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Head amp interest check

Latest names added. Nice to see so much interest! There must have been some huge ground swell in demand/market for head amps as about 5 years ago no one was interested!
 
I'm glad this is on track , I'm looking forward to trying it .

I think there is a market for headamps but they need to high quality and adjustable for gain and loading , the kind of thing you buy once and it suits all (within reason) of you future cartridge choices .
Having done the SUT merrygoround , it's a minefield that doesn't lend itself easily to choping and changing carts . Get it right and I'm sure there's a market out there , maybe it's a small one but it's there .
 
It has just occurred to me that that the simple common base design using a single OC81 (taken from an early sixties Mullard publication) that I used back around 1967 to match a low impedance tape head into the input of an EMI TR50 (normally a high impedance head straight to the first EF40) was in fact a head amp, not a term I was familiar with at the time.

I expect your new design will be a little more sophisticated....
 
early said:
I'm glad this is on track , I'm looking forward to trying it .

I think there is a market for headamps but they need to high quality and adjustable for gain and loading , the kind of thing you buy once and it suits all (within reason) of you future cartridge choices .
Having done the SUT merrygoround , it's a minefield that doesn't lend itself easily to choping and changing carts . Get it right and I'm sure there's a market out there , maybe it's a small one but it's there .
Click to expand...

As mentioned up thread, this is a transimpedance amplifier so everything is different compared to a conventional one. There is no "loading" as such with this type of amplifier. The cart see's a "virtual short circuit" and the head amp is "current input". Gain is not fixed with this type of unit and is in fact set by the internal resistance of the cart... the lower the resistance the higher the gain. Two gain ranges will be provided by a toggle switch on the back and should be enough to encompass >90% of carts.
 
Barrymagrec said:
It has just occurred to me that that the simple common base design using a single OC81 (taken from an early sixties Mullard publication) that I used back around 1967 to match a low impedance tape head into the input of an EMI TR50 (normally a high impedance head straight to the first EF40) was in fact a head amp, not a term I was familiar with at the time.

I expect your new design will be a little more sophisticated....
Click to expand...

This is of course mainly for the benefit of those with less knowledge of hi fi history than yourself Barry:) but back in the 50's and 60's a phono cartridge was often known as a pick-up head, also many pre amps had an input for direct connection to a tape head and so there could be quite some confusion as to what exactly a head amp was.
In fact MC carts were much rarer than today and suitably low noise amplification was largely absent and so for the few MC carts around (Leak, Ortofon, IIRC Voigt, early Denon 103 from '63 etc) an SUT was pretty much the only solution around and certainly in the 50's most would understand head amp as meaning an amp for a tape head.
As MC carts are so low in output and were called "pick up heads", and as tape heads had a low output, "head amp" gained some usage for anything where a very low signal level had to be pre amplified in order to be used with a "normal" pre amp, in fact the term "pre-pre-amplifier" was sometimes also used.
 
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