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Old 9th May 2003, 01:18 PM   #21
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Location: Lisbon, Portugal
Cool I surrender

Quote:
Originally posted by Kuei Yang Wang
Koinichiwa,

It is exactly that what I have/had. I recently re-arranged my system and put the Digital EQ that used to be on it's own little rack to be placed at the listening position and put this into my rack. While the EQ was in it's own rack on wheels it was connected by 6m balanced cable, driven by the passive preamp that you could say became the prototype for the unit illustrated above.

In the end, usually if the source can drive the cable you are using, a competently designed passive will drive it too. That is unless of course you take all that signal (current) and low output impedance of your source and throw it away, as incompetently designed passives usually do.

At the moment, if I put the EQ into bypass my passive preamp drives 3m Balanced cable using each a pair of 50 Ohm coax Cables, plus the input capacitance of a WE 437A (around 175pF) quadrupeled due to the input transformer with 1:2 stepup at the amplifier input. I'd estimate the differential capacitive load of the cables as 150pF and the effective input capacitance of the Amplifier as around 700pF. In total 850pF load capacitance. Still sounds fine, with no observable rolloff.

In measurement terms, I measured the passive line controller into 10k//1nF from a 1K Source. The behaviour in terms of HF rolloff equalled closely that I would have expected without the passive controller in circuit, excepting the added around 600 Ohm copper losses.

Sayonara

PS, I was peripherally involved with the development of the MFA unit as advisor, but other than that I have no connections, I do not earn commision on units sold, get paid for design input or anything of the like.

Quote:
Originally posted by Kuei Yang Wang
Koinichiwa,



Hey. Stop shifting goal posts. You never said anything about price. The best is rarely cheap. That's life. Though the very best in life is usually free....



I think you would want to FIRST try this out and secondly comment, rather than to prejudge. In my experience resistive volume controls have a "larger sonic footprint" than transformers and active circuits, no matter how good have an even larger one.

When I compared my transformer passive against a rather special "buffered passive" (here the INPUT is buffered and the passive section is very low impedance and used in a shunt control type arrangement with a Z-Out < 300R worst case) the improvements with the transfromer where so drastic, that friend of mine who had build the buffered passive "to save money" felt it had been a complete waste of money and went out and put the long green down for transformers. Try it.

Sayonara
Deam it, I surrender.
I just love when you're in a good mood and have the time to elucidate us all (me at least).
Thank you for that very nice photo.
What a bunch of wires.
Hey, just joking...
It looks very good indeed.
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Old 9th May 2003, 01:50 PM   #22
tiroth is offline tiroth  United States
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Default Re: Re: Re: Re: Re: Re: Re: Re: The reason

Quote:
Originally posted by Kuei Yang Wang
Koinichiwa,
鯉に地はですか。本当ですか。
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Old 9th May 2003, 02:03 PM   #23
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Question It may be dense here....

Quote:
Originally posted by tiroth


鯉に地はですか。本当ですか。

...but can any of you translate?
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Old 9th May 2003, 02:20 PM   #24
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Default Re: Re: Re: Re: Re: Re: Re: Re: Re: The reason

Koinichiwa,

Quote:
Originally posted by tiroth


鯉に地はですか。本当ですか。
No, it's not exactly true.

Kuei Yang Wang (Keiyanwang) is a figure from one of my favourite anime' series, sazan eyes. There he the one who is never seen, the evil presence in the background.

When I decided to create a new "on line personae" I was watching the whole series again (major otaku me is) and found the idea amusing. The japanese phrases are some of the very few I actually know (and thus an affectation), but I'm much fascinated with things japanese, when I get the time I'll try to learn japanese well.

Sayonara
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Old 9th May 2003, 02:38 PM   #25
tiroth is offline tiroth  United States
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Sorry just poking fun. ;) Koi (鯉) just jumped out at me.

Typo looks like:
鯉に地は
The earth at least is in the fish.
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Old 9th May 2003, 02:49 PM   #26
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Location: Lisbon, Portugal
Talking My god, this page got huge...

Quote:
Originally posted by Kuei Yang Wang
Koinichiwa,

When I decided to create a new "on line personae" ...
Sayonara
And it's my fault.
I'm gonna change the resolution to 2048x1600 to see if I cach it all.

Anyway, Kuei, for me, David Bowie's best years were when he incarnated Ziggy Stardust.
Maby that's happenig to you.
In fact, I was just trying to "pull your leg" to see if you showed us your preamp.
I knew it would be something special.
I did it!
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Old 9th May 2003, 10:59 PM   #27
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Talking transformers?

Koinichiwa,

Quote:
Originally posted by carlosfm


In fact, I was just trying to "pull your leg" to see if you showed us your preamp.
I knew it would be something special.
I did it!
Actually, what you saw is the "budget" commercial implementation. I know, many people would not consider the asking price for that little box to be "budget".

Yet I can confirm that a new, "serious high end" version is on the drawing board, using as full application of C37 principles, silver wiring, a new transformer winding geometry and core materials to seriously push the envelope and of course in a "hewn from solid" wooden case with a nice look (me being industrial designer) in a Philips Strack meets Bauhaus meets neo Victorian steam punk meets Cartier & Tiffanies style, that should appeal to people with more money than sense, plus sonics that will hopefully be as far ahead of the current units as a Transformer based passive line control is ahead of resistive attenuation.

Well, it's still on the drawing board. I might get MF-Audio to make a few after they sold the first 100 of the other line controls... ;-)

My own "personal" unit is a bit more involved and seriosuly crazy....

Click the image to open in full size.

All wiring, except the wires from the transformers themselves which I kept short are solid, uninsulated silver.

Switching of inputs, polarity (Phase) and gain (yes, this "passive preamp" has gain) are achieved using special low capacitance, super small size reed relais, in the worst case (unity gain) three reed relais contacts and one solid silver switch contact are in the signal circuit.

Of course, that means my passive linestage needs a powersupply, namely an external wallwart selected out of my huge collection for lowest leakage and fitted with schottky diodes and LC filtering....

The RC circuits on the Jacks terminate any cable shields at RF, the reed relais are encased in a block, covered with several layers of self adheasive copper tape, which forms the RF "ground". nAll XLR's are Plastic, with hard silverplating over brass. I wish I could have XLR's in wood and with solid silver contact.

The RCA's are fitted so I can use my VCR or any old review gear that comes my way, though fitting RCA's to high end gear should be made a crime.

The whole assembly is in a full size HiFi case from a preamp produced by Opera Audio (Reference 1.1. This case was specially made for me by Mr. Liu with a blonde wood top and the whole process facilitated and initiated by the sadly late Stanley Chu of Opera Audio Hong Kong, a great fellow and true gentleman, who passed away by far to young.

And if you think that passive linestage is far out, wait till you see the phonostage....

Click the image to open in full size.

Sayonara

Ziggie played guitar.....
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Old 10th May 2003, 12:11 AM   #28
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Ooooooohh, mom's gonna have a fit when she finds out you used her new cutting board to make your preamp.

se
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Old 10th May 2003, 08:22 AM   #29
Nuuk is offline Nuuk  United Kingdom
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Quote:
Ooooooohh, mom's gonna have a fit when she finds out you used her new cutting board to make your preamp.
Yeah but not as big a fit as if KYW's girlfriend uses the preamp as a cutting board
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
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Old 10th May 2003, 03:46 PM   #30
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Koinichiwa,

Quote:
Originally posted by Steve Eddy
Ooooooohh, mom's gonna have a fit when she finds out you used her new cutting board to make your preamp.
The board is not from Mom but from Woolworth. It's a "Chesse & Bisquit" Board, not a cutting board. The little ceramic tile that was sitting in the middle to place chesse upon makes a good little damping weight on top of my DVD Player (waste not want not).

And if I ever really get of Vinyl I can use the thing to serve cheese & bisquites...

All this wood actually is C37 lacquered and was applied because of the C37 principles....

SayonaraDieter Ennemosers C37 Theory and C37 lackquer
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