Work has begun on restoring 2 x 1962 Nippon Columbia (Denon) Valve Phono Stages. Both were built & supplied to feed the 1962 Denon RP53 turntables I restored a couple of years ago. I also found in a box of Tamura transformers I have a pair of very very rare Tamura SUT built especially to step up the Denon 103R MC cartridge that was invented at this time. 

I am excited to think I will have an all Tamur/Tamradio  Nippon Columbia Denon vinyl playback system ;-)

Detailed build thread to come.

Any advice or suggestions will be welcome because as yet I have not seen another on the net. All parts are branded. 











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Welcome back beeman....

Can you post a close up of the winding diagram on those wee transformers?

DarkLantern blog - darklanternforowen.wordpress.com

Hi Qwen & cheers been a while. The photos here are probably easier to see. I also have several similar Tamura transformers to the ones on this site. The strange thing is the phono amps are stereo & there is a hole in the front that perfectly fits the SUT but they are only mono so 2 x are needed. 

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Many vintage tube amps had Input Transformers - an input stage for microphones, etc.

Yes these are 1:10 ratio TXs, apparently ideal for DL103 (more so than 103R I'd say).

DarkLantern blog - darklanternforowen.wordpress.com

Ah that would be it Owen it would have been a mic input for talking over the record as these were from a radio station

Many enthusiasts use old mic TXs as MC SUTs.

1:10 gain/turns ratio means 470:47k imped ratio - which should be nice for a standard DL103.

DarkLantern blog - darklanternforowen.wordpress.com

Hi Beeeman,
I think I have one of those Tamuras somewhere...

Hey Paul - long time no talk. Would you have 2 x of them as I am renovating 2 x valve phono stages but only have the SUT for 1?

Hi Beeman. Long time no talk also !!!!
I trust those big bad Denon turntables are still spinning.
Cheers

If you have trouble sourcing another Tamura SUT, try these...

www.sowter.co.uk/specs/8055.htm

I have these installed in my "His Master's Noise Phono Stage" and they are really good.

www.diyaudio.com/forums/diyaudio-com-articles/163570-masters-noise-thoroughly-modern-tube-phono-preamp.html

Hi Graham - yep both going gang busters. Did a bit of a motor adjustment on Saturday & it was a worthwhile tweak. Still have the one in the cabinet if your interested in taking on another build? Thanks for the tip on the Sowters Jon I know they are well regarded. Probably would only include Denon SUT in this build because then it makes a complete Denon rig.

Sept 4, 2018 7:37:42 GMT 12 beeman said:

Hey Paul - long time no talk. Would you have 2 x of them as I am renovating 2 x valve phono stages but only have the SUT for 1?

Hiya, no, only one I am afraid.

What about Hifido Japan, email them.

Work has begun. There is some doubt about the 6AU6 in the circuit causing hum & roll off at the top end. The goal here is to have a great sounding phono stage as close to original as practical. I am not to worried if they are changed to ECC88 or similar if SQ is going to be significantly improved. They have come apart without too much fuss. Much of the original wiring will require replacement.


I would like to keep the original model plaques if possible but not sure how to do this during the re-painting process?

beeman - do you have a schematic, or have drawn one yourself?

DarkLantern blog - darklanternforowen.wordpress.com

Sept 13, 2018 7:28:07 GMT 12 beeman said:

I would like to keep the original model plaques if possible but not sure how to do this during the re-painting process?

There are a number of ways to do masking off...

a) masking tape - Frogtape is sold on Trademe
b) liquid mask - commonly available, dries to a clear coat, and some are soluble in water some are not, some peel off. 
c) PVA Glue - then have fun peeling it off.

Thanks Jon - great tips

All 4 x chassis stripped & ready for paint prep. What colour do you think. I am leaning towards silver hammer-tone same as the turntable? Not possible to save the ID stickers so now looking for someone that could reproduce them. Should not be too hard black copy on silver background - any suggestions?

Hi Beeman
I think silver hammertone would look great. Especially as it will match the turntable.
I have had lettering done by vinyl sign companies in the past. If you provide an example of the lettering you want they can load it into their computer and then cut it from vinyl in any colour you want. it can also be several layers to provide highlight or background effects.

Nice project, solid looking turntable :-)
It would be good to have the circuit traced out so we can see what to do about the frequency response issues. A 6au6 is a medium transconductance pentode with 7 pin base. A 6dj8 / ecc88 is a dual high transconductance triode with 9 pins. The two aren’t interchangeable. They could perhaps be used in place of the 12au7s though, depending on what they are doing.
Hum from the circuit could be due to an AC heater supply. DC is best for low level circuits. Hum could also be from old electrolytic capacitors that have lost their capacitance. Also perhaps from grounding issues.

AMR-iFi R&D

Hi Colin - Hum is theoretical using modeling with the existing circuit layout & tube selections. Replacing the 6au6 will be a revision of the design for better audio quality. All caps & will be replaced as required. This is a no compromise build.

Thanks Graham - would you recall exactly what the paint we used was? Also a link to the sticker people would be much appreciated. Please see a pic attached.

Shame not to retain the original ID labels.

Perhaps you could bolt or rivet a metal plate (rectangular or kite-ended) over before sandblasting the chasses clean.
Prime & spray paint.
Then replace protection plate with an elegant small 'picture frame' plate to cover the protection plate area.

DarkLantern blog - darklanternforowen.wordpress.com

Main problem is the oven baking

Bugger. I've just checked and both the car painter and decal company we used have gone !!
However any professional painter should be able to apply a hammercoat finish and I don't think it necessarily has to be baked. Usually the use of a bake oven is just to speed up the drying process compared to air drying.
I thought you were referring to a logo of some sort, so I agree with Owen that it would be a shame to lose the original spec label. I'm sure it could be carefully masked and retained.

Yup, the painting could be wet-spray or powder-coating.

My first pair or 'DIY' spkr stands were steel, 'silver spangle' powdercoated

I would go vintage grey/brown, something like what Line Magnetic do.

DarkLantern blog - darklanternforowen.wordpress.com

Is it possible to remove the labels intact? Then re-apply when painting finished!

Blue sky thinking.

Hi beeman, how have you been modelling the circuit layout and tube selections? I guess you’re not planning on keeping the circuit original then?

AMR-iFi R&D

Modeling the original circuit shows limited top end & some hum issues. Hence the reason for changing out the 6au6 section. Not surprising I guess as they were made in 1962 & full range speakers would have been rare back then.  I am after the vintage heritage look but sound quality is the main goal. No point in spending $$ & it ending up sounding like crap. Happy to make changes if they pay off SQ wise.

After almost ten years the first phono stage is complete. It is fitted with the period Tamura SUT specifically designed for the Denon 103 cartridge. The curcit design is a current Audio Note topography. Rubicon & Audio Note caps have been used throughout.  Running in at the moment but so far very impressed. This is a fine piece of kit & it's wonderful to have it up & running again ;-)  

Jeezus whats a guy got to do to get a comment around here?