Jens Rasmussen Leach clone group buy - Page 32 - diyAudio
Go Back   Home > Forums > Commercial Sector > Group Buys

Group Buys Members group buys

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 2nd January 2008, 03:38 PM   #311
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by pooge
I'd be concerned about the inductor being so close to the low level stages, where it might couple magnetically.

Also, the Zobel should ideally be placed as close to the speaker posts as possible to keep RF picked up by speaker wire out of the chassis. I have been considering a separate board for the inductor and Zobel that contains only these components on design I'm working on, and providing alternative Zobel arrangements, like the ones suggested by Cherry and Thiele, for ones choosing.

Taking these components off the main board would provide more room, and reduce RF on the antenna line from the speaker posts to the boards output. On the design I'm working on, this Zobel board will have holes properly spaced to mount directly on the speaker posts, for both mounting and for direct electrical connection between the PC traces and the posts.
I agree with all the observations here.
But, all builders always have the option to move the Thiele network off the PCB to the speaker terminals and simply short across the empty component locations.
__________________
regards Andrew T.
  Reply With Quote
Old 2nd January 2008, 03:49 PM   #312
pooge is offline pooge  United States
diyAudio Member
 
Join Date: May 2003
Location: Northern Va.
Quote:
Originally posted by AndrewT
I agree with all the observations here.
But, all builders always have the option to move the Thiele network off the PCB to the speaker terminals and simply short across the empty component locations.
But that would still not eliminate the real estate required on the main board if one chooses not to install these elements there, or not at all, as some advocate. Not to mention the much greater real estate required for other Zobel options. Besides, you know what a PITA it is to mount the Thiele/Zobel network on the speaker posts. Using a PC board mounting directly on the posts would make it much easier, and help keep capacitor leads short.
  Reply With Quote
Old 2nd January 2008, 04:32 PM   #313
diyAudio Member
 
BobEllis's Avatar
 
Join Date: Sep 2003
Location: Upstate NY
I'm not saying that Leach's original layout was perfect, but there doesn't seem to be a coupling issue with them. (Listening only, not hypersenstive measurement equipment) The Leach boards have the resistor//inductor closer to the front end than this verison of Jens' layout.

The half inch that could be saved doesn't make or break me.
  Reply With Quote
Old 2nd January 2008, 08:45 PM   #314
diyAudio Member
 
JensRasmussen's Avatar
 
Join Date: Jul 2002
Location: Denmark - Jutland
Send a message via ICQ to JensRasmussen Send a message via MSN to JensRasmussen
Quote:
Originally posted by pooge
I'd be concerned about the inductor being so close to the low level stages, where it might couple magnetically.

Also, the Zobel should ideally be placed as close to the speaker posts as possible to keep RF picked up by speaker wire out of the chassis. I have been considering a separate board for the inductor and Zobel that contains only these components on design I'm working on, and providing alternative Zobel arrangements, like the ones suggested by Cherry and Thiele, for ones choosing.

On my first design I wanted the end with the output to face the back of the amp, placing the zobel network only a few centimeters from the speaker terminals.....

So what should this be??

1) Original type layout with a long feedback loop, onboard zobel network.
2) New layout with shorter feedback trace, onboard zobel
3) External zobel..... long or short feedback??

\\\Jens
  Reply With Quote
Old 2nd January 2008, 09:01 PM   #315
pooge is offline pooge  United States
diyAudio Member
 
Join Date: May 2003
Location: Northern Va.
Jens and all,

I don't mean to be disruptive about this process, or sound critical of Jens' design.

I started a design process to please myself for my design criteria for these boards, with lessons learned. In the meantime, a group buy was done on the old design, which took a lot of potential customers away from a buy I was anticipating. There still seemed to be enough interest in more boards, so I intended to continue with my design. Jens told me he was not interested in being involved in this any more. Now there is involvement again, and it is doubtful that two more GB could be accomplished at this time. I'm kinda stuck about what to do. Any changes to Jens' design, or my design, should be prototyped to see how well they do. That takes time. That's not something I'd want to do if there is no hope for a GB.
  Reply With Quote
Old 2nd January 2008, 10:59 PM   #316
diyAudio Member
 
Join Date: Dec 2004
Location: Rijeka, Croatia
pooge, where can I see your design?

I am in for GB, 4 pcs, and if you guys do not make it until end of January I will have to make my own boards.
Jens' last board is great, in my opinion it is much better than original one. I understand that you want to design "ultimate" leach clone but 80% of builders wont be able to get all that fancy parts.

My suggestion is:
-check price for 52 boards GB (if it matters I can talk some people to buy boards)
-find good price for capacitors
-find good price for output transistors



Like it or not.
Zeljko M
__________________
Zeljko M
  Reply With Quote
Old 2nd January 2008, 11:22 PM   #317
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
hi,

i put my zobel netwrok on the speaker terminals of the amp and not on the boar itself, so for me this is non-issue,

what i like with the latest revision is that it opens up more possibilities imho...
  Reply With Quote
Old 3rd January 2008, 10:28 AM   #318
diyAudio Member
 
Join Date: Apr 2007
After constructing several of Jens Leach Clone boards the only major concern was routing the signal input all the way to the front without crossing or coming into close proximity to the power supply leads or the transformer housing. I know that any design that has the signal input in the middle or at the rear of the amp is hard to design in. It would if possible make proper signal routing easier. Also, If the signal in could accomadate a screw type terminal assembly would be easier.
I personally like most if not all of the solderable components on the pcb. It makes for a neater less cluttered chassis.
What ever design is chosen I am still in for a GB. Tad

I use the word easier because as I get older I find that my magnifier lens gets stronger and my hands get less steady. Soldering these small components can be challenging if you want a nice clean finished unit.
  Reply With Quote
Old 4th January 2008, 12:46 PM   #319
diyAudio Member
 
Join Date: Apr 2007
Default Build Spec's

Could anyone more knowledgable than I tell me what a good bias setting would be for the Jens Leach Clone. Tad
  Reply With Quote
Old 4th January 2008, 01:00 PM   #320
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
set bias to give 15 to 25mV across each of the output emitter resistors.
__________________
regards Andrew T.
  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
WTB:2 boards from Jens Rasmussen Leach clone group buy mpmarino Swap Meet 0 12th January 2009 11:53 AM


New To Site? Need Help?

All times are GMT. The time now is 10:26 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