John Curl's Blowtorch preamplifier part III

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I'm sure Waly, witch seem so interested, will try-it and provide detailed datas of his results and will explain-us what he did:
- What kind of "wideband inductive probe"? A current probe? Manufacturer? Model?

- What was the conversion constant for this "wideband inductive probe" probe (like input current to voltage into 50ohm)?

- What was the bandwidth of this "wideband inductive probe"?

- How was this probe coupled with the power cable? Unless you split the power cable conductors, the magnetic fields will cancel, what's left is kind of common mode noise.

- SA model and manufacturer? Frequency span and RBW used in these measurement?

- How was the "wideband inductive probe" connected to the spectrum analyzer? SAs are usually 50 ohm input impedance, any high input impedance preamplifier? If so, model, manufacturer, etc...

- How did he separate the cable magnetic field pickup from any over the air pickup?


For once, it would produce something useful and interesting. I should say for once he would produce ... something.


There is many solutions to design a low noise PSU. Of course, any reduction of the HF noise in the AC line will reduce the noise out of a psu with a given rejection.
Again (and again), it is not so much there that the double transformer filtering brings an audible advantage. It is in reducing the parasitic voltage between the grounds of the equipment you will connect together.
Of course, this voltage will be highly reduced, once connected, due to its high impedance and the low impedance of the connection. But...it is HF, you know ?
And those currents, once connected, will be superposed to the signal's references.
Well, if it is HF, we cannot hear-it, right ? Yes, but, once mixed with the signal, how much IM will-it produce in your amplifier ?
Measurements that will reflect the improvements are not so easy to do. But listening is.

Probably more effective spending your time converting your single ended equipment to balanced I/O.
 
I’m really surprised you did not notice the posts quoted above. Nothing, zip, nada. The question still stands.
Datas, evidences ?
And, please, your amp + your cd player (or tuner, or any digital source connected to AC, but not connected together: photos of your oscilloscope with the prob connected between the 2 grounds. With and without this 20$ I am sure you still have on your bench (and its schematic, of course).
 
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Probably more effective spending your time converting your single ended equipment to balanced I/O.
Not so easy, OMHO.
Do you want to electronically and mechanically (holes for XLRs ?) modify each and every equipment in your hifi system ? CD player, DAT, Tape recorder, minidisk, computer source, preamp, digital filter, tuner+ amplifiers.

SSM2141/42(or equivalent) are not so good at HF common mode rejection,
and If you power them outside each gear, you are still in the same situation between this gear and its balanced line driver.

Good enough audio transformers are lot lot more expensive than a pair of 20W AC transformers, have very limited bandwidth and other shortcomings.

It's a commercial mid-fi product, you need to upgrade to true hi-fi gear to get significant RF ingress and mains noise on the output.
Easy irony, but you obviously don't understand the purpose of this improvement. Ground loops don't care about any mid or true (call it what you want) hifi.
 
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Disabled Account
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Hi Richard,
Good luck in getting your lady out of the country. Hopefully this happens without any excitement. I think she'll do well. She's got a very good idea of what living in poverty really is and will probably work hard to distance herself. She'll make you proud of her.

May good karma follow you around for this.

Now, as for people trying filtering. I suspect that some lurkers will be trying these things out. We will never know of course. I'll be doing this down the road once I receive boards and bits.

-Chris

You are exactly correct about her... she has told me that she will make me proud. She has that fire inside to succeed and is self motivated. She will not pay me back -- but I asked her to pay it forward and help another person like herself. In helping her, I have helped the whole family because Sarada (Sara) will get job and help her sister get college ed. Her sister will help others and other will pass forward also. Maybe in a hundred years Nepal will be doing a lot better. Some of them will for sure.

People like Waly seem to have a bias and think that all I do is spend money on Things that cost a lot. I spend a lot more on lifting this girl (and other) out of poverty situation than I ever did on audio. Being her Godfather has been the best thing I ever did. The hardest also.


Sarada.jpg



<3



-Richard
 
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Datas, evidences ?
And, please, your amp + your cd player (or tuner, or any digital source connected to AC, but not connected together: photos of your oscilloscope with the prob connected between the 2 grounds. With and without this 20$ I am sure you still have on your bench (and its schematic, of course).

You are looking for a prove of Nothing. What do you want to see, 500uV of 150Hz harmonic at the speakers terminal? I can do that. But Nothing would still be exactly Nothing.

Sorry for taking you seriously for a jiffy. This would be funny if it wasn't so sad.
 
Disabled Account
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Waly -- didnt you get the memo?

It affects the amps distortion. How can you know that by looking at output with no signal analyzed.

This has been shown by other in print.

get head out of …..


As in all situations... it depends on your equipment and noise on line etal.


THx-RNMarsh
 
Waly -- didnt you get the memo?

It affects the amps distortion. How can you know that by looking at output with no signal analyzed.

This has been shown by other in print.

That’s rich, reference please. The Nothing creates distortions. Would playing a 0 dBFS digital signal get distorted by the Nothing? Wait, why am I bothering you with such trivial questions?
 
You are looking for a prove of Nothing. What do you want to see, 500uV of 150Hz harmonic at the speakers terminal? I can do that. But Nothing would still be exactly Nothing.

Sorry for taking you seriously for a jiffy. This would be funny if it wasn't so sad.
I just asked you to do yourself what you ask to others.
You cannot compare apples to nothing.
You can not say that a medicine does not work for you if you have not swallowed the small blue pills.
You are talking of something you never tried, just for the pleasure of the contradiction, as always.
You have not measured the difference with it vs without, not tried to even listen to it. Nada.
"Nothing would still be exactly Nothing."

Same answer than the one i made to KSTR: If you are fully satisfied with your perfect system, what the hell are-you doing in here ? Oh, yes, I forgot: nibble Mr. Marsh's ankles, whatever the subject.
 
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Not so easy, OMHO.
Do you want to electronically and mechanically (holes for XLRs ?) modify each and every equipment in your hifi system ? CD player, DAT, Tape recorder, minidisk, computer source, preamp, digital filter, tuner+ amplifiers.

SSM2141/42(or equivalent) are not so good at HF common mode rejection,
and If you power them outside each gear, you are still in the same situation between this gear and its balanced line driver.

Good enough audio transformers are lot lot more expensive than a pair of 20W AC transformers, have very limited bandwidth and other shortcomings.


Easy irony, but you obviously don't understand the purpose of this improvement. Ground loops don't care about any mid or true (call it what you want) hifi.

Ground loops are a fact of life and you are going to have interchassis currents flowing between two pieces of equipment. It's going to work out better if you don't use that connection as a signal reference.

I am not saying that you are wrong to minimize the other potential sources of problems, but they feel like band-aids to me.

With regard to the mid-fi comment - No, I do understand. A lot of boutique ultra high-end gear is designed without things like adequate input RF filtering and with wiring schemes that guarantee failure. Probably all of these will sing with if a nearby GSM phone is negotiating with a tower, for example. Don't tell me you haven't heard the 217 Hz and harmonic tones from equipment before.

What is enough? If my DAC has a SFDR of 110 dB, why do I care to even spend $20. I would rather not use a power conditioner that hasn't gone through the relevant standards testing either... (yes, I am aware the Monster has).
 
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If you are fully satisfied with your audio system and don't want to improve-it, what the hell are-you doing in here ? Play sports, instead.

So your because Waly doesn't believe there is an audible improvement to be had in his system with a line conditioner, he should go play sports? :confused:

Why does it matter what he does anyway? Whether one "participates" or not does not affect the validity of a statement.
 
Don’t put words in my mouth, where did I say I’m satisfied? I only said a $20 or $1300 power filter won’t help.
I just hope you will not die from a disease just because you do not "believe" in vaccines.
Do an adequate power filter can reduce RF pollution from AC plug ? Yes.
Do a power filter can reduce parasitic "ground currents". Yes.
Do you *know* if this can reduce HD and IM in your system ? NO.
What you imagine "can help" or not is irrelevant. Period.
 
- I have no RF pollution from the AC plug at the speaker terminal
- I don’t see any symptoms of “ground currents” at the speaker terminal.
- I don’t know many things, one of them being how to reduce HD and IM by removing a whatever amount of Nothing at the speaker terminal.

I’ll look for your precious help in my next life as a stork nesting on top of a radio station antenna pole.
 
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