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#441
RIAA Caps

Hi,

I am somewhat confused about the RIAA Caps. The manual states 1 x 33.3nf and 1 x 11nf. However, there is another thread about V-Caps, where 1 x 32nf is going to be used instead of the 33.3nf.
Thel offers KP Caps with 33nf.

My question now is: Shall I go for FKP2 with exactly 33.3nf or shall I go for the 33nf?

Many thanks, tom
 
#445
Gents,

thanks for your response. I feel very safe with your values. So I go with 33.3nf and 11nf.

I just talked to Oppermann regarding Styroflex MESK25 Caps with 0.5%. They have following values:

1) 27700 + 5690 = 33390
2) 10000 + 1000(only available in 2%) = 11000

Three questions:
1) The values are not exact. What would you recommend. a) go for exact values and use FKP2 b) go for these values
2) They are really big. Has someone tried them
3) If they are an option, does someone else like to have some?

thanks, tom
 
#448
Holger Barske said:
33,3 / 11 nF are the official values. There's even a third combination floating around somewhere (from RCruz, me thinks).

33,3 nF is best done with 10nF || 10nF || 10 nF || 3.3nF, 11nf is 10nF || 1nF.
Click to expand...

No big fuss about RIAA small difference, as long as it comon on both channels

Riccardo combination (which I trust ) may be a better one,and shows in which direction to compromise when sorting the caps out
 
#449
Hello .

I have matched the BCs and got a set BC327 nice around 400 hFE and one around 500 hFE.
From the BC 337 i´ve got a Set around 500 hFE .

What is to do ; using thr 500 wiht the risk of ozillation , or buy / swap some BC337 with lower hFE ( around 400 ) with someone here ?

What´s best ?
 
#450
It is all depending on your skill set, how much work you are villing to put on it and the lab set up you got.

400 Hfe is best safe options at least for current mirrors but input benefit from hi Hfe as far as I understand

I will need to vear same artic gear to work in my loft (around 7 C at the momement) and get same set matched up so if you got time I am willing to help but maybe finding some body near you may be best option

Did I say this before?

PS some how with poorly matched set at around 540 I got no oscillation on R2 so ....
 
#451
FdW said:
That is 1.9 + 3.4 = 5.3V the expected voltage here is V(L111) + V(L112) - Vbe(Q104) and that is 1.9 + 1.9 - 0.6 = 3.2V. It is actualy 2.1V to high, check the led voltages L111 and L112 and replace them if needed. Replace Q4 and posibly replace Q103.

There is one thing that I do not understand, V(L110) = 1.918V so V(R104) should be 1.9 - 0.6 = 1.3V and I(R104) should be 1.3 / 10 = 130mA and that should not depend on V(TP103), mmm... anyone else?
Click to expand...

Could it be that Q104 has to high hfe or something? I just replaced Q104 and I(in) @30V is now 196mA. Before it was 210mA. I believe this is still to much as it is 148mA at neg rails.

By the way... all LEDs measure 1.9V.
 
#452
beetle said:
Could it be that Q104 has to high hfe or something? I just replaced Q104 and I(in) @30V is now 196mA. Before it was 210mA. I believe this is still to much as it is 148mA at neg rails.

By the way... all LEDs measure 1.9V.
Click to expand...

Hfe problems? not seen yet 🙂 The small signal transistors in the PSU are good as long as they have 'any' Hfe (20 and up will do 🙂). I think you should also replace the associated power transistor (just to be sure).
 
#454
https://www.rush-on-line.co.uk/cap_index.php

I bought a bag of 33nf and 11nf, they needed padding out to get them perfect, 0.1%, but they came out of the bag within a % or so of each other.

Of course they are polystyrene caps so don't 'weld' them to the ground plane. Much easier to solder them like smt caps to the top of the pads in the RIAA section and not risk melting them.

8252261216_6cff3c1666_b.jpg
 
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