TUBE Tape Head record / playback amp....

[Tomom]

I have Ampex MM-1200 and would like to replace solid state amps for record / playback heads with tube amps. I do play music, but my electronic knowledge is limited; is anyone there able/willing to help in such a project.

[Osvaldo de Banfield]

If you have limited knowledgements, I suggest not to modify it. Tape haeads gives very few millivolts at its output, and need to be loaded with some capacitance and resistance to give good performance. So, the levels of amplifications are great, the possibility of noise and hum pick ups are high, and finally you need an equalization networks in any way, similar to the RIAA, but called NAB, and it depends of the tape velocity.

Regards.

[Tomom]

Appreciate reply Osvaldo. Still I am keen to do it. I understand about small signals comming out of tape heads, and equilization networks too, I can work with soldering iron and a lot more... but to design the circuit is slightly beyond me; I could try, but this is not something where I would want to "learn" by making costly mistakes.

[Osvaldo de Banfield]

I forgot some details. Do you have sufficient space for a new power supply, and the tubes itself, and the sufficient air flow to prevent them overheating itself and surrounding elements?

[Tomom]

This is valid point, Osvaldo. Yes i was thinking about that, I think there is enough space, and I could surely use switch mode PS, as the current requirement will be relatively small...

[DF96]

SMPS spraying interference near a head amp? Lovely!

You have been given good advice. Why try to ruin a perfectly good device?

[Tomom]

Hmm...not realy near tape head, on a safe distance, just where the main power supply and the rest of power electronic for the whole unit is situated now.

[firechief]

Yea - this is a huge undertaking. Do you have complete technicial information on this lovely, complecated piece of equipment? You can't even address the question properly without that in hand.
Space is not even the biggest chalenge.

[DF96]

This is one of those projects where if you need to ask then you don't know enough to do it successfully. You may find someone local who is happy to do the job for you at commercial consultancy rates, but I suspect that their initial advice will be the same as ours.

Why do you want to make this change anyway? Are you after 'tube sound'? i.e. you want to turn a sound reproduction machine into a sound effects machine?

[Tomom]

Yes I understand it is a great challange; and yes, I have all service manuals, this is why I started thinking of the project. And I know if it can be done properly, reward soundwise will be equaly great...