Harman Kardon Citation I with "Real Sound" Concept

Harman Kardon Citation I pre-amplifier was a one of top quality in it's era.

Great phono-stage with "Turnover" and "Roll-off", very usable features.

4 tube's stages passive equalizer per channel in phono-stage

with high quality capacitors in equalizer too.

And the most surprise for me is a filter choke in power supply !!!

Many of famous tube pre-amplifiers in that time like Marantz 7c, McIntosh C22 or Fisher 400CX

did not use any of filter choke, only resistors in rectifier section.

Very usable features in phono-stage.

Backside with different design.

Top view for inside.

This is only 1 channel with 9 of 0.1uF Sprague Bumblebee capacitors

and 3 of green 0.47uF/10V ceramic disc capacitors in signal path.

Many of capacitors in equalizer section.

Bottom view for another channel and power supply.

Filter choke on left side of photo.

"Bass" and "Treble" components in selectors for each channels. 

Rectifier section.

Loading resistors for "Phono 1" & "Phono 2" inputs.

Time to modify with "Real Sound" concept.

18 of 0.1uF Arizona "Blue Cactus" Capacitors and use 0.5uF PIO capacitors from WE

for replace 0.47uF ceramic type.

Top view after finish modified.

Bottom view for channel A.

Replace rectifier components with Ohmite "Brown Devil" resistors, Ultra Fast Recovery diodes

from ON semiconductor and decoupling capacitors for each high volt points 

with Obbligato film capacitors.

Replace "Phono 1" loading resistor with 2W Allen Bradley resistors.

After "Run in" time for 20 hours, more transparent and good sound quality from bottom to top range.

In my opinion, it's a high quality pre-amplifier with a half or quarter price of more famous brands.

Worth a try and you will find a new sound.

Cheer!!!

New Version of WE421A & Another WE Tubes Amplifier

If you have seen my previous WE421A tube amplifier that I've post in November 2015.

http://mellowgroovy.blogspot.com/2015/11/WEamplifierPart2.html

Sound from that amplifier impress me and my friends very much.

So I plan to build the new one with all WE tubes again but using higher level P&C transformer.

Schematic seem like the previous one but I use WE352A for driver stage

http://mellowgroovy.blogspot.com/2014/01/WE352A.html

with Ampex input transformer and use P171A output transformer from P&C Electronics

that almost using in WE91 clone amplifier.

Custom power transformer from J&K work with original WE149E filter choke.

Schematic for this amplifier.

4 watts single ended power amplifier.

Our logo.

5 WE tubes in front row.

WE352A, very good sound WE triode tube.

Back side.

Us!

Aerovox 4uF Oil Capacitor.

Original WE149E filter choke with repaint.

Inside amplifier, using cloth wire for all connections.

Parallel electrolytic capacitors with PIO and film capacitors.

Using Ohmite "Brown Devil" resistor if need high power.

Arizona capacitor "Blue Cactus" as a coupling capacitor.

Try to make all short paths if possible.

Please let me know if you need more information.

Cheers !!!

SPEC. Ruby Mica Capacitor Replaced in RIAA EQ of Marantz Model 7

After finish modified signal & rectifier section of Marantz Model 7c in 5 months ago.

http://mellowgroovy.blogspot.com/2016/01/marantz-7c-modify-Real-Sound.html

Mr Shirokazu Yazaki from SPEC Corp. recommend me to test their Ruby Mica capacitor

that custom-made for RIAA equalizer of phono section in Model 7c.

http://www.spec-corp.co.jp/e/audio/MC-DA/

RIAA equalizer in phono section of Model 7c use 2 capacitors ; 5600pF and 1600pF.

The original using film type capacitor that has quite high tolerance.

Information from SPEC website claim that Ruby Mica has higher quality

in term of tone and transparent than traditional Silver Mica capacitor. 

Orange one for 5600pF and another in the bottom side.

2 brown capacitors near 560k resistor are 1600pF (1500pF).

After replace with SPEC. Ruby Mica capacitors : 5600pF.

Bottom side.

2 of 1600pF have replaced too.

Result after replace 4 Ruby Mica inside, every good points have improved.

Sound has more dept, detailed, transparent and beautiful tone.

Worth to test & taste. Cheers !!!

Visit Mr Shirokazu Yazaki's Audio System

Last 2 weeks, I just came back to Tokyo again with plan to visit Mr Shirokazu Yazaki's home

to listen his audio system after he had invited me in last time.

http://mellowgroovy.blogspot.com/2016/04/spec-corporation.html

I feel excited that I'm going to hear and see his audio equipment.

Because I want to know how he's train his ears for tuning all "SPEC" products.

And all of products designed with intention both electronics & appearance.

I just met him at old SPEC office and take the train to his home in west side of Tokyo.

His system use bi-amp with DA30 tube amp for mid-range horn & tweeter 

and prototype class D of SPEC amp for woofer. 

In his speaker system, he's use Altec 414 woofer in old Coral cabinet,

mid-range driver is Onken 500MT with wood horn and Onken 5000T tweeter.

All speaker wires using WE16GA from Western Electric.

Pioneer digital players and Marantz model 7 with "Real Sound" modification 

that I follow in his footsteps.

http://mellowgroovy.blogspot.com/2016/01/marantz-7c-modify-Real-Sound.html

His own DIY tube amp with WE310A as driver and DA30 for power tube 

with shoot-out some of 5U4G rectifier tubes in that day .

Replace and test some of them for find out each own taste.

Prototype of class D SPEC amplifier for low frequency driver.

Many experiments inside.

Yazaki-san describe how to tuning capacitor in output stage.

Nice dessert from his wife, thanks Yumi-san for her warm welcome too.

Thanks Yazaki-san again for his time to made a magic moment with his audio system. 

And more valuable knowledge from his ideas and action.

His system present as he did with all of his products.

Dynamic, speed, detail and tonal balance can describe only one word.

"Real Sound" is all good listeners need.

Hope to come back to his home again soon. 

Beautiful flower in front of his lovely home.