What does it take to add a head....

T

technoplayer

Recovering Gear-aholic
I would like to have a quarter track play head on my half track Ampex 440C.
Ampex did offer the half track head stack with an optional quarter track play head and a built in switch to flip between half track and quarter track, but I have been unsuccessful in finding one at a reasonable price.

Sooooo.................

I have a set of 4 channel 4 track quarter inch heads from a Teac...probably a 3340 or 3440. What are the issues if any with fitting the play head into the spare slot on the 440 headblock and hooking up my own switch to have quarter track play capability? I suspect there is some compatability issues/ equalization/ impedance/ etc that I do not know about. I guess it cant be that straightforward or it would be done more widely.

>>> And while Im at it, what about hooking up the record (and erase) heads?
I imagine now I am into bias issues and etc.

Opinions?? Facts???
 
I can only offer opinions, but I think you're going to get into some considerable compatability issues between the two. I think the gaps are different (0.25mils for the Teac heads and 0.30~0.50 for the Ampex), and I think there are impedance issues between the two. Have you tried measuring the coil resistance of the two brands? And then there's the whole other issue of mounting...I'm pretty sure you're going to have to have some custom machining done both to make an adapter/spacer plate as well as potentially modding the headstack base...ugh...and the head plug...

If you try it, post back the results though. Could be verrrrrry interesting.
 
There is a lot of after market support for Ampex machines. JRF Magnetics and Sprague Magentics are the first that come to mind that supply Ampex heads. Also, JRF has the stock of Nortronics heads, not sure of compatibility, but you can email JRF and he'll respond. What is the price point that you're looking at?
 
Cory, unless the gap size makes a difference for the playback electronics, thats not a problem. I am not trying to be compatable with anything except the 4 track tapes recorded on other machines. Is coil resistance the key factor? If so this is simple enuff to check.

I have a "spare" 440 that i figured I could pilfer a head nest from, which should simplify the mounting issue

Jinn: I had not thought about buying a new bare head, but certainly could. I was starting with inquiries on using the 4track/4 channel head I have as I also have 4 channel of 440C electronics I could interface to and potentially play my 4 channel tapes on this transport.
 
Well, I've read bits and pieces here and there regarding the impedance and I'm assuming that the coil resistance has a pard in the nominal impedance load of the coil circuit and the amplifier, but I'm kind of speaking out of my derrier a bit on that, and the bits and pieces that I've picked up here and there on this aren't contiguous or complete in any way. Hm. Maybe you just give it a try and work out the bugs from there?
 
technoplayer said:
Cory, unless the gap size makes a difference for the playback electronics, thats not a problem. I am not trying to be compatable with anything except the 4 track tapes recorded on other machines. Is coil resistance the key factor? If so this is simple enuff to check.

I have a "spare" 440 that i figured I could pilfer a head nest from, which should simplify the mounting issue

Jinn: I had not thought about buying a new bare head, but certainly could. I was starting with inquiries on using the 4track/4 channel head I have as I also have 4 channel of 440C electronics I could interface to and potentially play my 4 channel tapes on this transport.
Click to expand...

If you already have the mounting hardware, I'd bet JRF has a head.
 
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