Simplistic NJFET RIAA

[RCruz]

Originally posted by ikoflexer


Nice board Ricardo! Well done. Once you find the proper paper for the transfer, you will not see many flaws at all. It is also important to press decidedly with the iron edge (or tip) in one place repeatedly, Also, when printing it, the printer has to be set to the darkest setting (done in properties in software, advanced option). They also sell special transfer paper in electronics parts stores, but it's a bit pricey.
When I have to retouch, I use black nail polish (donated somewhat reluctantly by my wife ).

Yesterday I etched the schunt board. Very messy procedure, my lungs "and my wives" where affected and I do not know how to dispose the used etchant !!!

Now the board looks ok but I can not remove the paint over the copper easily. I tried nail remover "acetone" and the paint comes off but smudges the board (White glass fiber now becoming black "I doubt the paint dielectric properties"). I searched for lacqer thinner but can not find it easily in Portugal. Can I try regular celulosic thinner ?

Ricardo

[Salas]

kstlfido:

In your case it was the small heat sinks. You had 120mA running and you reduced to 100mA. Iko must measure his current draw and given his heat sinks maybe save off 50mA from his 200mA target, if heat sinks are small or check the quality of heat transfer, maybe some smoothing of the sink's back with sand paper and some silicone grease if not used already. If the LEDS are stronger than recommended it may well over shoot the 200mA target also. Those Mosfets are strong, but better be conservative for long life. In any case, we use plenty of current here for quality reasons and we can always reduce some, if our sinks end up rather small for what we originally set.

[nicoch58]

EB tin the pcb ,old school but fine

iko ad some alu ,big washer in front and back of mosfet ,long screw and so on ,to tame a little....

[Salas]

Originally posted by nicoch46
just if you have suggention on pcb design.....

the guys make good works, can do better ?

I am no PCB expert. I do point to point, you know. I would try to exploit the PCB opportunity so to be more creative with grounding if I was making one, sub stars, separation of nodes, ground planes, very compact gain stages, such stuff I guess.

[Thomo]

Originally posted by nicoch46

pcb design is a art ,hope this help and I do not know more

Tomo you make a discount on box for Salas gang ? or GB ?

PCB design is something I quite enjoy, but it does take practise and I still have lots to learn.

I shall do my absolute best to help out anyone of this forum/thread with good prices on cases or parts or anything. It's the least I can do in return for all the help and advice I've received.

Regards,

Lee.

[RCruz]

Originally posted by Thomo
Hi guys. I just swapped the 100nF cap from a Mundorf Supreme, to a Russian Paper in Oil 47nF and got quite an improvement! Treble is definitely better and mids seem more open. The soundstage also seems more 3d.

I am really surprised by this, as the Supreme's are really great caps.

Hi Lee

Those are very good news. I believe that seetles my decision regarding the coupling cap

[iko]

Originally posted by kstlfido
Jeez- lame-o review dumped attachment..here it is-

-K

Kent, that is one PRETTY board. Very nice indeed!

[nicoch58]

tin is good frend for cable, all know prevents copper oxidation... but for skin affect the rfi go on tin usefull on main cable and psu

[nicoch58]

some links on caps-resistor test

http://www.tempoelectric.com/caps.htm
http://www.sasaudiolabs.com/resistor.htm
http://www.ecp.cc/cap-notes.html
http://www.audiocircle.com/circles/i...opic=54218.0--

I post too much today

[RCruz]

Originally posted by nicoch46
HI Cruz

I see that you mod a lot your meridian ......

by the way he have metal shield around phono ,a simple psu design and one opa-amp ,buffer?

I thinks the Salas phono-shunt are super design ,DIY are always better you want connect in the meridian ?

you can thinks a pot like otptivol and connect direct to amp

I modded the Meridian PSU (with stupefyingly good results) and replaced the coupling cap between the Head amp and the Riaa.

There is no metal shield on the Riaa (only a plastic cover that I removed). (As a matter of fact, the +-15v rayregs I built are quite close to the head amp).

Layout is like: MM head Amp -> 100uF BG Nx 6.3v -> Riaa -> 10k linear pot -> output metal can opamp -> no output caps to the 103 pwer amp.

Sounds fabulous but I want to get rid of the opamp.

I believe I will build a preamp using Salas Riaa -> 50k linear pot -> buffer -> output to the 103 power amp.

Ricardo

Note: At lunch time I used Dyrup 8004 celuloid thinner and the ink just dispeared... (also ate the Paterson Photo cuba I was using for the bath "Dustbined").

Tonight I will drill the holes, than clean up with Duraglit.
Latter I will build the schunt (parts = +-15€ )

I do not know if it can be better than the expensive Spower (this sreg can output 5Amps heavily heatsinked and sounds wonderfull in my CDP jfet output stage) but I am following the threads indications.

Hope my new preamp can drive the 103 power amp without any fuzz.