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Old 23rd November 2012, 08:44 PM   #8601
Doug R is offline Doug R  United States
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Ordered some Russian caps.

OK, I played it a bit after six hours, putting a high signal through the circuit (speaker output of a radio.)
Doesn't sound bad at all. Seems lacking in the bass so far. No noticeable hum - my 300b already provides that. A good start I would say.

Gutted my Denon CD player to use the case for the RIAA and its PS. Not optimal, I know, but I will carefully separate the two compartments. I don't have the energy to build a case right now. Maybe later.

Still overhauling my 300b amps. Converting the Esmilla amp to Thorsten's Legacy with a pentode driver, and adding Rod Coleman's DC filament supplies. It's quite a bit of work, since I added three oil PS caps.
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Old 23rd November 2012, 08:50 PM   #8602
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Quote:
Originally Posted by Doug R View Post
Thanks Salas.
OOOh, I just found some more vintage RelCaps - some 15 nF for the RIAA.
Amazing what cleaning your bench can turn up.
Cool... that is what I use in my builds
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Old 23rd November 2012, 08:55 PM   #8603
RCruz is offline RCruz  Switzerland
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Speaking of relcaps.... It took me a while but I finally got things right in the "Wallis experiment".

Folded cascode input and jfet CCS in the output buffer makes the simplistic sound much more "snapy" and detailed so extreme care is needed to get the riaa filter right.

15.18nF was too spiky... 15.19nF was dull... 15.183nF is quite good.... incredible... here am I again stating I can hear pico farad differences.... but I do
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Old 23rd November 2012, 09:03 PM   #8604
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RC, but now you have to go down the fF path.
Doug
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Old 23rd November 2012, 09:11 PM   #8605
RCruz is offline RCruz  Switzerland
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hehe
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Old 23rd November 2012, 09:30 PM   #8606
Salas is online now Salas  Greece
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With gen and meter shows next to textbook around the 15.2nF mark for the folded but slightly low beyond 15kHz. The gen has 0.1dB flatness spec but it should be consistently off by whatever degree in just a 20kHz band VS the 12MHz it spans. So you must be spot on saying that's optimal just below 15.2nF.
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Old 23rd November 2012, 09:44 PM   #8607
Salas is online now Salas  Greece
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...Not to forget the proverbial spaghetti proto-test photo of course.
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Old 24th November 2012, 02:32 PM   #8608
RCruz is offline RCruz  Switzerland
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Ok, as promised here it is my subjective listening impressions report:
The "normal" simplistic provides a wide soundstage with liquid mids and highs beeing very good for complex instrumental pieces. It can produce a credible image from very complex and heavy piano pieces and excells in big orchestral moves with loads of simultaneous violins or human choruses. It is able to produce a coherent fluid picture that I consider very pleasing.

The Wallis experiment (better known as the folded cascode simplistic) has the familiar simplistic presentation but has more attack and detail in the bass. Single acoustic guitar becomes more agile and spiky. As a result, there seems to be a more analytical presentation... some hidden notes and sounds are more easily detected.

My folded cascode build is lower noise than the "normal" one but maybe that is due to the use of paralleled jfets in the input.

As I said before, the inherent higher attack and detail of the wallis makes it more sensible to the choice of the 15n cap.... (Hi can hear picos again )

As gain is quite high I neede to build a copper screen that worked wonders (after all I live in switzerland where everybody uses copper in their roofs )

Some pictures of the spaghetti:
Attached Images
File Type: jpg DSC_4194 BIG.jpg (442.4 KB, 148 views)
File Type: jpg DSC_4193 BIG.jpg (410.6 KB, 141 views)
File Type: jpg DSC_4192 BIG.jpg (454.5 KB, 139 views)
File Type: jpg DSC_4189 BIG.jpg (378.8 KB, 135 views)
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Old 24th November 2012, 02:40 PM   #8609
RCruz is offline RCruz  Switzerland
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As can be seen here I upgraded output caps to some new low voltage MRs... (shortage of t$me).... The big MRs I used for the "normal" simplistic are much much better.

The ESA caps on the shunts are slightly better the the usual MKPs... maybe in the future I will save some t$me for obbligato gold (principaly the 10u... these really make a difference)

Now time for some more spaghetti:
Attached Images
File Type: jpg DSC_4175 BIG.jpg (438.0 KB, 74 views)
File Type: jpg DSC_4170 BIG.jpg (454.8 KB, 60 views)
File Type: jpg DSC_4165 BIG.jpg (321.2 KB, 53 views)
File Type: jpg DSC_4163 BIG.jpg (372.7 KB, 63 views)
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Old 24th November 2012, 03:02 PM   #8610
Salas is online now Salas  Greece
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Nice shots. Having less noise than in a 48dB build normal, with a near 60dB one, no mean feat. Paralleling is just 3dB better SNR at same gain, the rest is design & execution. Copper shielding and reference to ground for 1st stage folded should have helped towards that goal. Also your total build execution is expert in those photos. Using K369s than K170s and same class caps as in the other maybe could reveal a bit more performance, but as it is its more than enough to prove that the concept works indeed. There will be proponents of the normal or folded regarding system synergy nonetheless. The normal is more configuration flexible OTOH. Like changing sensitivity easily or for combining pre pre stage. More focus and detail across the audio band can make the folded more finicky for parts, values, synergy I guess. I would consider the folded as the ''expert'' fixed build path. Is that a valid approach in your opinion RC?
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