Mario 300B



Mario 300B SE amp , with many different driver alternatives

Hello to all ,

This is the std high end integrated amp that uses an excellent rugged quiet powersupply ,

Runs on classic proven 300B valves and uses Lundahl output transformers .

I build many versions of this amp :

The C3M is based on the Legacy version by Thorsten Loesch ( his version is based on the version with Western Electric penthode as used by La Maison de L’audiophile or Jean Hiraga ) also available with SV83 and tube rectification .There is not much to say , this version uses the same high quality components that I supply and has 1 coupling cap , a paper in oil type the 300B is autobiased and runs on DC , you need two separate filament supplies to achieve a stereo version .

The cathode bypass capacitor needs to be of high quality , as a cathode resistor I propose either paralleled dale 5watt types or a caddock . ( I prefer the paralllell solution ) , and by far the C3M driver over the EL84 or SV83 .

The Meziani version is the high power version , this version was running at 535volts DC and 140mA of bias and proved how unreliable the KR52BX actually is , oure other design the Kurt KR52BX also proved to have the same problems although tubes lasted longer there , this tube does not seem to live up to its specs , 85watts anode dissipation or a mu of 3,65 , the max anode dissipation would be 55 to 60 watts and the mu is closer to 3 , the low mu could explain the excellent sound of the tube but try to get power out of this and you need to raise the voltage like in my tests to about 725vdc to get to the announced 25 watts SE with 1 tube , and then I am way over max spec , and it sounds bad as well .

But anyway the new Meziani runs on std VV300 tubes know at 465vdc and 110mA for a nice 9-10 watts of output retaining the quality of the KR tubes .

Upgrades in Meziani version : tube rectification using a 274B tube

As a standalone rectifier it would probably die very fast having to charge the 1100µF and having to supply 250mA of current , so its used in an intelligent way ( I dare to say this )

Silicon diodes do the heavy work , they rectify and charge the 1100µF and then only we use the 274B as a series pass diode where it does its job of slow start up and not allowing the current spikes to pass as it is very current limited , I still advise however to leave the soft start switch on for reliability and stand bye issues .3 chokes are used for not only adequate filtering but also for excellent channel separation .It welcomes all types of 300B tubes , with the new power transformer ( suitable for USA ) many different high voltages are possible.

As a driver the 2C51 from Western Electric is used , you can modify it and use it as an SRPP , or even just parallel it to reduce the number of stages .only local feedback is tolerated (BY me at least ) and it sounds really good , just ask Franck Meziani himself .

The Mario no Fuzz Version ,

This version is the simpler version aimed at high quality at more moderate a cost, simple but very effective runs on Chinese tubes or Svetlana or Sovtek and uses the proven 2C51 driver with a modified volume control , after the first amplifying stage . It was also the first commercial integrated stereo kit I sold .can also be quipped with 2A3 tubes on demand

Or 6B4G ect .(could use pse 6B4G )

The power house monoblok version :

This is not yet build , just in the design idea I do supply its schematics , the idea is to get lots of power excellent reliability and low cost using standard 300B types and returning to my basic old time philosophy : triode – penthode – triode , with or without interstage .

The output stage uses 3 parallell 300B’s running at 425vdc , negative bias or for the fans of cathode bias 475vdc .(this is all possible with the new power transformers )

The input tube a 2C51 western electric direct coupled Loftin White circuit to the driver tube aC3M from Siemens and as an interstage (if used ) LL1660/18mA , penthode connected . ( this is done by using the transformer inverse , we actually get a step down but much better load distribution = lower distortion ) and then the outputstage uses an LL1620/120mA with the primaries connected so they can handle 240mA and the secondaries for 28 watts of outputpower , the load the tubes sees is approx 800 ohms which is perfect for low distortion and good power , expect 25 watts .nice voltmeter and switchable mA meter for monitoring of bias in outputtubes , unfortunately matched tubes are needed and compensation resistors for aging , only the use of capacitor coupling could provide separate bias adjustements .

If you want one of these kits email me for price and delivery status

See links to the schematic and pictures

Rgds benny glass

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