DRIP BA6A Limiter Metering

[GJB17]

Hi... from down here in AUS. I have a DRIP bA6A unit belonging to a mate that I am trying to sort... mainly the metering circuit... or lack thereof! It is vastly different to the RCA original. Does anyone happen to have a schematic of the DRIP unit that I could use to help sort what I need to do. My mate purchased an original RCA meter... but it does not seem as sensitive as the DRIP unit and is only reading around 50%. I need to find a means of sorting this... any suggestions most welcome. Thanks. Graham

 

[Martan]

Been there. Never found a good solution other than "live with it". Here's a thread about it and a link to the BA-6A docs I have.

https://groupdiy.com/threads/ba-6a-meter-zero-problem-question.83043/#post-1075218

https://www.dropbox.com/sh/5zqwlmwtoxqxatx/AADJ3mRsrDth5UTy6Klj_u8ua?dl=0

 

[GJB17]

Been there. Never found a good solution other than "live with it". Here's a thread about it and a link to the BA-6A docs I have.

https://groupdiy.com/threads/ba-6a-meter-zero-problem-question.83043/#post-1075218

https://www.dropbox.com/sh/5zqwlmwtoxqxatx/AADJ3mRsrDth5UTy6Klj_u8ua?dl=0

Hi. Many thanks for this. It has given me a few clues to follow. Will keep you posted. Cheers, Graham

 

[GJB17]

Hi. With the help of the schematic you sent I have got this sorted... thanks!
My problem was that the owner of this device wanted to use an original RCA meter in the DRIP clone version. The difference being that the RCA meter is a 500uA device and the one DRIP clone has used is 200uA. Thus, when connected, the RCA meter was reading less than half scale when it should have been showing 0dB compression... i.e. FSD. It took me a little while to figure out that the -ve terminal of the meter did not go to ground (as would be expected) but was actually connected across a 16 ohm resistor in the cathode circuit of the 6SK7(s)... which are noted as points A and B on the schematic... but the connection label on the -ve of the meter was illegible. It should be (re)marked as "A". To solve the problem the two (one for each 6SK7's) 16 ohm resistors were replaced with 47 ohm resistors... thus providing a higher source voltage for the less sensitive RCA meter. In fact if you do the maths (47/16) works out to pretty much the same ratio as the two meter sensitivities (500/200). The 100 ohm zeroing pot does not now have quite the same range... but is well good enough for the application. All good... thanks again.

 

[Martan]

Just tried this and it worked perfectly! Replaced the 2 16R resistors with 47R and the meter zeroes now. For the record, it was a Drip pcb using a 200uA meter from metersales. Thank you for the insight!

 

[Martan]

Just to update this thread. I was getting some static from my BA-6A when using it with my DAW and an Apogee symphony mk2. Decided to remove the above mod and look for other solutions (thinking that the mod was causing the static). Found an old version of the Drip BA-6A manual that has ideas for interfacing with convertors and also a meter fix to get it to zero (see attached). The Jensen transformer mentioned in the doc solved my static problem. The meter zero solution worked as well.