Mpp

[Joachim Gerhard]

Yes, it is the Olympia.

[Joachim Gerhard]

Good that the PNPs arrived.

[pdul]

The pnp (darlingtons)

[FdW]

Originally Posted by pdul

The pnp (darlingtons)

Darling-trannies

[Joachim Gerhard]

Here are the electrolytics. I took Panasonic 4700uF/63V.

[Stefanoo]

I have just built once channel of the paradise and it is running on the bench table and I am getting very anxious to hook it up and listen to it.

However I am having difficolties making the servo section properly working.

I haven't matched the BJTs just to run it on the bench but planning on matchin before building both channels and give it a serious listening.

Preamp is outputing a DC offset at the ouput of about 4-5V and wondersa lot which I am assuming it is normal when servo is not on (please confirm this statement).

For servo I am using Ad797 and I have noticed that when servo is connected voltage output is not 0 but something like 70-80mV.
However when fully tested, it looks like signal wabbles and then gets stable in about 1 second when I suddenly switch gain at the signal generator.

I would appreaciate very much if the people who have built it already could comment on these points and share their know-how with me.

Thanks.

[Bksabath]

I had no truble with my build of beta but I did match the transistors and did use the spec chip
AD797 may be the problem.
Is it motorboating? in wich case look at pre regulators to much Capacitance may be a problem there so maybe small coke or small resistor folowed by 2000uF just before PSU imput solve that.

There were no problem with oscillation on Paradise R2, still same ceramics caps where put in as by pass but some said they did not use them with no problems.

[RCruz]

Originally Posted by Stefanoo

I have just built once channel of the paradise and it is running on the bench table and I am getting very anxious to hook it up and listen to it.

However I am having difficolties making the servo section properly working.

I haven't matched the BJTs just to run it on the bench but planning on matchin before building both channels and give it a serious listening.

Preamp is outputing a DC offset at the ouput of about 4-5V and wondersa lot which I am assuming it is normal when servo is not on (please confirm this statement).

For servo I am using Ad797 and I have noticed that when servo is connected voltage output is not 0 but something like 70-80mV.
However when fully tested, it looks like signal wabbles and then gets stable in about 1 second when I suddenly switch gain at the signal generator.

I would appreaciate very much if the people who have built it already could comment on these points and share their know-how with me.

Thanks.

What loading value are you using for he cartridge ?
Are you experimenting with the cartridge connected ?

[Stefanoo]

Originally Posted by RCruz

What loading value are you using for he cartridge ?
Are you experimenting with the cartridge connected ?

No cartridge connected, I don't take any chance till I am confident with the built.
Input load is 100ohm, but eventually when things start working I will load it witht he cartridge equivalent impedance 4ohm and adjust input offset.

[Stefanoo]

Originally Posted by Bksabath

I had no truble with my build of beta but I did match the transistors and did use the spec chip
AD797 may be the problem.
Is it motorboating? in wich case look at pre regulators to much Capacitance may be a problem there so maybe small coke or small resistor folowed by 2000uF just before PSU imput solve that.

There were no problem with oscillation on Paradise R2, still same ceramics caps where put in as by pass but some said they did not use them with no problems.

I remember having some weird bahaviour with 797 as a servo on other designs I have done while the TL081 worked just fine.
I have never understood the reason, so maybe the problem is on the servo, don't know, I will order the IC spec'ed here.

Question: if you take the servo off, what is the offset you see at the output and how much does it wonder?

I don't have too much capacitance as I am powering it up with lab PSU and then I will power it up with batteries.