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Drawing Board / Re: Output transformer mounting onboard
« Last post by Deepdark on Today at 04:03:47 PM »
"static noise" is a wrong word. It dates from early days of wireless, and does not relate to audio, except when used as "similar to".  In fact, NO. Noise  does not stick to anything. Outside interference is capacitively coupled from secondary to primary. Grounding the core makes it act as a partial electrostatic screen. 

Sorry for being punctilious, but I believe some day you'll have fond memories of my lectures... ;)

haha thanks. It's ok to be punctilious, I prefer to learn the good termes :) Thanks a lot. So I was ok to ground the core :)
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Drawing Board / Re: Output transformer mounting onboard
« Last post by abbey road d enfer on Today at 04:00:18 PM »
, but is static noise tends to stick to the core?
"static noise" is a wrong word. It dates from early days of wireless, and does not relate to audio, except when used as "similar to".
Quote
  I guess yes.
In fact, NO. Noise  does not stick to anything. Outside interference is capacitively coupled from secondary to primary. Grounding the core makes it act as a partial electrostatic screen. 

Sorry for being punctilious, but I believe some day you'll have fond memories of my lectures... ;)
3
Drawing Board / Re: Theoretical question
« Last post by abbey road d enfer on Today at 03:53:36 PM »
But even if it was rectifying… wouldn't 4VDC be a little on the low side at full gain?
I was referring to rectification due to non-linear behaviour of the input stage of teh voltmeter (assuming it was a digital VM); there is almost no correlation between the HF voltage and the apparent DC value.
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Brewery / Re: getting organized in the new year + goals check-in
« Last post by Whoops on Today at 03:49:48 PM »
my gigging amp now is a Princeton Reverb on steroids: 12" alnico spkr, Mercury Mag fatstack low B+ PT (B+ ~400VDC) and Deluxe reverb OT, slower trem, and a few extra resistors to help the overdrive tone, it's soo good.

Great Setup you have,
I started my Hoffman Ab763 in 2008, was never able to make it work properly.  Oscillations, Squeals, Tubes mechanically hissing, a lot of crazy stuff. Hopefully this year I will find all the problems and make it work properly.

Let's talk 1 year from now

;)
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Brewery / Re: Donald trump. what is your take on him?
« Last post by Matador on Today at 03:40:03 PM »
and the humanist in me wants everyone to be well (since we're all special snowflakes).

Why do you hate freedom? :)

Quote from: John Roberts

the same way he always reacts when an opening negotiation is declined

You know, I never thought of it that way.

First, you grab them by the pussy.  If you don't get kicked in the crotch and arrested, then you negotiate to grabbing breasts, but OVER the shirt.  If you aren't slapped, then you offer dinner and a preview of a prenuptial agreement.

It's actually the way pretty much all consenting relationships start nowadays, amirite?  8)
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Brewery / Re: Donald trump. what is your take on him?
« Last post by DaveP on Today at 03:33:48 PM »
Quote
PS: I find myself deeply conflicted and torn between hot women with tattoos, some piercings, and revealing or provocative clothing, and on the other hand modest down-to-earth 'innocent' Scandinavian women on the country side.... I probably need a couch and an accompanying therapist to work that stuff out....
This is probably a generational thing.  I don't have any issues with women wearing next to nothing as long as it's feminine.  I don't think they have to be particularly modest either, I hate what women have to put up with in Muslim countries and India for that matter.

When I see tattoos and piercings, I get a warning bell saying this person has self-esteem issues................. :-\

There is something about the direction that modern life has taken since the war that has had a very detrimental effect on the self-esteem of girls.  Anorexia and Bulimia were unheard of in the 50's and 60's, as were piercings and tattoos, I can only put it down to TV advertising, magazine articles and latterly FB and smart phones.

DaveP
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Drawing Board / Re: Output transformer mounting onboard
« Last post by Deepdark on Today at 03:31:35 PM »
The body of the input transformer may be different. As well as reducing magnetic interference, the body of an input transformer also acts as a screen from electric fields. The secondary, which is usually unbalanced, would benefit if the body was connected to a local 0V in the same way that an unbalanced screened cable would have the screen connected to 0V. For example, Sowter mic transformers do not generally have a wire connection to the body. So, if you use a PCB mounted version, the body is unconnected. If you touch the body with your finger, audible hum is induced in the mic input circuit. This is especially so when the input stage is a high impedance tube. In the identical circuit, using a PCB mounted Jensen or Cinemag transformer ,which do bring out a connection to the body, if the body connection is tracked to 0V then the hum is not induced when you touch the body

In an output transformer there generally is no overall electrostatic screen so this does not apply.

Cheers

Ian

Thanks Ian. Pretty good explanation. And for the output one, there is no can around the transformer, but is static noise tends to stick to the core? I guess yes. So, having a path to the ground plane on one of the transformer mounting hole would be just fine, right? Or, better, a trace from its mounting hole to the nearest mounting pad of the pcb, which will touch the chassis with metal standoff. This gives a direct path to the chassis. But I guess the first option will work just fine, given the pletora of people who just did it.
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Preamplifiers / Re: Soundtracs FM series schematics
« Last post by monty b on Today at 03:26:56 PM »
I am also keen on a copy of the schematics if you are kind enough to share  :D
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Drawing Board / Re: Theoretical question
« Last post by sahib on Today at 03:25:11 PM »

If voltmeter rectification was eliminated then I would speculate on the clipping of the output transformer. This will raise the  right hand side of the 2.2uF to a DC potential.

In situations like this without a scope is like shooting in the dark.
10
Brewery / Re: Donald trump. what is your take on him?
« Last post by mattiasNYC on Today at 03:18:25 PM »
Well, the repeal effort is happening predictably.

I wish the Republican legislative branch would just come out and admit "We don't believe the government should be involved with health care (unless you are a woman, of course)." Then the lack of a viable alternative  after 7 years of pleas from Congress makes sense, as they want the tax cuts to the 0.1% to go through as quickly as possible (which they can do through reconciliation). Whether millions lose their insurance is besides the point.

I don't know why, in this new era of the Republican "mandate", they aren't clear with their intentions, as it would absolve everyone from playing these games of smoke and mirrors.

I would say that the masses, even Trump supporters, actually appreciate health care and being taken care of, but they're so deeply indoctrinated by American culture that they think they have a shot at the "dream", which won't happen. But since that's their belief, you can't really undo that and still have the wide population be semi-servile workers creating wealth for the top (trickle-up economics, or, as I like to call it, wealth redistribution).

In other words, it's just a need to keep the status quo. The sadist in me wants Trump supporters to lose their health care and suffer the consequences, because they were dumb enough to vote for that nonsense (not all, there are exceptions), and the humanist in me wants everyone to be well (since we're all special snowflakes).
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