D1 to drive an F4 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 16th June 2011, 07:08 AM   #1
diyAudio Member
 
oon_the_kid's Avatar
 
Join Date: May 2008
Location: Singapore
Default D1 to drive an F4

Hi,

I am wondering if it might be possible to modify the D1 to directly drive an F4. I kinda like the idea that I/V conversion is done on a resistor. At the moment I think the output is approximately aproximately 3Vp-p on a +/- 1mA input. I was thinking of increasing the supply voltage to +-60V or more. Use a 15K ohm resistor, to have a higher gain. Reduce the bias current to 2mA by increasing the 3.3K resistor to about 16K. Should be able to achieve achieve a voltage swing of 30Vp-p on a +/- 1mA. This should be high enough an F4.

I would like to hear your comments on what you think of such a modification.

Thanks.

Oon
  Reply With Quote
Old 16th June 2011, 11:28 AM   #2
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
2mA of bias is good for ..... phono stage ?
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 16th June 2011, 09:37 PM   #3
Itsmee is offline Itsmee  England
diyAudio Member
 
Itsmee's Avatar
 
Join Date: Feb 2009
Quote:
Originally Posted by oon_the_kid View Post
Hi,

I am wondering if it might be possible to modify the D1 to directly drive an F4.
Oon
I like the idea. I haven't checked your proposed mods for the D1, but if it works, 2mA would be technically enough, although i would be tempted to increase it to a minimum of 10mA and replace the 47K in the F4 with 100k.
  Reply With Quote
Old 17th June 2011, 01:10 AM   #4
diyAudio Member
 
oon_the_kid's Avatar
 
Join Date: May 2008
Location: Singapore
Quote:
Originally Posted by Itsmee View Post
I like the idea. I haven't checked your proposed mods for the D1, but if it works, 2mA would be technically enough, although i would be tempted to increase it to a minimum of 10mA and replace the 47K in the F4 with 100k.
Well the issue with the circuit is this. While the AC current signal actually forms a out voltage across the resistor (1.5K), so does the DC signal. So if you multiply the 10mA across 1.5K, it would form 15Volts below positive rail (30V) which will be quite nice. Giving it good headroom for the voltage swing (since the voltage cannot swing below the intended Iout ). So if you want to increase the gain, it can be achieved by increasing the resistance, you need to deal with the DC part as well which means you would need to decrease the bias current or raise the supply voltage or both.... alternatively get a DAC with very high Iout, or parellel a few DAC chips...

So hence for my case I increased the resistance 10X, doubled the supply voltage, reduce bias current 5X to compensate for it. And I would definitely like to replace the resistor at F4 with 200K or so (need to account for the volume pot in between). On a different note, if we were to use the buffer stage in the D1 circuit, we could bypass the first stage of F4 or if we use the first stage of F4, we could bypass the buffer of the D1.

BTW, this has to do with my other posting on power DACs on this forum...

Oon
  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
WTB : Direct Drive Standalone TT Drive Razorblade Swap Meet 0 2nd January 2011 05:22 PM
D1 dac, D1v3, Pass D1 with jFET IV tritosine Swap Meet 0 19th May 2010 03:41 PM
Help to choose a Pre-amp to drive F4 fastvideo Solid State 1 3rd April 2009 12:36 PM
mix current drive with voltage drive at LF? capslock Multi-Way 0 27th April 2006 10:17 AM
Computer Question-Any Problems Transferring Office 97 From D Drive to C Drive kelticwizard Everything Else 12 22nd January 2003 03:34 AM


New To Site? Need Help?

All times are GMT. The time now is 12:59 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