TLE2426 or TLE 2425

[domi33 0]

I can get from my parts supplier only a TLE2425. Can I use it in place of a TLE 2426 for a virtual ground? What is the difference between these two rail splitters?

[bpribadi 0]

TLE2425 is for spliting 5 volts voltage only, therefore not suitable for headphone amp.

[domi33 0]

Thank u bpribadi. In fact I intend to built a A47, therefore I will use the TLE2426 for +9v/-9V power supply. About the A47 which of type cap shall be used, for the cap in the input line just after the panasonic 10K pot (1uf or .47uf, depending on A47 or CHA47), are they MKT,MKP ? What are the best?

Edited October 11, 2004 by domi33

[bpribadi 0]

Polystyrene is the best, but the biggest capacity is still too small for input cap. So the next best is Polypropylene, so far I saw 2.2 uF is the biggest for polypropylene. Actually beside polyprop, paper oil cap is also good for audio, some said even better than the plastic family. But paper oil is difficult to get.

 

Size is depend on the input resistor after the pot. If you use 100k, and you wish to have bass roll of below 20 hz, you can use this formula to get the frequency roll off:

 

f = 1/2*3.1416*R*C

 

With R=100k, 0.47 uF is sufficient, which will give bass roll off starting from 3.4 Hz. You can buy Solen cap from Well Audio, it is one of the best input cap. But even better if you don't use any input cap like most of my amps.

 

 

 

 

 

[domi33 0]

Thank u for the explanations! In the A47 schematic, you have on input line after the cap, the signal going to V+ of the opamp and a 100k resistor going to the ground. As the input impedance of the opamp is very high, the input resistor is 100K.

If you can omit input caps, what are their function? do they prevent DC offset?

For Solen cap, I noticed there is "made in France" printed on them. I live in France and have found a cap manufacturer which products have same specs than Solen caps. I am quite sure they are manufacturing for Solen.

I know there are Solen caps in the RA1, but are there Solen caps in the original A47?

[jtfoo 0]

The only reason why there's an input cap(DC blocking cap) is to decouple the DC. Basically it prevents the DC from passing thru. The RC filter causing the low freq rolloff, which is unfortunately formed by the DC blocking cap and input impedance, is an unwanted side effect of this DC-blocking cap. Another undesirable side effect of the input cap is phase distortion in the bass. So having a large value cap to push the rolloff lower, and the bass distortion also shifted lower too. Having fast polyproplene caps will help too.

 

And I'm with Bprilda here, no cap is the best. No low freq rolloff and no phase distortion. But you just gotta make sure that there's no oracceptable dc offset coming before you decides on a no cap path.

[bpribadi 0]

but are there Solen caps in the original A47?

 

What cap to put is really up to you, the original schematic won't give you the cap brand, only the suggested cap value.

 

I'm not a fan of A47, it is not easy to find an op-amp with very low phase shift (output to input). As you see, the output of the main op-amp is splited, one way feed the input of the other op-amp used as a buffer to increase the output current. The output of the op-amp buffer will have phase different than the output of the main op-amp, therefore the signal out is a combination of 2 outputs with different phase, therefore suffer from phase shift. If the different is small, it will have minimal effect to the sound, but if the different is large, the sound will be dirtorted.

 

I suggest you try something else than A47.

 

And don't forget to bring us some France caps as goodies when you come to Singapore

[domi33 0]

In fact I hesitate over 3 projects based on 2x9v batteries: the RA1, the A47 and the 3 channel opamp from digi01. Knowing that my headphones (not Grado) are 32 ohms, which project would you recommand ( I listening classic & jazz) for me?

[Q00 0]

how bout the white noise audio headamp. the kit seems to have a following in head-fi's diy forums.