Line output transformer question - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 29th April 2009, 03:59 AM   #1
pftrvlr is offline pftrvlr  United States
diyAudio Member
 
Join Date: Feb 2007
Location: SoCal
Default Line output transformer question

I am building a tube mic preamp with a 12au7 SRPP output. I am planning to use a 1:1 turn ratio line out transformer. I feel that I should get one with 10K:10K impedence ratio, but will a 600:600 also OK for this application?

How is the impedence of a transformer determined? Thought it is determined by the actual load impedence, right?
  Reply With Quote
Old 29th April 2009, 05:28 AM   #2
diyAudio Member
 
dsavitsk's Avatar
 
Join Date: Jan 2005
Location: Hartford
Default Re: Line output transformer question

Quote:
Originally posted by pftrvlr
I am building a tube mic preamp with a 12au7 SRPP output. I am planning to use a 1:1 turn ratio line out transformer.
Why? I am all in favor of transformers, but this is one place that it doesn't make much sense.
  Reply With Quote
Old 29th April 2009, 05:38 AM   #3
pftrvlr is offline pftrvlr  United States
diyAudio Member
 
Join Date: Feb 2007
Location: SoCal
Default Re: Re: Line output transformer question

Quote:
Originally posted by dsavitsk


Why? I am all in favor of transformers, but this is one place that it doesn't make much sense.
Why not? Gyraf mic preamp uses a 2:1 transformer in the output.
  Reply With Quote
Old 29th April 2009, 07:43 AM   #4
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Default Re: Line output transformer question

Quote:
Originally posted by pftrvlr

How is the impedence of a transformer determined?

By the primary inductance.

What is this transformer going to actually do?
  Reply With Quote
Old 29th April 2009, 09:29 AM   #5
diyAudio Member
 
dsavitsk's Avatar
 
Join Date: Jan 2005
Location: Hartford
Default Re: Re: Re: Line output transformer question

Quote:
Originally posted by pftrvlr
Why not? Gyraf mic preamp uses a 2:1 transformer in the output.
A 2:1 gets you better current drive, lower Zout, and less gain. A 1:1 gets you an expensive part and higher distortion for your trouble.
  Reply With Quote
Old 29th April 2009, 10:08 AM   #6
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
Default Re: Line output transformer question

Quote:
Originally posted by pftrvlr
I am building a tube mic preamp with a 12au7 SRPP output. I am planning to use a 1:1 turn ratio line out transformer. I feel that I should get one with 10K:10K impedance ratio, but will a 600:600 also OK for this application?

How is the impedance of a transformer determined? Thought it is determined by the actual load impedance, right?
they are not the same, the 10k line traffo will handle substantialy more voltage than a 600 ohm one...ohm's law is right at work here..

while the two will have the same turns ratio, the 10k one will have about 4 more turns than the one turn of the 600ohm ones...
  Reply With Quote
Old 29th April 2009, 08:17 PM   #7
pftrvlr is offline pftrvlr  United States
diyAudio Member
 
Join Date: Feb 2007
Location: SoCal
The transformer will generate balance output to feed into a DAC for recording. I assume the input impedence of the DAC pretty high. Think 10K load is what the mic preamp will see?

I may just get a few of different transformers and see how they all play out.
  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
line output transformer help milen007 Tubes / Valves 8 17th April 2009 03:03 AM
PCB mount line input transformer question audiowize Tubes / Valves 0 11th July 2008 07:05 PM
Line output as line input transformer? bambadoo Tubes / Valves 7 22nd January 2008 06:44 AM
Transformer hook-up question to 115V AC line Joseph0 Tubes / Valves 10 19th August 2005 02:00 PM
Line Output Transformer needs schema Ralph Tubes / Valves 8 17th July 2002 04:17 PM


New To Site? Need Help?

All times are GMT. The time now is 12:36 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