The Frugalamp by OS - Page 65 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 9th January 2009, 10:04 AM   #641
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Default FA1 schematic

Hi,
the NFB and a Ground is shown connected to the bottom of R3, 22r.
Is this the way you built it?
Would the Signal Ground and NFB go to the top of R3 and the main Audio Ground to the bottom of R3?
__________________
regards Andrew T.
  Reply With Quote
Old 9th January 2009, 11:41 AM   #642
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Quote:
By andrew t. - the NFB and a Ground is shown connected to the bottom of R3, 22r.
I thought I did something wrong, BUT... I reviewed PCB and
schema.. the 22r is R36, at the top of it ,the DC NFB cap and
input comp. are attached, giving an isolated ground reference,
(A in attached schema). Also both "B's" (also in attachment)
are connected by separate trace to star ground on PCB.(GRND)

Zobel ground connects back to connector at star ground(GRND) , too.
All grounding seems to be in order..

The input connector ground connects right at "A" in attachment,
this might be where a slight confusion could arise..will correct.
I return the speaker ground right back to the main star/supply
ground also.

OS
Attached Images
File Type: gif fa3_schema.gif (57.8 KB, 265 views)
  Reply With Quote
Old 9th January 2009, 11:51 AM   #643
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
yes, Signal Ground connects at A in FA3.
But I was referring to FA1 in my post641.

It would help if we could adopt different symbols for the different Grounds/Returns. Then there would be no confusion. Even better if we gave them all individual names. They all do a different job and deserve to be differentiated. But the software designers will never do that for us.
__________________
regards Andrew T.
  Reply With Quote
Old 9th January 2009, 11:58 AM   #644
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Quote:
It would help if we could adopt different symbols for the different Grounds/Returns
Good suggestion, Even as they are right on the PCB, a standard
convention must be observed , I alway did it right on the real
thing, never experiencing "hum" on any of the FA's (even with
various unbalanced inputs..soundcards/cd outs,etc.)
I will also change ground designations on both FA1/3..

OS
  Reply With Quote
Old 9th January 2009, 12:51 PM   #645
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Hey, FA1 and 3 downloaders... download the ZIP files...
to download the original uncompressed bitmap of the PCB is
unneeded.. all are in the ZIP's (FA1_full.zip and FA3_full.zip), much
faster download...
OS

PS ..If I make any changes/improvements I will also update
the zipfiles for your convenience(speed).
  Reply With Quote
Old 9th January 2009, 12:59 PM   #646
Account disabled at member's request
 
Join Date: May 2006
Nice Os, strap output on it, and tell us how it compares to fruga1and 2
  Reply With Quote
Old 9th January 2009, 03:20 PM   #647
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Default Trouble with triples

Quote:
By homemodder - Nice Os, strap output on it, and tell us how it compares to fruga1and 2
Already at that point, HM , have it hooked to my SUB!! bass
is incredible! I temporarily tried it on a fullrange and it sounded
as good or better than FA2.. but the bass is the surprise.

I want to put a "beast" OPS on it (8 devices)but I'm having
"trouble with triples". I can drive the 4 pairs well just from
my present drivers (mje15032/33) but for my 4R peerless
I would like to use a leach type OP stage.

When I simulate the triple, any crossover distortion or
clipping makes the whole thing breaK out in oscillation.
Is the triple just a unstable type of Op stage??Or is there
a trick to it??

My only other option for More power is a "quasi" type
6/8 device mosfet OP stage running higher rails.
Schema of "beast" is attached.. any triple experts welcome
to comment..
OS
Attached Images
File Type: gif fa3_beast.gif (55.2 KB, 214 views)
  Reply With Quote
Old 9th January 2009, 04:19 PM   #648
diyAudio Member
 
Steve Dunlap's Avatar
 
Join Date: Sep 2008
Location: Here
Hi ostripper. I'm not sure how much power you need (or want) but I have built amps with 1200W at 8 ohm using my Krill design. Would that be enough?
  Reply With Quote
Old 9th January 2009, 04:44 PM   #649
Account disabled at member's request
 
Join Date: May 2006
Os why dont you use the cfp ef, works well, the triples are tricky sometimes, for 4 outputs try increase the cap between predriver bases a bit more, a sure way to stabilise it more is a small cap from the base of predriver to the rail. It helps when the predriver is a low cob device so 1381 would be good in that position, I dont think you running high current there anyway. I dont know if any will help because you talking of clipping here, this is not easy. It might not oscilate real time but if you wrong their might be some damage which is not good.
  Reply With Quote
Old 9th January 2009, 05:13 PM   #650
andy_c is offline andy_c  United States
Banned
 
Join Date: Apr 2003
Hi OS,

Looks like Q14 emitter and collector are swapped.
  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



New To Site? Need Help?

All times are GMT. The time now is 05:50 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