Monarchy SE 250 + ATT PS1

Service & Tuning

Although the Monarchy SE 250 is a fairly known amp, this sample is obscure and was rebuild from the ground up by the Germany based Advanced Tube Technology. There is very little to find about ATT Germany let alone information on this particular design. The whole circuitboard has been redesigned with 2 tubes opposed to a single tube in the original SE 250. There is the ECC88 as input and now the 6N6P as a follower. It is still estimated 50 Watts Class A and up to 250 Watt in AB. We decided to add it to our own stable since we were quite impressed with the sound and convinced on a good amount of potential lurking inside.. A stock SE250 is to be seen here under. The single input tube is obvious as is the transformer. It is quite busy with parts and we can only observe what the plans were by ATT Germany..

A stock Monarchy SE250

ATT decided to move the transformer to a separate box. This has only but benefits as the transformer can grow larger and a source of noise and resonance is taken away from the actual amp section. The Transistor bank consist of 6x Mosfet type 2SK2221 and 6x 2SJ352 in PP. The ATT circuitboard is now much larger but apparently with fewer parts count and so more room in between components which gives less interference. Looking more closely at the ATT design it was clear that someone gave it a good thinking. The amp has been playing very nicely in stock form and is dead quiet on all accounts. No hum, no buzz, no hiss.

The ATT PS-1

The ATT PS-1 offers a larger Transformer which is now potted and housed in a casing made of Perspex or Lexan. Another benefit of this amp is the fact of having 4 boxes, each with a very reasonable weight. With a double Hernia in the lower back this is a very nice thought. The switch at the power supply is actual ON/OFF and the switch at the amp activates a relay in the output, and this comes in very handy when changing loudspeaker cables.

The SE250 by ATT

The plan to fully service and upgrade with audiophile parts grew and a parts list was made. Wiring to be replaced with Jena Labs 18 Gauge. Speaker terminals to be replaced by the Cardas CCBP-S. All Capacitors to be renewed with Panasonic and Nichicon. The power capacitors could use some more capacity and grew from 8200uF to 10000uF with the same diameter. Coupling caps to be upgraded with Audyn True Copper and Jupiter JCW. Cardas Eutectic solder is used and the input wires were upgraded with Mundorf Copper. The cinch input upgraded with WBT 0201. Input tube E88CC/CV2493. The 6N6P has been upgraded to an early USSR production sample. The total sum of all parts reached 1500 euro for both mono's. The goal was to unleash the sound quality and it turned out a great succes. The SE250 sounds like a Turbocharged FirstWatt !

New original Monarchy circuitboards, original Hitachi Mosfets matched, resistors and diodes
WBT 201 Classic, Cardas CCBP-S
Audyn True Copper 0.68uF 630Vdc
Jupiter JCW-050 0.1uF 600Vdc
Panasonic 100uF 350V
Panasonic 100uF 63V
Panasonic 47uF 63V
Panasonic 4.7uF 350V
Nichicon 470uF 400V
Nichicon 220uF 400V
Nichicon 10000uF 80V
Nichicon 10000uF 35V
RS-pro 2SK2221 mount kit
Molex KK nylon connectors
JenaLabs 18AWG UltraWire
E88CC/CV2493
Mundorf CUW210GY/06 Copper wire

 

The SE250 Signature

We focussed on an all-out Pure Copper parts job. All wires were replaced and soldered right into the circuitboard where possible. The trick is to go from A to Z and adress every part but at the same time beware to alter the circuit or tamper with safety. The basic design was great but cost savings can always be observed. This sort of project is highly rewarding and gives great satisfaction but mind that months of TLC labour in our workshop was spent. For now the Class A bias level may be lowered just a bit, the 50 Watt A is pretty bold.

The stock circuitboard with an inventory of the capacitors. The 8200uF was upgraded to 10000uF.

The arrow points to a capacitor which shows some gassing.. not yet faulty but the degeneration process has already started.

The huge U profile and bolt on cooling fins do their job very well, it takes some 45 minutes to get fully warmed up.

In this case safety overrules purism and both fuses are kept in the circuit although it was tempting to bypass.. With some repositioning of the huge Audyn caps the Bias pots are still accessible. After some burn-in time the bias will be finely adjusted.

The JenaLabs 18 AWG UltraWire. The Audyns are a snug fit but clearance is still OK.

Cardas CCBP-S pure Copper terminals, and the WBT 201 Classic.

Mundorf CUW210GY/06 wire

The Molex KK connectors, colorcodes are for reference purpose.

The capacitors have some bitumen on top to adress resonance.

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