Akarakrit 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, all audio solution provider.
Experienced and lively explore the listening rooms & audio shops in Japan as his most favorite to do.

Friday, November 18, 2016

Marantz Model 1 Audio Consolette & Type 4 Modification

Marantz "Audio Consolette" also known as Model 1 is the one in list of collective items.

It is a beautiful mono preamplifier, so need "2" for using in stereo system.

It's adjustable for turnover and roll-off in record equalizer that Marantz 7C removed.

One of my friend has 4 pairs of Marantz Model 1, so he need to try 1 pair in "Real Sound"

like Marantz 7C that I've modified for him before.

3 of 12AX7/ECC83 for 1 preamplifier (mono).

It need external power supply like Marantz Type 4 that I mention in the end of this post.

Top view for both channels of original with many Bumblebee "an easier to leak" capacitors.

Bottom view of originals.

Rectifier section with carbon composition resistors that cause noise into system.

Components for modify both channels.

Arizona "Blue Cactus" capacitors, wet tantalum capacitors and high quality wirewound resistors.

Top view after modified.

All coupling capacitors using Arizona C50309 "Blue cactus".

Bottom view after modified.

Use wet tantalum capacitors for 12AX7 cathode bypass.

High quality resistors in rectifier section and add filter capacitor to final stage.

Change 47k cartridge loading resistor from 0.5W to 2W for more mellow tone.

And this is Marantz Type 4, external power supply unit for Model 1.

1 box supply to 1 channel Model 1. 

Use selenium rectifiers like all equipment in same era.

Selenium produces good tone but shorter life and cause toxic when it has failure. 

Modified by using STTH6112V2, great ultrafast & soft recovery diode for high voltage.

and good quality silicon bridge diode for filament voltage.

Parallel HV output with PIO capacitor, seem like bi-cap with first filter capacitor inside Model 1.

Better, can easily listen both Model 1 and Type 4 after modified.

Everything will be more better after run in for hundred hours.

Cheers !!!