Why 7805 is better than LM1085?

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My ears, the audio measurement tool

No measuring rig can acurately display what we hear.
OTH,there is far more that can be measured then most seem to believe.

It is possible though, as your second statement suggests to correlate PSU measurement with the perceived sound in almost every area.

This took me some time, and resulted in some suprises, but to those with the time, will and necessary test gear (a good PC soundcard and a spectrum analyser program should do it) the results are there for the taking.

You may then, like me, be astounded at just how much difference an apparently tiny change in performance can have such an amazing perceived effect on just about every area of a musical performance.

Never forget that's the ultimate goal - if it sounds good, it IS good. Finding out why is often the hardest part...

Andy.
 
Re: smile

patwen said:
Anybody in his right mind would be absolutely delighted with the concentrated knowledge and experience he got for free.

Not this guy. He just started a new thread, complaining that on the other one they gave him so many different answers, and pleaded if someone now please give him the RIGHT answer.


janneman>

Please don't be offended. We are all discussing here, right? For some answers which from my limited experience, I cannot agree on, I expressed my opinions. Taking other's comments without self-thinking is, IMHO. counter productive.

Please don't take that as anything negative, as my opinions could well be wrong. But at least I am trying, testing, listening and try to learn and share as I go along, so please don't shoot.

Anyway, I will post the circuit diagram up when I am back in town in a few days, so we could have something more solid to discuss our opinions on.

Many thanks for all the inputs.

Patwen,

I appreciate the reply. This was not meant at you personally of course.

I am very well aware that there is a wide range of experience on this board. I have often fallen in the trap of thinking to know it all. This board puts you back on the floor again now and then. This is my gain.

What frustrates me so often is that people are so uncritical not just to others but also to themselves. Does anyone belief that those people in the know got where they are just by swallowing other peoples opinions uncritically?

If you have the feeling that a 7805 sounds much better than a 1085, which is totally contradictory to all other data, doesn't that ring all the bells and flash all the lights? With me it would.

Take two amps, one with a 7805, one with a 1085, put them behind a curtain, match levels, let someone switch back and forth so you don't know which is playing, and score for 20 trials. Now, if you report those results, whatever they are, people on this board will have a very high regard for you. You have done research, you have exercised your intelligence, you have added to the body of knowledge, you have learned. And yes, very often you will have to swallow your conviction, that's part of it.

Why doesn't anyone do this? (Don't look at me, I've done my share).

Jan Didden
 
Jan, that's certainly one excellent way of verifying your perceptions. There are other ways, too- for example, I prefer to let the listener control the switch. When I hear things that don't make sense to me, doing some sort of controlled test will either clear up the mystery or give me vital and verifiable data to use as a tool.

Frank, my specialty is the wines of the Northern Rhône Valley, though there are a few others scattered around on my racks. Don't let the Napa Valley address fool you- I'm a true Francophile.
 
WINE

Hi SY,

Frank, my specialty is the wines of the Northern Rhône Valley, though there are a few others scattered around on my racks. Don't let the Napa Valley address fool you- I'm a true Francophile.

Glad to see I'm in good company.
I may be tempted to crack a bottle of Chateauneuf du Pape later on tonight since I ran out of Cahors.
My landlord imports wines from France,let me know if you need a case or two.
I love a good glass of wine but I'm no oncologists,that would spoil it for me.

Hello Jan,

Nice to see you're such a good sport.

😎
 
Power supply and Chili cook off......

"Both supplies show nothing but DC and have noise below, say,
-100 dB." 100dB referenced to what level?😕

The order of merit for power supplies is usually give as:

1. PSRR power supply rejection ratio ie. the change in output votage for a given change in input voltage. The ratio is usually in dB voltage as a function of frequency.

2. Output impedance ie. the change in output voltage as a function of AC load current. This again is shown as a function of frequency.

3.Output voltage noise ie. the absolute voltage noise of the regulator given in microvolts.

Lets assume we are talking about a typical supply for an op amp audio circuit. Lets say 50mA DC current draw, 10mA AC current draw, and +/- 12volts. To give us enough over head let's say +/-27 to 24 volts DC for the raw supply range.

Since you threw 100dB out as the number,
Let's say 100dB PSRR 50 to 10KHz

-100dB with respect to 1V or 10uVolts output votage for 10mA AC load current 50Hz to 10KHz

-100dB with respect to 1V or 10uVolts noise from 500 to 10KHz bandwidth.

The frequency range being specified for easy measurement with a PC sound card based system.

This is fairly demanding but not state of the art. For fun try it with a three terminal regulator circuit and then with whatever it takes to get there.

Since the Layoff I don't have access to the company Gulfstream G4 that I used to hitch a ride on to Santa Rosa, followed by the short drive to Petaluma to dig the less enlightened California Telecom Engineers out thier mess. I guess we will have to do this on the forum and perhaps ALW will act as technical referee.

Ready,
Freddy:wave:
 
SY said:
Jan, that's certainly one excellent way of verifying your perceptions. There are other ways, too- for example, I prefer to let the listener control the switch. When I hear things that don't make sense to me, doing some sort of controlled test will either clear up the mystery or give me vital and verifiable data to use as a tool.

Frank, my specialty is the wines of the Northern Rhône Valley, though there are a few others scattered around on my racks. Don't let the Napa Valley address fool you- I'm a true Francophile.

I agree with most of what you said. There are many ways to skin a cat. My point was of course that there's no way around thinking for yourself.

Now, about the wines, I must disagree. My experience is that Italian wines, especially from Tuscany and to a lesser extend Sicilly, taste better then French wines at the same price. OK, for very expensive ones, that is probably not true, but I can't afford those anyway.
I'll take a Rosso di Montalcino at $15 for a Saint Emilion Grand Cru at the same price anytime.

Jan Didden
 
..and for most of us (?) listening is the only way since we don't have the proper testing equipment.

And for the wines I to a certain extent agree with Jan at the price discussion but very often I find myself with an Italian wine that is excellent (thinking Amarone evenings of recent) but very often lacking the oompff (now what is the word for that with wines) that is needed by the food I cook. The Italians simply don't survive. I say the same is price/performance rule is true for Spanish wines of better qualities and that is where my loyalty lies.

/UrSv
 
*OT WARNING*

Amarone ain't so cheap anymore. If you want a heart attack, check the prices for Quintarelli.

St-Emilion is Bordeaux. That's industrial stuff. There's more acreage just in St-Emilion under vine than Côte-Rôtie, Cornas, Hermitage, Vacqueyras, and Chateauneuf-du-Pape combined. Give me the small stuff any day. For $15 (in Europe), a Côte-Rôtie from Henri Gallet will hold its own just fine against the Spanish or Italian competition.
 
Re: Printed out the 7 points and taped them on the wall

jean-paul said:


We are talking about the 78xx series here and 2200 uF is overkill.
2200 uF is more likely to be used before the regulator. 😉
Please see the datasheets for proof/ evidence or whatever it takes to believe it.

Most of you've heard about Pete Goudreau and his mods on Parts Connection DAC. Here is a qote from his post:

" All 7805 and 7905 regulators
were bypassed locally with Panasonic HFQ 12mF/6.3V 'lytics and the
7815 and 7915 regs were bypassed locally with Panasonic HFQ 8.8mF/16V
'lytics at their outputs. "

Am I missing something, or this are really outrageously big values? The rest of post can be found here:

http://groups.google.com/groups?q=a...536d4p$bqc@eyrie.graphics.cornell.edu&rnum=72
 
7815 and 7915 regs were bypassed locally with Panasonic HFQ 8.8mF/16V

8.8mF is 8,800 uF and is probably 4 times 2200uF in parallel. I've seen stuff like this done all the time. I believe he calls for 120uF HFQ caps close to load also. I t is a matter of how much work you want the caps to do vs. how much you want he regulator to do.
Pretty common approach.

Different strokes for different folks,
Fred
 
SY said:
*OT WARNING*

Amarone ain't so cheap anymore. If you want a heart attack, check the prices for Quintarelli.

St-Emilion is Bordeaux. That's industrial stuff. There's more acreage just in St-Emilion under vine than Côte-Rôtie, Cornas, Hermitage, Vacqueyras, and Chateauneuf-du-Pape combined. Give me the small stuff any day. For $15 (in Europe), a Côte-Rôtie from Henri Gallet will hold its own just fine against the Spanish or Italian competition.

OK, OK, I give up! I'll try the Côte-Rôtie when I find it. What's your opinion on a St Estèphe? I like that one as well.

Jan Didden
 
ONCOLOGY REGULATED

Hi Jan,

What's your opinion on a St Estèphe?

It doesn't surprise me that you like the St Estephe.
Very fine wine indeed.
I can't measure it's performance as a regulator though.

Fred,

Nice avatar,I could dig out some more in case you need a change of clothes.😉


Cheerio,😎
 
So much for power supplies....

Try the wine.


You can rely on me,
Fred
 

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Power Supply for the TDA1543

Hi ,
After I discovered that the 7805 worked better sonically than the LM1086 for the TDA1543 I decided to explore this issue in more detail. The Jung like regulators sounded hopeless in this application.
I started with a simple emittor follower and TL431 and feedback from the output to the adjust pin of the TL431. I ended up with a triple Darlington connected transistor and no feedback at all from the regulated ouput. I deliberately choose a slow transistor ft 3MHz. 🙂 The circuit is called a capacity multiplier in the book Low-Noise Electronic Design, C.D. Motchenbacher and F.C. Fitchen, Wiley & Sons.
The 2.2mH inductor (DC-resistance 30 Ohm) , the 2200µF cap and the main filter cap of the analog supply (four 11DQ10 Schottky diodes and 4700µF caps) form a PI-filter. The resistors around the TL431 are choosen to provide 5V output, actually it is 5.08V. The circuit shows absolutely no oscillation and sounds fine to me.🙂 It has of course poor load regulation but good line regulation.🙂
 

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