F5 power amplifier - Page 1093 - 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 27th August 2011, 05:18 AM   #10921
diyAudio Member
 
Join Date: Dec 2009
Location: West Coast
Default Re: Thermistors TH1 and TH2; Gate Resistors R13 & R14

A May 2008 6Moons review of the F5 shows a few pics of the amp interior. It appears that TH1 and TH2 are 2K2 (4K7 on the schematic), and R13 and R14 are 150R (47R on the schematic). Anyone know why the deviation?
  Reply With Quote
Old 27th August 2011, 10:45 PM   #10922
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
ClothEar

Realy interesting question

There is quite a bit I also do not know and get blown away by post such as Papa mention of P3 and post 10855 SCH show quite a few values changes

Such as 0.68 source resistors and 10 to 1 relationship on the Imput resistors R13/R14 are100 homs in that one and few conection are different as well as the thermistors are after R7/R8



Papa said that almost any change would efect the way the F5 sound.

I have tried P3 and left it out after blowing a couple of mosfets as Bias got realy hi even with a 10 turn pot and very small turn on it.

I have to finish off a second channell with Cascode and 2 paralel J fets as mentioned in another post before I can post my listening impressions on that change.
So far I can say that the first channel on which I made the change sems to have less distorsion and lover gain but this is based purely in what I can ear as my knolledge of electronics is wery limited.

As I am etching my own boards is quite easy for me to put a few extra pads in and try things out.

But like you I would realy apreciate if we could get same pointers on the caracter of those "small" changes
  Reply With Quote
Old 28th August 2011, 02:58 AM   #10923
diyAudio Member
 
Join Date: Feb 2005
Hi Huseyin,

One thing I would do is find some discrete diodes (fast, soft recovery types) and discard those KBP block bridges that do add a definite "edge" to the sound that's nearly impossible to get rid of.

I assume there are 4 Kendeils 47,000uF caps? What are the black 470uF/200 Daewoo caps for?


If you're going to mount the power fets to the top flat bar that's holding the 2 seperate heatsinks together, there is quite a bit of added thermal resistance between the plate and the heatsink - suggest using a smaller bar, or angle bracket, to hold the top and bottom edges of the heatsinks together and fasten o/p fets to heatsinks directly - more efficient and simpler.
Also, the angle bracket can be used to mount the bottom and top covers.

... just my 2 cents.
__________________
... jh
  Reply With Quote
Old 28th August 2011, 04:28 AM   #10924
dnewman is offline dnewman  United States
diyAudio Member
 
Join Date: Jan 2007
Quote:
Originally Posted by Nelson Pass View Post
Hasn't this been around?

Are Q3 & Q4 still being biased at 1.3 amps in this revised F5 circuit (F5 Amplifier R1; 7/30/2008)? Am asking as that answers the question as to what voltage drops to look for across R7 & R8 when adjusting P1 & P2. (1.3 A * 0.68 Ohms = 0.88 V)

Thanks
  Reply With Quote
Old 28th August 2011, 05:41 AM   #10925
diyAudio Member
 
Join Date: Dec 2009
Location: West Coast
Bksabath: thank you for pointing out the R1 schematic.
  Reply With Quote
Old 28th August 2011, 08:50 AM   #10926
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
ClothEar you welcome.
dnewman
About R7 R8 I have tried 0.22 Homs Futabas MPC 74 with Paralell Toshibas as I was biasing each at over 2 A and the 0.47 Where a bit hot, sound wise all was fine (IMO I like farchild sound better).

I am not going in the math for it as there are much better "professors" around here but I would wach out for the power rating of those.

Last edited by Bksabath; 28th August 2011 at 09:04 AM.
  Reply With Quote
Old 28th August 2011, 11:51 PM   #10927
diyAudio Member
 
Join Date: Jan 2008
Location: İstanbul/Turkey
Send a message via MSN to huseying
Quote:
Originally Posted by jameshillj View Post
Hi Huseyin,

One thing I would do is find some discrete diodes (fast, soft recovery types) and discard those KBP block bridges that do add a definite "edge" to the sound that's nearly impossible to get rid of.

I assume there are 4 Kendeils 47,000uF caps? What are the black 470uF/200 Daewoo caps for?


If you're going to mount the power fets to the top flat bar that's holding the 2 seperate heatsinks together, there is quite a bit of added thermal resistance between the plate and the heatsink - suggest using a smaller bar, or angle bracket, to hold the top and bottom edges of the heatsinks together and fasten o/p fets to heatsinks directly - more efficient and simpler.
Also, the angle bracket can be used to mount the bottom and top covers.

... just my 2 cents.
Thanx jameshillj.
I think the fast diodes will be better.
I just have 2 kendeils,but ı can add the 10,000uf caps,I put the black caps instead of 4700uf 25v by mistake.
yes I'll mount the outp. fets as you first said.

I'll keep in touch the forum on my project.
__________________
My ebay tube store
http://www.ebay.com/usr/hgungor10
  Reply With Quote
Old 29th August 2011, 01:23 AM   #10928
diyAudio Member
 
umut1001's Avatar
 
Join Date: Mar 2007
Location: Istanbul
I have a lot of BYT56G and BYV36C.Where can they be used for?Maybe in a preamp of F5?Thx
__________________
My New and vintage capacitor store: http://stores.ebay.com/Paradise-of-H...dio-components
  Reply With Quote
Old 29th August 2011, 01:37 AM   #10929
diyAudio Member
 
metal's Avatar
 
Join Date: Jan 2004
In tube preamp PSUs.
  Reply With Quote
Old 5th September 2011, 10:58 AM   #10930
diyAudio Member
 
Join Date: Aug 2009
Quote:
Originally Posted by Nelson Pass View Post
Hasn't this been around?


Hi,
I'm a long time lurker who's just finished reading this thread and I'm putting the finishing touches on my first F5 build. I have a little confusion to clear up before I put the "firstwatt" to my build.

My build is on Peter Daniel's version of the PCBs and I bought the bits and pieces from TechDIY as "F5 kits". The Peter Daniel's board follows the original schematic, but the TechDIY kit is for the "R1" version. It was no problem to put a couple jumpers to modify the Peter Daniels board to follow the "R1" schematic and then install my "R1" parts kits.
Click the image to open in full size.Click the image to open in full size.
Two questions before I risk some smoke.
What is the function of R1 (4.7k) on the new (left side) schematic ? The input resistor divider R9-R10 of the original (right side) schematic has changed in the new drawing. Should I jumper my board to match the new "R1" schematic for the connections of R1 (4.7k signal input resistor) ? I'm not understanding what current flows through R1 as drawn and what it's function is ?

I'm guessing the only difference in the initial set up of the original and "R1" version is to center (measure) the P3 pot prior to power on ? Any other caveats ? Is P3 useful for anything other than changing the harmonic distortion distribution ?

Thanks for any advice, and thanks especially to NP for the design and all the regulars for this entertaining thread, even though it is a bit long. It has been kind of like a long novel with a surprise twist to the ending. The new "R1" version schematic cleared up all kinds of "WTF" on my part, as I compared my boards to my parts kits and read the first thousand pages or so.
  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
Rockford Fosgate Power 20001 bd amplifier power rating?? pachoorion Car Audio 8 8th May 2011 10:49 PM
Power transformers versus amplifier output power..what is your option? destroyer X Solid State 38 9th May 2009 05:23 PM
McIntosh Power Amplifier Power Guard johnnyrt Solid State 2 23rd August 2007 10:22 PM
Output power for a power amplifier Progg70 Solid State 33 10th September 2006 08:44 AM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 04:06 PM


New To Site? Need Help?

All times are GMT. The time now is 09:15 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