Some questions about 1176 meter

[ForthMonkey]

I'm trying to calibrate.Everything is ok.Q adjust and distortion ok.

But i can't adjust meter zero!When i change ratio,meter zero changing,too.Meter at zero with 8-12 and 20 ratios but when i select 4,it goes down about 1 dB.What is wrong?

By the way meter circuit is not discrete.

And sometimes meter going to +3(Fully CW).When it happens,i'm turning Input to CW,After this,meter working normal,again.

And any tricks to calibrate meter?Especially about GR tracking.

Thanks.

 

[radardoug]

Why do you think UREI put the meter zero pot on the front panel?

 

[ForthMonkey]

Why do you think UREI put the meter zero pot on the front panel?

Yes,it's funny.

But i'm already adjusting meter zero when ratio is 20.Then i'm changing ratio and ratio 4 is goes down around 1 dB.

And when i select +4 or +8 meter,it's ok.But when i turn back GR mode,meter going all the way right(+3).

 

[radardoug]

Thats right! It is affected by the Qbias setting though, play with that. And temperature.

 

[ForthMonkey]

Thats right! It is affected by the Qbias setting though, play with that. And temperature.

Thanks for advice.

Qbias affecting meter,right?So i need to re-adjust Qbias.

How about temperature?What you mean?

 

[ForthMonkey]

By the way i read manual and it says "A small amount of drift (+/-1dB) is normal in this circuit." in meter zero section.

My GR meter starts at 0 with ratio 4 and starts at +1 with other ratios.Is this big problem?Manual says it's normal.

 

[radardoug]

Correct! So you finally RTFM, and it answers your question.  Temperature variations is one of the reasons the meter will drift.

 

[ForthMonkey]

Correct! So you finally RTFM, and it answers your question.  Temperature variations is one of the reasons the meter will drift.

So it's good.

I have last question.

With +4 or +8 when connect input,meter starts at -20 as normal.But when i connect output,meter goes to -10.If i remove in or out,meter goes -20 again.What causes this?

I'm using different sources for input and output.I believe it's not feedback.

 

[radardoug]

You have something wired wrong. Check your work.

 

[ForthMonkey]

You have something wired wrong. Check your work.

So you say nothing wrong with meter? Someting wrong with in & out?

But when in with bass guitar,there is no problem like this.

 

[radardoug]

I can only go by your descriptions of the problem. I note you have some problem with writing good English.
From your previous description, it sounded like when you plugged in an input signal, and then connected the output to something, the meter changed. When in +4/+8/ the meter should not change much when you put a load on the output. It will change a little when going from no load to 600 ohms load. You said it was reading -20 with input, and then went to -10 when  a load was connected. This would imply that there was some strange connection between the output and input maybe.

 

[ForthMonkey]

I can only go by your descriptions of the problem. I note you have some problem with writing good English.
From your previous description, it sounded like when you plugged in an input signal, and then connected the output to something, the meter changed. When in +4/+8/ the meter should not change much when you put a load on the output. It will change a little when going from no load to 600 ohms load. You said it was reading -20 with input, and then went to -10 when  a load was connected. This would imply that there was some strange connection between the output and input maybe.

Hmm...Thanks for explanation.I will check in & out connection.

Yes,when i connect input and output at the same time,meter goes from -20 to -10.But when i connect bass guitar,meter working as it should be.I must check in & out connection.

Meter calibration is ok now.Now only one problem is this.I believe it's not hard to solve.

When i check,i will write results.

Thanks for your interest and help!

 

[ForthMonkey]

I have fixed my last issue.

It's about connection.I very very end of circuit as output.So it causes impedance problem.

My design has impedance balanced output.I added output before output  buffer(no level change),and now everything is ok.

Big thanks radardoug!