Robuk RK4

[liamoliver]

I have aquired this machine recently, and I was wondering what the spcifications are. It is lighter and smaller than my Philips EL3542A/15 and I was wondering how the two compare? The Phillips model is four rather than two track, but other than that I can't find much difference (they are both monophonic valve-amplified consumer machines). One thing that I am curious about though... the line input is marked "Gram" (with a knob next to it marked Gram Gain). Does this mean that this machine has a built in RIAA preamp (thus making the socket unsuitable for ordinary sources)?

[Stewart]

I don't have the spec for the Robuk to hand - but they were a budget machine and not the best either electrically or mechanically. The Philips you mention should be much better if running well. The Robuks only just managed at 7.5ips to get what the Philips did at 3.75ip!

Great for sorting through tapes though with its super fast winding!

Is the gram gain not just reffering to the recording level for that input?

[Tim]

OOH, I used to have an ORANGE one of those. I agree with Stuart, they weren't brilliant but would wind through a 7" spool in record time. Don't forget the screwdown caps...............

[liamoliver]

Funny, I noticed it's excellent winding ability too!

[Paul_RK]

Details from Hi-Fi Year Books...

Robuk RK4 (1965-6 edition) - Frequency response 7.5 ips 60-14000 c/s +/- 3dB, 3.75 ips 60-7000 c/s +/- 3dB, 1.875 ips 60-3500 c/s +/- 3dB. H. and H. (this abbreviation I don't recognise - hiss and hum? ) <-40dB. Wow and flutter < 0.2%. Price £37 16s.

Philips EL3542 (1961 edition) - Frequency response 7.5 50-20000 c/s, 3.75 50-15000 c/s, 1.875 50-7000 c/s. Weight 30 lb, price £61. 19s.

So as Stewart says it looks as though the Robuk would perform about as well at 7.5 ips as the Philips at 3.75, though the Philips data don't include a dB limit for the frequency response figures. Of course head wear etc. will likely have eroded both machines' capabilities considerably, and nothing like these figures would ever have been produced if the limitations of the internal 'speakers were taken into account.

Regards, Paul

[Steve_P]

I've never had one of these through my hands, so I decided to look up the circuit and have a gander.

The wind is fast - I hope not too fast. I once had a Dynatron TRP1 (Magnavox Studio Deck) where the wind was so fast that it actually broke the sound barrier! It came in with a complaint of Noisy Wind and stretched tape. I just slowed it down.

Anyway, the Gram Input. V1 is an ECC83, and one of the triodes is used as a Pre-Amp for the Microphone. The Gram input goes in at the second amp, via a pot. Just set it for whatever you want to record from. Circuit Below. I wonder if those level controls interact at all?

Interesting use of a serparate EL84 as an H.F. Bias Oscillator.

The deck is manufactured by Motek.

Cheers,

Steve P

[Nickthedentist]

Originally Posted by Steve_P

The deck is manufactured by Motek.

Never heard of them... Not English, presumably

[Brian R Pateman]

Originally Posted by Nickthedentist

Never heard of them... Not English, presumably

Au contraire!

They advertised in PW during the late 50s and early 60s. Motek stood for Modern Techniques and they were in Wedmore St, London N19.

The model K9 retailed at 21Gns.

Regards,

[reelguy]

Robuks.
If memory serves the Robuk recorders where of English manufacture.
The decks also of Robuks design and manufacture.
I think there was a MK 3 and 4. Not many about though..

Sorry, All I can remember.
Peter .......

[Tim]

ISTR having trouble with the side operated "knobs". I also seem to remember they were strange values(or was it that ALL I HAD the same physical size was a strange value. Never mind it worked!!)

[Stewart]

Tim is quite right, the "Clarostat" controls used on this machine and a few Elizabethan models (Popular, Automatic etc) could become very noisey indeed......

[brenellic2000]

Hi,

Robuk and Motek are the self-same business, set up by Sam Korobuk (hence Robuk). Motek was his his manufacturing company who only made tape transport decks (and in the early days their own heads). The Robuk was their first complete tape recorder and was marketed under the 'Robuk' name to distinguish it from the Motek deck. Many were used by the BBC researchers/editors/programme makers to listen to tapes.

The full story is in my "Guide to British tape-recorders" ; a second edition is near completion and is twice the size (and price!)

Best wishes
Barry

[peter_sol]

Hi
Just noticed this thread and that Liams question has not been answered
The "gram" input was always at high impedance and for medium output crystal pickups such as used in cheap to medium record players
No RIAA preamp as no need for one
So input similar to line in ETC
Hope this helps
Peter.

[Mike Phelan]

Originally Posted by Nickthedentist

Never heard of them... Not English, presumably

I used to handle a few of the Motek K9 and K10 decks from these machines and others that I cannot remember.
They were a good, but fairly basic, 3-motor deck.
I still have a flywheel / capstan assembly which is a solid brass lump.

The main faults were the push-button switches carrying mains (plus a bit of unwelcome L di/dt from the motors) - they arced and eventually burnt out. I think the K10 was improved in that respect, but it is a long time ago.
As said, the fast wind was like a 737 spooling up for the take-off run!

[plumbweiss]

I've just aquired one of these!

[stendec]

I had one of these from new in the early 60s. Loved it, never had any trouble. Plenty of volume. One and seven eighths speed was great for recording speech/comedy programmes off the radio. Mainly used it to record pop music from the pirate ships (at 3.75 or 7.5 ips) so wasn't too demanding on quality but it worked fine.

[davidbn1]

Hi. I had a Robuk Regal in the late 60's which had same deck as RK4 but I remember that the machine overall was huge (and it too had an unbelievably fast re-wind).
Anyone recall this machine ?
Cheers