The servo in The Paradise works by altering the voltage over the current setting resistors in the driving 4 transistor CcS. This changes (skews) the currents in the top and button part of the circuit, this moves the operation points of the gain transistors to a point where they reach a balance
Please let me remark that changing dc current conditions or
"injecting DC (voltage) into the signal" is the same thing in
different words as long as the ac operation of the amplifier
is not affected (and this is the sole purpose of a dc servo).
In fact an important point in making use of a servo or other
form of dc feedback is to find a point in the circuit where it
can be applied properly.
"injecting DC (voltage) into the signal" is the same thing in
different words as long as the ac operation of the amplifier
is not affected (and this is the sole purpose of a dc servo).
In fact an important point in making use of a servo or other
form of dc feedback is to find a point in the circuit where it
can be applied properly.
Again I don't completely agree. Even at startup or turnoff any input offset in a BJT
base input is that of a base current difference only (sub microamp region).
I have even used mc phono emitter inputs for years (since 1992), that means an input
offset is the difference of the base emitter voltages of pnp and npn. Unadjusted it may
be some millivolts. I had never problems with that even with turnon and off.
Off course you are right in therms of not getting DC out, both ways works the same. But I can assure you they don't sound the same, the skewing of currents is much to be preferred, at least in the paradise where you have no feedback to correct the signal
I really can't explain why they put the cap there, we both agree on that its not needed, do you have an idea..?
Still I can't really make my mind up what is best for a phono stage, servo or DC cap(s) in the middle of the circuit
I really can't explain why they put the cap there, we both agree on that its not needed, do you have an idea..?
Still I can't really make my mind up what is best for a phono stage, servo or DC cap(s) in the middle of the circuit
Last edited:
Like I said (see http://www.diyaudio.com/forums/analogue-source/154210-mpp-1049.html#post4291519), some type of security (IMO not needed).
That is the interesting question, IMO use a servo and no caps. (But not both
)
That is the interesting question, IMO use a servo and no caps. (But not both
)
Yes, i am good.
I will be home soon.
Thanks for talking care.
I have aranged to exhibit on the HighEnd 2015 in Munich so if you want to chat with me, come to my room.
It will be anounced soon on Suesskindaudio
I will be home soon.
Thanks for talking care.
I have aranged to exhibit on the HighEnd 2015 in Munich so if you want to chat with me, come to my room.
It will be anounced soon on Suesskindaudio
Welcome back Joachim it was getting rather quiet without you.
Here is is something else from Marantz.
Trick gain stage..................
Jam
And where is the tricky part. The output stage is driven from the supply current of the opamp? that's it? IMHO this is really bad, please don't (do this at home), take this as a bad example!! Even Marantz seems to make mistakes.
I did not say it was good but but I have never seen this topology implemented in a line level product let a lone a phono stage .........I wonder what it measures like?
It is a 'relatively' normal circuit and old also, but not tricky at all.
The thing is, here we talk about Joachim's circuits (and related (even remotely)) not Marantz. So where is the reference to any of Joachim's circuits?