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Marantz EQ551

Stereo Graphic Equaliser (1985-90)

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Marantz EQ551


Output Level: 1V (7V max)

Frequency response: 10Hz to 50kHz

Signal to Noise Ratio: 110dB

Total harmonic distortion: 0.005%

Control Range: ± 10dB

Frequency Bands: 31.5, 63, 125, 250, 500, 1K, 2K, 4K, 8K, 16KHz

Dimensions: 420 x 73 x 194mm

Weight: 2.7kg

Year: 1986


service manual   English - SittingCrow

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Reviewed Jun 16th, 2015 by Stimpy

I have owned one of these lovely EQ's since new. It has suffered some damage due to when I first owned it, I lived with my parents for many years, and they were both heavy smokers. Somehow the smoke has attacked the metal casing at the back, and also the plastic inserts used inside the RCA phono sockets have broken up. One day I will try to replace the sockets... I also had to clean the EQ sliders with switch cleaner a few years ago, due to some loud static sounds when adjusting many of the EQ bands. Probably also caused by the smoking!

On to the Audio part of my mini-review...

This EQ is one of the best I have ever used. It really has a fantastic frequency response, and the attenuation the unit offers is great. But one thing that let this unit down, as the outright lie of a promised 110db s/n ratio. This is simply not true by any stretch of the imagination. It's true that there is very little audible hiss or mains hum, but the electronics used to drive the fantastic display (which has still to this day be bested, in my opinion!) is connected via a series of very thin and unshielded ribbon cables. This results in a kind of low-level humming/buzzing noise that is contained in the midrange of the audio spectrum, and is audible when listening to quiet music through headphones late at night with the volume up! But that really is this units only real problem.

Apart from the issues mentioned above, this is miles better than more modern EQs, such as the Technics SH-GS91 and some computerised high end Kenwood EQ I also owned for a while.

The main reason for this, I think, is down to the fact that the EQ551 is totally analogue, and well engineered. It really does boost the frequencies in a way you can expect, unlike the digital EQs that followed this model.

If you love your Analogue stuff, then this is a fantastic EQ to find and use. I have seen many in great condition on Ebay for under £100. I keep thinking of maybe replacing mine for one of those, as I suspect it's going to be hard to find a way to renew the Phono sockets...

Reviewed Feb 11th, 2014 by Denny74

I have one of these in my system..
Works great in deep frequency range, but you must becareful on mid frequency....
The LED display looks quiet impresif when you listening music in the dark...



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