Linear regulator for Pimeta V2 - Page 2

Okay BTW I was just watching your "How to use a multimeter" tutorial video Your website is very helpful!

I'm almost certant that I'm going to get Sigma 24 and 25 boards and make the power supply from them. Sigma 25 uses linear regulator with TO-220 package and I'm going to add a heat sink with it, so the heat shouldn't be a problem. Even if I would make my own regulator the space wouldn't be a problem since the enclousure propably will be 6.3 x 6.3 x 2.03 inches. It will be a desktop amp and since this is my first project it's better to have a bit too much space than too little. My current plan includes Pimeta V2, bass boost, power switch, BantamDAC, a switch for dac and rca inputs, isolated Neutrik plug and Sigma 24+25 power supply so I will need that space.

Okay. Now I just have to order the rest of parts and wait their arrival!

Many thanks for all the repliers, you have been very helpful!

Hi guys,

...and sorry for bothering you again! I'm gonna make bass boost into my Pimeta V2 and I don't know how to deside the capacitor values or connect RK097 -pot into caps. Could someone help me!

Here is what it said in Tangents website:

"There are two extra pads off the ends of the thru-hole footprint for R4, plus the SMT pads on the bottom side. This allows for up to 3 components here, a resistor, a cap, and a switch. This is enough to give us a weaker form of bass boost than in the PPA, which I call “unity boost.” The difference is, the resulting amp is effectively just a unity-gain headphone driver with bass boost. This is fine for many situations. Most sources these days have enough voltage to drive headphones; they’re just current starved and have too high an output impedance to drive high-quality headphones to their full potential. A PIMETA in unity gain solves that problem. If you do this, I recommend using the outer pair of holes for the caps, the inner pair for the switch, and the 1206 SMT pads on the bottom side for the R4 resistor."

I've planned to use normal thru-hole R4's (Vishay Dale CMF metal film resistors 1/4w 4.7kOhms), add jumpers to extra pads and make something like this into scratchpad:

I have no idea where I've got those cap values... For potentiometer I've thought to use Alps RK097 50 kOhms (this one here: https://www.elfaelectronics.com/elfa3~ex_en/elfa/init.do?item=64-115-32&toc=0). Would those 0.22 uF Wima caps do the job?

I hope you get the idea!

Now I've played with bass boost calculators and got the idea what different part values do. The R3 is unnecessary with pimeta, right?

The results I got from calculator was R4 = 6.65 so the amp's gain would increase a bit (my headphones are DT990 pro 250 ohms), R7 = 50kOhms (RK097 50kOhms) and the cap value was decreased to 0.15 uF.

My Pimetas gain would now be 7.25. Is that appropriate with my dt990s?

Bass boosts corner frequency would be 157,1 Hz, shelf frequency would be 21,6 Hz and boost 17,7 dB.

How I should connect the pot since the RK097 has 6 pins?

Oh, now I think I got the idea!

Once again one of my fancy pictures..

This one should work? 

BTW I found this image (below) from your website and it points out for what those pins in potentiometers stand for. Could I leave those two ground pins as they are and use only inputs and wipers? And that is only for bass boost. Or should I solder those to chassis or something?

Thanks!

Quote:

Originally Posted by tangent 

Tie the ground side lugs to the wiper, as shown in the PPA schematic.

Oh, right! I'm not so good at reading schematics.

Thanks for helping me Tangent! Finally I know all the parts I have to order.