Simplistic NJFET RIAA

[Joao@AltheaMusica]

Originally Posted by RCruz

Well, in this case we have the same number of active devices for 44dB or 57dB.

So the stepup TX just adds one more component in the signal path

I already experimented a Denon stepup TX with my 48dB riaa and liked it but it adds some hiss (imperceptible).

Off course I needed more cables and the signal passed on several more switches

A friend had hum problems with the same stepup device......

Correct, the same number of "active" devices but the step-up TX is not to be seen like a transistor stage, remember a transformer produces LINEAR distortion and a transistor NON-linear distortion - which is given by it's data.

I never had hiss pronlems with step-up transformers, so what's going wrong? Ground loops or shielding problems of the TX?

Agreed, you need more cables etc... but who cares when it sounds good. BTW, I build my step-up TX into my phono preamps so we have fewer cables and shorter connections.

Ricardo like I told you, come over when you are in Germany and have a listening session here.

[The Space Egg Corp]

Originally Posted by Salas

The 160 and 301II should be about 25-30mm/N. That is why the carts work on some seemingly impossible arms. For so many years people get confused and the hi-fi press could do some subsonic measurements on some disputed carts, see what happens. Instead, they wax away lyrically.

Yes indeed Salas

All the Denon figures are useful for (if that even) is to indicate the relative compliance within their own range.
Thanks for the 'real world' figures.

Goldring state the 'static' compliance of my previous cartridge, the 1006 to be:-
24mm/N lat & 16mm/N vert
Which seems to be similar territory to the DL-160 & DL-301 II.

Anyway I still have a bit of 'make up your mind time' left.

I'm going to strip down the Thorens and SME at the weekend hopefully, for a good cleaning, and since I fancy building a whoping great mains filter for it, I will also investigate the electronics, and see if it's worth taking the AC stuff out and building an outboard PSU.
Have also got some plinth painting to do.
What do you think about a bit of a Jackson Pollock rip-off, like John Squire of the roses did his guitars (and the inside of their record labels offices!).

As for the 'Hi-Fi' press, If I had anything to do with it, I wouldn't let 'em waste good trees on it!

Cheers for now Simon

[Salas]

Maybe a Geddon PSU like they DIY for Sondek. Just don't listen to the Stone(d) Roses while wiring up. Else its going to end up replaying only reverse drumming.

[The Space Egg Corp]

kednoS eht rof USP noddeG eht tuo kcehc ll'I

sreehC ...

[Salas]

OK check it out. There is good word of mouth about it.

[CaNNA3IS]

Hi all,
I run through the topic more or less and started to build a phono with shunt.
Please find version below on picts. With the early Salas shunt ( changed the zener to 36V) it worked with an audible hum but did well. So i went forward on making a new shunt (r6 mod, led vref ). The shunt is working R1(10ohm) makes 1,9V so i have approxx 200mA but the Riaa sound on very low volume.
Some changing in components was made in riaa that i orderd riken and prp resistors and low esr elkos. Since 2.4k in prp was not available it was substituted with 2.2k.
With the other shunt or with a lm317 the volume was on the right value.
I am totally down and thinking of giving up.

Any advice would be appreciated.

Karesz

[Salas]

Do you have an oscilloscope? If there is oscillation at the output of your new shunt, then signal volume goes down and hum appears. Do you have hum also? Any pictures? Delete C9 and make R7 1k2 for a start. Maybe there is interaction by the cap or the buffer overrun with current especially when with a smaller R11.

P.S. What is the mV reading across your new shunt's R4?

[CaNNA3IS]

Yes I have scope and hum also but signal seems stronger then hum. I'm working now so any try will be place lately afternoon at home.
I took shots yesterday but forget to bring cable for phone :-(.
For base i used ikoflexer "squared" pcb and in place of R6 i changed to 2sk170.
All fet's IDSS are between 7 and 8. IRFP's on sink generating light warm.
I did a measure last night on the shutn output on positive side connected a 0,47 ohm 5W resistor and mesured Voltage and get 50mA on it.
As i get home i will make and upload photos. What should i measure with scope?
Anyway sorry for my neewbie question and thanks for your quick reply.

Karesz

[Salas]

If you will just hook up the scope between B+ and gnd, setting the scope in AC mode, you should see a straight 37V line. If you see waves or other weird things then the power is oscillating. Make sure about the orientation of the 2SK170 you substituted R6 with it has pin 1 towards +Vout line. In general don't worry, you have built two very classic and repeated circuits around here, and its impossible they will escape us and not work perfectly. Don't forget to take out C9 and make R7 1k2 on the phono. Do you have 7mA IDSS on that phono too? We will have to check out some bias voltages when you will be near it later. All drain to earth points and Q3's collector to earth so to see if there are issues there. With 0.47K dummy across the reg's output you should get nominal 78mA through it and the Vout should stay at 37V.

[CaNNA3IS]

Thanks
When i get home i will try your suggestions.

P.S. C9 has been already eliminated because i forget to solder it in.