meq 5 matching process

[hugo]

Hi,
I finishjed a pair of meq5, and i have 1db more on one unit. I would like to find the exact place where i get this loss, would you know how to proceed ?

Thank you

H

 

[zamproject]

Hello

Can't say if 1 dB is simply due to component tolerance/matching or if you have some issue,
but flowing the signal at each stage with a RMS multimeter should do the job...

Best
Zam

 

[Rob Flinn]

If it worries you a lot, you should check whether it is 1dB at all freqencies &  similar boost/cut levels on didderent frequency settings.  If it is then it's in the amp & you should be able to sort it out. 


If it's not then it will be a cumulative effect of component tolerance in the filter section.  Bear in mind pots have something like a 20% tolerance .  If you used CC resistors they will be 5% tolerance.  The caps will be something like 10%.  So if it is to do with the filter section you may struggle to match them.

 

[hugo]

If it worries you a lot, you should check whether it is 1dB at all freqencies &  similar boost/cut levels on didderent frequency settings.  If it is then it's in the amp & you should be able to sort it out. 


If it's not then it will be a cumulative effect of component tolerance in the filter section.  Bear in mind pots have something like a 20% tolerance .  If you used CC resistors they will be 5% tolerance.  The caps will be something like 10%.  So if it is to do with the filter section you may struggle to match them.

Hi Rob, thanks for answer.
I actually measured every single component to have a perfect matched pair..that is why i dont know how to find the origin of the difference

 

[Rob Flinn]

Hi Rob, thanks for answer.
I actually measured every single component to have a perfect matched pair..that is why i dont know how to find the origin of the difference

Did you measure each pair of pots to see if their resistance was exactly the same at the exact same degree at of rotation at different places in their rotation ?

 

[CJ]

designed in the 50's for crude telephone eq,  not meant for 1%,

 

[hugo]

designed in the 50's for crude telephone eq,  not meant for 1%,

yes i get it but 2db difference between 2 channels could probably kill a good stereo mix

 

[PRR]

> i have 1db more on one unit. I would like to find the exact place where i get this loss,

If you have two "identical" units, and can measure different overall loss, open the box and go step-by-step along the signal path.

 

[radardoug]

This will of course require some decent test gear, and an understanding of testing methodologies.