Akai CR-80D-SS Tape Head Replacement

[scifi]

Someone sent me the following information about some 4 channel 8 track tape heads.

1. #B354364 100mHy / 100u-inch gap Record/play with 4-inch leads
2. #B356301 200mHy / 100u-inch gap Record/play
3. #B356361 200mHy / 100u-inch gap Record/play with rear mount and leads
4. #B357300 400mHy / 100u-inch gap Record/play
5. #358342 20mHy / 100u-inch gap Record/play

mHy apparently means millihenry

Does anyone know if any of them can be used in an Akai CR80DSS quad 8 track and/or an Akai 1730D-SS reel to reel tape recorder? How would it affect the equalization? I googled mHy and tape heads, and inductance and tape heads and found some information about having a tape head inductance that combined with any capacitance, should move the resonant frequency as far up as possible (apparently out of the audible range). I have schematics for the CR80DSS and 1730D-SS.

 

[scifi]

Some good links I found are

http://www.audioasylum.com/forums/bottlehead/messages/13/130902.html

http://www.jrfmagnetics.com/headtrip.html

100 or 200 mHy might be a good value with a solid state (ie. transistor) preamp. According to the jrfmagnetics link, inductance drops as the tape head wears.

 

[scifi]

I looked in the Akai CR80DSS service manual and its says the R/P tape head has an impedance of 650 ohms at 1 kHz. If R and C are both 0, then its all inductive reactance. Plugging in the numbers at the link gives 0.1 Henry (100 millihenry) for the tape head inductance. With all the windings, R probably isn't 0.

http://www.easycalculation.com/physics/electromagnetism/inductive-reactance.php

 

[scifi]

Looks like subscripting and superscripting work here. You can't simply add R, X[sub]C[/sub] and X[sub]L[/sub] to get impedance Z. If I understand it correctly, they're all vectors and you have to use this equation to calculate total impedance Z.

Z = (R[sup]2[/sup] + (X[sub]L[/sub] - X[sub]C[/sub])[sup]2[/sup])[sup]1/2[/sup]

 

[scifi]

I found the equation here http://www.kpsec.freeuk.com/imped.htm