Post by jh4db536 on Sept 2, 2021 18:51:18 GMT -5
This will be a little work in process but i don't imagine it will take me that much time to get it all fixed up
I grew up with tapes because i am barely that age to have experienced analog and then digital revolutions, but honestly it has been so long that i really forgot what it was like to make a mixtape. I also wanted to get into tapes because i wanted a recording solution to rip vinyl and "other sources", but i didnt want to deal with the complexity of ADCs, software, or computers. I have a lot of friends with cool vinyl setups, and i figured this might be a cool way to bring some home with me.
I wanted a good starter player with a Solid and Reliable mechanism to learn the playing field with. That lead me to a Nak CR-1A with 2 heads (Record/PlayB and Erase) to set my baseline of expectations with. I only vaguely remembered what type 1 and 2 tapes were, had to learn what bias and azimuth adjustments were all over again from scratch. Sorry i cant afford to start and learn on a dragon, revox, tandy 3014 or Nagra. Being a single head unit for record/playback, adjustment of the head is literally one screw and a spacer shim. Once the height is correctly set, azimuth and phase can be adjusted. Since record and playback functions are a single head, this deck should record and playback perfectly on the same unit because there is no variation possible once azimuth is adjusted. This is Not auto reverse tape deck, very basic fixed head mechanic perfect for learning and getting high quality sound without much cost. Also, unit maintenance friendly, top and bottom covers come off can work on PCB from both sides very easy. Not much going on inside.
I found a good conditions CR1A online and brought it home for less than $200 bucks went to my parents basement and found a box of NOS tapes brought those home too. I had to find specialized tools to restore this after watching lots of youtube videos. I bought a tape head demagnetizer, bulk tape nuker eraser, and calibration and tone tapes. All this stuff actually costed as much the as the deck itself :yikes: There's only a belt for the tape counter and it's still good.
Upon cleaning and inspection, the tape deck appears never to been opened ever. Tape deck is very out of adjustment especially with type II and IV tapes.
I calibrating the capistan (metal roller that pulls tape at constant rpm) tape speed to 3khz
I adjusting tape head azimuth and phase
BEFORE
AFTER
Based upon waveform and lisajst stability on scope, i am conclude that capistan and roller are still good. No need to replace.
I adjust levels to 500mA then confirm 500mA record>playback at 500mA for all tape types. This unit very off calibration.
I adjust playback eq to match test tones level at 400hz and 18khz for all tape types according to service manual specs
I adjust recording bias to match test tones level at 400hz and 18khz for all tape types according to service manual specs
Sounds much better now. Must play soundtrack for the gram
.
I will recap unit in bias oscillator section to see if settings change. Then will reassess further recap of analog filter and eq circuits,
Type IV metal tapes much better sound quality once adjustment and calibrations completed. Will never be quiet as a DAC, but very musical, good tone qualities, clarity better than i expected. I forget about tape hiss once music starts playing. Transient and macro slam performance to be desired. I think l need a better preamp because output stage is weak point and cannot push my power amp sufficiently. Will build a Sangaku as preamp then report back later on this.
Tape hiss and noise levels down to pretty low levels after adjustments and using metal tapes. This tape deck will probably perform better than new once i recap it. Very importantly, the deck can record and play back to a certain degree the "high energy" and "engaging sound" from sources; this alone is well worth the price even if it cannot nail down the technicalities. I would appreciate this much more if i could fix the transient performance though.
I grew up with tapes because i am barely that age to have experienced analog and then digital revolutions, but honestly it has been so long that i really forgot what it was like to make a mixtape. I also wanted to get into tapes because i wanted a recording solution to rip vinyl and "other sources", but i didnt want to deal with the complexity of ADCs, software, or computers. I have a lot of friends with cool vinyl setups, and i figured this might be a cool way to bring some home with me.
I wanted a good starter player with a Solid and Reliable mechanism to learn the playing field with. That lead me to a Nak CR-1A with 2 heads (Record/PlayB and Erase) to set my baseline of expectations with. I only vaguely remembered what type 1 and 2 tapes were, had to learn what bias and azimuth adjustments were all over again from scratch. Sorry i cant afford to start and learn on a dragon, revox, tandy 3014 or Nagra. Being a single head unit for record/playback, adjustment of the head is literally one screw and a spacer shim. Once the height is correctly set, azimuth and phase can be adjusted. Since record and playback functions are a single head, this deck should record and playback perfectly on the same unit because there is no variation possible once azimuth is adjusted. This is Not auto reverse tape deck, very basic fixed head mechanic perfect for learning and getting high quality sound without much cost. Also, unit maintenance friendly, top and bottom covers come off can work on PCB from both sides very easy. Not much going on inside.
I found a good conditions CR1A online and brought it home for less than $200 bucks went to my parents basement and found a box of NOS tapes brought those home too. I had to find specialized tools to restore this after watching lots of youtube videos. I bought a tape head demagnetizer, bulk tape nuker eraser, and calibration and tone tapes. All this stuff actually costed as much the as the deck itself :yikes: There's only a belt for the tape counter and it's still good.
Upon cleaning and inspection, the tape deck appears never to been opened ever. Tape deck is very out of adjustment especially with type II and IV tapes.
I calibrating the capistan (metal roller that pulls tape at constant rpm) tape speed to 3khz
I adjusting tape head azimuth and phase
BEFORE
AFTER
Based upon waveform and lisajst stability on scope, i am conclude that capistan and roller are still good. No need to replace.
I adjust levels to 500mA then confirm 500mA record>playback at 500mA for all tape types. This unit very off calibration.
I adjust playback eq to match test tones level at 400hz and 18khz for all tape types according to service manual specs
I adjust recording bias to match test tones level at 400hz and 18khz for all tape types according to service manual specs
Sounds much better now. Must play soundtrack for the gram
.I will recap unit in bias oscillator section to see if settings change. Then will reassess further recap of analog filter and eq circuits,
Type IV metal tapes much better sound quality once adjustment and calibrations completed. Will never be quiet as a DAC, but very musical, good tone qualities, clarity better than i expected. I forget about tape hiss once music starts playing. Transient and macro slam performance to be desired. I think l need a better preamp because output stage is weak point and cannot push my power amp sufficiently. Will build a Sangaku as preamp then report back later on this.
Tape hiss and noise levels down to pretty low levels after adjustments and using metal tapes. This tape deck will probably perform better than new once i recap it. Very importantly, the deck can record and play back to a certain degree the "high energy" and "engaging sound" from sources; this alone is well worth the price even if it cannot nail down the technicalities. I would appreciate this much more if i could fix the transient performance though.
. 
) . Post mortem showed C317 was still in spec on the meter. C318 should still be okay...i reflowed it.
