1176 Hairball/Mnats - small issues with the VU meter

[bram9206]

Hi,

Just finished my Hairball/Mnats 1176 kit and powered it up. I checked voltages and everything is fine. I calibrated the 1176 without any problem and adjusted the VU meter like it is shown in the movies on mnats.net. Everything seems to work perfect, no noise, compression sounds good, but I have two small issues with the VU meter:

1) When I power up my unit, it takes 10 minutes for the VU meter to get to the zero point. When powering up the meter goes to -05dB and only then within the following 10 minutes it goes very very slowly to the zero point. Once it reached the zero point it stays there for a while, but after a few hours it even goes to +0,5dB. So no big deal here but is this normal?

2) Also, when I change between ratio's (push buttons) my meter goes very quickly to -5dB and then goes back to zero. This is when I go up from 4:1 to for example 8:1. When I go down, from lets say 8:1 to 4:1 the meter goes very quickly from 0 to +3dB and back to zero. Also, when I do the 4-button trick (and here comes the real problem) the meter is at max all the way to the right, even across the +3dB... At this point it's not possible anymore to use the meter for readings. Doesn't seem normal to me either (since my original 1178 doesn't have it). The good thing might be that I don't hear a pop or any click when changing between ratio's.

Anybody any thoughts on this?

For the rest I have only this to say: Mnats and Hairball did an amazing job on this 1176 clone!!!

Bram

 

[MicDaddy]

All seems normal.

I let them 'burn in' for a good day and redid ALL calibration procedures.  Simply leave them on over night with the meters in Gain Reduction mode.

My meters perform much tighter now, and rarely do I have to use the zero adjust.

You should stick questions like these in the dedicated help thread for the specific project.

That way the forum doesn't get cluttered with redundant questions.  The next guy may see your issues and answers and not have to search around for a web of threads/info.

 

[bram9206]

Thanks very much for the info!

Yes, and well, sorry about not posting my questions in the right thread, I'm brand new here on this forum and still have to find my way around a bit. Thanks for the tip!

 

[MicDaddy]

No problem, glad to see another kit up and running.

I think the meter with 'all buttons in' mode throw off a lot of folks at least it did me. 

 

[Alistair]

I have similar issues to you.  It takes about a minute for my meter to zero after turning on the 1176, and it moves a little bit sluggishly all the time.  It also has to 'reset' after changing ratios.  The turn on time doesn't worry me at all, but I do wish it followed the audio a little bit more closely.  At the end of the day, it sounds great though and the meter is perfectly useable, just not perfect.
In all buttons mode the meter goes hard right, but this is normal AFAIK.

 

[bram9206]

What do you guys mean, that it's just normal the meter isn't working with the all-buttons-mode? Then why is it working on my original 1178? I guesse it's something small that can be fixed easily?
Anyway, nice tip micdaddy to "burn in" your meter and re-callibrate it. I will do that tomorrow!

 

[Echo North]

What do you guys mean, that it's just normal the meter isn't working with the all-buttons-mode? Then why is it working on my original 1178? I guesse it's something small that can be fixed easily?
Anyway, nice tip micdaddy to "burn in" your meter and re-callibrate it. I will do that tomorrow!

The meter is working like the original 1176 circuit Rev D.  I've used several UREI Rev D's, the meter pegs right in ABI mode.  You're comparing it to a different circuit.  The 1178 came out around the same time as the REV H which uses a very different IC meter circuit.

Edit: Also the other issues you describe are normal for the discrete meter circuit.

 

[fredouille]

old post, but I will like to update it.

I see also fluctuations of the gain reduction vu, but I understood where it comes from, I have bad electricity with fluctuations from 225V to 220, for example when I plug heating in studio, I loose 10 to 20V.. and I see the Vu of the 1176 going down, it is crazy. I saw in the schematics that the power section is basic, I still there is power zener which should keep the proper voltage, I assume the fluctuations are of course coming from DC voltage changes ? I have a blackface also which remains totally stable, of course he has 2 LM317 regulators.. I don't know if it is part of the charms of the rev A but I don't like this sensibility to main AV voltage.. did somebody modified the power section to get it more stable ?