PL7000S2

[George S.]

Right on. These are the first I've changed. Got the old ones out and new put in.
Hooked up the gear, and the old Lenovo T410 laptop died.
Updating a fresh Windows install on a old work station as a replacement.

 

[George S.]

Making progress.
Using a 7 decade resistor substitution box to dial in the playback head parallel LCR circuit damping.
I'm finally understanding a little about how to match heads to the deck.
Problem is magnetic heads aren't ideal inductors and the on-line calculators give poor results. Very little info out there about actually matching the head.
The unit has a nice flat frequency response now out to 16 KHz, then falls due to the tape, not the electronics.
Pretty damn happy with a 15K and 330pF parallel with the playback head.
But I'm going to try a 220 pF and shift the heads resonate frequency up north another 5 kHz, then calculate the damping resistor again with the decade box.
Need to test that before settling on final values.
Listening to a "all the best from Ireland" tape on headphones.
Sounds damn good,
Need to order some 220 pF caps. Later.

 

[laatsch55]

Quite the project still George...I am still thoroughly impressed.

 

[George S.]

So here's the Playback EQ FR I'm going to run with for now.
A +3.5 dBV peak at 2 kHz.
Read somewhere that being within a 5 dBV variance is good. I don't know.
I'll revisit this later.
Thanks to whoever made the Exel program, can't recall where I found it.

 

[George S.]

Raised the head height with a hard paper shim.
Had some erratic high frequency distortion on the right channel and a somewhat lower signal amplitude. All fixed with the shim.
Read that it's common for Pioneer heads to be mounted slightly low. Sure was the case here with the replacement head.
Also removed the heads tape guide, it's not needed
.
The tape guide is attached to the left pinch roller and the entire pinch roller assembly adjusts the tapes tracking across the heads.

 

[laatsch55]

Excellent George!!

 

[Gepetto]

Raised the head height with a hard paper shim.
Had some erratic high frequency distortion on the right channel and a somewhat lower signal amplitude. All fixed with the shim.
Read that it's common for Pioneer heads to be mounted slightly low. Sure was the case here with the replacement head.
Also removed the heads tape guide, it's not needed
.
The tape guide is attached to the left pinch roller and the entire pinch roller assembly adjusts the tapes tracking across the heads.

George, your wife is getting jealous...

 

[derek92994]

Also removed the heads tape guide, it's not needed
.
The tape guide is attached to the left pinch roller and the entire pinch roller assembly adjusts the tapes tracking across the heads.

I don't know why manufactures didn't install pressure pad lifters on play/rec heads in a dual capstan transport, it seems to me the pressure pad is not needed as the dual capstan and back tension provides all that is required for stable tape tracking. I have done tests by removing the pressure pad and playing the tape in a dual capstan deck that does not have a pad lifter. The heads would surely last a lot longer without the pressure pad.

 

[George S.]

The HP Magnetic Tape Recording Handbook.

 

[derek92994]

The HP Magnetic Tape Recording Handbook.

Some super detailed info there, I couldn't stop reading it. I didn't understand it all but still a great read.

 

[George S.]

Haven't done much to with this lately.
The Microscan calibrates nicely to TDK D and SA tapes, but fails on the metal MA due to low output to the Microscan board,
Clearly have a level issue with the tape selector switched to metal.
Was a good point to take a break from this.
Just got around to picking up four more MA-C90 tapes to verify if my one MA is good or bad.
Will hopefully get back to this after a home renovation project that's underway.

 

[J!m]

I can't say for the MA tapes, but there was a distinct change in the SA tapes between the early ones (like your MA labels) and the later ones. Color of the tape itself is clearly different, and they calibrate quite differently as well. Early tape is chocolate brown, and later tape is dark chocolate, almost black-brown on the SA.

MA may be the same across the board forever, but thought I'd mention this in case you were not aware.