Some Nice Phono Stages

analog music reproduction discussion

Some Nice Phono Stages

Postby Geek » Sun Jul 11, 2010 3:23 am

Hi Folks,

Would like to discuss some nice phono stages I've been listening to :-)

The Koren "Purist" stage found here:
http://www.normankoren.com/Audio/Spice_preamp_2.html

For a NFB stage is really sweet and brings back fond memories, as it reminds me of a late 70's, early 80's Kenwood sound.

Bass: Full, authoritive.
Lower Mids: Great detail, slightly pronounced.
Mids: Slightly recessed, very clean.
Upper Mids: Detailed, clear.
Treble: Neutral.

First (input) stage tube used: GE (Canada) 7025/12AX7A
Second and follower tubes: Brimar ECC83

Pic: http://geek.scorpiorising.ca/contrib/Ge ... _Board.jpg

(no, the PCB's aren't available.... just yet ;-)


Another is the BoZ inspired one from Linnenberg-Audio, found here:
http://www.diyaudio.com/forums/pass-lab ... e-zen.html

Honestly, the best sand-state phono I've heard under a zillion dollars.

Bass: Full, authoritive without being boomy or muddy.
Mids: All mids are neutral, but not boring by any means.
Treble: Crisp, clear, detailed with good downward-dynamic-range, pulling out the quieter instruments in a loud passage.

Not the least, a GREAT soundstage. Nice and wide.

This, as with the BoZ that inspired it, is *very* sensitive to component quality... the better the parts, the better it'll sound.

Always keeping in with what the average weekend experimenter can get their mitts on, all parts are obtainable from Digikey or Mouser.

For the circuit, I used Panasonic FC-series for the electrolytics, RIAA
network capacitors were EPCOS MKP (the blue ones... they're like the red
WIMA's) and Panasonic/Matsushita ECW-FB polypropylene for input and output.

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby battradio » Sun Jul 11, 2010 2:38 pm

Hi Greg ,

When will your RIAA phono boards be ready and do you have a projected price .

Mark
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Postby Geek » Sun Jul 11, 2010 3:47 pm

Hi Mark,

battradio wrote:Hi Greg ,

When will your RIAA phono boards be ready and do you have a projected price .

Mark


1) When my PAS arrives and I confirm fitting and that the power tranny can handle them OK without an additional filament booster (there's a 3-tube mainboard to me powered too).

2) One is being tossed around a tad below the DynaMutt range, but we'll have to see after I run final costs and everyone's commissions through a spreadsheet ;-)


I wish costs weren't prohibitive, otherwise I'd play with MC stages as well. This is so nice listening to vinyl 'all over again' with each preamp ^_^

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby battradio » Sun Jul 11, 2010 7:20 pm

Well save me a proto type , i have a very nice potted RCA power transformer and chicago transforner choke waiting for a tube pramp board .
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Postby Geek » Mon Jul 19, 2010 12:17 am

Progress pic! :-)

Image

Layed in place are the Koren boards, plus my regulator PCB. All fit perfect!

I rewound the little gold transformer as an auxillary 12V for powering the 12X4.... that leaves us juice off the PA-211 for powering the 6 x other tubes (the mainboard will use the 5751 mod, phono board as-is)

I'm redoing the faceplate to accomodate the "sans-tone/shaping-controls" out of some 1/8" aluminum stock I have on hand.

I'll likely replace the selector with a silver contact C+K too.

TODO:
- LED power light (hmmm, seafoam green?)
- Fused power trannies.
- Gold connectors.
- Rescaned/processed rear sticker.
- Polarized power cord and power jacks.
(likely after audiofest... thanks Digikey for being out of stock until September *rolleyes*)

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby MashBill » Mon Jul 19, 2010 6:57 pm

Very nice! Keep us informed as things progress.

Have you seen these faceplates before?

Image

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They are sold be ebay seller "michael_nipomo".

Bill
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Postby Geek » Mon Jul 19, 2010 8:46 pm

Very nice!

Thanks, Bill :-)

I'm planning on doing similar to this one:
http://home.comcast.net/~netminer/image ... pg9p12.png

Selector, volume, balance... tape switch and power.

Cheers!
-= Gregg =-
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Postby battradio » Tue Jul 20, 2010 4:28 am

Hi Greg ,

Is there a time frame for the face plate , have a pas 3 out in my black hole of a garage with out a faceplate .
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Postby Geek » Tue Jul 20, 2010 5:44 am

Hi Mark,

battradio wrote:Hi Greg ,

Is there a time frame for the face plate , have a pas 3 out in my black hole of a garage with out a faceplate .


The one I'm doing is a one-off for my rig.

But I'm looking into doing copies of the original.

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby TerrySmith » Tue Jul 20, 2010 10:32 am

Any idea where you can buy a new rotary off-on switch with the same dims as a volume pot?

I like Geek's panel layout, those on ebay look nice but look lop-sided with the tone controls left out.
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Postby MashBill » Tue Jul 20, 2010 2:00 pm

Geek wrote:Very nice!

Thanks, Bill :-)

I'm planning on doing similar to this one:
http://home.comcast.net/~netminer/image ... pg9p12.png

Selector, volume, balance... tape switch and power.

Cheers!


I like your version better. It looks more "Dynaco-ish" ;) Are you having this made? If so, I would like to buy one too. Is this possible?
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Postby Geek » Tue Jul 20, 2010 4:40 pm

TerrySmith wrote:Any idea where you can buy a new rotary off-on switch with the same dims as a volume pot?


Apex Jr. has one of a coupl bucks, dunno his stock level.

Sometimes they show up at lighting places or farm electrical surplus houses.

Most rotary switches are of the pot dimensions, but the ones certified for line switching use can hit over $30 from places like Digikey.


I like Geek's panel layout, those on ebay look nice but look lop-sided with the tone controls left out.


I'll post a pic of mine ASAP. I just finished handbrushing the aluminum and drilled the holes. Now have to cutout the rectangle ones for the two switches I'm leaving in....


I like your version better. It looks more "Dynaco-ish" Wink Are you having this made? If so, I would like to buy one too. Is this possible?


Of what I know (and can share) at this point, expect an original case that the 'PAS boards just happen to fit in perfectly' and a replacement for the original PAS3 faceplate. Nothing spectacular.

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby Geek » Wed Jul 28, 2010 12:12 am

My one-off faceplate :-)

Image

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby Geek » Mon Aug 02, 2010 3:27 am

Boards in and smoke testing :-)
(it draws *right* at the PA-211 HV winding limit)

Image

Cheers!
-= Gregg =-
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