Cassette deck head alignment - a surprise

[knobtwiddler]

I don't have a micrometer (probably should buy one!), but I have a couple of Verniers. I also have an original ABEX gauge. If there is a particular dim on the gauge you'd like verified against the ABEX THG-801, I can check?

EDIT: I presume you have seen this: https://www.youtube.com/watch?v=q86T8KC0kWc&t=300s

[TIMTAPE]

Originally Posted by cmjones01

I knew cassette interchangeability could be a problem, but I had no idea it could be quite this bad!

Chris

Unfortunately Dolby B, C and S exaggerated even minor record/playback errors, errors which might not be even noticed with no Dolby. The same to some extent with all the compander types for cassette such as dbx, Toshiba ADRES, Nakamich HiCom etc. Good performance depended on very high standards of machine and tape condition and alignment, both at record and playback stages, which I think in a consumer context was somewhat unrealistic. It's fine for us technically inclined folk but most people just wanted to hear their favourite music, not become technicians, tweaking things to the nth degree.

Tim

[Ted Kendall]

Originally Posted by cmjones01

This further reinforces my suspicion that my Technics cassette deck's head height was wrong from the factory, and so its recordings will always need special treatment to play properly.

I knew cassette interchangeability could be a problem, but I had no idea it could be quite this bad!

"Once upon a time there was a wheel-tapper called Fred, and he tapped all the wheels on all the trains that came into the station, and they changed 577 wheels. And then they found out - his hammer was cracked."

The age of that story indicates this is nothing new...

[cmjones01]

Originally Posted by knobtwiddler

I don't have a micrometer (probably should buy one!), but I have a couple of Verniers. I also have an original ABEX gauge. If there is a particular dim on the gauge you'd like verified against the ABEX THG-801, I can check?

The thickness of the back plate would be very interesting to know. Mine measures 2.40mm, but I have seen measurements of the THG-801 which indicate that it's 2.45mm thick, like on this page (in Polish): https://serwisvintageaudio.pl/2019/0...ontra-thg-801/
This is interesting because the difference I observed between "correct" and "wrong but plays tapes from my Technics deck properly" is about 0.07mm, so if my gauge was 0.05mm thicker I'd probably not have noticed the problem. That said, if such a small change makes such a difference the head is clearly right on the edge of the track anyway, so it's probably not relevant. But my calculations (assuming cassette 8.61mm thick and tape 3.81mm wide) come out to a back plate thickness of 2.40mm. Who's right here? Certainly not my tapes...

EDIT: I presume you have seen this: https://www.youtube.com/watch?v=q86T8KC0kWc&t=300s

Not that one in particular, no, but similar things, and it confirms the way I've been using the gauge at least

Chris

[cmjones01]

Originally Posted by TIMTAPE

Unfortunately Dolby B, C and S exaggerated even minor record/playback errors, errors which might not be even noticed with no Dolby. The same to some extent with all the compander types for cassette such as dbx, Toshiba ADRES, Nakamich HiCom etc. Good performance depended on very high standards of machine and tape condition and alignment, both at record and playback stages, which I think in a consumer context was somewhat unrealistic. It's fine for us technically inclined folk but most people just wanted to hear their favourite music, not become technicians, tweaking things to the nth degree.

Hear hear. I'm constantly amazed by the results possible from cassettes when everything is set up exactly right, and constantly frustrated by how difficult that is!

Chris

[knobtwiddler]

Originally Posted by cmjones01

The thickness of the back plate would be very interesting to know. Mine measures 2.40mm, but I have seen measurements of the THG-801 which indicate that it's 2.45mm thick, like on this page (in Polish): https://serwisvintageaudio.pl/2019/0...ontra-thg-801/
This is interesting because the difference I observed between "correct" and "wrong but plays tapes from my Technics deck properly" is about 0.07mm, so if my gauge was 0.05mm thicker I'd probably not have noticed the problem. That said, if such a small change makes such a difference the head is clearly right on the edge of the track anyway, so it's probably not relevant. But my calculations (assuming cassette 8.61mm thick and tape 3.81mm wide) come out to a back plate thickness of 2.40mm. Who's right here? Certainly not my tapes...

Not that one in particular, no, but similar things, and it confirms the way I've been using the gauge at least

Chris

Sorry for the slow progress on this. My ABEX 801 measures 2.38mm - but I emphasise that I used a Vernier, not a micrometer (which I can't believe I don't have...). The Vernier zeroes nicely to 0, but it's a mid-price one, not Mitutoyo. I find that Verniers always measure around 0.02mm less, as you have to hold them with your thumb. It could well be 2.4mm with a micrometer. Will ask my neighbour if he's got a micro I can check with...

[cmjones01]

Thank you for the update, knobtwiddler. 2.38mm does sound a little on the small side so I'd be interested to know what a micrometer says...

Chris