Rebuilt Onkyo TX-2500 MK II

Posted by sony6060 (A) on May 12, 2021 at 13:48:33

I finished the TX-2500 rebuild using audio grade Silmic II capacitors, CIS Cree Schottky diodes in the two sub power supplies and Hexfred diodes in the main power supply. Main power supply capacitors upgraded from 8000uF to 18000uF. All other capacitors values are same as factory stock.

The Onkyo TX-2500 was good sounding in stock form, but now after rebuild has an edge in performance. The phono section is especially good. The audio is very clear & micro details are superior to stock. Part of these details are likely from the Hexfred very low switching noise. The FM tuner is a quartz lock type (1st quartz lock design) and has automatic center tuning.

I like these Onkyo TS-2500 due to 25-35% the cost of a Marantz in similar power output range. The TX-2500 is rated at 45 watts per channel. I cannot say if a modified Marantz would sound better than the Onkyo. The MKII series do use op-amps, but these sound good unlike many others. The TX-2500 (not MKII) have no op-amps, but power is lower at 27 watts. The TX-4500 (non MKII) is also without op-amps and is rated at 60 watts per channel. The TX-4500 is about $300 in good cosmetic & working condition. I suspect both would have a slightly better sound being fully discrete.

I would guess the upgraded Onkyo TX-2500 would perform as well as a Rega Brio amplifier. If you cannot DIY, upgrades costs about $400 and you usually pay extra for new power supply main capacitors and Hexfred rectifiers.

Note- a 1/2 size TO-220 heat sink is required on the Hexfred diodes due to 1.75 forward voltage drop.

Why Hexfred- a standard diode is very noisy. It chops a hole in the waveform output. The DC power is applied directly to the output transistors. The Hexfred has close to zero noise. It provides clean 120Hz DC to the filter capacitor and this provides clean DC with only a few volts AC ripple. No harmonics across the audio range either. The bass is tighter and tiny details with clarity appears on the higher frequencies. Every rebuild should include Hexfreds just as every rebuild uses audio grade capacitors.

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Topic - Rebuilt Onkyo TX-2500 MK II - sony6060 13:48:33 05/12/21 (21)

My daily driver is a TX-4500 MKII; it beat out a Kenwood KR-6600, Pioneer SX-780, and Outlaw Audio RR-2500 ... - J. S. Bach 06:54:47 05/13/21 (14)

RE: My daily driver is a TX-4500 MKII; it beat out a Kenwood KR-6600, Pioneer SX-780, and Outlaw Audio RR-2500 ... - sony6060 06:57:26 05/13/21 (13)

RE: My daily driver is a TX-4500 MKII; it beat out a Kenwood KR-6600, Pioneer SX-780, and Outlaw Audio RR-2500 ... - sony6060 07:48:51 05/13/21 (12)

Onyko Op-Amps - sony6060 20:58:57 05/13/21 (11)

Problem with Onkyo gear is when you tell your buddies you own - kff 09:49:29 05/15/21 (2)

RE: Problem with Onkyo gear is when you tell your buddies you own - sony6060 10:07:51 05/15/21 (0)

RE: Problem with Onkyo gear is when you tell your buddies you own - sony6060 10:02:58 05/15/21 (0)

RE: Onyko Op-Amps - sony6060 21:46:01 05/14/21 (7)

RE: Onyko Op-Amps - sony6060 21:49:47 05/14/21 (6)

RE: Onyko Op-Amps - rivervalley817 22:10:51 05/14/21 (5)

RE: Onyko Op-Amps - sony6060 10:05:36 05/15/21 (4)

RE: Onyko Op-Amps - rivervalley817 15:37:17 05/15/21 (3)

RE: Onyko Op-Amps - sony6060 15:29:02 05/17/21 (2)

RE: Onyko Op-Amps - rivervalley817 20:42:03 05/17/21 (1)

+1 )MT( - J. S. Bach 09:27:25 05/19/21 (0)

As an old Marantz guy..... - airtime 17:29:32 05/12/21 (2)

RE: As an old Marantz guy..... - sony6060 05:16:10 05/13/21 (1)

End of an Era - Triode_Kingdom 06:20:49 05/13/21 (0)

RE: Rebuilt Onkyo TX-2500 MK II - Triode_Kingdom 14:54:35 05/12/21 (2)

RE: Rebuilt Onkyo TX-2500 MK II - sony6060 15:10:48 05/12/21 (0)

RE: Rebuilt Onkyo TX-2500 MK II - sony6060 15:10:22 05/12/21 (0)

Rebuilt Onkyo TX-2500 MK II

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