F6 Amplifier - Page 336 - 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 19th December 2012, 05:41 PM   #3351
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
dont you need a cap on secondary connection to prevent DC
__________________
...Shape the sound , Man!
  Reply With Quote
Old 19th December 2012, 05:54 PM   #3352
DougL is offline DougL  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Wheaton IL.
Blog Entries: 30
The FET's are going to be in the Meg Ohm range, and there is no other path through the secondaries. So it isn't going to bother the transformer, if thats your concern.

It may be useful to have the upper JFET with an adjustable bias and AC coupled to the output, but I don't feel its necessary for operation.
__________________
Scienta sine ars nihil est - Science without Art is nothing. (Implies the converse as well)
Mater tua criceta fuit, et pater tuo redoluit bacarum sambucus
  Reply With Quote
Old 19th December 2012, 06:05 PM   #3353
flg is offline flg  United States
diyAudio Member
 
flg's Avatar
 
Join Date: Jul 2005
Location: North East
I think R1,2 and 3 and R1,2 and 3 need to be about 1 ohm not 2 ohm! And, that +23v on the top, needs to be about +60V Of coarse you will need the appropriately sized sinks...
Otherwise, I like it!
__________________
"It was the perfect high end audio product: Exotic, inefficient, expensive, unavailable, and toxic." N.P.
  Reply With Quote
Old 19th December 2012, 07:10 PM   #3354
DougL is offline DougL  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Wheaton IL.
Blog Entries: 30
Fig,
Can you explain why does the Vcc need to be +60?
In the F3, the extra voltage was there to bias the active load.

Doug
__________________
Scienta sine ars nihil est - Science without Art is nothing. (Implies the converse as well)
Mater tua criceta fuit, et pater tuo redoluit bacarum sambucus
  Reply With Quote
Old 19th December 2012, 07:13 PM   #3355
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I like your sig and Monty python.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 19th December 2012, 07:40 PM   #3356
flg is offline flg  United States
diyAudio Member
 
flg's Avatar
 
Join Date: Jul 2005
Location: North East
More Vcc allows for more output voltage. More Iq allows for more output current
Gain might even increase slightly so you have the option of lowering F.B.
__________________
"It was the perfect high end audio product: Exotic, inefficient, expensive, unavailable, and toxic." N.P.
  Reply With Quote
Old 19th December 2012, 09:10 PM   #3357
DougL is offline DougL  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Wheaton IL.
Blog Entries: 30
More is better!

With the Cascode, it shouldn't change much.
__________________
Scienta sine ars nihil est - Science without Art is nothing. (Implies the converse as well)
Mater tua criceta fuit, et pater tuo redoluit bacarum sambucus
  Reply With Quote
Old 19th December 2012, 09:14 PM   #3358
diyAudio Member
 
Join Date: Jan 2012
Location: Pennsylvania
Blog Entries: 1
Quote:
Originally Posted by DougL View Post
Fig,
Can you explain why does the Vcc need to be +60?
In the F3, the extra voltage was there to bias the active load.

Doug
DougL: Please refer to the upper cascode circuit. The idle voltage between the drain and gate of IRFP240 is Vdg ~16 Vdc. Suppose that a positive output signal peaks at 11 V. This transient state leaves a dynamic Vdg ~ 5V; which I am tentatively assuming to be needed for the proper operation of this MOSFET. The expected output power under this proposed condition is ~8 W(rms) into 8 Ohms. I reiterated in other words the response of flg above.

Best regards.
  Reply With Quote
Old 19th December 2012, 09:56 PM   #3359
DougL is offline DougL  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Wheaton IL.
Blog Entries: 30
Antoinel,

Thanks for the explanation.

I am going to have to think about this some more.
Sounds like other topologies are more cascode suitable.
__________________
Scienta sine ars nihil est - Science without Art is nothing. (Implies the converse as well)
Mater tua criceta fuit, et pater tuo redoluit bacarum sambucus
  Reply With Quote
Old 20th December 2012, 12:29 AM   #3360
diyAudio Member
 
Join Date: Jan 2012
Location: Pennsylvania
Blog Entries: 1
Quote:
Originally Posted by DougL View Post
Antoinel,

Thanks for the explanation.

I am going to have to think about this some more.
Sounds like other topologies are more cascode suitable.
DougL, you are welcome. Your schematic is a functional design; noting that nobody complained about its topology. Suppose that the power rails you wish to use are +/-30 Vdc [flg] instead of +/-23 Vdc. The output voltage may then swing 36 Vp-p into an 8 Ohm load for an output power of ~20 W(rms). Please recall what Mr. Pass wrote in his F6 article [and his demo on the scope] that 1 Watt can be fully adequate with a sensistive loudspeaker; maybe of 93 dB SPL.

Best regards.

N.B. Will a darlington instead of a MOSFET be suitable? One may be able to getaway with a Vcb ~1.2 Vdc for more output power with lower power rails.
  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
New F6 diy coming soon ? Nounours18200 Pass Labs 37 31st August 2012 04:35 PM
Hi Vi F6 box ioro Multi-Way 4 15th April 2012 08:27 PM
Whats happening with F6? jugoslavija Pass Labs 1 1st November 2011 07:39 AM
Hi-Vi F6 kkosiba Multi-Way 14 9th November 2007 08:38 AM
F6 traw Pass Labs 7 2nd November 2007 07:09 PM


New To Site? Need Help?

All times are GMT. The time now is 03:15 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