restorer-john
Grand Contributor
No tweaking at all. Bias was not adjusted, just at +/- 0.
Well, that response is pretty darned good for any deck. The head wear must be minimal and the alignment must be pretty much spot on. Well done.
No tweaking at all. Bias was not adjusted, just at +/- 0.
OK, problem detected!
Using my SMS Sanskrit 10ht Mk2 as signal generator is not a good idea, lots of distortion from 180-500hz (with & without external power supply)!
Anybody knowing an good signal generator with lower distortion?
Or is this "performance" enough for measuring the Pioneer 737...
View attachment 135187
Good idea but those tend to be rubbish. And won’t let Amir into account wow, flutter are not like a flexible tape moving across a head at a precise speed and tension etc.Was thinking that you could use a tape adapter, like:
https://www.amazon.com/Reshow-Car-Audio-Cassette-Adapter/dp/B07FKFMRGF
I guess that would have to be measured though somehow.
I see your SINAD and raise you wow and flutter! And tape bleed through. And head vs tape alignment. And wear of tape head and tape. And….come on man, it’s not Amir who is being deceptive or in denial here?It's an apples and oranges comparison and you know it. S/N is a valid, standalone measurement. So is total harmonic distortion.
Amir lumps them together with SINAD.
Of course any tape based analog format is going to have more THD than digital, but S/N is a function of how quiet the electronics and the noise reduction system are.
How will you know how quiet in real terms anything is, if you have harmonics dominating a SINAD number? Remember, S/N is measured in the absence of signal. SINAD notches out the fundamental and measures everything else. It's deceptive.
I see your SINAD and raise you wow and flutter! And tape bleed through. And head vs tape alignment. And wear of tape head and tape. And….come on man, it’s not Amir who is being deceptive or in denial here?
I’m just saying that all those things would seem accumulate in, to use your phrasing “real terms”.We are talking electrical noise and distortion, not mechanically induced issues, media flaws or wear. All of those things have their own measurement protocols.
The one thing that Digital record/play changed permanently is wow 'n' flutter and pitch. The inability to hold a correct pitch, or produce a vibrato-less pitch: those are musical distortions, serious ones, and are of greater importance to the music itself than distortion or noise.I’m just saying that all those things would seem accumulate in, to use your phrasing “real terms”.
And I would have thought wow and flutter is electro mechanical.
Maybe I’m being thick, but it seems Not taking into account distortion due to transport is like measuring a cars performance only by the engine while ignoring the suspension.
Yep, you can use REW to measure a tape deck. You'll need a calibration tape, which typically has a 3 kHz tone on one side, and a 8-12 kHz tone on the other side. You use this to tune the speed, azimuth and channel balance (these tapes are mono). You can get one on eBay.I should be getting my Nakamichi RX-505 from the shop this coming week. If anyone can walk me through the measurement process, I'd love to post some for you all.
I have a bunch of blank tapes, some ABEX test tapes, and a miniDSP SHD that can be used as an interface with my laptop. Would I be able to use REW? Are the programs used above readily available?
I was able to tune the cassette player using a variety of ABEX tapes I have and I have sent it in to a shop for general service, so that part is taken care of. The confusing part for me has to do with using REW to get frequency responses and measure THD and noise.Yep, you can use REW to measure a tape deck. You'll need a calibration tape, which typically has a 3 kHz tone on one side, and a 8-12 kHz tone on the other side. You use this to tune the speed, azimuth and channel balance (these tapes are mono). You can get one on eBay.
Azimuth is the angle of the head, you want it perfectly parallel to the tape. If you don't have a scope, the next-best way to adjust it is to play the high frequency tone (8-12 kHz) with the tape deck output into your sound card, use an app that shows you the input level (Audacity works, especially if you go into settings and narrow the range of the VU meters). While it's playing, slowly turn the azimuth screw back and forth to find the position that maximizes the signal level.
You adjust the channel balance using the internal playback level pots. Once you have this perfect when playing the calibration tape, and the azimuth is also right, then you can make recordings and adjust the internal recording gain pots to perfect the channel balance during recording. Then measure frequency sweeps in REW and adjust the internal fine bias pots so the 2 channels stay perfectly in sync throughout the frequency range.
I was able to tune the cassette player using a variety of ABEX tapes I have and I have sent it in to a shop for general service, so that part is taken care of. The confusing part for me has to do with using REW to get frequency responses and measure THD and noise.
Do I simply record a sweep from REW onto a tape and then analyze it with REW after digitizing the results, or perhaps do so through a loopback connection? Is this the basic idea? I have a variety of blank cassettes that I can try out.