Need help, Tape Machine / Audio Head > PreAmp > Interface

[BurningShrine]

Hey There!


Now this one's a special question.
I have an old Grundig TK 125 deluxe tape machine and want to get the audio tracks into Pro Tools.

Here's what I've been thinking:

Wire the Head (has two wires) into a DI Box.
Feed the signal into a preamt and then into my interface.

Do you guys think this will work?

Any other ideas?


Thanks,
Eric

 

[DrNewcenstein]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

Does it not have regular outputs? Headphone, RCA Main Out, 1/4" Line Out? Something marked "to power amp" or some such? I can't see jumping wires from the playback head to an external unit.

 

[BurningShrine]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

It has an external speaker output.
This would work with the -40dB pad on my DI box but
the amplification circuit seems to be broken.
There's an extreme amount of "transformator-hum",
that's why I'm trying to find a better solution.

Thanks though ;o)

 

[GoldenVulture]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

Taking it straight from the heads won't work. At best you'd get squealing noises. The signal from the heads needs to be processed to remove the sound from the bias signal and then is EQ'd so it has a balanced frequency response. That's all done in the tape recorder before it is amplified.

Tap the sound at the volume control where it would be at the front end of the pre amp /amp in the tape recorder. It should be at line level at that point.

Grundig TK 125 deluxe; that's an old valve recorder. By now it caps would be stuffed and that's where your hum willl be coming from. As it uses valves there's valve type high voltages in there so I'd be carefull about poking around in it and where you connect wires or touch things.

 

[Funkfingers]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

Try obtaining a schematic circuit diagram before opening up the case. It should provide some idea of the component specs. Where original components are no longer available, at least you can research workable alternatives before wielding the soldering iron.

THINKS: Are the old recordings mono or binaural? If you know the head layout of the Grundig, it may be wiser to replay the tapes on another, compatible machine. Rental charges might work out cheaper than repairing the Grundig thoroughly.

 

[Funkfingers]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

Those old Grundig RTR machines tend to have 5-pin DIN audio connector sockets. You need the manual to ascertain the pin out sequence.

Typically, for binaural machines, the pins will carry Left In, Right In, Common Ground, Left Out, Right Out …BUT… not necessarily in that order.

The old Deutsche Industrie standards found numerous uses for that one socket.

With the pin outs established, you will require a two-con + shield cable and some means of adapting this to either 2 x 1/4" jack or 2 x RCA Phono plugs. (Whichever better suits your in/out interface device.)

It is highly unlikely that a domestic tape recorder will have been fitted with Balanced audio in/out connections. In the event that it has, the 5-pin DIN pin out layout will be different again.

 

[GoldenVulture]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

Those old Grundig RTR machines tend to have 5-pin DIN audio connector sockets. You need the manual to ascertain the pin out sequence.

Typically, for binaural machines, the pins will carry Left In, Right In, Common Ground, Left Out, Right Out …BUT… not necessarily in that order.

The old Deutsche Industrie standards found numerous uses for that one socket.

With the pin outs established, you will require a two-con + shield cable and some means of adapting this to either 2 x 1/4" jack or 2 x RCA Phono plugs. (Whichever better suits your in/out interface device.)

It is highly unlikely that a domestic tape recorder will have been fitted with Balanced audio in/out connections. In the event that it has, the 5-pin DIN pin out layout will be different again.

Looks like it should have the Din Plug.

- http://www.richardsradios.co.uk/tk125.html -

- http://galerie.experimentierkasten-board.de/data/media/2/TK125_01.jpg -

 

[BurningShrine]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

Thanks!
I really appreciate your input.

It's a mono tape.

http://galerie.experimentierkasten-board.de/data/media/2/TK125_01.jpg

Although I can read wiring diagrams this is just too much for me... ;o)

I tried taking it from the volume pot, but i could have taken a wrong lead, it's pretty tight in there.
Anyway while I was fooling around i decided to clean the pins of the tubes with steel wool.
The hum is pretty low level now. Maybe I'll just use the speaker cables...

 

[BurningShrine]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

The 5 pin plug is used for a footswitch, at least google told me so ;o)

 

[GoldenVulture]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

That appears to be correct according to the manual I down loaded here - http://elektrotanya.com/grundig_tk120_tk125_tk140_tk145.pdf/download.html -
There should also be a three pin din plug that inputs "Radio " on pin 2 and " microphone " on pin 3 and pin 1 is earth.

[ The Manual is mainly in German ]

 

[BurningShrine]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

That's right. The microphone plug is on the top.
German is my native language but it didn't help at all ;o)

I'll just use the speaker connections. I think my DI box should be able to
lower the voltage enough to ge a usable signal.

Thank you so much for your help guys!

I'll keep you updated.

 

[BurningShrine]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

Update:

Alright, my BSS DI worked like a charm.

Recorded 3hrs of audio into Pro Tools.
Did some editing, 70+ Songs.
Inserted HPF and Izotope to get rid of noise and hum.

Still a few things left to do: EQing, Kompression, Saturarion...

Annoying but I'm progressing rather smoothly now.


One more time: Thanks! ;o)

 

[GoldenVulture]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

I presume you did a head clean and maybe a demag too ? A head alignment doesnt go astray either.

 

[BurningShrine]

Re: Need help, Tape Machine / Audio Head > PreAmp > Interface

Sorry, I wasn't at home this weekend.

Yeah I cleaned and demagnetized the head right when I got the machine.
I didn't align the head though.
Seemed to be too much of a hassle and i don't think it would have solved the hum problem.
Well, just call it laziness... ;o)

Anyway, it's done.
I'm happy with the result. The noise floor is rather low (except some parts that were recorded at an extremely low level)
and I was able to remove most of the tape hiss without sacrificing high frequencies.

Cheers mate!