MPP

[RCruz]

And now some curves.....

 

[analog_sa]

As there is a 10x ratio if I load the cart in the secondary with 470ohm, the cart will see 10sqr x 470 = 47k if I am not wrong.... do you believe it can be done ?

It will also see whatever capacitance is at the input x100 + the parasitic capacitance of the transformer. The S/N will also suffer. Still, it doesn't hurt to try.

 

[Joachim Gerhard]

In Germany we call it a shott in the eye from behind.

 

[analog_sa]

Ouch, that would hurt

 

[RCruz]

Well, I could reduce the gain so to feed it with a Sounsmith cart but I need to have 47k load impedance.... how can I do that without the trafo ?

is the imput impedance of the paradise high enough ?

 

[as_audio]

In the schematic of post 10938 the input resistor is missing anyway.
The circuit does not work properly without. Change it to 47 k and
check for no dc / oscillation..

 

[RCruz]

I remenber Joachim informed natural input impedance should be around 10k

If so, even with 47k load, the cart can not see more than 10k..... am I in the right direction ?

Anyone has a method for simulating input impedance ?

 

[as_audio]

This may be true - I am too lazy to calculate it now.
You can always measure the input impedance.
Depending on the cartridge 10k may be OK.
This is Try It Yourself Audio.

 

[RCruz]

Acording to my sim, input imp is around 2.4k with a 47k load..... not good for MM

 

[RCruz]

Try It Yourself.....

That is why I was considering the SDT

maybe I can place a jfet follower in the imput to have high impedance and than reduce the voltage with a L pad......

 

[as_audio]

A rough calculation gets me around 1k2 input impedance,
β taken as 200 and Ut 28 millivolts (warm transistor).
Other gentlemen agree ? Schematic again post 10938.

 

[as_audio]

For MM I recommend a different phono stage ..

 

[as_audio]

A rough calculation gets me around 1k2 input impedance,
β taken as 200 and Ut 28 millivolts (warm transistor).
Other gentlemen agree ? Schematic again post 10938.

According to the data sheet of BC337-40 current gain may be 400
rather than 200 so Re would be 2k4 according to your simulation ..

 

[misterdog]

I think 1k2 is on the money. A friend has simmed the whole circuit and he came up with the same figure.

 

[as_audio]

Well, do not compare to my calculation but to the other sim.

 

[keantoken]

In my experience the BC337-40 tends to be around 400.

 

[as_audio]

Who can explain two simulations differ by a factor of two ?

 

[FdW]

Who can explain two simulations differ by a factor of two ?

Publish both and we will see...

 

[FdW]

In my experience the BC337-40 tends to be around 400.

Some have selected for near 500.

 

[FdW]

A rough calculation gets me around 1k2 input impedance,
β taken as 200 and Ut 28 millivolts (warm transistor).
Other gentlemen agree ? Schematic again post 10938.

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