Linkwitz "Transform" Circuit Help - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 April 2008, 07:17 PM   #1
Shike is offline Shike  United States
diyAudio Member
 
Join Date: Jun 2007
Default Linkwitz "Transform" Circuit Help

Hey guys, I've been trying to build a linkwitz transform circuit and had a quick question. Are the grounds shown supposed to be connected to the RCA ground, a chasis ground, floating, or virtual?

Thanks for your time in advance,

-Andrew
  Reply With Quote
Old 2nd April 2008, 06:40 AM   #2
Shike is offline Shike  United States
diyAudio Member
 
Join Date: Jun 2007
Hey guys, sorry for the bump, but I really need to know what I'm doing wrong with this circuit.

The schematic can be found at:

ESP Project 71

Thanks
  Reply With Quote
Old 2nd April 2008, 06:52 AM   #3
diyAudio Member
 
Ouroboros's Avatar
 
Join Date: Dec 2003
Location: Nottingham UK
The schematic shows that the filter is running off +/-15V lines, so the so-called 'ground' is really the 0V of the amplifier. If you're putting this into a seperate box then the 'ground' of the circuit will be connected to the shield (outer) of the RCA plug.

How are you intending to power this circuit? You probably don't want the mains Ground/Earth to be connected to the 0V at this point to avoid injecting hum into the following power amp.
  Reply With Quote
Old 2nd April 2008, 07:10 AM   #4
Shike is offline Shike  United States
diyAudio Member
 
Join Date: Jun 2007
So far I am hooking the grounds to the RCA outer jacket and power with a regulated 15v wallwart.

Here's another question, would having a polarized C1 and C3 cause the circuit to break?
  Reply With Quote
Old 2nd April 2008, 08:33 AM   #5
diyAudio Member
 
Ouroboros's Avatar
 
Join Date: Dec 2003
Location: Nottingham UK
I wouldn't advise the use of non-polarised electrolytics in these positions. Have you downloaded John Murphy's Linkwitx Transform Excel spreadsheet from the True Audio site? This will allow you to play with scaling the values so you should be able to use ordinary film capacitors.
  Reply With Quote
Old 2nd April 2008, 08:57 AM   #6
Shike is offline Shike  United States
diyAudio Member
 
Join Date: Jun 2007
Yes, I've used the spreadsheet. In fact, everythings already put together it's just not working, thus the troubleshooting aspect right now which is driving me up the wall needless to say.

For C1 and C3 I have polarized electrolytics in place (shame on me). I need to know if they would somehow break the circuit though since it's showing the use of nonpolarised, because I've gone over everything else and it's the only thing I didn't really follow.
  Reply With Quote
Old 2nd April 2008, 09:12 AM   #7
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
C1 & C3 are shown in figs 2 & 3 as non polarised.
I would use a film cap for these. But I don't know what value you are using. non polarised electrolytics could be substituted but may reduce performance. I doubt that the signal levels on the polarised electros would cause them to break that quickly, but if you've used Tantalum then maybe they have failed quite quickly.

The input ground goes to signal shield. You must return the input signal from whence it came.
The output ground and the 10uF decoupling cap go to the power supply return. Again you must close that loop for current to flow.

The ground triangle symbol under the input is confusing, but I would take that to your audio ground star. If you do this, you must break the link between the GND symbols or you will create a hum loop.
It's the usual problem of calling everything "ground" when they all have a different purpose.
__________________
regards Andrew T.
  Reply With Quote
Old 2nd April 2008, 09:22 AM   #8
diyAudio Member
 
Frank Berry's Avatar
 
Join Date: Sep 2003
Location: Midland, Michigan
You're using a regulated 15 volt Wall Wart?
Is it a Bipolar supply?
The circuit needs + 15 volts and - 15 volts.
A single +15 volt supply won't work with this circuit.
__________________
Frank
  Reply With Quote
Old 2nd April 2008, 10:00 AM   #9
Shike is offline Shike  United States
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally posted by Frank Berry
You're using a regulated 15 volt Wall Wart?
Is it a Bipolar supply?
The circuit needs + 15 volts and - 15 volts.
A single +15 volt supply won't work with this circuit.
Well, seems I probably just found my largest problem.

What the cheapest way about going to make a 15V Bipolar supply?
  Reply With Quote
Old 2nd April 2008, 10:11 AM   #10
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
go back to ESP and read
__________________
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
Linkwitz Transform Circuit skogs Subwoofers 1 26th October 2006 11:03 PM
Dayton RS HiFi 12" Sub using Linkwitz Transform EQ--Design Proposal dfdye Subwoofers 23 24th January 2006 01:18 PM
Linkwitz transform circuit? Dxvideo Subwoofers 5 30th August 2005 02:20 PM
linkwitz transform circuit pkgum Multi-Way 8 14th December 2001 12:08 PM
Variable Linkwitz Transform Circuit? Ignite Solid State 8 28th November 2001 05:17 AM


New To Site? Need Help?

All times are GMT. The time now is 07:13 AM.


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