Tuesday, November 10, 2015

Marantz Model 30 - Upgraded Redux!

Marantz Model 30 Revisited and Upgraded 

I wanted to share about about a very special piece to me. I found this Model 30 a few years ago in just dire straights, boards were amiss and wires everywhere, the RCAs were damaged and catastrophic cascade failures from the driver to protection supply.  Below is a link to the original write up.

 The unit has since regrettably changed hands, but alas found its way back to me for basic general maintenance and decided to run a little with it!

Polypropylene Film Capacitors
The biggest update was replacing the original plastic films with high quality polypropylene (PP) equivalents. I typically go for films if the microfarad value allows because of the superior characteristics of polypropylenes amongst other film dielectrics. PP's tend be more reliable and stable in comparison to response/operating parameters (Drivers) based upon notably lower dissipation factors (DF) and equivalent series resistance (ESR). Below is graph archived relating the above comments. Films have notable uses in tube topographies due to their more reliable higher voltage characteristics and coupling/bypass applications. 

All the remaining films and low value tantalums were replaced here with high quality Panasonic ECW and Solen MKP PP films, both driver/coupling and pre stages. 


Driver Assemblies

Another upgrade was to update the repaired output devices with matched OnSemi's MJ21195/96G TO-3's and new MICA and compound. Another item to note is a redo on the Bias protocols. Reviewing the service manual it utilizes an odd bias method of measuring the current draw and adjusting. A more reliable accurate method would be to measure at the emitter resistors and compensate. For a 120VAC line @ 130mA draw we need to adjusts R224 bias potentiometer for 26mV across one set of Emitters or 52Mv across both. Below are my bias notations for the Model 30. 

Model 30 Bias -Notation für 130mA @ 120 V AC =

Unter Verwendung eines DMM , legen Sie die Messleitungen über entweder R230 / R231 Emitterwiderstände und passt R224 Pelz 26mV > (EIN) 
oder (OR)
Unter Verwendung eines DMM , legen Sie die Messleitungen über weit Bein des R230 / 231 Emitterwiderstände und passt R224 Pelz 52mV > (Zwei)

I know this is an awfully big statement…but this has got to be the best Marantz I have heard yet. As I think the customer can attests to, at a mere rated 60W/ch this integrated plays at the top end. Very different than your typical Marantz sounds..think elegant :)

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