I built the recommended 4x33000uF CRC PSU for the M2. It did not change the distortion measured at the speaker but the soundstage is subjectively better. Wider better imaging.
Here is closeup of the PSU made with P2P.
I guess it works pretty well as I get 19mV ripple when running at full class A mode with 1.3amp bias current.
Here is closeup of the PSU made with P2P.
I guess it works pretty well as I get 19mV ripple when running at full class A mode with 1.3amp bias current.
Hello all.
If you want to hear fantastic class A amplifier, look at the side of the series USSA by Fab on the Quebec DIY forum.
USSA-1
Amplificateur USSA 15W - Conception
For the latest version there is a group buy for pcb by Alex in time but the Lateral mosfets are hard to find.
USSA-5
Amplificateur USSA-5 : évolution de la conception de la version 4
I have the first version and it's a gem this amplifier.
If you want to hear fantastic class A amplifier, look at the side of the series USSA by Fab on the Quebec DIY forum.
USSA-1
Amplificateur USSA 15W - Conception
For the latest version there is a group buy for pcb by Alex in time but the Lateral mosfets are hard to find.
USSA-5
Amplificateur USSA-5 : évolution de la conception de la version 4
I have the first version and it's a gem this amplifier.
The schematic is actually a complete manual for build this amplifier but you have to request to Fab, I have the manuals of versions 1,2 and 5 but I can not share them.
Fab is a very friendly guy.
diyAudio - View Profile: fab
The schematic is actually a complete manual for build this amplifier but you have to request to Fab, I have the manuals of versions 1,2 and 5 but I can not share them.
Fab is a very friendly guy.
diyAudio - View Profile: fab
Okay, thanks (I forgot that I have heard that many times hehe)
I might have to make an F5 to compare as similar to M2 but with BJT gain stage vs transformer. The parts and boards are cheap enough. I think USSA1 may be based on F5.
On another note, I am perfectly certain that the M2 doesn't use more than 65w or 1.3amps at 25v per rail. So a 24v 3a SMPS brick should be able to power this amp when two are in series with ground center tap. This may make for a very compact amp actually if forced air is used for cooling vs big passive heatsinks.
On another note, I am perfectly certain that the M2 doesn't use more than 65w or 1.3amps at 25v per rail. So a 24v 3a SMPS brick should be able to power this amp when two are in series with ground center tap. This may make for a very compact amp actually if forced air is used for cooling vs big passive heatsinks.
Last edited:
Hi
For small class A amp with double mono linear supply :
http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-358.html#post4720116
However, since the small heatsink only about 800ma or so of bias ...
This one here (F5-USSA) is more similar to F5 but different sound signature (mainly use of output transistor designed for audio, different open loop gain, different close loop gain and more important a lower amplifier damping than stock F5). Find the complete schematics here: http://www.quebecdiy.net/t768-f5-avec-la-recette-ussa
For USSA-1 I wanted first to have good feedback on a small scale before releasing for large audience and control the build quality....So far, 4 out of 5 builders (excluding me ) are now using the USSA1- or -2 as their main amplifier in their system and report feedback even better than I had anticipated
Since it uses an existing F5 pcb with important addition/modifications I had to create and provide a detailed build manual to ensure good implementation and obtain same results as I did ....
Of course it is just a different sounding amplifier and is class A so maybe not for all everybody 's need...Maybe it is time to share the complete schematics now..
For SMPS in class A amplifier I am not aware of good one so maybe share your findings.... In fact we have one designer on this forum working on a dedicated SMPS for about 1,5A class A amplifier at +/-25vdc but still to be finalized since a challenge compared to SMPS for class AB as per his findings...
By the way, thanks X for sharing your passion about Diyaudio.
Fab
Last edited:
For clarification USSA-5 build is still not completed yet so only electrical test results so far. However, USSA-1 , -B (output darlington Sanken bjt), -2, -3 and -4 were fully built. I am now using USSA-4 as my main amplifier.
I have a second pcb group buy on-going for USSA-5 pcb where it can accept USSA-3, -4 and -5 versions. Versions -3 and -4 are even better( to my taste and a few other peoples) than earlier versions. I can add your name if you are interested...
Fab
No problem with that at all. I know 2 very good source for genuine parts and one of them is actually selling big quantity on this forum just Check the vendors bazaar thread....
I know that the other source have a few hundred transitors available..
Note that for the schematics , feedback resistors should be all the same value but I had not them stocked when I decided to build the amplifier...
Also R25/R26 were added to fit my standard gain of class A amp.
Fab
Last edited:
Transconductance is too low, the overall open loop gain too low thus too low damping...bass too slow....
Also, even in a follower type of output stage the indicated Toshiba one has its own sound signature which is more in-between the lateral one and usually used IRFP240/9240..
Fab
F5-USSA board
Fab
This version is the same layout as the stock F5 so no modifications on pcb required but only parts change. Very easy to do. Maybe not as good as USSA versions (to my taste) but still worth the try because I like it better than the F5 I had built...
Fab
Is this the seller in the vendors bazaar you're referring to?
http://www.diyaudio.com/forums/vend...uding-some-very-rare-toshiba-transistors.html
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.