John Curl's Blowtorch preamplifier

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stinius

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Juergen Knoop said:

Do they all use fancy connectors beyond the usual XLR or whatever?
regards
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No
If the pro equipment was so lousy made that you needed those”fancy” modified connectors, it wouldn’t be possible to do a live act.
Sorry for chiming in so late, but I think this is all BS, maybe Wavebourn has a problem with his equipment, but that does not reflect the real world in pro-audio.

Cheers
 
Wavebourn

Wavebourn

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stinius said:


maybe Wavebourn has a problem with his equipment, but that does not reflect the real world in pro-audio.
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I don't have problems with _my_ equipment, but sometimes artists bring own gear, and when they bring it, it is mandatory to use it, since it is their gear, for their sound.

That's why designing equipment I have to keep in mind that sources of interferences will be connected to inputs, outputs, and grounds

Do you hear me now?
 
Wavebourn

Wavebourn

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Juergen Knoop said:
as being not familiar with real world studio equipment, I'm curious...
Do they have a 'mobile ban' in recording studios?
How do broadcasters handle FM and UHF transmitters?
Do they all use fancy connectors beyond the usual XLR or whatever?
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No. They use transformer balanced ins/outs with additional filters. Designed by pro's who know well how to deal with interferences.

Semi-pro recording studios, that grew up like a grass after the rain in Los Angeles garages, uses semi-pro with "electronically balanced" ins/outs, and they pick up cellphones easily.
 
Magura

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syn08 said:


It would be much easier to build those rings on a custom PCB with appropriate size and populated with chip caps in house. Unfortunately, I'm not aware of any PCB manufacturer that would route round small double sided PCBs with vias, in relatively small quantities, for a reasonable price. If anybody is aware of such, I can do a design for the PCB to fit in a Neutrik cup and provide the Gerbers.

Spak gaps and ESD diodes on the PCB are really an overkill for audio.
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If somebody will take care of having the boards made, and have the centre hole made by the PCB house, I could take care of the machining of the outer diameter.

I recently machined a few PCB's, so the start up problems are cured by now.


Magura :)
 
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stinius

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Wavebourn said:


sometimes artists bring own gear, and when they bring it, it is mandatory to use it, since it is their gear, for their sound.

That's why designing equipment I have to keep in mind that sources of interferences will be connected to inputs, outputs, and grounds

Do you hear me now?
Click to expand...


Sorry to say, but this has nothing to do about designing a mixing console, and curing the problem by using some” fancy” plugs.

If the problem is “ground” loop, ever heard about DI boxes, with a good Jensen transformer, lifted ground?
 
jan.didden

jan.didden

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linearaudio.net
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Magura said:



If somebody will take care of having the boards made, and have the centre hole made by the PCB house, I could take care of the machining of the outer diameter.

I recently machined a few PCB's, so the start up problems are cured by now.


Magura :)
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I'll check my Bulgarian PCB maker Monday.
What would be the center hole, approx? 4/10 of an inch?

Jan Didden
 
Wavebourn

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KSTR said:


@Anatoliy, do you breed spiders in your gear?:D :D
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No, I let them live in my barn where donors for parts that I save for my prototypes live. They don't cause RFI. :D :D

But I did not mean spiders, I meant that ferrite beads. It is an engineering dilemma: either to buy fancy sockets, or to order PCBs with beads. But anyway RC filters are needed before the transformer, because it has some stray capacitances so don't isolate from common mode interferences absolutely.

Also, you can see very wide ground traces that connect everything together, no matter is it input, output, or a safety ground. If you don't design a console such a way it will cause problems because input, output, insert grounds will be for sure interconnected by an outboard gear.
A first, a power supply has to be very clean. And second, each and every board have to contain some power filter, at least 10 Ohm (flame proof) in series, or even own voltage regulator per board in the top range gear.
 
Wavebourn

Wavebourn

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stinius said:



Sorry to say, but this has nothing to do about designing a mixing console, and curing the problem by using some” fancy” plugs.

If the problem is “ground” loop, ever heard about DI boxes, with a good Jensen transformer, lifted ground?
Click to expand...

Sorry to say, but your jokes sound as if you don't know some basics. It is much easier to learn them than collect recipes from gurus.
 
KSTR

KSTR

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Joined 2007
syn08 said:
Spark gaps and ESD diodes on the PCB are really an overkill for audio
Click to expand...
No, not overkill. Just thing of the ballpark 120V (60V for 120V mains) transient that an input has to withstand when you connect non-safety-grounded gear to safety-grounded. Or the typical human ESD pulse (rubber soles + synthetic carpet + dry climate).

My criterion is more stringent, any input (or other user accesible connection) should withstand the ~4kV surge pulse from a piezo oven lighter, directly fed into it. A piezo oven lighter with a horn or dipole antenna also is an excellent test tool to check if the microcontrollers/etc in your AVR/CDP or what have you is competently designed, that is, wether the whole device is protected against ESD events or not

EDIT resource: http://www.emcesd.com/. look a the tidbits section
EDIT2: and I'd sacrifice a toe (with nail polish, for Walter Sobchak :D) for his HP54845A...

- Klaus
 
KSTR

KSTR

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bear said:
KSTR - I am interested in the experiment on group delay... link?
Presumably Gurgle Translate will do the trick for me... :D
Click to expand...
Here we go:
http://www.aktives-hoeren.de/viewtopic.php?f=28&t=851&start=0
first pages are rather general (recapitulating things, etc, digressing a bit, the ususal way things go), the more specific stuff to the experiment starts here
http://www.aktives-hoeren.de/viewtopic.php?f=28&t=851&start=35
(there is more going on in the non-public background, though).

I doubt some of the slang/akronyms etc will be handled meaningfully by any translation robot, though :xeye:

Please rest assured, in case we find out something significant we'll let the english speaking community know.

- Klaus
 
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