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Improve S/N ratio of my Fostex 1/2" E16
Old 17th August 2005
  #1
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jetboatguy's Avatar
 

Improve S/N ratio of my Fostex 1/2" E16

Got one of these machines for tracking drum sessions mainly... I just calibrated the ins and outs with a brand new MRL reference tape as best I can, I spent about 6 hours triple checking everything in the calibration stages... the MRL tape was a special order for this specific machine/model... I've already noticed a big difference with balancing the sound and lowering noise... there still seems to be a signaficant amount of noise though... I try to record signals hot with a bit of peak style compression during the tracking... the results aren't too bad... but if I want to improve the machine's S/N ratio, do you think re-capping would do a difference... I've noticed this machine's electronics emits very hot during sessions... I've had to buy a dedicated fan to cool down... I was wondering if higher heat tolerence electrolytic caps would improve this machine's power supply and/or audio cards ??
Old 17th August 2005
  #2
As Frank Zappa once said, "You are what you is". Changing caps will not lower noise. This is a 1/2 " machine with music, oops, I mean noise reduction! It has a 3 1/2 db head bump at 120 hz. Sell it. Get a MCI 2" for next to nothing.

Jim Williams
Audio Upgrades
Old 17th August 2005
  #3


That's what everybody forgets about when they do the "analog tape" retro thing:

Except for the very best units, the real to real tapes had more noise than you are used to hearing in digital recordings.

You can get a DBx or Dolby compander set to lower the noise floor a little (if you can still find them.....)



-tINY

Old 18th August 2005
  #4
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audioez's Avatar
 

you mention using an MRL tape... how a about the record calibration???
Old 18th August 2005
  #5
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jetboatguy's Avatar
 

Quote:
Originally Posted by audioez
you mention using an MRL tape... how a about the record calibration???

Yes, after the playback alignment I spooled a blank Quantegy 456 tape, and went through each track's record calibration procedure with oscillator tones from the console... I found that tryin to find the happy meduim between 100Hz and 10KHz is the trick with the Fostex, there's a seperate adjustment for lows and the highs... and there's also a EQ bias that goes in between to flaten the response between lows and highs.... it's was a little tricky and time consuming, but I mangaed to calibrate the machine.
Old 18th August 2005
  #6
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gyraf's Avatar
 

Defluxing the tape path is essential for low noise on these machines.

Also, for 2-3dB lower noise (actually higher output level), you could try 499 tape...

Jakob E.
Old 18th August 2005
  #7
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Are you using the built-in Dolby noise reduction? These machines aren't really usable without it.

The top of the case will get hot because it is the heatsink for the motor drive transistors. These have to dissipate a great deal of heat and I remember having to uprate them in my machine because the originals never seemed to last very long. The audio electronics are nowhere near the top of the case and shouldn't be worried by the heat.

Cheers.

James.
Old 18th August 2005
  #8
Years ago I attempted to align one of these with my Audio Precision analyzer. You can't get enough bias current out of it to align 499 or GP-9 above SOL. You can't get the top end response flat, there's a dip at 8k. There's a 3 1/2 db head bump at 120 hz, made worse by the dolby C. The bass sounds like a juke box.

Why not dump this thing and get a tascam MS-16 1" for a few hundred bucks?
At least that will align flat and doesn't require music, err, I mean noise reduction.

Jim Williams
Audio Upgrades
Old 18th August 2005
  #9
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jetboatguy's Avatar
 

Quote:
Originally Posted by Jim Williams
Years ago I attempted to align one of these with my Audio Precision analyzer. You can't get enough bias current out of it to align 499 or GP-9 above SOL. You can't get the top end response flat, there's a dip at 8k. There's a 3 1/2 db head bump at 120 hz, made worse by the dolby C. The bass sounds like a juke box.

Why not dump this thing and get a tascam MS-16 1" for a few hundred bucks?
At least that will align flat and doesn't require music, err, I mean noise reduction.

Jim Williams
Audio Upgrades
There's a fellow who wanted to sell his 1" MS-16 a few months ago in Canada... wanted way too much for it... wanted aprox' $3000

Seems like alot of people ask too much for older analog machines.
Old 19th August 2005
  #10
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I just remembered another trick if you want better signal to noise - use more than one track for each sound. The signal will be boosted by 6dB while the noise, because it is random, will only be boosted by 3dB.

Cheers.

James.
Old 19th August 2005
  #11
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tmarra's Avatar
Quote:
Originally Posted by jamesp
I just remembered another trick if you want better signal to noise - use more than one track for each sound. The signal will be boosted by 6dB while the noise, because it is random, will only be boosted by 3dB.

Cheers.

James.
oooooh I don't know about that... doesn't 3dB of noise pluse 3dB of noise equal 6dB of noise, random or not.

-Tony
Old 19th August 2005
  #12


When signals add in-phase, they are boosted by 6dB (twice the amplitude).

When things add with random phase between them, they may be in-phase and twice the amplitude at some points and 180 degrees out-of-phase at others and completely cancel. ON AVERAGE, you can add the powers together (and you'd calculate the right level).

As we all know, twice the power is +3dB and twice the amplitude is +6dB....





-tINY

Old 20th August 2005
  #13
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Tim Farrant's Avatar
 

If you are not using the built in Dolby C noise reduction (switch on the back) then it WILL be damn noisy, the actual tape track widths are the same as cassette. Make sure you have the Dolby switched OFF when you align it, and the record/replay levels should be as accurate as you can get it so that the Dolby C does not mis-track and sound bad. Don't try and push the top end EQ in record and attenuate in replay, this will cause the Dolby to mis-track, plus, the record electronics just can't deliver the power.

I am not sure what fluxivity you have on the MRL test tape, we used to use 320nWb/m with Ampex 456 tape with over-bias about 3.0-3.5dB at 10kHz. You need to watch the record levels of high frequency sounds like cymbals, as the machine quickly starts to distort. Also, as the head wears, tracks 1 and 16 will begin to loose treble and eventually become unusable. I spent quite a few hours maintaining these machines, used carefully, they can sound reasonable, but certainly not what we have come to expect these days!

Cheers
Tim.
Old 20th August 2005
  #14
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jetboatguy's Avatar
 

Thanx you all and Tim for the constructive criticism, nice to hear from you again Tim, you and talked briefly on mojopie.com about your preamps and such etc... my real name is Marc Gosselin... in the future I do plan to upgrade to a Studer 2" 16 track of sorts... but in the meantime I'm trying to work within my budget... I do belive that I can get half decent results for mainly drum tracks with the Fostex E16 machine, and I was mainly lookin' to see if this medium could be improved without having to result to Dolby noise reduction. which I leave disabled at all cost... I do agree that noise reduction = music reduction... I'm not oblivious to this phenomenon, I'm just lookin' to push the envelope like any creative engineer would in this crazy analog world.
Old 22nd August 2005
  #15
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Quote:
Originally Posted by jetboatguy
I do belive that I can get half decent results for mainly drum tracks with the Fostex E16 machine, and I was mainly lookin' to see if this medium could be improved without having to result to Dolby noise reduction. which I leave disabled at all cost...
There's absolutely no way that you'll get usable results without Dolby. Learn how to align it properly and it will be usable - maybe not great but usable. Most of Dolby's bad reputation is down to poor alignment.

Cheers.

James.
Old 22nd August 2005
  #16
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jetboatguy's Avatar
 

Quote:
Originally Posted by Tim Farrant

I am not sure what fluxivity you have on the MRL test tape, we used to use 320nWb/m with Ampex 456 tape with over-bias about 3.0-3.5dB at 10kHz. You need to watch the record levels of high frequency sounds like cymbals, as the machine quickly starts to distort.

Cheers
Tim.

Hi Tim,
the fluxivity of the MRL test tape that I'm using is indeed with 320 nWb/m with IEC equalization standard.

could you please elaborate on what you've talked about with the over bias procedure... does this mean that I should push the calibration record/playback levels over the 0 mark on my machines LED meters...?

what does +3db at 10KHz represent on my machines LED meters ?
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