F5 Turbo Circuit Boards - Page 91 - 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 3rd March 2012, 09:23 PM   #901
diyAudio Member
 
Join Date: Sep 2006
Location: Santa Rosa Beach, FL
Guys, as someone who's DIY for cases, it's really not that difficult.

The on-going debate is "right on the mark". For an amp with two (left-side and right-side) heatsinks, it's easiest to allow the heatsink dimensions determine the size (depth and height) of the case. Once the heatsink dimensions are known, aluminum sheet/plate can be cut for the base plate, top plate, rear apron and front panel (four pieces). A metal shop with a good metal shear can cut these to size, only for the cost of materials and a "cut charge". We all should be able to drill the holes for the "small stuff" like binding posts, RCA jacks, panel switches. (Admitedly, drilling and tapping blind machine threads into an expensive heatsink can be a little nerve-racking.) A good "water jet" metal shop can cut larger or more exotic shapes like chassis vents, IEC outlet holes, fans, etc, etc. Other shops (like Front Panel Express) can do engraving, if you desire....and shops that do powder coat or anodizing should not be that far away (or are accessible through UPS, FEDEX, and other mail services).

My amp cases are home made, typically using 1/8" or 3/16" T-6061 aluminum.
No reason why you can't DIY a case that looks as good as a commerical unit, and to the specific design you want.

If we GB PCBs, components, transformers, and cases--then aren't we really just putting a "kit" together? (...... in sucn an instance, aren't we becoming KiyAudio'ers, and not DIY'ers?....)
Attached Images
File Type: jpg 105.JPG (43.7 KB, 372 views)
File Type: jpg 114.JPG (52.9 KB, 374 views)
File Type: jpg DSC02751.jpg (327.8 KB, 381 views)
File Type: jpg DSC02763.jpg (312.5 KB, 371 views)
  Reply With Quote
Old 3rd March 2012, 09:25 PM   #902
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally Posted by lhquam View Post
The amp does not stay in class A when the diodes are active unless the bias current is greater than 1/2 the current at which the diodes are active.
Now that is what i call an aenigma.

And which current would that be ?
__________________
The buck stops Here
  Reply With Quote
Old 3rd March 2012, 09:26 PM   #903
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally Posted by Tea-Bag View Post
simple and easy
s = source resistor
d = common cathode diode
I = current
V= voltage drop between rail and source

It = I(total) = Is +Id
Vs = Rs * Is
Vd = Vdrop = Rd * Id (Rd = dV/dI)

No1 condition : V = Vs = Vd

=> Rs * Is = Rd * Id = Vd (Vd = 0.5 * Is)
=> Rs/Rd = Id/Is
=> Rd = 0.5 (It/Id - 1)

If It goes up, Vd goes up. (or as Vd goes up, It goes up)
When Vd goes up, Rd drops, Id goes up => Rs/Rd goes down, Id/Is goes down.

You should have driven this car : Variomatic - Wikipedia, the free encyclopedia

Between source resistor only and full diode open, there's a smooth transition phase with proper diodes.
Which is what the nfb can track.

[equivalent resistance diode : dV/dI. Between 0.8V and 0.5V : (0.8V -0.5V)/10 = 0.3/10 = 0.03 Ohm ]
__________________
The buck stops Here

Last edited by jacco vermeulen; 3rd March 2012 at 09:35 PM.
  Reply With Quote
Old 3rd March 2012, 09:54 PM   #904
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally Posted by NYCOne View Post
with Fets you get an output stage that will deliver more Class A power at a given bias figure due to the square law character of the Fets."
Square law character means that one goes open further than the other closes.

square 2 = 4
square root 2 = 1.41
source resistors linearise.
__________________
The buck stops Here
  Reply With Quote
Old 3rd March 2012, 09:59 PM   #905
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
Quote:
Originally Posted by jacco vermeulen View Post
s = source resistor
d = common cathode diode
I = current
V= voltage drop between rail and source

It = I(total) = Is +Id
Vs = Rs * Is
Vd = Vdrop = Rd * Id (Rd = dV/dI)

No1 condition : V = Vs = Vd

=> Rs * Is = Rd * Id = Vd (Vd = 0.5 * Is)
=> Rs/Rd = Id/Is
=> Rd = 0.5 (It/Id - 1)

If It goes up, Vd goes up. (or as Vd goes up, It goes up)
When Vd goes up, Rd drops, Id goes up => Rs/Rd goes down, Id/Is goes down.

You should have driven this car : Variomatic - Wikipedia, the free encyclopedia

Between source resistor only and full diode open, there's a smooth transition phase with proper diodes.
Which is what the nfb can track.

[equivalent resistance diode : dV/dI. Between 0.8V and 0.5V : (0.8V -0.5V)/10 = 0.3/10 = 0.03 Ohm ]
Dutchie ....So with diode the best way ...? if so why not this way before ...?
  Reply With Quote
Old 3rd March 2012, 10:06 PM   #906
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
Quote:
Originally Posted by Geofd View Post
Yes I agree that the units has a number of parts that are heavy, the only thing i wont have is the chokes,
I got a couple of kilos (that is how they sell it) of 2mm cooper made a cuple of coils an went that way next time I will try same again but wind them as comon mode (1 coil 2 wires side by side)



work quite well as CRCLC
Attached Images
File Type: jpg FAIR F5boards 007.jpg (607.3 KB, 361 views)

Last edited by Bksabath; 3rd March 2012 at 10:09 PM.
  Reply With Quote
Old 3rd March 2012, 10:16 PM   #907
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by Tea-Bag View Post
So still high bias rules the day.
So I go back to my Balanced Cascoded F5. 16V rails and high bias. Lots of Class A. I'm not sure why one would chase high rail voltages instead of high current.
  Reply With Quote
Old 3rd March 2012, 10:26 PM   #908
diyAudio Member
 
bobodioulasso's Avatar
 
Join Date: May 2008
Quote:
Originally Posted by lhquam View Post
The amp does not stay in class A when the diodes are active unless the bias current is greater than 1/2 the current at which the diodes are active.
If now i understand "more classA for a given bias" I still do not get what you are stating.
  Reply With Quote
Old 3rd March 2012, 10:42 PM   #909
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally Posted by a.wayne View Post
why not this way
Push-Pull Class AB is a way to get more power per lb, also with tricks as (feed-forward) EC or TMC, is it the best way or a practical way ?

For me just fun, i get bored easily.
__________________
The buck stops Here
  Reply With Quote
Old 4th March 2012, 12:05 AM   #910
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
Quote:
Originally Posted by jacco vermeulen View Post
Push-Pull Class AB is a way to get more power per lb, also with tricks as (feed-forward) EC or TMC, is it the best way or a practical way ?

For me just fun, i get bored easily.
Dutchie ,

i'm going for 600-800b watts @1 ohm(28volt trans) and will run as much class-a bias as necessary for best sound. As you i'm using 50 watts/8ohm class-a to start with , if more sound better, then up, if going lower still sounds good then lower ...

Since I also plan to use somtimes on 8-4 ohm speakers 50 watt class-a might be the magic number ...

Should i keep the diodes ...?

Last edited by a.wayne; 4th March 2012 at 12:08 AM.
  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
F5 clone boards (inc PSU boards) Tazzz Swap Meet 39 7th June 2014 07:02 AM
F5 Turbo is posted Nelson Pass Pass Labs 635 6th April 2014 10:51 AM
F5 turbo problems Rob Dingen Pass Labs 17 11th January 2013 08:38 PM
F5 Turbo ............. if only !!!!!! a.wayne Pass Labs 23 21st January 2012 02:24 AM
UGS Boards and F5 boards DUC985 Swap Meet 0 7th January 2009 07:21 PM


New To Site? Need Help?

All times are GMT. The time now is 03:50 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