Simplistic NJFET RIAA

Thanx

Yes i love my WTT, some dont like the lack of a lift but after some training i find the way of operating the arm much more comfortable and secure (even after a few single malts)

My WTT is the Record player witch is the least expensive i believe the more expensive have more arm adjustments.

Possible upgrades will probably be be motor related.

This "beginner" WTT is great as well and worth to upgrade it. I used 3 spikes as "feets" and a granite base plate - sounds wonderful. For the motor I'd try a small DC-Motor from Premotec :: Premotec :: Precision Motor Technology B.V. :: Your ideal partner for total drive solutions ::
 
Could be,

But when testing out different transformer solutions and mains cables earlyer i found that the bass changed (got better) with better mains for the transformers.

I tryed to replace the 300VA R-cores in my BIII dac with the Shielded Torroids and the difference was not huge,
Could possibly had been some better resolution (hard to say) but i recognized the hump in the bass.

Thats when i tried to change to a better (audio) outlet without a jumper in between found that the bass was shaping up.

What i now hear now could be a mix of many: different load, less "micro-phonics" due to less vibration, better mains and shielded mains cable
Now that you know that Low Loop Area in your cabling is paramount to realising the performance of the system, do you think that putting the Rcore in, instead of the Toroid, will change the performance?
For the better, or for the worse, or identical?
 
No, experience with current phono stage

Are you in FSP test phase already?

Amazing how collecting parts and inserting them into the boards is the easy part.

Always takes longer to get the enclosures and the wiring finished than one wants to remember from the last project.

Don't want to screw it up so trying to be methodical. Never have built a semiconductor amp before so I am nervous about destroying those rare FETs.
 
Not afraid to solder them!

They aren't that flimsy if you will not overwork them. Use up to 25W wall iron or a controlled station at 360C with eutectic solder.

Just don't want to blow them up with improper final wiring/assembly.

Boards are complete. It is simply the wiring and enclosures.

I was alluding to the time I have ALREADY spent!

I am making my enclosure more complicated than is necessary. I am using Dave Slagle's autoformer attenuators at the output and those large caps require more space so my enclosure is growing.

I am hoping the phono stage will drive my 10K ohm impedance amplifiers along with a 40K impedance line stage for frequencies below 500 hz. Need the gain below to match the higher efficiency drivers above.

Made with a mixture of cedar and balsa - lots of gluing. This box will sit upon an HAMMOND seven inches square box for the transformers and rectifier board. If I have any noise problem I have some TIShield laying around though I do not want to use it. Hope there is no need.

I have found the heatsinks included do not readily fit on the input FETs. Had to "open" them up a little. Are you using any paste for these? I have not but started to wonder ... Any need for any additional heat sinks for the small FETs?

BEFORE THE MONTH OF APRIL COMES TO AN END - I will have this completed and IF I don't I hope you will scold me. I will deserve it!
 
diyAudio Chief Moderator
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@ Rick

-The third stage in the FSP is an AC coupled B1 like buffer, has about 60 Ohm output impedance and it can source up to IDSS current. I hope it will suffice in your system. You got to check that its C value regarding output coupling is good down to 10Hz at least with the line impedance you plan.
-Yes, those minisinks need some pre-formation to fit the TO-92s indeed. Maybe they make them like that to surely fit snugly. Paste, no, not really. The JFETs are not going really hot, its we saw that the mini-sinks keep them more controlled regarding self current drift. Make their cold to warm distance shorter. Useful in the double and single JFET input MC configurations only. But not absolutely necessary.
-Alright, take your time, we hope to see nice pics from your highly customized TT and phono when ready.
 
Amazing how collecting parts and inserting them into the boards is the easy part.

Always takes longer to get the enclosures and the wiring finished than one wants to remember from the last project.

Amen brother! :D

I enjoy stuffing boards and soldering. Case work is the hard part for sure. Layout, drilling, wiring, etc. Always harder than I remember. Also a lot of time spent thinking about how to get from here to there, the best way vs the most practical way. Silly things like "Do I have enough of those screws? Can I get more locally? Why didn't I order more of those?"

Enjoy!
 
I have found the heatsinks included do not readily fit on the input FETs. Had to "open" them up a little. Are you using any paste for these? I have not but started to wonder ...

Salas' answer is definitive, but yes, I used paste. Just because I never fit heatsinks without it. I'm not saying it is needed, just that I have a tube so why not put a skiff on the sink to improve heat transfer? It can't hurt.
 
Now that you know that Low Loop Area in your cabling is paramount to realising the performance of the system, do you think that putting the Rcore in, instead of the Toroid, will change the performance?
For the better, or for the worse, or identical?

The R-Cores installed in my BIII dac is same ratig 300VA bought from Selectronic and made by Shilchar.
The test i did by replacing the 2 R-cores for the I/V (Legato) vas brief and not scientific.
The installed R_cores had better mains cable and proper Furutech mains plug.

The toroids had a simple mains wire with a pre-installed socket.

Still (after getting rid of some unwanted extension cable) i believe the toroids beats the R-Cores.

And after discovering how much better the toroids became with proper mains wiring i believe the toroid wins the race.

The difference was most eminent that the hole sound was more quiet by that i mean less noise.

The physical difference between the 2 transformers it that the torrid comes out with the actual secondary winding (sold core) and its MASSIVE.
The R-Core has a multi-strand wire coming out from some cind of junction where several wires meet (probably they make several voltages out of one template.

pictures here, (time to test your Norwegian Vikings)

http://www.hifisentralen.no/forumet...va-rt-pa-lokalpostkontoret-4.html#post1620662
 
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diyAudio Chief Moderator
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Salas.

i am considering a passive preamp setup, (have tied briefly and it worked ok)
Omitting the whole preamplifier an just leaving my favorite 10K Seiden attenuator in.
The power amp has 20K input impedance

Do you think the Folded will match a 20K input impedance?

Its 2u2 coupling is good down to 20K and it has a buffer output stage, so yes it can drive it. But it will be driving the 10K pot and this is heavier. You could use a hot rod DCB1 and that pot. More red LEDS even, he, he.
 
Perfect, ill try the 10K Seiden for a while and work out if i like it.
I wondered about the volume when it was connected via the preamp at full volume vs the folded connected directly to the poweramp.

Whith 6db gain the poweramp should have sent out a higher signal than the folded itself.

The funny thing is that the volume with the folded connected directly is not lower (possibly higher)

I guess its because the folded "sees" 20K instead of 10K input impedance.

I will possibly modify the attenuator to a 20K, and see if it likes it its a shunt type type and i guess its only a matter of changing the load resistor to get 20K input
 
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