Simplistic NJFET RIAA

[Salas]

I know a lot of people with SL1210 turntables change the cables, considering them not up to the standard of the rest of the wonderful deck. I used to love my SL1200. The arm is good too. I'm on a DIY Lenco these days though, with a terminator style linear tracker I've nearly finished.

He has 1710. I think there is some form of suspension involved.

 

[LucasAdamson]

Sure, but they have the same arm, and share a lot of aspects, including the cabling by the looks of things.

 

[stajo]

1710 is basicly a semiautomatic 1200. I dont see anything with suspension that cabling would affect.

Im thinking of changing the little AC cord also to something twisted. Any reason why not?

 

[AndrewT]

Cabling from the arm board is part of the suspension.
It will affect the effective spring rate.
If the cable has different stiffness in different directions then the change in stiffness due to the cable can have a deleterious effect on replay.

 

[stajo]

It is the cabling after the little board on the pic and the tonearm that bridges to the free mass area

 

[LucasAdamson]

Yes Stajo, the cabling out from the little PCB is NOT part of any suspension. It's just cheap phono cable with cheap molded phono plugs. Ripe for replacing, in my view.

 

[stajo]

Ah well I didnt wanna wait so I did some quick and dirtys so I can listen to it when I build the rest.

Putting them in boxes needed some 50 mV adjustment again on VR2. Even without full enclosure (no lid) there is hardly any hum to mention. I can hear some 100 Hz in right with ear in cone. Left is dead hum free.

Gain is about one quarter of pot setting less then my Focusrite Scarlett. Bass is impressing from start. Overall sound is nice, after first record.

I set the load switch to 6K51 from start. I guess I need to read up on needle pressure etc now to tune it in.

I found only one screw to fasten the puppy with. The ones that were was to long. And I couldnt find my record brush

Whatever. Cool start

Sorry for the bad pic, holding cam with one hand.

 

[Salas]

All works properly then, no doubt. The gain is 43dB in your config. Use shorter signal cabling when finalized.

 

[stajo]

Worked even better when I didnt use max needle pressure. Cart chassie was touching the vinyl

Oh. Scary resolution. Feels like gain is coming to. Maybe cappys needs some softeninng. Turning knob down every minute

 

[stajo]

Gain is now fairly much on par with soundcard. more burn in tomorrow, off to some concerts

 

[Salas]

Worked even better when I didnt use max needle pressure. Cart chassie was touching the vinyl

Oh. Scary resolution. Feels like gain is coming to. Maybe cappys needs some softeninng. Turning knob down every minute

The suspension was depressed and output went down. Watch the cart, take it easy with TT set-up. After all is well checked try about 3K load switch point too.

 

[LucasAdamson]

You can buy stylus weight scales on eBay for $10 from Hong Kong!

NEW Vesion Professional LP Digital Turntable Stylus Force Scale Gauge led dzr | eBay

 

[stajo]

The suspension was depressed and output went down. Watch the cart, take it easy with TT set-up. After all is well checked try about 3K load switch point too.

Yes no wonder. I had it apart for some greasing some time ago, prolly I just left the arm for max stability.

Cant see the stylus weight on my cell but I sure need one thanks.

Impressive with that little disturbances in open chassie. Theres a bad over dimensioned trafo some 40 cm away and it stands right under the deck trafo.

 

[Salas]

Maybe the cart itself or the TT wires pick a bit of fields too. Later when all is dressed and put properly its possible even little hum traces will nearly vanish.

 

[stajo]

Maybe the cart itself or the TT wires pick a bit of fields too. Later when all is dressed and put properly its possible even little hum traces will nearly vanish.

I'm planning to laminate top and bottom with grounded alu/steel/alu with insulation inbetween. Id be surprised if anything gets in. Final placement is further away from trannys. Sure looks promising

 

[dimkasta]

Quick question. Do we solder the heatsinks to the SFP pcb or do we let the thing hang from the transistor's legs??

 

[Salas]

Never hang on the pins. Sinks soldered firm to PCB. Align and tighten the MOSFETS and solder their pins last for no mechanical stresses to remain on pins.

 

[stajo]

The deck seems to have lost right channel over night.

 

[AndrewT]

You set the alarm clock differently.
It's still asleep.

 

[stajo]

You set the alarm clock differently.
It's still asleep.

Thank god

Well it seems like its the candycables with stupid RCAs. Possibly in the end cause I can wiggle it and get resistance 148 ohms and zero ohms. Didnt I just say that I hate RCA? And now I have to solder new ones