MPP

[keantoken]

I'm guessing the "friend" simulated using BC3x7 models and not BC3x7-40 models. The -40 has higher Hfe.

My calculation using Hfe=400 comes to 2.031k. 1.97k including the DC trim resistors.

 

[as_audio]

My guestimate was (near) 2k (no simulation involved )

See post 10973

 

[keantoken]

Well, it's not a contest. 2k4 is a reasonable estimate if Hfe is selected for 500.

 

[FdW]

That is what I thought, I was just confirming 'as_audio's result

 

[RCruz]

So my sim is aok

This circuit is not suitable for MM carts that need 47k load..... maybe I can put a jfet follower in front of the paradise and than cut the gain.......

 

[avinunca]

Surely a phono amplifier of the calibre of the Paradise is best used with a decent MC cartridge. Maybe I am mistaken but my belief is that ultimately a MC cart can offer higher fidelity than MM though I suspect there are some very good MM cartridges out there.

 

[RCruz]

Yes, I have two B&O MMC20CL and one Soundsmith The Voice... these are outstanding sounding carts with 2mV output.... not really MM they are MMC (Moving micro cross)

 

[FdW]

Just tried Q&D (quick and dirty) removed the input BJT's substituted 2 JFets (more or less randomly selected) and guess what, it works, the gain is down to 60dB (from 80) and the sim seems to work just fine, I'm sure you can take it from here

 

[RCruz]

Thank you Frans


It was a real pleasure to meet you again in Munich.... Hope to see you soon....

Did you like my speakers ?

 

[RCruz]

What do you think about J112/J175 ?

 

[Joachim Gerhard]

2SJ103, 2SK246.
They are still to get. Much easier then 2SJ74 for example.

 

[Joachim Gerhard]

I like that Fet version for MM. Much easier to bias, no big elcaps required for decoupling and very high input impedance. 47kOhm is easy to get. No input DC nulling pot required.
I also heard that Soundsmith MI cartridges sound very good.

 

[analog_sa]

I suspect there are some very good MM cartridges out there.

There are. As well as a disturbing number of pretty bad MCs. Hard to generalise.

 

[as_audio]

I like that Fet version for MM. Much easier to bias, no big elcaps required for decoupling and very high input impedance. 47kOhm is easy to get. No input DC nulling pot required.
I also heard that Soundsmith MI cartridges sound very good.

The decoupling caps (at sources here) are still required
and can be seen in schematic of post 10988.

 

[RCruz]

I have been working hard in this project and maybe now got something that works.

Jfet IPS and double output mirror.

63dB gain.... comments are welcome off course

 

[RCruz]

What i need to know is your imput regarding the amplifying current mirror. Is it stable?

 

[Hans Polak]

What i need to know is your imput regarding the amplifying current mirror. Is it stable?

I just came across this thread, not knowing the history.
But there are a few things that I noticed:

1) The 5 Ohm resistors are connected to the Drains of J3&J5, but to the Sources of J4&J6. They should all be connected to the source.
2) Of course the current mirrors are stable, but I don't get why the emitters of Q10&Q25 and Q15&Q25 are connected, leave this connection.
3) I see no reason why the current mirrors around Q1-8, Q19-22 are so extremely complex.
This could be done with far less components only playing a role for DC.


Hans

 

[as_audio]

1), 2) I agree,
3) complication is the trick pony of this thread.

 

[as_audio]

Correction to my post 10997:

2) I do not want to speculate about the "stability" of the current sources,
my comment applies to the "Q10,Q25 and Q15,Q25" issue only.

In fact I am in doubt the circuit as seen in the schematic 10995 can run
stable without servo.

 

[RCruz]

Thank you gentlemen... corrections added...

Also reduced gain to have better THD