Why 7805 is better than LM1085?

[janneman]

Originally posted by Terry Demol



The OP Z of the jung reg shoots up at only a few hundred
kHz. The OP Z of a good discrete can be kept quite low AND
flat to 10's of Mhz before it goes south.
But the result was attained from listening by me and others.
Flatness of OP Z and settling time was the only thing I could
corelate to naturalness of sound. They all have very low noise.

Perhaps a better measurement would be wide band
FFT at DAC analog OP?

Maybe you should ask yourself why everyone here is
so interested in replacing their OPA based I-V's with
resistors, transformers and 0 FB cascodes when
the OPA I-V's can be shown to measure superior!

It's not always cut and dry on a scope or APII.

Terry

Terry, it is true that the Jung regs shoot up, as you say. But if you compare it with the discretes, it actually is the other way around. The Jung "shoots down", and is generally much lower than discretes below supersonic frequencies. If you can have extra low Z at some part of the range (the important midrange!), I fail to see that flatness in itself is a benefit.

I readily accept that you heard a difference, but what was it? Just different, worse, better? We too often assume that a difference MUST be an improvement. Having made a change anticipating and actually actively listening for an improvement, it is very, very hard to find anything to the contrary.

And as for why everyone wants to change to transformers & open loop stuff, well, for one it is much easier to do, you need much less technical expertise, you don't need sophisticated test equipment to see if all is well. It has an elegant attraction to it: put in one of these nice transformers, weighting at leat two pounds, now there is quality! See, I put it in, and how much the sound field opened up! Incredible!
But I am sure there are other reasons as well.

Jan Didden

[jean-paul]

Maybe you should ask yourself why everyone here is so interested in replacing their OPA based I-V's with resistors, transformers and 0 FB cascodes when the OPA I-V's can be shown to measure superior!

Where's Jocko when we need him ?

Anyhow, please see this thread: Easy-to-build I/V stage

OK, I know better but I still use the OPA's mostly because of convenience... Have experience with discrete built I/V though and they can be a lot better than even the best opamps when designed right. But results till now were very good, only voluminous and difficult to build in the cdplayer. I am about to make a replacement board for a cdplayer. It will contain a discrete built I/V.

And as for why everyone wants to change to transformers & open loop stuff, well, for one it is much easier to do, you need much less technical expertise, you don't need sophisticated test equipment to see if all is well. It has an elegant attraction to it: put in one of these nice transformers, weighting at leat two pounds, now there is quality! See, I put it in, and how much the sound field opened up! Incredible!
But I am sure there are other reasons as well.

Jan, the tone of your posts gives me the idea that one is stupid not to believe the standard stuff and that it is a waste of time wanting to try transformers or such things. And open loop designs are nonsense too according to you because one doesn't need technical experience. Come on man, wake up !

[ALW]

Re: POOGE

If you use the search for this site you will find them.

Andy.

[Elso Kwak]

Originally posted by tbla
hi alw,

could you please post the scematics for the +/- POOGE discrete reg ?

best regards,
troels

Hi Troels, You mean this one from 1995:
Voltage regulators for line level circuits

[peranders]

Originally posted by ALW
Re: TL431

Peranders,

Some people actually rate TL431 as the be-all and end-all of PSU's, not on this well-informed place though.

They are poor in both noise and impedance, when used alone.

You are right though - filter them and they make good references.

431 is the cheapest "variable zener" on the market and also very good, to be a zener. The dynamic impedance is very low but it is still a zener-like component. 431 is at it's best if it is used as a voltage reference.

[tbla]

thanks........(to all of you)

merry x-mas,
troels

[Elso Kwak]

Hi All,
Attached is a further improved powersupply circuit.
The red LED and the PNP transistor provide a 2mA constant current source for the LM329. The red LED is used as a 1.6V reference providing a 1V drop across the 470 Ohm resistor in the emittor lead.
This circuit also works with four green LED's, in a series string, in place of the LM329 but sound is better with the circuit as depicted.

I also did some experiments with LT1021-5 and MAX 6250. These are expensive low-noise 5V references. I amplified the 5V to 6.9V with a OP27 and connected this to the base of Q1. Sound is definitely different but I am not sure it is better. It has a kind of inflated quality just as the sound of commercials on our national television. Also more fatigueing. I keep lowering the volume, not a good sign...

[Elso Kwak]

Hi,
I forgot the two 4700µF caps in parallel with C10 to include in the picture. Of course you can also use a higher value of choke and less capacitance.

[Pjotr]

Hi Elso,

What is the reason you are still using a “triplet”? The output impedance is mainly defined by the current flowing out of the emitter of Q3. For this reason the circuit should have a minimum standing load current of over 10mA to 25mA. So it is wise to add a load resistance of 220 ohms to the output. Or does the supply modulation due to the high output impedance + varying load current add to the sonic qualities of the circuit? And why are you loading the driving transistors to ground? (R1 and R3). A resistor between the base and the emitter is a more efficient way. I don’s see any advantages over a normal darlington build with a BC649 and a BD135 (See my pervious posted circuit). Your circuit is still spitting out the excessive noise of the reference zener directly. Take rid of it at the origin: the zener itself and not by large output caps.

Feeding the zener by a current source only reduces ripple, but not noise

[machinow]

According to some sources /LC Audio/ the noise in the power rail can seriously damage the sound due to inducting jitter in the clock generator. You, Patwen, can check this out by a connecting a passive RC filter right in front of the Clock generator IC /and before that check which it is/ os, say, 10-100ohms and 1000-2200uF, depending on consumption. Please reply to me if you find something true in this! 10-x