F5 power amplifier - Page 119 - 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 13th June 2008, 02:32 PM   #1181
diyAudio Member
 
despotic931's Avatar
 
Join Date: Jan 2008
Send a message via AIM to despotic931
Quote:
Originally posted by defect9



you can build most of the power supply on the terminals of the caps. Literally lay it out like you see in the PS schematics (which are in the user manual for the F5, available at firstwatt.com in the product section)

I find power supplies easier to build than almost any other part of amps, so I'll pop in and do whatever I can to help you.

-Jared

Hehe, I'm not scared of building the PS from scratch (hence the rolley eyed smiley), but I'll admit I've never done it.

Thanks for the offer to help Jared, I'm sure we will be having many a conversation on here.

I've read everything there is to read on PassDIY and FirstWatt, but there are some concepts that still escape me. I can solder pretty good, and can stumble my way through a schematic alright, but things like matching fets and setting biases I'm not to keen on. Either way this will be fun (as long as you guys don't kick me out of the forum first for asking too many stupid questions down the road... )

-Justin
  Reply With Quote
Old 13th June 2008, 03:12 PM   #1182
DaveM is offline DaveM  United States
diyAudio Member
 
DaveM's Avatar
 
Join Date: Feb 2003
Location: Vermont
There are no stupid questions, only stupid people. Those not smart enough to ask questions when they need help would qualify if you ask me. The only way to find out how to do it is to jump in and try. If you can solder and read a schematic, you can build these amps. When you get stuck, ask. I used to call myself "and electrical idiot". I now have 6 functional Pass DIY projects at home. All are awaiting enclosures. I have a Bridgeport and lathe and full wood shop, so no excuse other than I would rather build circuits. I think I am addicted to building electronics.

Jump in, the water is fine.
  Reply With Quote
Old 13th June 2008, 04:48 PM   #1183
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
Default Re: Lost in Sarcasm

Quote:
Originally posted by vdi_nenna
You know I was kidding?
Of course not, i asked a second opinion.

Naah, just kidding, i can still remember your amp project from a couple of years ago.
Attached Images
File Type: jpg fozzie.jpg (39.6 KB, 3629 views)
__________________
No More Mr Nice Guy
  Reply With Quote
Old 13th June 2008, 09:15 PM   #1184
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
I had a second look at Tino's balanced circuit :

http://www.diyaudio.com/forums/showt...77#post1485677

Suppose we only connect R1 ro R12 directly but without connecting to R2 or R11, and then for R2 directly to R11 without connecting to R1 or R12, would that not be an X-Topology ?


Patrick
  Reply With Quote
Old 14th June 2008, 02:07 AM   #1185
KSTR is offline KSTR  Germany
diyAudio Member
 
KSTR's Avatar
 
Join Date: Jul 2007
Location: Central Berlin, Germany
Patrick,

I'd say no, at least along the lines of the SuSy patent we need inverting gain stages, having positive inputs too (if you think opamp-style), which are coupled together then to form the SuSy config.

One can rearrange the F5 to inverting config (mirroring the front-end currents to the opposite rail) and in fact I successfully tried that in simulation (with my BJT front-end variant), but I was unable to modify it into a SuSy config which would actually improve things over the simple bridge. But I didn't try too hard and maybe missed something important...


TimS' variant of a cross-coupled bridged F5 is quite nice I have to say, I simmed it (both JFET and BJT variants) and due to the cross coupling it also works well with unbalanced inputs (unlike a simple bridge). There is only some loss in headroom, but distortion performance doesn't seem to be affected.


BTW (and to those who have built/measured the circuit -- including Nelson), I seem to have found a potential stability problem with very capacitive speaker cables (say, several nanofarads). The overshoot seems to reach some scaring tens of dB's, much more than the slight rise that is there with plain resistive load (as reported, also in accordance to my sims). Jackinnj has proposed parallel caps to the feedback resistors (dropping gain to unity for HF), but those don't give signifigant improvment. For me using a series RC parallel to the I/V-resistors gave better results, dropping open-loop gain, introducing a pole and a zero to it (at ~20kHz and 200kHz, resp), pretty good damped response with any cap load. Another option would be the classical L//R at the output to isolate the capacitive load. Just my 2cts...

- Klaus
  Reply With Quote
Old 14th June 2008, 04:51 AM   #1186
diyAudio Member
 
despotic931's Avatar
 
Join Date: Jan 2008
Send a message via AIM to despotic931
Quote:
Originally posted by DaveM
There are no stupid questions, only stupid people. Those not smart enough to ask questions when they need help would qualify if you ask me. The only way to find out how to do it is to jump in and try. If you can solder and read a schematic, you can build these amps. When you get stuck, ask. I used to call myself "and electrical idiot". I now have 6 functional Pass DIY projects at home. All are awaiting enclosures. I have a Bridgeport and lathe and full wood shop, so no excuse other than I would rather build circuits. I think I am addicted to building electronics.

Jump in, the water is fine.

Thanks for the encouragement Dave! I'm ready to jump, so I'm guessing the first step is to keep on reading, and to wait for the boards to become available through Pass DIY. I'm hoping there will be a group buy for matched fets or something, hehe!

-Justin
  Reply With Quote
Old 14th June 2008, 05:47 AM   #1187
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
> I'd say no, at least along the lines of the SuSy patent we need inverting gain stages, having positive inputs too (if you think opamp-style), which are coupled together then to form the SuSy config.

I am not sure I'd entirely agree with that.

The essence of the X-topology, as far as I understand, is to feed the residual distortion of one half of a bridged amp to the other half for cancellation in differential mode, even if you can see them in common mode. It is not restricted to inverting amps, although it is easily implemented in an inverting amp configuration.

What I "proposed" would, IMHO, provide that cross-feedback. The main problem is (differential) DC stability, as the junction from R1 to R12 and R2 to R11 should be floated and not grounded. But maybe it is not a problem if the inout FETs are well coupled thermally.


Patrick
  Reply With Quote
Old 14th June 2008, 04:42 PM   #1188
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Default Balanced Version with Toshiba MOSFETs

My PRP resistors arrived from the States Thursday evening.

After a few hours of soldering, setting bias, running the normal square wave and frequency response tests, etc., I have been listening to one channel for a few hours now.

Quite listenable. A touch on the bright side, but surprisingly tight bass. Source for the quick test was headphone output from Micromega Stage 1, via battery powered DRV134 for balance conversion. Loudspeaker was B&W CDM1 with (DIY) Mundorf Crossover.

Circuit is similar to the balanced version posted by Tino.
Rails are +/- 16V, total bias 4A.
JFETs are matched 2SK170BL/2SJ74BL running at 5mA.
Output MOSFETS are 2SK1530/2SJ201.
Source resistor 0R22 & 0R18 respectively.

Here are a few photos.
Attached Images
File Type: jpg f5p1 pcb top.jpg (92.7 KB, 4040 views)
  Reply With Quote
Old 14th June 2008, 04:55 PM   #1189
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Bottom View :
Attached Images
File Type: jpg f5p1 pcb btm.jpg (27.8 KB, 3798 views)
  Reply With Quote
Old 14th June 2008, 04:56 PM   #1190
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Fully assembled :
Attached Images
File Type: jpg f5p1 module.jpg (98.3 KB, 4395 views)
  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 08:02 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