F5 Turbo Builders Thread - Page 354 - 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 23rd August 2014, 07:20 PM   #3531
BigE is offline BigE  Canada
diyAudio Member
 
Join Date: Aug 2008
Location: Toronto
Spikes on the output of the PSU or on the amp?

ZM,
I think the soft start he is referring to is the toroid, not a slow charge on the caps.
  Reply With Quote
Old 23rd August 2014, 07:28 PM   #3532
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
in any case -Egg needs to observe DC at cap bank in moment of mains soft start relay(s) energizing
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...Đ by Mighty ZM
  Reply With Quote
Old 23rd August 2014, 11:45 PM   #3533
SRMcGee is offline SRMcGee  United States
diyAudio Member
 
SRMcGee's Avatar
 
Join Date: May 2004
Location: Wynnewood, PA
Nash:

I suspect the hole sizes on the new F5T pcbs are the same as the version I used. To make a good connection using stranded 14 gauge wire, I cut away just enough of the strands to allow those that would fit through the holes to do so. The strands that were cut shorter were all cut to the same length, so they ended up "kissing" the top surface of the solder pad. I soldered the longer strands on the rear side of the pcb and added solder on the top side as well, so the shorter strands would be contained and connected to the solder pad.

Regards,
Scott
__________________
Good decisions are derived from experience; experience is derived from bad decisions.
  Reply With Quote
Old 26th August 2014, 02:13 AM   #3534
diyAudio Member
 
Join Date: Jul 2012
Quote:
Originally Posted by SRMcGee View Post
Nash:

I suspect the hole sizes on the new F5T pcbs are the same as the version I used. To make a good connection using stranded 14 gauge wire, I cut away just enough of the strands to allow those that would fit through the holes to do so. The strands that were cut shorter were all cut to the same length, so they ended up "kissing" the top surface of the solder pad. I soldered the longer strands on the rear side of the pcb and added solder on the top side as well, so the shorter strands would be contained and connected to the solder pad.

Regards,
Scott
Scott,

If you look at pics of the older version and the latest you can clearly see the reduction in hole size. In the version I believe you used, you could easily get 16AWG stranded wire in and with some trimming a 14AWG stranded as you have done. If this is incorrect please let me know. What is the version # silkscreened on your boards? In the latest version you can just about get a 18AWG stranded in. That is the problem. Otherwise the boards look good.

Any luck sorting out the "thinness" in sound you complained about?

Nash (Southern NJ)
  Reply With Quote
Old 26th August 2014, 10:28 PM   #3535
diyAudio Member
 
Join Date: Dec 2005
Location: Norway
hello folks
have some problems with my F5Turbo

having problems with offset and started to measure bias at the different 1R pairs by the output devices
Across PNP side
R17 and R18 365mV
R19 and R20 352mV

Across NPN side
R21 and R22 368mV
R23 and R24 344mV

Offset approx 5mV
Is this sign of badly matched output transistors or normal?

best
Leif
  Reply With Quote
Old 26th August 2014, 10:32 PM   #3536
6L6 is offline 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
Your bias readings are actually quite good - remember you are comparing N and P channel devices.

If your offset is stable at 0.005V (5mV) it's set very well!!

Is there any offset drift once the amplifier is power on for 45-60 minutes? If no, you are done. Connect speakers and enjoy!
  Reply With Quote
Old 26th August 2014, 10:41 PM   #3537
diyAudio Member
 
Join Date: Dec 2005
Location: Norway
it takes close to an hour to reach thermal stability and these bias readings
but what about the difference within the PNP and NPN devices?
arenīt they too big?
donīt like that offset starts way ahead (about 90mV) and creaps slowly down
not good for compression drivers (TAD4001 and 2001)
approx 33vdc supplied from choke input supply and 1kva 40vac powertransformer
best
Leif
  Reply With Quote
Old 26th August 2014, 11:13 PM   #3538
6L6 is offline 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
Quote:
Originally Posted by leifchristensen View Post
it takes close to an hour to reach thermal stability and these bias readings
That's about normal, the big amos take a while to get to thermal stability.

Quote:
but what about the difference within the PNP and NPN devices?
arenīt they too big?
No. In fact, your devices are quite close. Anyway, the N and P Vgs rarely, if ever, match

Quote:
donīt like that offset starts way ahead (about 90mV) and creeps slowly down
not good for compression drivers (TAD4001 and 2001)
... that's part of it being an F5. You may want to install a relay or switch on the output if you are concerned.
  Reply With Quote
Old 27th August 2014, 12:42 AM   #3539
diyAudio Member
 
Join Date: Mar 2014
Location: Berkeley, CA
I apologize in advance for being such a noob. I have been doing research and have read about 300 pages of this thread and am still confused on a bunch of things.

I was planning on building F5T V2 or V3 monoblocks, but am not sure which one is better suited for my needs. I am looking to get 100W class A into 8ohms.

First of all the Mosfets. The recommended FQA12P20/FQA19N20 seem to be very hard to find unless you want to risk buying them from china. Does anyone know where to source these? Then there are the Toshiba offerings (2SK1530/2SJ201) which because of their lower current ratings may or may not work, but are also very hard to find. Finally the ones that are still in production seem to be the FQP12P20/FQP19N20, IRFP9240/IRFP240. Which is recommended?
  Reply With Quote
Old 27th August 2014, 01:10 AM   #3540
6L6 is offline 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
Use the IRFP240/9240 The factory-build Pass amps are using them. If they are good enough for Papa, they are good enough for me.


You say you need 100W into 8R...

What kind of speakers do you have, how big is the room, what kind of music do you listen to, and (be honest) how loud do you like it?

And can your room deal with the heat from an amp that big?
  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 Circuit Boards chchyong89 Pass Labs 2363 27th September 2014 03:10 PM
B1 builders thread Bas Horneman Pass Labs 696 14th July 2014 01:57 PM
F5 Turbo is posted Nelson Pass Pass Labs 635 6th April 2014 11:51 AM
F5 turbo problems Rob Dingen Pass Labs 17 11th January 2013 09:38 PM
F5 Turbo ............. if only !!!!!! a.wayne Pass Labs 23 21st January 2012 03:24 AM


New To Site? Need Help?

All times are GMT. The time now is 10:04 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2