Playing and transferring 8 track tapes

[andrewferguson]

Originally Posted by Ted Kendall

High speed transfer is not the way to go if you want the best results. It's a simple enough matter to juggle resistor values in the Fostex varispeed circuit to bring 3 3/4 into range. The EQ needs tweaking, of course, but this can be done externally.

Ted, I'd be really interested to hear more about this. I have a Tascam 38 which is 15ips but I have several tapes that were recorded at 7.5ips and even 3.75ips. I did have a poke around the "pitch control" circuitry a while ago, but couldn't figure out how it worked - it looked to me like the resistance got smaller as the tape speed decreased, and my rough calculations (based upon the changes in resistance for the +/- 12% pitch control) indicated that the resistance needed to halve the speed would be stupidly low ... tens of ohms if I recall correctly.

No doubt I was looking at the wrong section of the electronics, or some other "rookie" mistake.

[derekheeps]

Originally Posted by andrewferguson

Ted, I'd be really interested to hear more about this. I have a Tascam 38 which is 15ips but I have several tapes that were recorded at 7.5ips and even 3.75ips. I did have a poke around the "pitch control" circuitry a while ago, but couldn't figure out how it worked - it looked to me like the resistance got smaller as the tape speed decreased, and my rough calculations (based upon the changes in resistance for the +/- 12% pitch control) indicated that the resistance needed to halve the speed would be stupidly low ... tens of ohms if I recall correctly.

No doubt I was looking at the wrong section of the electronics, or some other "rookie" mistake.

I suspect that what Ted is getting at is that the frequency response from a tape/head interface is finite - not withstanding changes in equalisation - therefore playing back a tape at a speed at speeds higher than it was recorded at will always have the potential at least to lose higher frequencies .

Entirely the opposite effect to half ( or slower speed ) mastering which places much lower demands on the equipment ,

[andrewferguson]

Originally Posted by derekheeps

I suspect that what Ted is getting at is that the frequency response from a tape/head interface is finite - not withstanding changes in equalisation - therefore playing back a tape at a speed at speeds higher than it was recorded at will always have the potential at least to lose higher frequencies .

Entirely the opposite effect to half ( or slower speed ) mastering which places much lower demands on the equipment ,

I should have clarified - these aren't commercial tapes, but ones recorded by others on equipment capable of 3.75ips / 7.5ips. My Tascam 38 is only capable of 15ips, but my understanding was that Ted had modified his Fostex to play back at a lower speed, which is exactly what I would want to do.

[Cobaltblue]

Split off from this thread https://www.vintage-radio.net/forum/...d.php?t=172931

Cheers

Mike T

[jamesperrett]

Remember that the Tascam 38 is a half inch machine whereas 8 track cartridges use quarter inch tape.

One of the reasons that I asked Ted about changing the speed on the Fostex is that I have an E-8 here which is a larger and possibly slightly more sophisticated version of their smaller 8 tracks. I have often wondered about using it at 3.75ips as it appears to be possible to make it run at that speed just by changing a couple of jumpers on the capstan motor controller and setting a control line high or low (I can't remember which off the top of my head). The control line was used by the speed switch on the E-2/E-22 two track mastering machines which appear to be use an identical tape transport but with a more sophisticated audio section.

I've had the E-8 running at 30ips, 15ips and 7.5ips by setting the jumpers on the capstan controller but not yet tried changing the control line.