Very slim reactions, see graphs.
Attachments
Yes that is the one. New stuff discussed is some beta modding to see if we can positively revise. Still to do that successfully to a widely liked design it will take time and it may very well be a thumbs down in the end. Numbers mean Feb. 2011 and document code, to allow correct reference.
Hey Kent
Your build is one I've been following with great interest since ploughing (backwards!) through this thread all afternoon!
Firstly, would you mind if I emulated your very neat layout please?
Secondly, how did your stage come out sounding in the end? Would love to hear your views.
Cheers.
John.
I notice a nitid deviation on the second inflection point between second and thir graph.
K369 for noise is as using 2 K170 roughly. Yfs and Ciss go up together, so no free lunch, it shows some advantage in lower frequencies for a special kind of noise named generation recombination as Scott W. explained. Here you are, another toy attached.
This will be my next build.
I like the sound of my actual 48d "stock" version so much, I decided not to tamper with it and use it as "pivot".
I will do this 57db as soon as I collect enough CHF to buy the parts needed
Really happy about this.
The scale is so much zoomed in that with real parts tolerances I am not sure that we will ever be able to emulate those curves, the idea was to initially have a very faint droop as we progress in higher frequencies. Still if the modded gain blocks will work to satisfaction, those curves will possibly need to be more heavily voiced to subjective synergy or left alone. Till then, some road. But its a non problematic starting point, not too deviant IMHO. What do you think?
Hey Kent
Your build is one I've been following with great interest since ploughing (backwards!) through this thread all afternoon!
Firstly, would you mind if I emulated your very neat layout please?
Secondly, how did your stage come out sounding in the end? Would love to hear your views.
Cheers.
John.
Hi John- Please feel free to emulate away!
How does it sound? Great! I only have a Mitsubishi Integra preamp to compare it to. My Salas RIAA build has more dynamics and life. Very happy with it's sound. Of course there are many variables and subjectivity. I'm also using a lab supply to power the shunts as I've been too distracted/busy to build a transformer/CLC power supply.
It doesn't have quite as much gain as the Integra but plenty loud enough. Possibly the latest ideas on this thread will address that. Still good to go. I hope I can get into in a box for Burning Amp in October!
-Kent
58db cascoded build
Hi Salas
For Q8, can I use a BF245C instead of a BF245 A ?
It sets the current in the leds that provide bias for Q3 (folded cascode trannie).. do you believe higher current might modify bias too much or is it about noise ?
In alternative, I can use a suitable 6mA K170 right ?
Hi Salas
For Q8, can I use a BF245C instead of a BF245 A ?
It sets the current in the leds that provide bias for Q3 (folded cascode trannie).. do you believe higher current might modify bias too much or is it about noise ?
In alternative, I can use a suitable 6mA K170 right ?
Attachments
You may either put a resistor between G&S BF245C pins with a value that will get it down to circa 5mA (try 470R) and take current output from G pin, or use 2N5457 3-5mA natural. My BF245A little stash averages at 3.5mA for instance. They are both low capacitance higher RDS ON JFETs but suitably quiet also that will meet the 4 Leds impedance better for minimal harmonic noise pick up of CCSed Leds Vref in that cascode transistor's base bias system. Not a big deal but prefer them to K170 for the job if able.