lonewhitefly
Active member
I just listened to your “hiss” mp3, and it sounds completely normal. What is the issue exactly?
Have you actually measured your signal to noise? Just listening for hiss is not a valid measurement. If you're expecting it to sound like a typical digital "silence", then you're going to be disappointed.
It should be about 72/70dB NAB Wtd and 67/65db Unwtd. at 15"/7.5" measured at 3% THD @1kHz. DBX adds about 30dB Noise Reduction.
The specs are here: Tonbandmuseum - Sie sind im Bereich: Tascam ATR-60-8-Docs
Ah! That is rather better than my crude result by just playing OP's clip in Samplitude. I got -5dBfs for the tone and the noise fell to -60dBfs so a S/N of 55dB and that is really where I would have expected an OR machine to be? Yes, a top bllx Studer carefully setup with a really good tape will be 10dB better.
Op might have a distorted bias waveform? Tricky to tell without a decent scope and that is the buggerooter of tape recording! To do it well you need to spend about AS much on test gear as the bloody recorders! As Rob alluded to, bias should really be set for best distortion.
One test would be to measure the replay noise of virgin tape and then after just a silent pass with the taps shut so you are only getting the basic noise of the recording amplifiers plus DC noise from a wonky bias oscillator.
Dave.
I saw similar results, but I didn't know if the posted sample was from a single channel, or from 8 channels at the same time. Obviously, if its a single channel, he has some room for improvement, but if it's an 8 channel blended sample, it's probably right in the range. I don't remember for certain, but I think 8 channels would be somewhere close to 9dB noise increase. Plus the S/N is measured at 3%THD, not at 0dB which is less than 1%. If the signal was recorded at -5dB, then there's unused headroom that could be added.
A Technician can only test and adjust the machine according to the service manual and the specs that are there. I have done it many times but then once in a while a complaint comes in that is based on abstract testing and usually by a person with very little knowledge of the subject. Then you need to explain to them the right way to test these types of equipment.
No they are not perfect and the reason the commercial tapes do not have hiss as most of them used Dolby A that cost at least $1000 per track.
You can not compare consumer level equipment to that which is 10 of thousands dollars more expensive. However if you know what you are doing you can come out with a very close result. I am afraid you will need to use dBx for the unit if you are looking for dead silence. Or go off and buy a rack of Dolby A processors.
When setting your repro levels use -2dB reference instead of 0 when adjusting the reference level. Do it for 1k & 10k.