I always did it by ear - I found I got better more accurate results.For those of you who have real experience in setting the bias to your own satisfaction, did you eventually find any significant difference between setting the bias by ear and setting it by technical protocols?
This explanation may help. The "curves" attachment shows how a change of bias affects output, sensitivity, noise, and distortion. The purpose of a bias current is to reduce distortion and increase output. The "proper" bias is a compromise between low frequency MOL and high frequency SOL. Too much bias increases low frequency output and reduces distortion (note the nadir of the distortion curve), but at that point the high frequency wavelengths are being recorded below the surface of the tape, and treble response drops off due to spacing losses--too far from the playback head gap. Too little bias causes too little low frequency output and dramatic increases in distortion.
IMHO manual adjustment using your ears is best.I have a TC-KE600S and a TC-KE500S, both of which have the "auto" calibration feature. I find the auto level recommendations on both of them are off. That is "off" as far as my ears are concerned, much like what you're experiencing. It probably actually is what follows "protocol" but that's not the same as satisfying your ears. "Protocol" states that least distortion of the bass tones comes at a bias level 2 or 3 dB (or whatever, depending on the tape) below what gives highest treble response, and that the correct bias level is therefore a compromise between the two and the "best" bias level is roughly half way between them. In real life, most people adjust bias for best treble response and most people find that they can't hear whatever tiny amount of bass distortion that might result, if any. Basically, adjust it so that the output sounds as close to the source as possible.
Interesting info. Thanks again Wilhelm!Wonderful attachment. Thank you very, very much.
Yes absolutely.
The adjustment pot will be inside, usually, the basic adjustment can be made just the same.
My old Denon DRM-34 Decks have fine tuning on the outside for Bias and Level, and also inside -
incidentally some decks have seperate left and right inside as well. They are HX Pro decks.
The HX pro will operate as well, but kind of seperately to the Bias pots
like another adjustment in series with the Bias pots.
:thmbsp:
I am suprised to hear that about the Bass :scratch2:
I would try doing all my bias test with the Dolby off first
Does the 710 have a 'Level' pot on the outside??
It is just concievable the Dolbly 'Level' is off and you have compensated with
the Bias (not very likely- but just possible)
If there is no pot on the outside - there will be one inside - I think this one only has fine Bias control (not talking about the output level)
Level was for making sure the Dolby tracked correctly as it is important
that the internal playback and record levels match so the Dolby variable curve
Matched record and playback.
Anyway - that thought aside - usually Bass would only suffer if the Bias was too low - and you would get too much treble.
If the head has become magnetised that maybe affecting the sound (usually makes it more muffled though)
So I would try deguasing the tape heads - this is like randon posative and negative magnetism pulses that get rid of any residual magnetism in the heads - could be they need this - you used to be able to get a TDK tape shaped one which was the easiest to use.
Try all these things and see if anything helps :thmbsp:
For those of you who have real experience in setting the bias to your own satisfaction, did you eventually find any significant difference between setting the bias by ear and setting it by technical protocols?