Standard Input Design Value - 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 23rd December 2010, 04:32 PM   #1
diyAudio Member
 
Troncones's Avatar
 
Join Date: Dec 2009
Location: Orange County, California.
Default Standard Input Design Value

Is there a standard Input Signal value to use when designing the gain stage?
__________________
The Myth: A hand full of Tubes, Caps, Resistors and Iron and you have an Amp. The Reality: You have self induced Dementia. Newbie.
  Reply With Quote
Old 23rd December 2010, 04:38 PM   #2
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
The gain stage of what? Context will be useful.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 23rd December 2010, 04:55 PM   #3
diyAudio Member
 
Troncones's Avatar
 
Join Date: Dec 2009
Location: Orange County, California.
Sorry, I quess that would help. In general any power amp that may be used with a CD Player, DAC, Reciever, Mp3 Player, PC, etc.

In detail I'm working on a SE 6BQ5 using a 6FQ7.
__________________
The Myth: A hand full of Tubes, Caps, Resistors and Iron and you have an Amp. The Reality: You have self induced Dementia. Newbie.
  Reply With Quote
Old 23rd December 2010, 04:57 PM   #4
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Generally, between 1 and 2V for full output is a good target.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 23rd December 2010, 05:06 PM   #5
diyAudio Member
 
Troncones's Avatar
 
Join Date: Dec 2009
Location: Orange County, California.
Are you talking P-P or rms?
__________________
The Myth: A hand full of Tubes, Caps, Resistors and Iron and you have an Amp. The Reality: You have self induced Dementia. Newbie.
  Reply With Quote
Old 23rd December 2010, 05:09 PM   #6
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
RMS.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 23rd December 2010, 05:14 PM   #7
diyAudio Member
 
Troncones's Avatar
 
Join Date: Dec 2009
Location: Orange County, California.
So it's normal to have an amp that with some souces you won't get full output. And with other sources you will over drive the grids and clip?
__________________
The Myth: A hand full of Tubes, Caps, Resistors and Iron and you have an Amp. The Reality: You have self induced Dementia. Newbie.
  Reply With Quote
Old 23rd December 2010, 05:16 PM   #8
LAJ is offline LAJ  United States
diyAudio Member
 
Join Date: Mar 2008
Location: Atlanta Ga. USA
Default Think in dB.

For microphones: -55dB (Although there is some variation in mics output level.
For consumer line: -10dB
For professional line: +4db

Personally I like 0 dB for line. And I would calibrate my VU meters to read 0dB to equal 0Vu. (Makes sense.)
The old Bell telephone standard was +8dB. (They wrote the book on audio level measurements.)
  Reply With Quote
Old 23rd December 2010, 05:34 PM   #9
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Quote:
Originally Posted by Troncones View Post
So it's normal to have an amp that with some souces you won't get full output. And with other sources you will over drive the grids and clip?
Not sure where you got the above impressions, there is always a gain controlling element ahead of the gain stages in a power amplifier whether that is an internal stepped attenuator, volume control pot or an external active or passive line stage.. (Or it could be the volume control in your iPod, Hifiman or whatever you choose.)

Generally you should design your power amplifier driver stage to provide sufficient gain to allow the lowest output source you use to achieve full output at something less than the highest setting on your volume control - this is to allow sufficient available gain such that you can achieve reasonable output levels with that source for any program material available.

The volume control ahead of this stage will provide sufficient attenuation to deal with signals that would otherwise overdrive the stage.

Note that providing more gain than is sufficient based on the above criteria usually results in some compromise of the signal to noise ratio so should be avoided if possible.

I use sources in my system that have maximum signal output levels of ~700mVrms to >3Vrms without any difficulty.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan

Last edited by kevinkr; 23rd December 2010 at 05:47 PM.
  Reply With Quote
Old 23rd December 2010, 05:44 PM   #10
diyAudio Member
 
artosalo's Avatar
 
Join Date: Feb 2010
Quote:
So it's normal to have an amp that with some souces you won't get full output. And with other sources you will over drive the grids and clip?
This problem can be avoided by using a real pre-amplifier.
To me pre-amplifier means such device that has several inputs with different kind of features.

There should be phono amplifier with RIAA correction. The sensitivity of such stage is typically few millivolts.

There should also be such inputs that drive the output stage full with, say 300 mV input signal.

There must also be inputs having sensitivity of about 1 to 2 V to be used with CD-players and similar-level signal sources.

Actually this input level ( 1 to 2 volts ) do not require any sort of pre-amplifier, only volume potentiometer between signal source and output amplifier.

However, it seems to me that very many pre-amplifier projects introduced here are such that both input- and output levels are from 1 to 2 volts.
I do not know what is the point to build such "amplifiers".
  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
How to design input stage with specific input impedance/pot value mahleriana Tubes / Valves 0 16th November 2009 09:37 PM
TL design Jordan vs standard conversation Coyote Full Range 0 3rd August 2009 12:01 AM
Need input on design kaffine Multi-Way 0 9th December 2003 11:54 PM
Standard wiring for 5-pin balanced input? paulb Parts 1 18th February 2002 11:10 PM
"Standard" EIC power input vs. Filtered EIC Eric Everything Else 16 18th May 2001 09:31 AM


New To Site? Need Help?

All times are GMT. The time now is 12:14 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