Thx Jason.
it's cleared now for me.
I have found now the added Gerbers on first page.
Cheers Bangla.
it's cleared now for me.
I have found now the added Gerbers on first page.
Cheers Bangla.
On feedback cap, it may be beneficial to use as low of an ESR cap as you can find. But really, probably just fine with whatever you have. I am using Rubycon 2200uF 35v.
I have been listening to it for extended sessions - 6hrs with many different tracks. This is a nice amp - best word to describe it is neutral and clear. Very happy with it. Runs fairly cool although with tiny heatsink I have for two channels having small air cooled fans is a must. They are quiet though as very low rpm.
VSSA is my basic design, First One M and First One L are sensible way to the musical heaven. 😉
Yes they are nice but we can't make them ourselves can we? Are bare PCBs available or we have to buy fully assembled amp board?
LC's First One is a fully commercial venture. He will interject in any VSSA thread to say how much we are missing by not buying one.
I'm grateful for Andrej's contribution of the base VSSA, but am growing tired of the other aspects.
I'm grateful for Andrej's contribution of the base VSSA, but am growing tired of the other aspects.
Yes, there is so much good stuff available as DIY fully open source why go commercial at this point. That's why I am here - to make my own amps rather than buy an amp someone else made.
The only right way to be, maybe someday you'll be grateful to sell First One PCB-s too. 😉
I have heard from others that your version, even simpler without CCS, still sounds fantastic. Transistors are cheap so I figured, why not? 😀
You could do the PeeCeeBee with dead bug P2P even given how simple it is...
Basic VSSA has resistor limited quiescent current injection into input stage which is fine, works stable and proves that this design concept will always deliver, which is good.
There are many feedback paths inside and outside the amp influencing the SQ negatively, the only desired, straight and shortest possible one is from output to negative input, others like via power supply rails, GND loops, acoustic to parts, etc., are all unwanted ones, so we have to avoid them as much as possible. To cut off undesired feedback from PSU rails and GND loops we need to use CCS, shunts, filters ... resulting in high PSRR, hence better SQ.
Main feedback has to be preserved and protected from unwanted influences, because this is the only one which corrects amp to follow the input signal faithfully.
So would the version with the two transistors on the CCS be better than the one with an LED with regards to SQ via improved PSRR or reduced feedback from rails?
In delicate places delicate solutions have to be implemented, in this case CCS is important as input stage, maybe even more. None of the mentioned CCS's are good enough to play the main role here, picking the best academy award winner is the way to go.
LC doesn't like either one. In my (meager) experience it is a CCS and makes little difference so long as it is adequate in maintaining its characteristics over a fairly wide frequency range. Guess I have tin ears and / or too pedestrian equipment to notice 🙄.
A two JFET cascoded self biassed arrangement or one using precision references (thinking of a Walter Jung article) are superior as a CCS, but I prefer to avoid JFETs simply due to decreasing availability in TH parts. If I were to go SMD then the choice widens and the JFET looks appealing again.
The CCS appears to be one of LC's pieces of intellectual property incorporated into his First One. I doubt he will say anything meaningful on the subject.
A two JFET cascoded self biassed arrangement or one using precision references (thinking of a Walter Jung article) are superior as a CCS, but I prefer to avoid JFETs simply due to decreasing availability in TH parts. If I were to go SMD then the choice widens and the JFET looks appealing again.
The CCS appears to be one of LC's pieces of intellectual property incorporated into his First One. I doubt he will say anything meaningful on the subject.
You are completely wrong here, you don't know anything about the First One schematic, especially not about First One v1.4, count the parts on PCB and you'll see you are very badly informed. Listen to the First One amp or ask honest people who has one what's their opinion, it certainly blows away all amps you've ever owned. And finally please show some respect and don't talk to me in third person.
So what is the CCS architecture you suggest as being "delicate" here? A TL431 shunt?
Wow, that is quite a bold statement when exclusive "all" is used. Would all happen to include the ExtremeA, for example?
Mr. jk... obviously has more knowledge about the amplifiers, why not ask him how to make proper amp. I think his good only at copying things..
- Status
- Not open for further replies.