Frans simulated the circuit and he thinks it is under biased because voltage is dropped in the resistors.
I will now substitude the transdiodes with red Leds.
I will now substitude the transdiodes with red Leds.
I bridged the 47 Ohm source resistor and trimmed the current sources.
Again 2OdB improvement.
Now it starts to look promissing.
Offset is 450mV now so i think this circuit needs selected Fets when lowest distortion plus lowest offset is the goal.
On the other hand it could be trimmed with the voltage devider. I try that tomorrow.
Again 2OdB improvement.
Now it starts to look promissing.
Offset is 450mV now so i think this circuit needs selected Fets when lowest distortion plus lowest offset is the goal.
On the other hand it could be trimmed with the voltage devider. I try that tomorrow.
Attachments
Frans made some more calculations and we came to the conclusion that is is a great buffer but when it gets to voltage amplification problems show up.
At this time we recommend it only as a buffer.
At this time we recommend it only as a buffer.
Hi Joachim,
Is Reichelt still the source for BC337/BC327?
On another matter. My 15 year old son has expressed interest in getting an turntable. Some time ago a friend of his turn up here at our house with 2 LP's. Daft Punk and Beatles the white Album. Kids now a days...
I found an nice Thorens TD318 for him and bought an Ortofon 2M Red as a starter pick-up to learn to handle these fragile things. Also, if VPI can sell this cartridge with their starter turntables, it's could enough for him to start with.
But, we need the "student RIAA". I have an idea, but would be interested in inputs. Are you game?
Cheers,
Mogens
Is Reichelt still the source for BC337/BC327?
On another matter. My 15 year old son has expressed interest in getting an turntable. Some time ago a friend of his turn up here at our house with 2 LP's. Daft Punk and Beatles the white Album. Kids now a days...
I found an nice Thorens TD318 for him and bought an Ortofon 2M Red as a starter pick-up to learn to handle these fragile things. Also, if VPI can sell this cartridge with their starter turntables, it's could enough for him to start with.
But, we need the "student RIAA". I have an idea, but would be interested in inputs. Are you game?
Cheers,
Mogens
Hi Mogens !
The best BC337/327 we found are from Diotec.
I think you get them from Conrad.
With other makers we had trouble to find fitting Hfe groups.
Hagerman made a new " Buggle ".
Our Pavel Macura made a nice MM stage too.
The best BC337/327 we found are from Diotec.
I think you get them from Conrad.
With other makers we had trouble to find fitting Hfe groups.
Hagerman made a new " Buggle ".
Our Pavel Macura made a nice MM stage too.
Hi Joachim,
Thanks! Unfortunately is not as cheap as Reichelt. However, I must buy some to have in stock.
With regards to the MM RIAA. of course there is a lot of those around. But, as you know. There is always a new mouse trap.
However, my idea goes towards something slightly different. I want a single supply RIAA, meaning coupling caps, so we can drive it from a standard wall adapter. My idea is inspired by x-pro's RIAA and the Vandetta. I'm thinking about using the x-pro stage as a first stage (without the correction of course) into a Vendetta like 100 nF + 750 ohm inverting stage with the low frequency correction wrapped into the feedback. The second stage could either be a 5534 or a discrete stage.
My take on this is that I have done my share of complementary stages over the years, but since true complementary transistors doesn't exist, why build them. Why not try to get the most out of single ended non-complementary stages.
I will try this myself, but I just wanted to see if I could wet your apatite ;-).
Thanks,
Mogens
Thanks! Unfortunately is not as cheap as Reichelt. However, I must buy some to have in stock.
With regards to the MM RIAA. of course there is a lot of those around. But, as you know. There is always a new mouse trap.
However, my idea goes towards something slightly different. I want a single supply RIAA, meaning coupling caps, so we can drive it from a standard wall adapter. My idea is inspired by x-pro's RIAA and the Vandetta. I'm thinking about using the x-pro stage as a first stage (without the correction of course) into a Vendetta like 100 nF + 750 ohm inverting stage with the low frequency correction wrapped into the feedback. The second stage could either be a 5534 or a discrete stage.
My take on this is that I have done my share of complementary stages over the years, but since true complementary transistors doesn't exist, why build them. Why not try to get the most out of single ended non-complementary stages.
I will try this myself, but I just wanted to see if I could wet your apatite ;-).
Thanks,
Mogens
Hi AS,
Yes, I know. But, for now I want to use a DC wall plug. I know. I'm stubborn. 🙂 But, it moves this old timers heart that the kids now a days are interested in vinyl. I thought of this as something that my sons friends could come here and build if they where interested.
This link is for Joachim. I think he has a soft spot for this, like me. This kid really restore my faith and she is really into this. https://www.youtube.com/channel/UCWeHBodddgK_qhIcXrBwL6A
Cheers, Mogens
Yes, I know. But, for now I want to use a DC wall plug. I know. I'm stubborn. 🙂 But, it moves this old timers heart that the kids now a days are interested in vinyl. I thought of this as something that my sons friends could come here and build if they where interested.
This link is for Joachim. I think he has a soft spot for this, like me. This kid really restore my faith and she is really into this. https://www.youtube.com/channel/UCWeHBodddgK_qhIcXrBwL6A
Cheers, Mogens
Also, AS. I want to see if I could get Joachim hooked to the idea of how far could one push the single-supply, single-ended concept.
The technician in me also like the symmetric and nice concept. But, is it good or just visual nice for the technician?
Cheers,
Mogens
The technician in me also like the symmetric and nice concept. But, is it good or just visual nice for the technician?
Cheers,
Mogens