New LM1875 pcb and kit pre-order special - Page 2 - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Chipamp

Chipamp IC amp kits & PC boards from ChipAmp

Reply
 
Thread Tools Search this Thread
Old 20th July 2008, 01:49 PM   #11
BrianGT is offline BrianGT  United States
diyAudio Moderator Emeritus
 
BrianGT's Avatar
 
Join Date: Jan 2002
Location: near Atlanta, GA
Send a message via AIM to BrianGT
Quote:
Originally posted by Peter Menting
Brian; Could you tell me what the board sizes are? Have a special project in mind.

Thanks,
Pete

The board sizes are:

LM1875 amp board:
1.6" x 1.2"
PSU board:
1.6" x 2.4"
  Reply With Quote
Old 24th July 2008, 03:12 AM   #12
KT is offline KT  United States
diyAudio Member
 
Join Date: Oct 2003
Location: USA
Received the kit and boards today, Brian. Thanks!

KT
  Reply With Quote
Old 24th July 2008, 12:08 PM   #13
diyAudio Member
 
Join Date: Nov 2006
Location: Lyon
Hi brain, received the PCBs today.
Thanks !

Do you have some hints to improve LM1875 response in high frequency ?
  Reply With Quote
Old 24th July 2008, 01:00 PM   #14
sonidos is offline sonidos  United States
Libertador de la Msica
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
Brian,

Thank you!! Got mine today and everything arrived in great shape. Can't wait to get started on this build.
  Reply With Quote
Old 27th July 2008, 10:50 PM   #15
vonfilm is offline vonfilm  United States
diyAudio Member
 
Join Date: Jun 2006
Brian,
When will the assembly manual be available on your website?
  Reply With Quote
Old 28th July 2008, 10:14 PM   #16
sonidos is offline sonidos  United States
Libertador de la Msica
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
I've got it pretty much figured out from the photos, but I want to be sure that I populate the locations for the resistors with the correct values.

I've already got the psu done and I'm heading to our local electronics surplus store at lunch to see if they have heatsinks and other assorted hardware so I can keep moving forward.

Brian, also, on your web page, I found the resistor designators but now I'm not certain what to do about those components that are considered optional. From the images, it looks like the boards are pretty well populated. When you have docs ready, can you address under what circumstances we will want to populate the optional components?

Thanks!
  Reply With Quote
Old 29th July 2008, 03:38 PM   #17
BrianGT is offline BrianGT  United States
diyAudio Moderator Emeritus
 
BrianGT's Avatar
 
Join Date: Jan 2002
Location: near Atlanta, GA
Send a message via AIM to BrianGT
Quote:
Originally posted by vonfilm
Brian,
When will the assembly manual be available on your website?
I will put more time into it this week, and try to get something up by the end of the week.

Quote:
Originally posted by sonidos
I've got it pretty much figured out from the photos, but I want to be sure that I populate the locations for the resistors with the correct values.

I've already got the psu done and I'm heading to our local electronics surplus store at lunch to see if they have heatsinks and other assorted hardware so I can keep moving forward.

Brian, also, on your web page, I found the resistor designators but now I'm not certain what to do about those components that are considered optional. From the images, it looks like the boards are pretty well populated. When you have docs ready, can you address under what circumstances we will want to populate the optional components?

Thanks!
As for the optional components, they are provided for optimal amplifier stability for using with a variety of output loads/impedances. It depends on your setup, whether you need them or not. Here is a list of optional components:

R1 - not used (optional resistor to ground before C1)
R5 - 2.7 2w (optional - zobel network)
R6 - jumper (optional resistor between input ground and output ground)
C1 - 2.2F (optional input capacitor)
C2 - 22F bipolar (optional)

For R1, this is omitted from the kit, and is provided if you wish to put a resistor to ground before the input capacitor. This is not needed, but provided for versatility for various input sources. I had a request for this a long time back, and retained it in the PCB layout, as it doesn't have any side effects if not populated.

For R5/C7, these are for the optional zobel network, which can stabilize the output by creating a pole that reduces high frequency instabilities. If you don't want to use these, simply omit these components from the pcb.

For R6, this is for an optional resistor between the input signal ground, and the output ground. This is specified as a jumper, meaning a simple wire connecting these terminals. You can utilize the extra wire from the 2.2uF film capacitor lead. You should not need to use this, unless you are having ground loop issues.

For C1, this is the optional input capacitor that blocks DC offset from the input source from propagating to the input of the LM1875.

For C2, this is the optional feedback capacitor that ensure unity gain at DC.

As for a bare minimum configuration, here is what you could run:
R1 not populated
R2 22k (input to ground resistor)
R3 1k (gain resistor, gain = 1 + R4/R3)
R4 22k (nfb resistor - on bottom of pcb)
R5 not populated
R6 jumper
C1 jumper, or put input source into pad by C1 label on pcb
C2 jumper
C3 0.1F (power supply decoupling)
C4 47F (power supply decoupling)
C5 0.1F (power supply decoupling)
C6 47F (power supply decoupling)
C7 not populated

I hope that clears it up for you.
  Reply With Quote
Old 29th July 2008, 03:52 PM   #18
sonidos is offline sonidos  United States
Libertador de la Msica
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
Brian,

Thanks for your patience and quick response to a noob building his first chip amp!
  Reply With Quote
Old 23rd August 2008, 05:08 PM   #19
vonfilm is offline vonfilm  United States
diyAudio Member
 
Join Date: Jun 2006
Brian,
Any idea when the 1875 manual will be up?
  Reply With Quote
Old 9th September 2008, 09:45 PM   #20
Frode is offline Frode  Norway
diyAudio Member
 
Join Date: May 2003
Location: Bergen
Very nice amp! Just finished mine and it sounds very nice. I've built it as the minimum configuration suggested by Brian.

Frode
  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
1st order Passive Line Level Crossover + 2nd order Highpass? alexclaber Multi-Way 11 4th January 2008 07:15 PM
deceptive perception ? 1st order-2nd order question poldus Multi-Way 4 10th April 2007 11:58 PM
My 1st order butterworth filter better than 4th order L-R: Why? philipreji Solid State 61 1st March 2007 04:50 PM
2nd Order Tweeter + 3rd Order Woofer = OK? Jay Multi-Way 3 12th September 2005 12:12 PM
1st order ? L-R 2nd order? or transient perfect?? Ken L Multi-Way 6 17th October 2003 04:22 PM


New To Site? Need Help?

All times are GMT. The time now is 06:02 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