Doubling up the amps!

[leftside]

Agreed a deal on another MC7270 today. This one looks just as nice as my existing amp. Absolutely mint.

I'm not expecting any difference in sound quality by running them as mono blocks, but they sure will look nice together.

 

[joeinid]

Congratulations! It's great to find a really clean piece. Enjoy!

 

[damacman]

You will be pleasantly surprised ...

 

[twiiii]

Its great you found a matching unit. I felt the same way back in the middle 60's when I found a matching 240 to go with my first one. Finding them - pre-owned back then was a rare event. The owner was upgrading from his 240 to a 275, and didn't have space for a second 240 like I did. I liked 7270's. They sounded the same as my favorite 2255's to me and were a great deal during that period. The Price of Mac power amps was beginning to sky rocket and the 7270 was Macs last attempt to keep a lid on price increases. By the time the 7300 came along it seemed like every time I turned around the prices were going up. I used to think what ever happened to the days when a 275 was $444.00 when introduced and $444.00 when discontinued.

 

[Velocityboat]

Agreed a deal on another MC7270 today. This one looks just as nice as my existing amp. Absolutely mint.

I'm not expecting any difference in sound quality by running them as mono blocks, but they sure will look nice together.

There is a difference in sound. Mono parallel is closer to stereo on MC2500 with better bass. Mono bridge really really opens the highs up. Amazingly so.

Tonight I try mono stereo running two pair of speakers.

 

[leftside]

Well good to know chaps! I wasn't expecting to hear any difference in sound quality, but I guess I'll find out later today. Also, as far as I know, there were 3 different versions of the 7270 produced. This second amp appears to be the same version as my existing amp (with the black plastic barrier strips on the back).

 

[damacman]

The MC7270 continues to be the very best value in used McIntosh SS amplification. I've had four . . . and I wish I still had them.

 

[4-2-7]

You will be pleasantly surprised ...

Hey you took my line after reading the OP.

 

[4-2-7]

You'll hear a difference, and your B&Ws will love the power so much you will be hearing a better bass note thoughout the volume levels.

 

[leftside]

Alright, I'm all hooked up and listening to music as I write this. I first of all tried the "new" amp on it's own and it sounded just like the other MC7270. Then I pulled out the manual and connected the two amps into mono block mode. I had my B&W's on the 4 ohm tap before, so this time they are now on the 2 ohm taps. I'm not sure the last time the screws on the 2 ohm taps had been used, but they required a bit of deoxit.

Sound superb straight away. I kept telling myself I'm simply imagining the bass is a little tighter/better, just because my fellow McIntosh buddies told me this would be the case! But, there really is a slight improvement. Very happy.

I did the LED upgrade on the first 7270 and it definitely looks better. The McIntosh light is brighter and the meters are a blue colour (similar to the C2300). The meters on the second 7270 are more of a turquoise colour and seem a little "dirty" due to the uneven lighting. This one will also be getting an LED upgrade.

Pics attached.

 

[4-2-7]

You want to run them on the 8 ohm taps!!

Anytime you mono birdge you step up higher in number.
If your speakers where run on the 8 ohms in stereo mode you then use the 16 ohm taps in mono bridge mode, or 4ohm to 8 ohm and so forth.

 

[4-2-7]

What is the impedance of your speakers?

 

[4-2-7]

Description: 3-way vented-box system
Nominal Impedance: 8Ω (minimum 3.0Ω)
Frequency Range: -6dB at 30Hz and 50kHz
Dimensions: H 1020mm W 238mm D 351mm H 40.2” W 9.4” D 13.8” (not including feet) Frequency Response: 38Hz – 20kHz ±2dB on reference axis
Weight: 28 kg / 62 lbs. Sensitivity: 90dB spl (2.83V, 1m)

 

[damacman]

Yeah, on the MC7270 a 4 Ohm speaker is connected across the 2 Ohm taps of each channel. These amps can only be bridged, not strapped.

So ... Notice any better stereo imaging with the pair?

 

[4-2-7]

SPECIFICATIONS: 270w/ch. (540w mono). Response: 20-20kHz (+0 -0.25dB). Distortion: 0.02%. Noise and Hum: -100dB. Output Impedance: 1, 2, 4 and 8 ohms. (2, 4, 8 and 16 ohms in mono). Damping Factor: 30 or greater. Input Impedance: 20k. Input Sensitivity: 0.75v or 2.5v. Sentry Monitor. Power Guard. Autoformers.

 

[4-2-7]

Yeah, on the MC7270 a 4 Ohm speaker is connected across the 2 Ohm taps of each channel. These amps can only be bridged, not strapped.

So ... Notice any better stereo imaging with the pair?

He has 8 ohm speaker he should be running off the 16 ohm tap right!!

You want to run them on the 8 ohm taps!!

Anytime you mono birdge you step up higher in number.
If your speakers where run on the 8 ohms in stereo mode you then use the 16 ohm taps in mono bridge mode, or 4ohm to 8 ohm and so forth.

 

[leftside]

You want to run them on the 8 ohm taps!!

Anytime you mono birdge you step up higher in number.
If your speakers where run on the 8 ohms in stereo mode you then use the 16 ohm taps in mono bridge mode, or 4ohm to 8 ohm and so forth.

The McIntosh manual says the opposite.

 

[chef free]

You will notice a lot more difference than 3dB more volume! I was really surprised when I got a second MC2200. More power means more woofer control and I swear there's better stereo seperation.

 

[leftside]

Yeah, on the MC7270 a 4 Ohm speaker is connected across the 2 Ohm taps of each channel. These amps can only be bridged, not strapped.

So ... Notice any better stereo imaging with the pair?

Yes I think so. Also the vocals sounds very centered. It was pretty good before, but now it really sounds like there is a centre channel speaker in operation.

 

[leftside]