Date:         Sat, 2 Feb 2008 15:11:47 -0500
Reply-To:     Association for Recorded Sound Discussion List
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Sender:       Association for Recorded Sound Discussion List
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From:         Tom Fine <[log in to unmask]>
Subject:      Re: Setting bias and EQ on ANY recorder
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Technics 1520 instructions are a bit different from this, Richard. Your way 
is pro-grade industry standard for 10kHz with 3dB overbias (Jay McKnight and 
I prefer 1kHz peak-bias, the "old-school" method). The Technics 1520, which 
was marketed as a high-end consumer deck but embraced by some professional 
users, is specifically designed to tweak bias and record-EQ at -10VU after 
getting in the range from the machine's 3-way bias and eq switches. The 
instructions are simple and laid out in the manual. If Sammy has a 1520 
manual, I'm not sure where he's running into trouble. You cannot set the 
playback EQ without taking off the bottom panel of a 1520 and knowing what 
you're doing, with a service manual at hand. So HIGHLY NOT RECOMMENDED for a 
newbie. That said, it's never a bad idea to run a MRL tape and see how close 
to flat your machine's playback is. Specifically, you should write down VU 
levels at 10K and 1K. They should be flat or very close to flat or your 
record tweaking won't render a flat playback.

Quick recap of 1520 record-setup:

1. look in manual and find tape type, set bias and EQ switches accordingly.
2. set meter switch to -10
3. set monitor to input
4. turn on internal oscillator, to 1kHz
5. adjust line-input level so VU meter reads 0 (actually -10 but scale has 
been 10x in step 2)
6. put machine into record with desired tape type (as Richard says, NOT an 
MRL or pre-recorded tape, obviously). Don't forget to turn both channels' 
record-engage switches on.
7. switch monitor to tape.
8. adjust bias tweakers until VU meter reads 0. If you're adjusting more 
than a quarter-turn either way, something's wrong. Switch the bias switch 
until you get closer to 0. A very few tape types are out of the machine's 
range, but not Q632.
9. switch oscillator to 10kHz.
10. adjust record EQ to get VU meter to read 0. Again, if you can't get it 
there in a quarter-turn one way or another, something's wrong. Switch the EQ 
switch until you get closer to zero.
11. take machine out of record, turn off oscillator, set VU meter switch 
back to normal.

I guess I should also say to make sure you are monitoring off the main (2T) 
play head and not the quarter-track head.

Sammy, just to be clear -- if you don't see controls for oscillator 
frequency, two bias tweak pots and two EQ tweak pots on the front panel, 
above the VU meters and record/playback level controls, you do not have a 
1520, you have a 1500 or 1506. Those machines cannot easily be tweaked. You 
can optimize those machines for a single particular tape type, but you need 
to do inside the machine and you need to know what you're doing and use a 
service manual.

-- Tom Fine


----- Original Message ----- 
From: "Richard L. Hess" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, February 02, 2008 2:37 PM
Subject: Re: [ARSCLIST] Setting bias and EQ on ANY recorder


> At 11:51 PM 2008-01-31, Sammy Jones wrote:
>
>> > From: Sammy Jones [mailto:[log in to unmask]]
>> > Subject: Setting bias and EQ on Technics 1520
>> >
>> >
>> > My problem is in setting the EQ and bias properly to record on this
>> > tape.  This is my first time recording tape on a machine with settable
>> > bias and EQ, and the Technics service manual does not specify how to do
>> > this.  I've found some information on the web for bias setup, but not
>> > EQ.
>
> I have placed a simplified set of instructions in my blog
> http://richardhess.com/notes/2008/02/02/aligning-a-tape-recorder/
>
> Please let me know if you have any questions -- I'd prefer you ask them in 
> the comments section of the blog.
>
> Cheers,
>
> Richard
>
>
> Richard L. Hess                   email: [log in to unmask]
> Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
> Detailed contact information: http://www.richardhess.com/tape/contact.htm
> Quality tape transfers -- even from hard-to-play tapes.