2. amps-preamps
  3. 1110950568

Are the MF308 and MC402 matching together ?

I got the Pre-amp Musical Fidelity 308CR and power-amp Mcintosh MC402. They sound great so far. Suddently I just read about the preamp - poweramp mismatch and just wonder are they perfect matching ? Cos I don't have a change to have another pre-am or power amp to compare... The preamp MF308 has specification as follow :
Voltage RMS, maximum > 30 Volts
Power maximum > 5 Watts
Peak-to-peak output current 0.5 Amps
Impedence 50 Ohms
Frequency response 20Hz to 20kHz ±0dB. 10Hz to 100kHz +0, -1.5dB.
LINE OUTPUTS
Total harmonic distortion + noise, 20Hz to 20kHz > 0.0035%
(5 Volts output, maximum volume).
Signal / noise reference 1 volt RMS output 104dB ('A'-weighted, at half volume)
Input sensitivity for 1 Volt RMS output 240mV
Input impedence 47k Ohms
Gain at maximum volume 12.5dB (4.2 times)
Overload margin 31dB
Channel separation > 88dB typical at 1kHz, maximum volume
PHONO INPUT
Frequency response reference IEC RIAA See graph below.
Signal / noise reference 1 Volt RMS output > 95dB Moving Magnet ('A'-weighted, at half volume).
> 85dB Moving Coil ('A'-weighted, at half volume)
Input sensitivity for 1 Volt RMS output 2.5mV Moving Magnet.
350µV Moving Coil.
Input impedence 47k Ohms
Overload margin 31dB

The Mcintosh MC402's specification :
Power Output 8 ohms 400 w @ 8 ohms
Power Output 4 ohms 400 w @ 4 ohms
Power Output 2 ohms 400 w @ 2 ohms
Power Bandwidth 20 Hz to 20 KHz
Total Harmonic Distortion 0.005 %
Intermodulation Distortion 0.005 %
Dynamic Headroom 2.1 dB
Frequency Response 20 Hz to 20 KHz +0.0 dB / -0.25 dB
Input Sensitivity 4.0 v
Signal to Noise Ratio 115 dB
Damping Factor 100 @ 4 ohms
Input Impedence 20 KHz
Power Requirements 120 v 10 A
Warranty (parts) 36 month(s)
Warranty (labor) 36 month(s)
Dimensions 24 cm. H x 44.5 cm. W x 51 cm. D
Weight 50.1 kg.

How can I know they are perfect match ? Or should I change the pre-amp to ultima the sound of MC402 ? Appreciate your idea. Thanks
Vincent

vincentdlee
aball
2,016 posts
 
You will never know if they are technically a "perfect" match. Your preamp's input impedance is quite low so there shouldn't be a problem - this is all you need.

Let you ears be the judge. You say they sound great - don't worry about anything else. Enjoy the music!
vincentdlee OP
8 posts
 
Aball, well I said they sound great...but you never know the potential of MC402 when you don't have the 2nd system to compare... that's why I wonder... If you've ever listened to a MC402 demonstration at the show then you would feel how good it is... Beside... technically, it said that the power-amp input impedance should be 10x to pre-amp output impedance,(I'm not familiar with it) so you can see the here in my system it's about 200x (Unbalance input) or 400x (banlance input) (MC402 has 10K ohms input impedance for Unbalance input and 20K for Balance input..)... so I feel s/t that's not quite right here...
aball
2,016 posts
 
I am an electrical engineer so I know the problem you speak of very well - you can believe what I told you. I have done research on impedance mismatches and how they affect traveling waves and what the optimal resistace/inductance and transconductance/capacitance ratios have to be for distortionless transfer. The issue is that you are taking "rules of thumb" as gospel. When people say the impedance ratio should be 10x, they mean AT LEAST 10x. This means that 200x is MUCH BETTER than 10x. If you had 10x, it would not be as good as what you have now.

In truth though, it depends on the impedance curves and not the values quoted on the brochure. I have seen systems with an impedance ratio of 1x and it be fine because the curves didn't hit each other. The fact of the matter is that the 10x rule is just to be sure that the impedance curves are far enough apart to not hit each other. The farther apart the better - and 200x just makes it all the more impossible for the curves to interfere.

Secondly, a second system for comparison is nice but how do you know that one is the best? Well, you don't! There is nothing perfect and there is no absolute. All you can do is experiment until you are happy.

Your system is just fine. Enjoy the music! take care, Arthur
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