Simplistic NJFET RIAA

[Salas]

...No, 56VA apparently. Problem is they jump from 28V CT model to 36V CT model with no option in-between. The 115VAC wall nominal hovering over 120VAC in many cities forms part of the excess vs expected nonetheless. 33VAC nominal model in same series should have been more compatible to our purposes.

 

[AndrewT]

An auto transformer would be a better alternative to a voltage dropping resistor.

 

[analog_sa]

An even better option would be to either wind a few more, or take a few turns down if the transformer construction allows it.

 

[Turbon]

Thanks Salas. I did have a quick test with my other rig but too brief to make any comment. I have been playing with my vintage rig and it is very good. There is plenty of bass and top end is silky. I have settled with loading of 220R with my modded denon 103(uwe body/ESC retipped).
Quan

Hi quan.

Haha, easy to get distracted for a while... Do you mind sharing what you are using at C3?

Regards

 

[Salas]

Some good option for US and Canada lower internal market freight charges, no customs, spec stated at a more real life 120VAC primary. It should put out ~33VAC in our low 0.1A per rail draw. Can drive two raw PSU as a single unit since it has two independent secondaries, has both static and magnetic shielding. AS-1232 - 100VA 32V Transformer - AnTek Products Corp

 

[Turbon]

Salas, a while back you informed us about what resistors made an impact on sq but I can't find the post. Could you elaborate on this and maybe direct to what appears to be the best for your ears (keeping in mind that you seem to prefer fast analythical tones ).

Regards

 

[Salas]

For what positions in the full circuit you refer to?

 

[Turbon]

For what positions in the full circuit you refer to?

Tha audio chain. RIAA, R1/14...(R5/7 i believe) and so on... Most important to least. Not to far I hope since these costs almost as much as an divorce .

Regards

 

[Salas]

Rhopoint MiniOhm or Vishay VAR in wirewound or Z foil, Welwyn 15ppm in thin film lower cost.

 

[Turbon]

So, RIAA, R1/14, R5/7 are the ones to target? I have the welwyns for now in R1/14 and as a 220R alternative for RIAA. Waiting for Charcroft Z-foils and miniohms.
But as I'm ordering miniohms now - would there be any gain to use them for R5/7? Or further down the chain?
Whatever of these will be reused in the mez and in other projs!

But lazy as I am, I should probably switch to my reference speakers before listening...

Regards

 

[Salas]

More to R5, bit less to R7, R10. Cart load one also of course.

 

[Turbon]

Ok, incorporated the miniohms for R5. Probably totally unhearable but we'll see.
Everything warmed up and changed speakers to R2 Linn Kans.
Cart load would be 47K with 220R in parallell.
At least for now

Regards

 

[Salas]

R5 is part of Riaa along with the more influential R14 47k while R6 is heavily shunted by R5 that dominates. You ordered the same type at least, not a bad thing.

 

[Turbon]

R5 is part of Riaa along with the more influential R14 47k while R6 is heavily shunted by R5 that dominates. You ordered the same type at least, not a bad thing.

Well, yes miniohms and velwyns but not the others. But then again - I do not have a proper C4, fiddled with C3 - obbligato 0.1 in place again, cart used less than 10h, shitty cabling in TT (waiting for renewal) and on goes the woes...

Regards

 

[Salas]

My Walker TT is at the surgeon's for a few days now. DC motor transplant was successful, I visited it yesterday. I asked the surgeon to perform many unholy acts like filling the 774's wand with silicone, bastardizing the counterweight, adding new perspex plinth base, drilling the plinth for motor controls etc. It already showed strong signs of better performance to be expected after full recovery.

 

[Turbon]

My Walker TT is at the surgeon's for a few days now. DC motor transplant was successful, I visited it yesterday. I asked the surgeon to perform many unholy acts like filling the 774's wand with silicone, bastardizing the counterweight, adding new perspex plinth base, drilling the plinth for motor controls etc. It already showed strong signs of better performance to be expected after full recovery.

Now Salas, just buy an old Lenco from an unfortunate widow - they are good just at stock level. I have 3 of them, just swet... I usually buy them for 50-60€ from end users.

Regards

 

[alexkosha]

47R 2W to yet another same type 4700uF/63V cap. So you form CRC. About 100mA X 47R=4.7V loss per channel raw DC line. Put 10K 2W bleeder across that last cap too.
If it is for R input filter, I.e. in line directly after the bridges feeding the existing filter capacitor only forming RC, use 15R 2W since there will be no cap directly to the bridge to hold the full peak voltage of the rectification cycle. Thus, its less efficient. Smooths for EMI in that position too. It rounds off the sawtooth looking charge edges.

Hi Salas,
Please see attached picture and let me know if I got you right.
I'll try to use 15R 2Watt wire-wound (inductive type). Or, should I use some other resistor type?

 

[Turbon]

Hi Salas,
Please see attached picture and let me know if I got you right.
I'll try to use 15R 2Watt wire-wound (inductive type). Or, should I use some other resistor type?

Are you shure Alex that this is the right picture?
Salas, would it be any gain in buying a heftier trans and follow this CRC to get it down?

Regards

 

[Salas]

@Alex
Non inductive is better. There are good metal film to use. The schema is alright. The noted slow blow fuse rating varies according to your specific transformer(s) primary fusing spec of course.

 

[alexkosha]

How about these chockes instead of resistor in RC:
1000uH 5%, 200mA, B82144A2105J, EPCOS