playback eq

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FALKEN

FALKEN

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as you can see I am trying to sort some stuff out. when calibrating my otari 8-track I have run across a quandry. I believe the machine is IEC and my test tape is IEC. The repro electronics have a playback eq adjustment but the sync head does not. when playing back the 10khz tone, the sync head shows -1db on every track. This can be compensated for with the repro electronics, but not the sync. Previously I had been compensating on repro to read "0", but now I am thinking the sync head might sound better. It could be a matter of head wear and compensating with the repro eq adjustment might work but might not be preferable? any thoughts??
 
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What figures are you getting for say 1khz and 10khz on the repro head? Can you get it to agree with the test tape? Is the head clean, demagnetised, aligned and in good condition?

Tim
 
yes I can get the repro head to show 0db flat on 1khz and 10khz. I think this is how I am going to keep it. the sync head is down 1db at 10khz, I am thinking from wear perhaps? the thing is that the sync head sounds pretty good on playback, even though there is HF loss...totally different sound from the repro...the repro seems to have more bass response than the original sound, whearas the sync seems to be flatter... even though it says response is down at 10k. I am wondering if eq'ing the repro head so that reading 10k at 0db flat is 'overcompensating' for the wear, and could be throwing the frequency response out of whack over the whole spectrum, not just the very high end.
 
You should really play a test tape with a full set of frequencies, from say 30hz right through to the highs. Remember there is a thing called "head bump" as well as the "fringing effect" so low frequencies wont be perfectly flat.

Yep, a worn or dirty play head can be adjusted for at 1k and 10k and you end up with a peak in the midrange. But you're talking about a bass boost.

Are you sure the Otari is IEC and not NAB? If it is NAB and you use an IEC test tape, you will see a bass boost on the repro head. OTOH there wouldnt be much you could do about it as the play eq only affects the highs.

When you say there is a bass boost do you mean on the repro head from the test tape or when playing back actual program you've recorded?

Cheers Tim.
 
On playback of recorded material, I hear a bass boost around 40-50 hz, and a mid boost...though harder to pinpoint for my ears.
 
Again, check the playback with the test tape to work out if the bass boost is a record problem or a playback problem.
Is it possible the Otari is switched to record in NAB but is playing back in IEC?
i think that would give an unnatural bass boost.

Cheers Tim
 
Yep, it is IEC (IEC 1) and factory set at 320 nWb/m.

The record (sync) head on the 5050-8 is different from the repro head. It’s not optimized for hi-fi like you find on the 2-head TASCAM and Fostex machines. It has a classic sync role in that it allows you to hear what you’re doing while tracking. The repro head and circuitry are designed for high fidelity playback.
 
Beck said:
Yep, it is IEC (IEC 1) and factory set at 320 nWb/m.

The record (sync) head on the 5050-8 is different from the repro head. It’s not optimized for hi-fi like you find on the 2-head TASCAM and Fostex machines. It has a classic sync role in that it allows you to hear what you’re doing while tracking. The repro head and circuitry are designed for high fidelity playback.
Click to expand...

As I recall reading on one of Jay McKnight's papers some years ago, all 1/2" 8 tracks are IEC1 at 15 ips. I believe that may also be true of all 1" 16 tracks.

Cheers,

Otto
 
ofajen said:
As I recall reading on one of Jay McKnight's papers some years ago, all 1/2" 8 tracks are IEC1 at 15 ips. I believe that may also be true of all 1" 16 tracks.

Cheers,

Otto
Click to expand...

Yeah, I think that's right... at least back to the TASCAM 80-8. I'm not sure about the model 70... a bit before my time. Same for the Fostex 8 on 1/4".

:)
 
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right....

but will adjusting the playback eq to read flat at 10k on worn heads actually make things worse or what?
 
FALKEN said:
right....

but will adjusting the playback eq to read flat at 10k on worn heads actually make things worse or what?
Click to expand...

It depends on what you want. If my deck can be pretty close to flat at 20K, I'll set it up that way, as long as it's not more than 2 dB high between 8K to 16K. Other folk would rather have less deviation and accept the roll off at 20K. With worn heads, the HF response can actually be hotter. I had some mono heads on an AG-440 that actually had a peak at 22K when they were flat from 10K to 20K. It's really up to what you prefer.

Cheers,

Otto
 
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