain of the amp. Is that something that's covered within the publication, or something that can be discussed here.

Paul.
__________________
Listening with Gusto!
  Reply With Quote
Old 19th October 2012, 02:07 PM   #478
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
I had some time last night to mess around and I decided to measure the hfe on the small signal BJTs I purchased from Avnet. The npn's are Fairchild and the pnp's are OnSemi. So the good stuff.

I sampled about 10 each. Like previous experience, the NPNs were all pretty closely grouped, and the PNPs as well.

Unfortunately, the NPNs all measured around 538 and the PNPs around 438. That's a pretty big difference. I'm hoping that I can find a few that meet somewhere in between that range.

Mr. Marsh, any comments on the difference? I'm assuming that's fine but I don't know how closely yours matched on your proto build.

Last edited by sonidos; 19th October 2012 at 02:08 PM. Reason: added comment to Mr. Marsh
  Reply With Quote
Old 19th October 2012, 02:31 PM   #479
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Default ac and dc match

Its been a couple years since I measured my transistors. I believe I used same mfr for npn and pnp. I try to match both dc (Vbe) and ac (Hfe). BUT, the heavy local degeneration being used means matching isnt super critical. However, it never hurts to do a reasonably close match, though.
  Reply With Quote
Old 19th October 2012, 03:29 PM   #480
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
Thanks. Great info. I'll be sure to look at vbe. The problem I had is that neither OnSemi or Fairchild make the npn/pnp combo available anymore. I even tried to place a large order from OnSemi and it was rejected and I was directed to order an alternative that was a 20,000 piece min.

But there are plenty of these on ebay and maybe I'll try some at a later date that are a better match. As you noted, they are heavily degenerated locally and the matching is not as critical. Thumbs up!
  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
FS: Meier Audio Corda Headphone Amp jtwrace Swap Meet 5 29th February 2012 11:34 AM
Histoically significant - Phase Linear audio pre-amp bobcul Swap Meet 0 21st February 2012 08:16 PM
Headphone amp with mixed-in telephone audio krfjr1965 Solid State 3 10th March 2010 03:50 PM


New To Site? Need Help?

All times are GMT. The time now is 01:19 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