LCR EQ Phonostage Prototype Just Continue ...

After made previous LCR EQ module for testing concept.

http://mellowgroovy.blogspot.com/2015/08/600LCREQPart1.html

This previous module show the great result, my friend asking to borrow for replace

his current LCR EQ module and return me with money not module. :)

So I need to do LCR EQ module again and I've found this video clip for

LCR EQ Phonostage with all WE parts.

http://tvpot.daum.net/mypot/View.do?ownerid=q69yWgQVpUs0&clipid=71163016

It's look interesting but I still prefer inductor from Sowter cause from low DCR.

Low DCR inductor make equalizer more accurate than higher DCR inductor like WE.

Other main components use WE parts for reliable quality and result.

LCR EQ module with "L" from Sowter and "CR" from WE.

Assembly with main phonostage plate.

Will update soon after finishing install all components.

JBL Solid State Energizer

I've got these 2 JBL power amplifiers for modification, SE408S and SE400E.

SE408S was design to use with JBL Paragon and use same circuit like SE400S.

But SE400E has less information than others.

After open SE400E, components and circuit inside is the same as SE401.

So I understand clearer about model of JBL power amplifiers.

SE400S = SE408S = SE460 (Silicon Transistor)

SE400 = SE400E = SE401 (Germanium Transistor)

And Germanium version using interstage transformers !!!

This card indicate that using for D50S8R Olympus.

Will check all coupling capacitors and resistors, bring vintage tone back here.

To be continue ...

100 Milestones in Audio Power Amplifiers

After travel to find any interest websites and schematics on the internet,

I just found out the great website that contain many nice articles.

http://lilienthalengineering.com/

Kurt van Lilienthal Heitmann Thaaning Steffensen is a founder of Lilienthal Engineering.

Highlight for me is an article name "100 power amplifiers to lift your hat".

http://lilienthalengineering.com/100-amplifiers-chapter-1/100-power-amplifiers-to-lift-your-hat

Founder said "I have made the 100 amplifier list with a little help of the highly skilled and knowledge members of the “Sound Practice” magazine forum “Soundlist” aka “The Joe List” and participants of the European Triode Festival. I asked them to suggest amplifiers they felt should be on a list of the 100 best or most interesting audio power amplifiers.".

I think all 4 parts of this article such a milestone that him said.

This is a history of audio power amplifier from past to present and must develop through the future.   

Thanks for did this great compilation.

I think people who interest in audio especially tube amplifier should be read and understand.

Cheers!!!

P&C WE310A Tube Pre-Amplifier for Reference

As I've said before in my "Japan Audio Trip 2015 Part 1" on June 2015.

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

When I visited Mr Toshiaki Kurashima at P&C Electronics shop

and listen to his main tube pre-amplifier using all Western Electric parts.

I still remember the sound from that tube pre-amplifier and

find the way to build my next pre-amplifier has a great tone like it.

So I have made my decision to order his custom made pre-amplifier for use as "reference".

Just order about 2 months ago and Mr Toshiaki brought the pre-amplifier to me in Thailand

by himself last weekend ! I appreciate so much.

This pre-amplifier look neat and attractive with nany iron and capacitors.

Using WE310A "small punch".

WE cloth wire for all wiring inside with AB carbon composition resistors.

Already use with my amplifier and the sound remind me to that day in Japan.

Western Electric parts always make me wonder especially signal transformers.

Frequency response over specification in datasheet and produce a great tone

that cannot find in others.

Simplicity so challenge me to build my new pre-amplifier to come close with this original parts.

Tuesday Tube : Western Electric 418A

Main reason that select this tube to work as driver for my amplifier

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

because it is a Western Electric tube that look like an expensive WE437A too much.

WE418A is an indirectly heated tetrode tube. Use 9 pin Magnoval socket.

Same base and bulb like WE437A and WE436A too.

Frame grid construction.

Square getter.

I've found this copper tube shield in ebay, it's look tight and rigid.

Keep it for my WE437A triode tube in the future. ;)

Tube shield inside with spring all around. Great design and usable.

Later version of WE418A had smoke glass and different font.

When I made a decision to use WE418A,

I'm searching more information and specification in google.

No triode curve from any sites. Only question but no answer.

Until I've found triode curve from project in MJ Audio magazine for February 2015 !!!

Plate Characteristic for triode connection of WE418A tube.

Characteristic & typical operation.

Sound of WE418A in triode connection so flat and powerful, 

easily match with almost power tube especially directly heated triode.

You can get the same feeling like looking and listening to WE437A. ;)

Cheer!

Marantz Model 7 After Modify with "Real Sound" Recommendation

I'm excited to get great result after using Arizona capacitor and other high quality components

that Mr Shirokazu Yazaki from SPEC Corp. have produced and recommended for "Real Sound".

After finishing modify McIntosh 275 amplifier with capacitors adventure.

http://mellowgroovy.blogspot.com/2016/01/mcintosh-mc275-modify-part2.html

I started continue modifying Marantz Model 7 to use them together.

This is a link for inside Model 7 before do anything.

http://mellowgroovy.blogspot.com/2015/12/marantz7beforemodification.html

The result can be predictable for upgrade sound quality of Marantz Model 7 to higher level.

And I want to share what did I do with this world famous tube preamplifier.

Components for do this "upgrade".

Top view.

Bottom view.

Rectifier section, both high voltage and filament supply.

Original electrolytic capacitors are in working condition and still produce great tone.

I use my favorite IRC GS3 metal glaze resistor to replace carbon composite type 

that too high tolerance for this section.

Change old selenium to silicon bridge rectifier for tube's filament supply.

Using STTH6110TV2 ultrafast recovery diode to replace selenium in high voltage rectify too.

Replace cement coated type with better wirewound resistors from Ohmite.

Use 680k carbon composite resistor to replace 500k potentiometer + 180k resistor

in level adjust before last tube stage.

This potentiometer almost had dirty contact, need to replace if somebody still want to use it.

47k resistor RA series from Tepro did it best in cartridge loading position before phonostage.

And all coupling using paper & polyester dielectric in oil-filled capacitors from Arizona capacitor.

Almost use C50309 "Blue Cactus" except 0.1uF that use C50313 "Green Cactus" 

for tuning some kind of timbre. 

Tube's cathode bypass capacitor using axial Mallory capacitors.

Coupling capacitors under the board.

Another coupling capacitors that stay in selector position.

Sing-along with McIntosh 275, produce mellow tone and "Real Sound" like expected.

Cheer !!!