Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 26th July 2011, 07:04 PM   #1
diyAudio Member
Join Date: Jun 2011
Location: SCOTLAND

I am about to carry out the usual updating of a Quad 34 preamp and wish to customise the tape input for use with the I/V transformer in my DAC.
The transformer secondary has a dc resistance of 900r and an impedance of 5K.

I intend to directly couple this to the non- inverting input of the buffer opamp and change the input resistor which is currently 10K. (ie removing the input cap and series resistor)

Am I correct in thinking that 5K is the optimum value - ie equal to the transformer output impedance?

I can't decide which op amp to use in place of the existing TL072 - a biploar NE5532 or a FET OPA2134. In view of the low impedances, might the NE5532 be better choice?
  Reply With Quote
Old 26th July 2011, 07:29 PM   #2
kevinkr is offline kevinkr  United States
diyAudio Moderator
kevinkr's Avatar
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Consider the LM4562, but do look for signs of oscillation on the output of any op-amp you swap in there. The TL072 is very forgiving of layout issues compared to many more modern devices and also has rather good EMI resistance as well.

You may need to experiment with loading on the secondary of the transformer to find the optimum load to reflect back to the DAC..
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote


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
Impedance matching taeedy Chip Amps 5 25th February 2011 08:30 PM
Impedance matching transformer rhapsodee Pass Labs 15 18th January 2009 11:02 AM
Impedance matching Triod lover Tubes / Valves 2 12th January 2007 09:59 AM
Need help understanding transformer impedance ratios and impedance matching percy Tubes / Valves 5 28th February 2005 08:35 PM
winding impedance matching transformer bbksv Solid State 8 7th March 2004 08:57 PM

New To Site? Need Help?

All times are GMT. The time now is 05:09 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2