Nattawut Uamkruea, blogger and audio gear maker who passionate in vacuum tube, audio & music.
Producing electronics projects since high school. Seriously upgrade and modify vintage audio equipment for “Real Sound” concept.
He is a co-founder of Soundaries and Sentimental Studio, all audio solution provider.
Experienced and lively explore the listening rooms & audio shops in Japan as his most favorite to do.

Tuesday, August 25, 2015

"Rotel" Design Concept

I just remember that about 10 years ago. Time that people excited with Marantz CD-63SE modification by replace stock components with better quality like ELNA Silmic, ELNA Cerafine, Nichicon Black Gate capacitors and Burr Brown OpAmps.

I went to my friend's house and asked for his Rotel CD player to do modification.
After I got it and then open the case, I've found nothing need to replace.

Full with Black Gate, Burr Brown, high precision resistor and other high quality semiconductors.

This is my memory about Rotel quality and Rotel still do until today!

On August 24, 2015 ; I have been invited from Zonic Vision to join Rotel product training by Mr Daren Orth : Chief Technology Officer of Rotel Electronics.



Their "Balanced Design Concept" include

Power Supply Design/ Component selection/ Circuit Topology

Build Quality/ Visual Appeal/ Ease of Use .


Mr Daren show us about PCB layout and well-built quality inside Rotel Preamplifier.



Rotel RA-1570 ; 120W Integrated Amplifier with multi digital inputs.




High quality components like Panasonic FC series, Sanyo OS CON 
and low tolerance Polystyrene capacitors.


Rotel RC-1570 ; Multi analog & digital inputs Preamplifier





Mr Daren has signed certificates for all trainees.


Glad to join and got many useful knowledge, especially circuit topology concept.


Thanks to Zonic Vision for great training with great trainer.


Cheers !!!

Tuesday, August 18, 2015

My new WE tube amplifier with P&C transformer Part I

After visiting Japan last 2 month and heard tube amplifiers

that made by P&C electronics with my ears.

http://mellowgroovy.blogspot.com/2015/06/japan-trip-part-1.html

Rewinding Western Electric's Permalloy and Iron core

made us impress with mellow sound and dynamic

even though listen from 1W power amplifier.

I plan to build my new tube amplifier with P&C output transformer.

So I select P609A model that has multi-tap in primary winding.

This model use Western Electric 1038A inductor core

and rewinding to use as output transformer.

2 aluminium plates with powder coating colors.



Install input transformers, cathode resistors and tube sockets on bottom plate.



Put all connectors on top plate and assemble 2 plates together.



Plan to wiring this week and will hear what I expect.

Report here soon.

Tuesday, August 11, 2015

Sansui XR-Q5 Direct Drive Turntable

Today, I have got Sansui XR-Q5 from secondhand shop with $30.

Bought without test and no headshell installed.

So lucky, all buttons can work properly !!!

Except tonearm that cannot operate automatic function.


After found out more information of this deck,

I think it so interest to make a new plinth with real wood.

See this link below for information of Sansui XR-Q5 

about Friction Free coreless motor and Dynaoptimum Balanced tonearm.


It's Sansui's step down from XR-Q7 top of the range model 

with less than 0.012% wow and flutter 

and a signal to noise ration of better than 78db. 

Silent synchrotor for smooth rotation 

and precise computer controlled fully automatic operation







Condition ......


Inside ...


Power Supply Board.


Tonearm control board.




Finally found cause that make tonearm not working in automatic.

Belt that hang between motor and gearwheel was melt.

So need to replace that confirm function again

before make decision to make a new plinth.

Monday, August 3, 2015

Monday Modify : 600 Ohm LCR EQ Phonostage Part I

I think LCR EQ Phonostage is one kind of phono preamplifier that

vinyl lover want to listen or own someday.


After find out many information, almost "RIAA equalizer" based on Tango EQ-600P.

It has 600 ohm impedance, so many methods to drive this EQ was applied.


This is Thorsten Loesch's design by connect signal directly from driver tube's plate to EQ.

Driver tube should has internal plate resistance less than 600 ohm or equal 

like E810F/7788 and E55L/8233.



Simple circuit and tube from Nobu Shishido.

Coupling capacitor quite high value, so choices will decreased.


More complicate and more tubes. Quite interesting.


Most advance with cascode design and interstage transformer 

for step down impedance to 600 ohm before drive EQ.


Hard to make a decision for select one style to do first.

Or mix and match all types together.