Easy-to-build I/V stage

[hollowman]

Huh??

Hi,

QSerra gave a hint in #185 ..... saying that the common collectors of Q2and Q4 needed a dc path to a defined potential (a supply lin, gnd, etc).
As both collectors are high impedance it his highly improbable that a certain stable idle potential develops, but rather that the voltage is driven 'into' one of the collectors .... to a,most 0V or V+.
One could either omit with the current source Q4 and just use a load resistor connected from Q2s collector to V+, or use a current mirror mirrors into a gnd (or V-) referenced load resistor.

jauu
Calvin

Huh?

As I noted, Rudolf's I/V (same topology as Jocko, but with slightly different values) works just fine.

Speaking of this topology (Rudolf version) ... I concur that it works and sounds "clean".
HOWEVER, after some recent extensive listening (in a classic Philips multibit CDP), I must confess I prefer the stock Philips opamps (or other opamps). The opamps just sound more punchy and dynamic. The discrete I/V sounds compressed.

 

[Calvin]

Hi,

if, You refer to the circuit You linked in #195 it is just that decisive small difference QSerra and I talked about.
Rudolf´s circuit connected a resistor from the joint Collectors to gnd (R4, 1k5) --> stable DC-potential at the collectors.
The Jocko connected not a resistor but a cap to the Collecors ... the resistor follows behind the cap --> indifferent DC-potential at the Collectors.

jauu
Calvin

 

[CeeVee]

Page 1, OP

Built that one ages ago with ZM's precious help and it has been working in my CD Player ever since, gorgeous sounding.



There is a thread here somewhere discussing the whole process; changing Shanling CD-S100MKII IV .

Found it....: Upgrade output Shanling CD-S100 MkII