What is difficult with a BJT singleton input is DC coupling to the cartridge. Nevermind.
This is cool :http://www.elv-downloads.de/Assets/...93/Downloads/109093_DCA_Pro_User_Guide_um.pdf
It comes with a graphics display now that shows the I/U curves. Very good to find transistors with high early voltage. I will buy one.
This is cool :http://www.elv-downloads.de/Assets/...93/Downloads/109093_DCA_Pro_User_Guide_um.pdf
It comes with a graphics display now that shows the I/U curves. Very good to find transistors with high early voltage. I will buy one.
Regarding the Peak: let us know your findings. I was also already peeking at this beast.
Mike
Mike
What is feasible is to make the input differential balanced with BJT´s.
That way we can DC couple and with BJTs 0.5nV/qHz is possible.
I will show a circuit soon. It is shown in Tietze-Schenk and has a lot of advantages.
That way we can DC couple and with BJTs 0.5nV/qHz is possible.
I will show a circuit soon. It is shown in Tietze-Schenk and has a lot of advantages.
Sure, that is the way to go. We have then one stage plus balanced plus DC coupled, that is what we all want.
We could make the first stage between the legs...and then the base cut after the folding.
think we need current mirrors to have enough gain for a One Stage
think we need current mirrors to have enough gain for a One Stage
As a newcomer I do not know what LTP means, probably Long Tailed Pair?
Anyway, when I seach this thread for LTP I arrive at a very early page 3 years ago:
http://www.diyaudio.com/forums/analogue-source/154210-mpp-5.html#post1974282
This is way back when I was not yet introduced to Master Joachim,
but I certainly could comment on the structure shown there, but it may be off topic,
agree?
I found it, post 42, that was a long time ago. I did also a balanced version of that one.
Post 42 has a little DC offset at the input that is the difference of the PNP and NPN Ube.
Could be solved by swapping the Ube transdiodes from one gender to the other.
The we have a PN NP drop on both polarities. Shunting the transdiodes with high value elcaps will lower the noise by 3dB.
Post 42 has a little DC offset at the input that is the difference of the PNP and NPN Ube.
Could be solved by swapping the Ube transdiodes from one gender to the other.
The we have a PN NP drop on both polarities. Shunting the transdiodes with high value elcaps will lower the noise by 3dB.
Yes, the link shows post 42.
The small offset is no problem if you adjust for instance one of the input current sources.
Some improvements to this basic circuit are possible in order to arrive at what is my preferred topology.
I am curious how you derived this "Malcolm Hawksford Homage", I am not familiar with the abbreviation LFD.
I don't agree with that, it is current in, current out and buffer.
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Think the buffer is too complex and fast....
The current "circle" driving the circuie is very suitable for a nice servo soulution
The current "circle" driving the circuie is very suitable for a nice servo soulution
The buffer as shown in post 42 is straightforward and standard in integrated circuits.
It can be built easily with discrete transistors also. The values shown are not significant
(editor presets). But you can obviously use a simple buffer also.
I was intrigued by your offset warnings earlier, so I did it this way with success.
Sure, Vbe is a weak function of Ic, but Vbe difference is not ..
Once upon a time the founder of a famous german high-end manufacturer told me to adjust both sides,
one side for offset and the other for total idle.
I looked at him but díd not answer.
C:
On my Nobrainer thread there are more varieties of bipolar, transimpedance inputs with offset adjust. Sure, no problem, can be solved.
I think it is overrated but some here even do not accept a tiny amount of DC through the cartridge. We have beaten that red herring so many times to death that it started to smell funny.
On my Nobrainer thread there are more varieties of bipolar, transimpedance inputs with offset adjust. Sure, no problem, can be solved.
I think it is overrated but some here even do not accept a tiny amount of DC through the cartridge. We have beaten that red herring so many times to death that it started to smell funny.