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ec ec is offline
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Default PHONE PREAMP

Hi
where can i find quality tube phono preamp schematics?

Thanks
ec


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Peter Wieck Peter Wieck is offline
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Default PHONE PREAMP

On Feb 26, 3:45 pm, "ec" wrote:
Hi
where can i find quality tube phono preamp schematics?

Thanks
ec


I put a search on dogpile.com using just those words... 60+ hits. Lots
of chaff, but a few that looked at least OK.

Naturally, Turner Audio figures highly in the "at least OK" hits.

Peter Wieck
Wyncote, PA

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John Byrns John Byrns is offline
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Default PHONE PREAMP

In article .com,
"Peter Wieck" wrote:

On Feb 26, 3:45 pm, "ec" wrote:
Hi
where can i find quality tube phono preamp schematics?

Thanks
ec


I put a search on dogpile.com using just those words... 60+ hits. Lots
of chaff, but a few that looked at least OK.

Naturally, Turner Audio figures highly in the "at least OK" hits.


Did you find any that you thought were better quality than "at least OK"?


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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Peter Wieck Peter Wieck is offline
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Default PHONE PREAMP

On Feb 26, 5:16 pm, John Byrns wrote:
In article .com,
"Peter Wieck" wrote:

On Feb 26, 3:45 pm, "ec" wrote:
Hi
where can i find quality tube phono preamp schematics?


Thanks
ec


I put a search on dogpile.com using just those words... 60+ hits. Lots
of chaff, but a few that looked at least OK.


Naturally, Turner Audio figures highly in the "at least OK" hits.


Did you find any that you thought were better quality than "at least OK"?

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/


John:

With respect, a home-brew phono-pre-amp is far down the line for me in
terms of what I feel qualified to attempt. Accordingly, I am not
really qualified to judge other than on the source of the design.
Patrick Turner appears to be a good source. Otherwise, the commercial
designs I have in present use work fine for me (AR, Revox, Dynaco,
Fisher & Harmon-Kardon, some tube, some SS).

Peter Wieck
Wyncote, PA

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Patrick Turner Patrick Turner is offline
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Default PHONE PREAMP



ec wrote:

Hi
where can i find quality tube phono preamp schematics?

Thanks
ec


See the preamps pages and re-engineering pages at

http://www.turneraudio.com.au


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Patrick Turner Patrick Turner is offline
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Bret Ludwig wrote:

On Feb 26, 8:07 pm, Patrick Turner wrote:
ec wrote:

Hi
where can i find quality tube phono preamp schematics?



Preamps are not too challenging to build. If you want one with lots
of rotary switch selectable features such as the classic commercial
ones that are convenient and spouse-friendly the issue becomes getting
the switches. Rotary switches are more or less modular and you build
them up or specify what you want but it can get expensive and time
consuming.

Many many many people have built Marantz 7 clones. Variations include
using octal or other miniature tubes or even FETs in places, getting
rid of the tape sections, transformer coupled outputs (the ollies have
developed a taste for the WE transformers for this even though they
aren't that great) etc, etc. The first and most famous M7 clone is the
factory Mc C-22. They are as identical as twin sisters with a Horns of
Venus.

In my opinion the best of the tube phono sections is that shown in
the German language book, "Audio-und-Gitatrrenschaltungen mit Rohren".
Pat Turner has a copy. I know he does. It's a two stage design.


Yeeeeaaaah, and I do have paper copies of something in German that
someone so kindly sent me.
But when I saw the schematics with 12AX7s I wasn't so awfully keen to
chuck out
what I have for 12AX7s.


I don't have an electronic copy I can send along to anyone who wants
one.

But....if you are not primarily using vinyl as a source....your
efforts are best directed to not having any preamp at all. You want a
CD or universal player with a output section that will provide 0 dB
into a relatively low impedance load. It's doable with tubes or
discrete or op amp solid state.



True, cd source just needs a 20k pot straight into the power amp.
The opamps in the cd player have very low Rout, and usually a buffering
resistor.

Patrick Turner.
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Andy Evans Andy Evans is offline
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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

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coffeedj coffeedj is offline
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Default PHONE PREAMP

Another very good option is the Hagerman preamp, found at hagtech.com His
schematics and manual are on line so you can build for free or buy his board
or kit. I found that the Hagerman budget priced preamps and phono stages
are very good as a starter set. You can upgrade pwr supply and components
at will to improve.

With respect to phono pre's I like the passive approach better than the
feedback driven one--although it requires (usually) an extra stage of
amplification. YMMV

"ec" wrote in message
...
Hi
where can i find quality tube phono preamp schematics?

Thanks
ec



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