Valve Itch phono

[merlin el mago]

Yes, I will look for.

 

[Salas]

Lets hope it will work as noiseless as before with no SQ loss also since common winding and heater voltage reference for both reg branches now.

 

[merlin el mago]

The two heater windings are separate!!!

Because they both now see the HV voltage divider heater lift. Put bigger sinks...

With this one still too hot. http://es.farnell.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=-5&urlRequestType=Base&partNumber=1319812&storeId=10176

What thermal resistance is necessary?

 

[Salas]

The tx have two secondaries more of 5,2V AC 3 A each so can reach together 11,8V AC?

I left the Lundahl heaters or I come back to the two 12V 3A?

The two heater windings are separate!!!

You planned to first try put two windings in series to make a higher one I thought.

 

[Salas]

Vin 12,49 & 12,63VDC

With this one still too hot. SK 129 63,5 STS FISCHER ELEKTRONIK, Disipador de Calor, Extruido, Montaje en PCB, SOT-32, TO-3P, TO-220, 4.5 degC/W, 63.5 mm, 42 mm | Farnell element14 Espana

What thermal resistance is necessary?

That one is the tallest sink of that series and it should do a good enough job when you need to replace a smaller one for 1-2W more demand on the same footprint. Each of your regs dissipates around 6W with that Vin and the two units two types tubes heaters as load. That sink says 4.5C/W but derate 30% for spot heating and it would be 6C/W ιn perfectly open surrounding to rise 36C above ambient. 3C/W after derating would have been more optimal.

 

[Salas]

Another way would have been to share some heat on a CRC or RC fat 15W resistor dropping Vin to 9V DC and keep those sinks.

 

[merlin el mago]

You planned to first try put two windings in series to make a higher one I thought.

Yes now 2 windings in series using only 1 Lundhal tx for heaters.

Another way would have been to share some heat on a CRC or RC fat 15W resistor dropping Vin to 9V DC and keep those sinks.

Very good idea, did you calculate the value?

 

[Salas]

No I did not I just said it in general. See for R between bridge and C in Duncan's PSUDII. RC won't ask for yet another reservoir capacitor. 0.9A draw for heating a 12AX7 class and a 6SN7 class bottle per branch. 1.8A total for one in series made winding.

 

[Salas]

Or put some 1R heavy resistor between bridge and reservoir, measure drop, and estimate a good value for losing enough down to 9VDC raw.

 

[merlin el mago]

I have some Caddoks 1R with heatsink, I wil try tomorrow and let you know.

Thanks for support and good night.

 

[Salas]

With the practical method you don't have to analyze much in sim how the trafo will drop under load etc. Cut and try they say. Bye bye!

 

[merlin el mago]

Yes I will use the practical method.

4Ω

 

[Salas]

4Ω

Alright

 

[merlin el mago]

Time to listen with 0,1uF interstage capacitor.

 

[Salas]

Yes, that one too. To be listening "by the book" first.

P.S. You put 1R one after the other until with four of them RAW Vin dropped to 9VDC? There is 3R9 value to get and finally install if so.

 

[merlin el mago]

No, only one 4 ohms resistor. Fortunately I have 1R and 4R both Caddock mp915, 15w using box as heat sink.

Now the mids and bass are ok, perhaps I will have to take off the 330pF added to the 15nF RIAA used to reduce the extra highs....

 

[Salas]

15nF+ reduces HF. 15nF- boosts HF. V1.2 schematic has 15.75nF HF RIAA cap and 2.2uF output cap. That one had a certain SUT and TT to align with so trimming to your own HF cap value sweet spot is normal.

 

[merlin el mago]

Salas can be enough 100uF + 100uF in place of 220uF + 220uF as mains filter caps?

 

[Salas]

Possibly

 

[merlin el mago]

Thanks, I will try.

Removed the Elna Cerafine 220uF+220uF 350V and changed for Rubycon Black Gate 100uF+100uF 350V and the difference in SQ is very big.

Added a second BG 100+100uF 350V & 44R to make CRC.