Hey all,
I work for a small production company and was recently tasked with installing XLR inputs on our Fostex 6301B full range monitors. I simply drilled a hole in the housing, rivet mounted the XLR input, and (I think foolishly) wired the pins of the TRS connector to the XLR connector.
Now the speaker has a few symptoms it didn't before. Sometimes it will operate smoothly, sometimes it will get fuzzy and distorted, and other times the volume will modulate while the signal cracks and distorts.
I am wondering if a direct link with the pins is the issue but am not sure. I would love some experienced help with getting the speaker operational again.
Here is a link to the circuit diagram.
Fostex 6301BEAV Service Manual (Page 9 of 12) | ManualsLib
I work for a small production company and was recently tasked with installing XLR inputs on our Fostex 6301B full range monitors. I simply drilled a hole in the housing, rivet mounted the XLR input, and (I think foolishly) wired the pins of the TRS connector to the XLR connector.
Now the speaker has a few symptoms it didn't before. Sometimes it will operate smoothly, sometimes it will get fuzzy and distorted, and other times the volume will modulate while the signal cracks and distorts.
I am wondering if a direct link with the pins is the issue but am not sure. I would love some experienced help with getting the speaker operational again.
Here is a link to the circuit diagram.
Fostex 6301BEAV Service Manual (Page 9 of 12) | ManualsLib
I think you should see if a TRS contact was/wasn't connected to the chassis, and if one of the xlr pins is/isn't connected to the chassis, if they match.
humm seems that the service manual shows an unbalanced input so if your wiring to the TRS connector is correct then there's a problem... the jack appears to have a switching function that is unused putting what would be a short across Pins 2 and 3 (with no jack inserted), not good if your feeding this with a balanced line.
i would use an op amp or appropriate transformer to make the xlr input balanced and feed the output to the unused switch pin in the TRS connector so you can retain the use of the TRS connector allowing you feed it either balanced (XLR) or unbalanced (TS) sources.
the only reason that it's working at all and intermittently is likely due to an oxidized switch contact that was unused till now.
i would use an op amp or appropriate transformer to make the xlr input balanced and feed the output to the unused switch pin in the TRS connector so you can retain the use of the TRS connector allowing you feed it either balanced (XLR) or unbalanced (TS) sources.
the only reason that it's working at all and intermittently is likely due to an oxidized switch contact that was unused till now.
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thanks for the link to the manual in looking that over i came across the BX version which shows the exact solution you need to implement and it contains a xfrmr and op amp buffer and does exactly what i described in the last post. look at page 10.
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That is incredibly helpful, thank you! I wish I understood more than I do but am excited to learn. The only questions I have are: A. Do you recommend any reading or sites to educate myself with? and B. Where do you recommend getting parts to do this modification?
Thank you so much for the help, I can't wait to get the mod working properly.
A: electronic circuit design is a heavy topic over the years i've read books like Don Lancaster's Active Filter Cookbook and just about all his work on op-amps.
B:depends on where in the world you are and whether or not you can either source or create the PCB you'll need.
B:depends on where in the world you are and whether or not you can either source or create the PCB you'll need.