Rega Brio (one channel dead) - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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 7th August 2005, 02:55 PM   #11
cosinus is offline cosinus  France
diyAudio Member
 
Join Date: Mar 2005
Location: paris
Hi there
Thank you for your replies. I finally decided to buy all the components for the dead channel, and to replace everything. It cost me something like 10. The fixed channel didn't sound as good as the original one, but it was OK and I gave the amp to a friend for his countryside house. Maybe the transistors were of poorer quality.
Here are the schematics that I received from rega. These guys are very friendly and provide a good support. I believe there is no problem posting the diagrams of such an old amp, as it may help passionate people.
FrancoB -> you may have the second version of the amplifier, where they changed the components' numbers (what a good idea). The diagram is almost the same. They just added a couple of fuses.
A question for the experts here: how to adjust IQ ? Where to measure the 15mA ?
Another question: I just bought another brio, almost identical, on a secondhand market. I would like to improve it. Is there anything that can be done, without changing too much the amp? Use better opamps ? Is there a pair of better transistors that could replace the 2955/3055 ? Anything else?
Best regards
Attached Files
File Type: pdf p1.pdf (60.2 KB, 713 views)
  Reply With Quote
Old 7th August 2005, 02:57 PM   #12
cosinus is offline cosinus  France
diyAudio Member
 
Join Date: Mar 2005
Location: paris
P2
Attached Files
File Type: pdf p2.pdf (58.4 KB, 545 views)
  Reply With Quote
Old 7th August 2005, 03:00 PM   #13
cosinus is offline cosinus  France
diyAudio Member
 
Join Date: Mar 2005
Location: paris
P3
Attached Files
File Type: pdf p3.pdf (55.0 KB, 515 views)
  Reply With Quote
Old 7th August 2005, 03:04 PM   #14
cosinus is offline cosinus  France
diyAudio Member
 
Join Date: Mar 2005
Location: paris
P4
Attached Files
File Type: pdf p4.pdf (54.6 KB, 441 views)
  Reply With Quote
Old 7th August 2005, 03:05 PM   #15
cosinus is offline cosinus  France
diyAudio Member
 
Join Date: Mar 2005
Location: paris
P5
Attached Files
File Type: pdf p5.pdf (53.1 KB, 450 views)
  Reply With Quote
Old 7th August 2005, 03:07 PM   #16
cosinus is offline cosinus  France
diyAudio Member
 
Join Date: Mar 2005
Location: paris
P6...
Attached Files
File Type: pdf p6.pdf (57.7 KB, 424 views)
  Reply With Quote
Old 7th August 2005, 03:09 PM   #17
cosinus is offline cosinus  France
diyAudio Member
 
Join Date: Mar 2005
Location: paris
...and P7
Attached Files
File Type: pdf p7.pdf (67.7 KB, 454 views)
  Reply With Quote
Old 7th August 2005, 06:02 PM   #18
jaycee is online now jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
Quote:
Originally posted by cosinus
The fixed channel didn't sound as good as the original one, but it was OK and I gave the amp to a friend for his countryside house. Maybe the transistors were of poorer quality.
The transistors probably need to be matched for best quality.

Quote:
Originally posted by cosinus
A question for the experts here: how to adjust IQ ? Where to measure the 15mA ?
Measure the voltage drop over R13 and R16.

Quote:
Originally posted by cosinus
Another question: I just bought another brio, almost identical, on a secondhand market. I would like to improve it. Is there anything that can be done, without changing too much the amp? Use better opamps ? Is there a pair of better transistors that could replace the 2955/3055 ? Anything else?
I really wouldn't bother. If you changed the outputs you would probably have to change the driver transistors, and that would mean going to TO-126 or TO-220 packages that wouldn't fit in the PCB.
  Reply With Quote
Old 7th August 2005, 09:54 PM   #19
diyAudio Member
 
Join Date: May 2004
Location: Hertfordshire
This amplifier design has an interesting history. It was originally designed by Texas Instruments (i think in Bedford England) as the "Texan" kit for "Practical Wireless" magazine back in the 1970's.
Rega borrowed the design but used more rugged output transistors than the original TIP41/42.
The main feature is that the output stage has some voltage gain which allows the op-amp to run off low voltage supplies.
I believe the original Texan design did not have quiescent current setting adjustment which can give the dreaded crossover distortion.
  Reply With Quote
Old 14th August 2005, 04:41 PM   #20
diyAudio Member
 
Join Date: May 2004
Location: Hertfordshire
I googled for Texan amplifier and about the only relevant ref I could find was:

http://www.angelfire.com/sd/paulkemble/sound5.html
which is part of
http://www.angelfire.com/sd/paulkemble/soundindex.html
excellent site which I had not come across before
scroll down to the fifth circuit down on the first page
Like the owner of the brio I am intrigued as to how such an amp would sound with better specified components.
Sgs/thomson have an old little known power buffer, the L149 which could be used as an integrated output stage for an op-amp for those wishing to play with a simple circuit. I am surprised this device is still avaliable from digikey
  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
Help. dead channel on GFA 555. chucker Solid State 4 17th May 2008 07:45 AM
Dead channel Carlp Tubes / Valves 15 1st February 2007 03:54 AM
2020 T-Amp Kit: One Dead Channel mourip Class D 5 14th February 2006 01:09 AM
HELP with a rega brio! jercab Solid State 1 5th October 2005 01:43 AM
Peavey 8.5C DeAd cHaNnEl Pbassred Instruments and Amps 3 9th May 2005 11:44 PM


New To Site? Need Help?

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


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki