Marconiphone Unit Four

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Aug 10, 2019
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Hi

I recently purchased a marconiphone unit four amp and speakers that are pre 1970. this means it has no phono input just a single gram 5 pin din and tape 5 pin din.

Using converter cables I have managed to hook up my NAD 5120 turntable to it.

So it works, problem is its really quiet, I cant find anywhere about the amp as its pre 1970. Another forum suggested using the tape input rather than the gram input? (both are single 5 pin din)

Or should I get a preamp or is the amp too old for this?

Would appreciate some advice :)

Nathan
 

Andrew Everard

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May 30, 2007
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Given that the Unit Four was originally sold as a package IIRC, complete with an autochanger turntable and a pair of speakers, I suspect the record player may have had a phono preamp built into it, so this is probably what you need between the amp you have and your NAD turntable.

However, in the absence of any detailed specs for the inputs on the amplifier, I'd suggest proceeding with caution in using a phono preamp between the two, as the results maybe somewhat unpredictable, and I'd hate you to spend money on a phono stage and a special DIN cable to hook it up, only to find it didn't do what you want.

Any experts on equipment of this era out there? Failing that, this site has downloadable servicing information (for a fee), which may offer some guidance.
 
A

Anonymous

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Thanks Andrew, so the preamp is the turntable, that would make sense
 

Andrew Everard

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Yes, it would, but that's only supposition on my part. I would think if you wanted to play it safe you could try an external phono stage via the amp's tape input.
 

chebby

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Jun 2, 2008
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If you read this link (fifth paragraph) you will find out why your MM cartridge sounds so quiet.

The 'Gram' input on your old amp was (probably) designed for ceramic cartridges with their very high output and little (if any) equalisation.

So I agree with Andrew. You need a modern (MM) phono pre-amp into the 'tape' input.

Something like this.
 
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Anonymous

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Thats great, will that preamp work ok with the single 5 pin din tape input?

I really want this thing to work, i love the vintage hi fi stuff
 

Andrew Everard

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mu301nh said:
Thats great, will that preamp work ok with the single 5 pin din tape input?

I really want this thing to work, i love the vintage hi fi stuff
With a phono-to-DIN cable, yes, but you may want to check the pin assignments on the DIN sockets on the amp: not all products conformed to the usual DIN standard pin layouts. Usually – viewing the plug from the outside, so you are looking at the pins – the screen is the top dead centre pin (to which the screen for both channels should be connected when using phono-to-Din connections), the one at about two o'clock is right channel, and the one at about three or four o'clock is left.

Also worth noting that this means not all two-phono-to-one-DIN cables you may buy off the shelf are suiitable for what you want to do: if the cable is wired up as an output cable (ie to take signal from the DIN out on a component to the phono in on another), it won't work in the other direction.

However, various manufacturers had their own variants, especially when components were designed only to be connected to their own products. For example, on some current Naim products the DIN connection (for example between a preamp and a power amp) carries power as well as signal, so you have to be careful about these things if making up your own cables!
 
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Anonymous

Guest
Got it working with a little pre amp, isnt the best sounding system but it is over 40 years old!

Thanks for all your help, one other strange thing about this amp is you need to start it up like a car, ie it needs three or four resets on the dial to get it working!!
 
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Anonymous

Guest
Hi there!

Ok so now ive got more problems! The system was working fine, I have the speakers (which are 5 pin din) into two seperate original inputs, for some reason one of the inputs is now really quiet, it is def not the speakers as they both work through the other input, what could this be?

Thanks!
 
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Anonymous

Guest
So it works now, but ive got more problems! The speakers (pin din) are attached to their original inputs but one of the inputs is really quiet, I have tried both speakers in the other input so it is not the speaker. Any reason why this is happening? I havent taken the back off to see if it is a loose connection. Could I have blown one?! It is nearly 50 years old so I imagine it wouldnt be too hard.
 
A

Anonymous

Guest
Hi there!

Ok so now ive got more problems! The system was working fine, I have the speakers (which are 5 pin din) into two seperate original inputs, for some reason one of the inputs is now really quiet, it is def not the speakers as they both work through the other input, what could this be?

Thanks!
 
A

Anonymous

Guest
Yes they are outputs, is there any reason one might be quiet?
 

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