Here's an excerpt from my notes on the subject:
#RIAA schematics:
http://www.kabusa.com/frameset.htm?/index.htm has curve calculator
Balanced - general
http://www.dself.dsl.pipex.com/ampin...d/balanced.htm
Balanced - ss
http://www.klaus-boening.de/html/schematics.html#MKIII
http://www.klaus-boening.de/html/phonostage.html
http://www.quadesl.com/pdf/icphono.pdf
http://www.chipcatalog.com/Datasheet...4216522E64.htm
ina103 data
Balanced - tubes
http://www.tubecad.com/july99/page9.html
http://www.rintelen.ch/pdf/DIY/Anastasia.pdf
I have built the single ended 5842 preamp and the balanced 5842 preamp
as described in the second edition of the Morgan Jones book. They both
are very good performers. The designs are very well described. They
both will accept 7mV input easily
http://www.members.iinet.net.au/~quiddity/audio.html
http://www.vacuumstate.com/schematics/rtp3b_s.gif
Single ended - ss
http://www.hiendfi.com/modules.php?n...article&sid=95
http://www.geocities.com/rjm003.geo/.../diy_pho4.html phonoclone
http://www.passdiy.com/pdf/pearlphono.pdf Pass Pearl
Single ended - tubes
http://www.triodeguy.com/other_projects.htm Cascode
http://www.izzy-wizzy.com/audio/preampnew.html http://www.lurcher.org/nick/audio/Phono-2.gif
http://www.lurcher.org/nick/audio/Phono-1.gif
http://www.rintelen.ch/hifi/lil_sis.pdf
http://geek.scorpiorising.ca/contri...hono_preamp.gif
The pre was actually designed to go into my "Ultimate Preamp" project.
The mWCF is not really going to be DC coupled to the stage. There will
be a cap and the selector switch and volume control in there. I just
left it in to do the noise and THD tests as accurate as possible.
(haven't settled on the line-gain tube yet, 6N6P or 12B4. Though I may
DC couple that into the mWCF after all...) For a standalone
phonopreamp, just leave the 120R||100uF cap out completely. The 10K
tail end resistor's sole purpose is to bleed the static charge off the
4.7uF polycap
I implamented a suggestion by SY over at diyAudio to reduce the first
LED's dynamic resistance by tossing some more current through it. I
wasted to keep this simple, so I skipped the CCS idea and went for
straight resistive divider. The 56K/2W resistor coupled with the 100uF
cap would take care of any supply noise. Any more noise injected by
the 10K to the LED, would be for all practical purposes be bypassed to
ground by the improved dynamic resistance. We have a total of ~6.3mA
running through the LED now, keeping the resistance below 10 ohms and
probably closer to 5. I also decided to clean up the schematic a bit
around the mWCF (which is now a true WCF) and parallel two LED's,
since it's drawing 16mA. I've also added measured voltages. The second
attachment is the noise from this thing, even though it's spread out
on a breadboard, looking like my typical mess. All the power supply
harmonics were because to make this thing portable, I just slapped on
a pair of 1N4007's to a Hammond 269GX I had laying around and AC fed
the heaters (lifted 40V above ground). THD measurements were
interesting. First time around, I ignored the 2nd harmonic. Well, all
there IS from this thing is 2nd harmonic (seriously, none higher) and
the fundimental difference with the 2nd harmonic tracked perfectly
regarless if the input was 2mV, 1mV or 100uV. So, THD figures are
regardless of input level.
30Hz - 0.4% (-48dB)
100Hz - 0.79% (-42dB)
1KHz - 0.45% (-47dB)
5KHz - 0.22% (-53dB)
10KHz - 0.13% (-58dB)
http://geek.scorpiorising.ca/GeeK_Zo...31339#msg31339
ETF winner 2005
http://www.triodefestival.net/forum/...4f4df23a23c f
The phono amp itself is simple and straight-forward: 6SL7 (or ECC35)
input tube, one half for each channel, anode out into a passive RC
RIAA, second gain stage is done with one EC86 per channel (I could
have used a ECC88 or 6N1P but I wanted a bit more gain). The tubes all
have auto bias, decoupled with 'naked' BG-N (stripped from their
plastic wrapping). Rs are mostly selected AllanBradleys, Cs in RIAA
are 1950's PIO (WestCap and the like) selected for 0,2 dB accuracy,
output caps are AN-Cu. So nothing shocking here.
In my opinion, what makes the difference is the power supply. In the
amp, the phono circuitry itself occupies 10% of the physical volume,
the power supply 90%. It starts with 6X4, followed by a CLC smoothing
filter (first C is kept rather small). Mains transformer and chokes
are C-cores. I use no electrolytics in the HT supply. I can do without
and still arrive at low noise levels because of a shunt regulated
current fed supply circuit, and
each channel has its own. The current sources consists of a few FETs
and a bipolar and give me 100 MOhm. The shunt is a E182CC (using a OB2
as its reference). Each channel of this is directly powering an EC86
(no electrolytic!), and from there via a RC (C is PIO again) to the
input tube. Because of an additional trick in the shunt circuitry the
PSRR is in the order of 130 dB in the audio band, and it will not dip
under 100 dB up to many hundreds of kHz. Wiring is point to point, of
course. Silver wire is used throughout, except for the filament
supplies (though some claim that it sounds better there too). Housing
is made of copper, as this tends to sound better than aluminum or RVS.
In my opninion it is better to avoid plain steel.
http://www.rintelen.ch/hifi/lil_sis.pdf Lil Sis