Sony TAN-8250

June
1 9 7 4 june 1974
1 9 7 8 1978

It looks like a V-FET amp... but it ain't.

Housed in the chassis of the TAN-8550 allright, but sans V-FET : inside are six pairs of 2SB520 / 2SD340 bipolars.

Housed in the chassis of the TAN-8550 allright, but with a power limiter : the TAN-8250 can become a 500W monoblock !

The TAN-8250 is a phase-linear dc pure-complementary circuit biased in Class A operation for everything but the power board.
Mirko Essling noted similarities inherited from the old TA-3200F bestseller - more about that later.

The output transistors are hooked to the double heatsinks like the V-FETs amplifiers (from below) and the diecast heatsinks are doubled with heat "chimneys" for even better convection.

The transformer is enclosed in a square box, no doubt to conceal its toroidal nature - we're in Sony territory so let's not show the good stuff :)

Features-wise, the 8250 bears more front switches than its TAN-8550 V-FET counterpart because of the three-step power-limiter.

The rest, front and back is equivalent : speaker B level control, DC or not DC inputs with front selector and individual level pots, three 'speakers terminals, plus meter sensitivity switch.

The speaker B control is the adjust output of lower-sensitivity speakers to that of the main (A) speakers. The third 'speaker output is called DIRECT and these are directly connected to the amplifiers' output point to provide a very high damping factor.

The inside of the 8250 is packed with said transformer (placed vertically in its square box), one choke coil box and a dual 10,000uF /70V capacitor (for a 20,000uF total) and the (invivible but from under) dual rails of diecast heatsinks.

The rest of the space is occupied by the Peak Program Meters box - big box.

Peak Program Meters rely on two independent mirrors to display peak and VU modes in a manner most intelligible - and beautiful. If Sony were to release the PPM meters today as pro studio accessories, they would sell like hotcakes.

These Peak Program Meters were included only a handful of units because of their size and manufacturing costs : TAE-8450 preamp, TAN-8550 amplifier, TC-880-2 open-reel recorder and... that's it.


The TAN-8250 is however a very very rare component : Sony probably should've kept the TAN-8250 as a V-FET but leaving the expensive PPM out.
It would have made more sense that way, marketing-wise, than to have a visually identical twin based, inside, on a completely different amplifiying technology...

Saving on the V-FETs didn't boost sales, though, and, at 1300$ in 1975, one can easily understand why.

Sony TAN-8250, image 1 Sony TAN-8250, image 2 Sony TAN-8250, image 3
Sony TAN-8250 specifications
Title Value
Power 2-channel : 2x 250W (1Khz / 4 Ohm / 0,2% THD)
2x 180W (1Khz / 8 Ohm / 0,2% THD)
2x 200W (20Hz...20Khz / 4 Ohm / 0,2% THD)
2x 150W (20Hz...20Khz / 8 Ohm / 0,2% THD)
Power Mono : 1x 470W (1Khz / 2 Ohm / 0,2% THD)
1x 350W (1Khz / 4 Ohm / 0,2% THD)
1x 550W (1Khz / 8 Ohm / 0,2% THD)
1x 380W (1Khz / 16 Ohm / 0,2% THD)
1x 400W (20Hz...20Khz / 2 Ohm / 0,2% THD)
1x 300W (20Hz...20Khz / 4 Ohm / 0,2% THD)
1x 500W (20Hz...20Khz / 8 Ohm / 0,2% THD)
1x 350W (20Hz...20Khz / 16 Ohm / 0,2% THD)
THD : 0,1% at rated output
0,05% at 1W
IMD : 0,1% at rated output
0,05% at 1W
Frequency response : 0Hz...100Khz (+0 / -1dB, test position)
20Hz...100Khz (+0 / -3dB, normal position)
Power bandwidth : 5Hz...50Khz (8 Ohm)
S/N ratio : 100dB (A-wtd)
Residual noise : 1uW
Damping factor : > 250 (1Khz, 8 Ohm, DIRECT output)
Power limiter : none, 1/2, 1/4, 1/8
Meter range : 1W...200W / 0,1W...20W
Meter response : 30Hz...30Khz (+0 / -3dB)
Inputs : 1V / 50kOhm
Output : 2 pairs
Output switch : 4 Ohm minimum ("2-Ch")
8 Ohm minimum ("mono high")
2 Ohm minimum ("mono low")
PC : 380W
Dimensions : 44 x 17 x 41cm
Weight : 23,3kg.
List price : 315,000¥ (1974)
1300$ (1975)
FEATURES : DC structure
DC or CC input
Tension Limiter Impedance
Load-triggered protection
Toroidal Transformer
Thyristor Rectifier
Chimney heatsinks
2 sets of inputs
page online since : june 2005
page updated : april 2010
page type : LGT / KNB
page weight : 176.19 Kb / 0 b
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