Anthem Amp 2 hybrid stereo power amp (Sonic Frontiers era) - PcX rebuilt/upgraded

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Anthem Amp 2 hybrid stereo power amp (Sonic Frontiers era) - PcX rebuilt/upgraded

These ‘Anthem’s’ were designed and built by Sonic Frontiers before the brand buyout and thenSF disappeared (Anthem continued under the new owners).

The original owners and founders of Sonic Frontiers, Assemblage and Anthem own and run PartsConnexion in Canada.

I bought this amp off them a few months ago. PcX often buy in older SF and Anthem kit, refresh them, offer upgrades, and then resell them on.

With this unit for sale I asked PcX to go all out on mods. They claimed this Anthem was a ‘sleeper’ before so it is now truly fully awakened!

Selling as I’m moving house, need funds for such, need space and it is going to be some time before I’ll get the HiFi kit out and up and running again.

With the true hybrid design (see photos for a proper valve pre/input stage), this unit is smooth with no hard edged nasties at all. Like silk

Power supply capacitance is more than doubled - so the fuse had to be up rated to cope with the current rush on switch on.

Price I’m looking for takes into account the cost of the upgrades, the many hours to do so, and the shipping of this massive new beast to this side of the Altantic. I am though selling for a lot less than I paid - it is kind of a bespoke build that not all will agree with or appreciate.

This is a rare chance though to buy such a sweet beast of an amp. It is large and heavy but I have suitable packaging to post (as it was shipped from Canada).

Price incl U.K. shipping: £1200

Details:
Dimensions: 48cm (W) X 13.5cm (h) X 50cm (d)
Power rating: 200w into 8 ohm and 300w into 4 ohm (600w into 8 ohm mono)
Non-inverting
Input impedance 100Kohm
Output impedance </= to 80 mOhms
Voltage gain 24dB (16x)
Input sensitive is 2.5V for the 8 ohm rating
30 second switch-on delay to sort the tubes
Weighs about 21kg

1.2kVa transformer is a little mechanically noisy (light buzz) when close to the amp.

One casework screw is missing from the top of the cover. I think the thread is worn and would not hold.

unpackedRATED POWER200 Watts per channel continuous into 8 Ohms or300 Watts per channel continuous into 4 Ohmsboth channels driven, from 20Hz to 20kHz with+0.0 -0.5 dB 2Hz to 140kHz (1W)FREQUENCY RESPONSE<1Hz to >180kHz -3dBPOWER BANDWIDTHSIGNAL TO NOISE RATIO-90 dB, IEC A weighted ref 1W-100 dB, IEC A weighted ref 200W0.1% 20Hz to 20kHz at rated powerTHD+N0.05% SMPTE method at rated powerIMD< 2µSecRISE TIMESLEW RATE100VµSecPHASE POLARITYNon Inverting100k OhmsINPUT IMPEDANCE80 mOhmsOUTPUT IMPEDANCE90 at 8 OhmsDAMPING FACTORVOLTAGE GAIN24dB (16x)INPUT SENSITIVITY2.5V for rated output into 8 Ohm
All the upgrades:

Tubes: Reflektor 6n23B (ECC88) EV/EB ruggedised types. These are from Pearl Cryo who only make tube coolers now. They had a cryogenic process that after the treatment each tube was burnt in the tested for spec as well as noise - then graded. These are the costly Gold Grade matched pair (super quiet).

Back panel:
IEC is now a Furutech gold and the amp sports a Synergistic Research Blue fuse. Speaker binding posts are now the copper variety from KLE - nice!

Moving to inside the amp:
Power supply capacitance doubled with Mundorf AG electrolytic caps. Film caps in the power supply mains feed is now a Jantzen Superior Z and a Milflex copper film type. Internal power supply cable lines now from Supra and a ptfe wrapped silver plated copper.

Input/initial gain stage board:
As seen in the photos, a work of art. All electrolytic capacitors replaced and upgraded.
All film caps now Clarity cap CSA types - huge upgrade.
Signal wiring now pure cast solid core silver, ptfe wrapped and screened.
3 resistor upgrades to Takman Rey where it mattered

Amp boards:
All electrolytic caps refreshed and upgraded to Nichicon and Audio Note types.
All film caps now Clarity Cap CSA.
Board fuses now from Wilbrand - silver wire with ceramic beading for mechanical stability.
Ceramic power resistors replaced with Mills type (24 of them!)
Output speaker wiring now from Kimber - their TCX 15awg

A total of 64 upgrades! 8 hours of labour.

A very music and easy sounding amplifier

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Some extra pics:

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