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chrisaterika
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neumann SAL 74b new needle alignment

Post: # 31656Unread post chrisaterika
Wed Oct 01, 2014 3:03 pm

Hello,

I was hoping to get some help with step by step instructions on the SAL 74b alignment procedure when replacing your needle on your cutting head [SX74 head, VMS70 lathe].

I understand that we first check our pickup response with our tone disc [100hz, 1000hz, etc.] and once my PU is at 0 we cut a tests groove using our oscillator at 1khz and A/B between our cut [monitor input] and our oscillator tone [feedback input]. Then compensate +/-dB if needed on my drive level to get to zero out my meter and re-check my monitor vs. feedback vs. pickup.

Assuming I did all that correctly and everything's at 0 next we check 100hz and I start to get confused.

If at 100 cycles I'm -3dB this means my curve isn't correct so I have to go back to my 1k tone and add 3dB to my feedback? After that my 100hz should adjust but wont my 1khz now stay -3dB?

I've seen this done before and it worked were 1khz and 100hz came out at 0 but I want to know the mechanics behind this so I can do it myself correctly. Please let me know if anyone can help or if anything I mention above isn't right.

Best,
Christopher

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markrob
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Re: neumann SAL 74b new needle alignment

Post: # 31657Unread post markrob
Wed Oct 01, 2014 3:21 pm

Hi,

I think you have to re-establish the "0" reference level at 1Khz (more drive) since the gain has been reduced by 3db with the added feedback. Then go back to 100hz and re-check. Should be correct.

Mark

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chrisaterika
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Location: buena park, ca
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Re: neumann SAL 74b new needle alignment

Post: # 31659Unread post chrisaterika
Wed Oct 01, 2014 4:19 pm

markrob wrote:Hi,

I think you have to re-establish the "0" reference level at 1Khz (more drive) since the gain has been reduced by 3db with the added feedback. Then go back to 100hz and re-check. Should be correct.

Mark
Thanks Mark, Ill give that a shot.

Chris

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tubefan
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Re: neumann SAL 74b new needle alignment

Post: # 32227Unread post tubefan
Tue Nov 11, 2014 11:48 am

You should check against the NAB disc first. Sometimes the playback electronics are out of alignment. Use the NAB disc to check playback levels, remember that a few of the frequencies are slightly up or down (Len remembers, I forgot off the top of my head.)

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