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 19th February 2012, 11:10 PM   #11
nrg2009 is offline nrg2009  United States
diyAudio Member
 
Join Date: Apr 2009
Location: Detroit, born and raised in the netherlands.
This is big time, wow pretty nuts, but awesome.
  Reply With Quote
Old 19th February 2012, 11:41 PM   #12
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
with 4 mosfets on each you may need to paralel the imput J fets
What bias current you planning on ?
Papa said mentioned the hiher the beter they sound
the traffo and I am most probably wrong shuld give you about 11A (750 VA / 70 V )
1 A bias wuld dissipate 48W device well in the TO3P specs and the 4 amps is again prety close to Papa recomendation for the trafos

You be looking at about 380W dissipation on the sinks
I got same 300 X 400 X 83 (12 x 16 x 8 ) and I recon they are good enoug for 250 W

With the rails split between the 2 sinks that sems to be prety much a good fit.

Sems like you done a fair bit of thinking about it already
  Reply With Quote
Old 20th February 2012, 12:07 AM   #13
ungie is offline ungie  Canada
diyAudio Member
 
Join Date: Dec 2002
Location: Ontario, Canada
Quote:
Originally Posted by Bksabath View Post
with 4 mosfets on each you may need to paralel the imput J fets
What bias current you planning on ?
Papa said mentioned the hiher the beter they sound
the traffo and I am most probably wrong shuld give you about 11A (750 VA / 70 V )
1 A bias wuld dissipate 48W device well in the TO3P specs and the 4 amps is again prety close to Papa recomendation for the trafos

You be looking at about 380W dissipation on the sinks
I got same 300 X 400 X 83 (12 x 16 x 8 ) and I recon they are good enoug for 250 W

With the rails split between the 2 sinks that sems to be prety much a good fit.

Sems like you done a fair bit of thinking about it already
From Papa:

"The V3 schematic shows 4 pairs of output devices. Realistically you can
expect to get more than 100 watts rms Class A into 8 ohms and 200 watts
Class AB into 4 ohms. You are going to need some serious heat sinking, and
I suggest that the power supply of V2 would be appropriate for a single
channel. Peak output currents of 70 amps are expected but not guaranteed."

The cascoding of the input Jfets solves the challenge of higher rail voltages and is suitable for 4 pairs of output devices. As for the efficacy of the heatsinks I have, this will be determined once I get a board layout completed, have PCBs fabricated, and actually build one!
  Reply With Quote
Old 20th February 2012, 12:30 AM   #14
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
Tanks for that
and have a nice day
  Reply With Quote
Old 20th February 2012, 01:22 AM   #15
diyAudio Member
 
Join Date: Dec 2006
I also have 2 pairs of the 11" R-theta heatsinks and am hoping to do something along the lines of 50W per channel balanced monoblocks per the V3 layout.

For you guys who are fans of big PS capacitance, have you done blind tests to see if you can tell the difference? Say between the 100K uF on the pass circuit vs something like 200K uF? Or lower ESR caps vs higher ESR? I've often wondered how much of it is simply for the bad-a** factor, and although better in theory, isn't audible.

Austin
  Reply With Quote
Old 20th February 2012, 02:09 AM   #16
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
I cold not hear much difference with 100 150 and 200 K rails apart from riple reduction that cames with CRCRC instead of CRC

It wuld be much different if the capacitance was low for the load

say going from 20mU to 40mU as 20 will be definetly to low and 40 border line.

about esr I got a mix of eswa 63 V (cheap) and Rifa 40 V (Rifa) so cant realy say

If I build the 48 V the Rifa are going in the bin (sinfull waste)

I shuld have got 63 V Rifa to start with

With the caps is beter if you get a few hi voltagge ones and add when possible
insted of loads of low voltagge and have no use for them later.

If you need just a 50 w even standard balanced F5 will do

Not many have eard the turbo so far so you may compromise sound quality for power

How did you decide on the 50 W figure?

Last edited by Bksabath; 20th February 2012 at 02:14 AM.
  Reply With Quote
Old 20th February 2012, 02:41 AM   #17
nrg2009 is offline nrg2009  United States
diyAudio Member
 
Join Date: Apr 2009
Location: Detroit, born and raised in the netherlands.
I always struggle with finding the right enclosure/sink. It would be great to have some guidance on where to get affordable sinks/enclosures that are sized for the job. Someone brought up that they got good sinks from Antek on their ebay store. I like Antek toroids, so that might be a good option.
  Reply With Quote
Old 20th February 2012, 03:26 AM   #18
diyAudio Member
 
Join Date: Dec 2006
Quote:
Originally Posted by Bksabath View Post
I cold not hear much difference with 100 150 and 200 K rails apart from riple reduction that cames with CRCRC instead of CRC

It wuld be much different if the capacitance was low for the load

say going from 20mU to 40mU as 20 will be definetly to low and 40 border line.

about esr I got a mix of eswa 63 V (cheap) and Rifa 40 V (Rifa) so cant realy say

If I build the 48 V the Rifa are going in the bin (sinfull waste)

I shuld have got 63 V Rifa to start with

With the caps is beter if you get a few hi voltagge ones and add when possible
insted of loads of low voltagge and have no use for them later.

If you need just a 50 w even standard balanced F5 will do

Not many have eard the turbo so far so you may compromise sound quality for power

How did you decide on the 50 W figure?
Oh not for any rational scientific reason - partly because I already have enough heatsinking for 50wpc, and 25wpc monoblocks with that much heatsinking feels a bit underwhelming. Also, I'll be using them on my zaph sr71 speakers, which aren't the most efficient. My cheap 15W T-amp is fine for now in a small room but I'd feel better with the head room. I have been watching the F5X threads, but I'm guessing the F5T will start gaining more popularity and support over time, as I won't get around to starting assembly for another half a year or so.
  Reply With Quote
Old 20th February 2012, 03:42 AM   #19
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
Scientific reasons and math escape me (or me try to escape)

Yeah I wan't more power to.

There is an easy way to find out how much you need

Set the volume to party time (Uny dorm party time maybe not)

and then play low frequency sine at -12 dB mesure up with DM and multiply by 4
that is the max voltagge you will ask out of the amp F5 clip at 2 V from rails so a bit spare on top of that bit of mat give you the minimum rails voltagge from that the rest is post 12 but I am shure you have read Papa paper and don't need patronising old git to go over it a different way.

Pano started a tread about it on multy way and first few post are worth reading.

If you are planning to wait for 6 months by then F6 shuld be out and then it all change
If you got spare bits start with F5 well worth it.

F5turbo sound good on paper for now but does it sound better than F5 ?

Head room is big thing especialy if you listen to Classical
Not so big an issue with modern CD

Last edited by Bksabath; 20th February 2012 at 03:53 AM.
  Reply With Quote
Old 20th February 2012, 03:47 AM   #20
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
Quote:
Originally Posted by nrg2009 View Post
I always struggle with finding the right enclosure/sink. It would be great to have some guidance on where to get affordable sinks/enclosures that are sized for the job. Someone brought up that they got good sinks from Antek on their ebay store. I like Antek toroids, so that might be a good option.
If you are after same monster sinks gogle up Gorini SRL
They do up to 400 mm wide and can weld 2 or more togheter and cut to any leght

Price put to shame the rest but P&P is the killer
  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 Turbo is posted Nelson Pass Pass Labs 635 6th April 2014 10:51 AM
B1 builders thread Bas Horneman Pass Labs 694 25th February 2014 06:29 PM
F5 Turbo Circuit Boards chchyong89 Pass Labs 2327 8th January 2014 02:14 PM
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


New To Site? Need Help?

All times are GMT. The time now is 11:27 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