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Mcintosh MC-240 Stereo Tube Amplifier

4 Oct

Mcintosh MC-240 Tube Amplifier

Image Credit: LotLogginon eBay


Mcintosh MC-240 Stereo Tube Amplifier (1960-1969 MSRP 288 USD)

The Mcintosh MC240 is a 40 watts per channel tube amplifier first produced by Mcintosh Labs in 1960.  It uses 4 6l6GC tubes to achieve it's rated output, and a mix of 12ax7, 12au7 and 12bh7 tubes in the signal path.   The MC240 has a unique place in audio history, it was used by Brian Wilson of The Beach Boys to master Pet Sounds in 1966, one of the most famous albums in rock & roll history.


ELECTRICAL: 40w/ch stereo, 80w mono. Response 16-40kHz (+0 -0.1dB). Distortion 0.5%. Noise & hum -90dB. Output impedance 4, 8, 16, 125 and 600 ohms. 600 ohm center tap internally grounded. (2, 4, 8, 16 and 32 ohms in mono). Output voltages 25 (isolated), 70.7 (one side grounded) and 140V (center tap grounded). Internal impedance less than 10% of rated impedance. Input impedance 250k. Input sensitivity: 0.5V (in mono or twin amp). 2.0V in stereo.

MECHANICAL: Chrome chassis. Line output octal socket for higher impedances and voltages. Barrier strips for 4, 8 and 16 ohms. Audio inputs: stereo, twin and mono. Gain controls: twin amp, balance and mono. Input switch: stereo, twin amp or mono. Can be used for 80w mono. Line voltage switch: 117 or 125V.

TUBES: 4-6L6GC/7027A output, 3-12AX7, 2-12AU7, 2-12BH7 Solid state rectifier.

Size 8"H, 10-3/4"W and 17-1/4"D. Weight 56 lb. Sold from 1960-1969.



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Mcintosh MC-2505 Power Amplifier

8 Jun


Image Credit: Starsky on eBay

Mcintosh MC-2505 Power Amplifier (1967)

The McIntosh MC2505 is a solid state power amplifier with a maximum power output  50 watts per channel operating simultaneously, into 4 ohm, 8 ohm, or 16 ohm loads.

"When introduced in 1967 the McIntosh MC-2505 was a revolutionary amp in many respects and served as the blueprint for all future McIntosh amps to come. Not only was it McIntosh’s first solid state amp ever, it was also their first to have a full glass panel faceplate, precision calibrated output level meters, the panloc mounting system, and it was the 1st sold state amp to incorporate McIntosh’s famed Unity Coupled Autoformer for full rated output at 4,8, or 16 Ohm impedance."

For Sale:   This Mcintosh C-20 is currently for sale on eBay via seller Starsky. Get your bids in now, auction ends June 10, 2014.


Power output: 50 watts per channel into 8Ω (stereo)

Frequency response: 20Hz to 20kHz

Total harmonic distortion: 0.25%

Damping factor: 10

Input sensitivity: 0.5V

Signal to noise ratio: 90dB

Speaker load impedance: 4Ω to 16Ω


Marantz Model 9 Amplifier

13 Apr

Marantz Model 9 Amplifier

Marantz Model 9 Amplifier  (1960 - 1968)

Tube Complement: 2 x 6DJ8/ECC88; 1 x 6CG8; 4 x 6CA7/EL34; 1 Zener Diode; 5 Silicon rectifiers.
Overall Dimensions: 15⅜" x 8¼" x 10½" (W x H x D); Panel 15⅜" x 7¾" (W x H)
Shipping Weight: 60 lbs

70 watts continuous - 140 watts peak. Switch for 40 watt triode operation.
Response: At full rated power; within 0,1 dB - 20 cps to 20 kc; within 1 dB - 12 cps to 40 kc. At 0,5 watt, within 1 dB - 3 cps to 40 kc
Harmonic Distortion: At full rated power; less than 0,1% at mid-frequencies, less than 0,33% - 20 cps and 20 kc.
I.M. Distortion: less than 0,5% at full rated power.
Hum & Noise: better than 100 dB below 70 watts.
Damping Factor: 17. Damping factor may be changed internally by adding current feedback.
Output Impedances: 4, 8 and 16 ohms, plus 1 ohm tap for center-speaker conection.