diyAudio - Entries for April 19, 2013
Go Back   Home > Forums > Blogs
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

Discrete transistor line amplifier stage mod 1

Posted 19th April 2013 at 10:24 PM by rjm (RJM Audio Blog)
Updated 20th April 2013 at 05:04 AM by rjm

Changed the collector load on the voltage amplifier stage to a current source (Q3), as per the Marantz SR2285B circuit.

Also increased the resistance of the feedback connection, R6+R8, there seemed to be no obvious advantage in making it much smaller than the typical load (>10k). The compensation capacitor C2 is increased to match, to flatten the HF response.

The circuit can drive light loads to +20 dB. Of course that's not much of a challenge for this general class of circuit.

I'm a bit stumped as to what the next logical step is from here. Seems to me to depend on what you actually want the circuit to do.
Attached Thumbnails
Click image for larger version

Name:	RJM discrete mod1.png
Views:	1268
Size:	59.2 KB
ID:	963  
Attached Files
File Type: asc RJM discrete mod1.asc (3.5 KB, 185 views)
rjm's Avatar
diyAudio Member
Posted in The Lab
Views 1063 Comments 0 rjm is offline

Progressing - Low Power Desktop Amp

Posted 19th April 2013 at 09:49 AM by BuildMeSomething
Updated 25th April 2013 at 08:36 AM by BuildMeSomething

Holiday: Bad weather to a point it was near impossible to take a steady photograph due to the gusting winds. Hiding from the winds meant poor vantage points, very much non-idealistic for photographing landscapes.

Digi-key: The order turned up on the Monday morning, roughly 10 minutes before leaving. The PSU boards must have arrived mid week, a neighbour had those...

The parts order was enough components for one power supply and one amp. The PSU is assembled but untested as yet. The toroidal and 10K Alps RK27 are to be ordered from RS Components later today.

PCB issues: C1-C6... this is where trusting the people who generate default libraries for FreePCB falls down and my inexperience shows. Lead diameter on the caps is 28MIL, default part through-hole diameter is 28MIL... Each lead needed a quick file to reduce its width enough to fit the board. No other issues to report.

I don't think I could have made the overall size of the board...
Attached Thumbnails
Click image for larger version

Views:	325
Size:	327.1 KB
ID:	960   Click image for larger version

Views:	357
Size:	316.9 KB
ID:	961   Click image for larger version

Views:	328
Size:	323.9 KB
ID:	962  
Attached Files
diyAudio Member
Posted in Uncategorized
Views 630 Comments 0 BuildMeSomething is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 01:53 AM.

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