Reel to Reel revisited; Philips N4510 + NAIM NAT05

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Your articles on vintage equipment spurred me to take another look at my Philips N4510 reel to reel recorder (circa. 1974). The last time I used it was 5 years ago when the recorder stuck on the rewind function. Hence it was consigned to the attic. However after some fiddling I’ve managed to get it back into working order. The problem is, when I try to record from the output (75 mV/600 ohms) of my Naim NAC552 to the recorder tape in/out socket (input sens.:- pins1 & 4: 2 mV/20 kohms, pins 3 & 5: 100 mv/2 Mohm, output voltage: pins 3 & 5 : 1 V/50 kohms) it overloads the recorder, creating distortion, when trying to record. Playback into the NAC552 is fine.

If I plug my NAT05 tuner directly into the recorder’s tuner input socket (input sensitivity : 100 mV/100 kohms) it records perfectly.

For convenience and flexibility’s sake I would prefer to record from the output of the NAC552. Could you advise me on the attenuation required for an interconnect cable?

I have to say I’d forgotten how good reel to reel recordings sound, and it’s a crying shame that this medium seems to have been consigned to history. As a regular reader of your e-zine I love the articles on retro hi-fi gear; more please.

Hmm. You quote two input sensitivities. The high one of 2mV is likely for a microphone and it’s this you are overloading. Pins 3&5 you quote as 100mV in, as well as 1V out, so I presume these are inputs whilst recording, switched to outputs on replay. It’s these pins that have what appears to be suitable line input characteristics. The tuner input almost certainly uses the same input route, switched through, and it has the same sensitivity.

If you cannot use Pins 3&5 as inputs then make up a special split lead taking the NAC552 output to the tape recorder’s tuner input, and the tape recorder’s output to the NAC input. I am sure this, or some similar arrangement if I misunderstand input conditions, will work, because the Philips recorder obviously has a suitable input; it’s just a case of finding it.

It’s not a good idea to attenuate down into the mic input, but a 10k, 0.125W resistor in series and 1k to ground will give you a ladder attenuator with 10:1 signal reduction that may well do the job. If not just increase the 10k resistor. Soldering these into a lead or DIN plug will be a fiddle.