recently scored an allen & heath quasi (quasi-modular) 10 channel mixer. I have removed the channels and retro fitted them into an empty (psu is still there) Yamaha m512 im using its recapped psu to power the channels as both mixers use 24v, leaving the -24 floating. ive recapped the modules, raised input coupling from .22 to .47, i have some wima 1uf and 3.3uf caps i may try to. im looking for help with coupling caps values like the 10uf out of the eq, its going to 33k ohm load, if i change it to 3.3 wima
that would give me 1.46hz -3db point, correct? any other suggestions of the coupling values?
Looking for help with direct outs, im taping the post fader buffer just before the pan pot, i have plenty of 600:600 transformers, but im not sure if what the post fade buffers output impedance is and if can drive a transformer. direct out of the post fade buffer with a 330uf output cap sounds fine but i would love to get some use the transformers i have im also not using the echo send or summing if that matters, i may use the pre fade foldback as an echo send
for grounding im a bit confused with the pcb boards. i plan on having all chassis sheild and signal grounds meeting at the psu, but the original quasi E buss is connected to the casing of the foldback output pot would that give me noise if the pot connects to the chassis from multiple channel pcb's or will the chassis just act as the ground buss back to the psu?
all help appreciated
here are the schematics, sowter 200:7k2 mic in transformer has been left out of the schematic but its there
https://www.allen-heath.com/media/QUASI-SCHEMATICS.pdfhttps://www.allen-heath.com/media/QUASI-USER-GUIDE.pdf
heres schems for their minimix which has similar preamp design and may be easier to read (mod1 mod2 and mod3 are also similar)
https://www.allen-heath.com/media/MINIMIX-MANUAL.pdf
that would give me 1.46hz -3db point, correct? any other suggestions of the coupling values?
Looking for help with direct outs, im taping the post fader buffer just before the pan pot, i have plenty of 600:600 transformers, but im not sure if what the post fade buffers output impedance is and if can drive a transformer. direct out of the post fade buffer with a 330uf output cap sounds fine but i would love to get some use the transformers i have im also not using the echo send or summing if that matters, i may use the pre fade foldback as an echo send
for grounding im a bit confused with the pcb boards. i plan on having all chassis sheild and signal grounds meeting at the psu, but the original quasi E buss is connected to the casing of the foldback output pot would that give me noise if the pot connects to the chassis from multiple channel pcb's or will the chassis just act as the ground buss back to the psu?
all help appreciated
here are the schematics, sowter 200:7k2 mic in transformer has been left out of the schematic but its there
https://www.allen-heath.com/media/QUASI-SCHEMATICS.pdfhttps://www.allen-heath.com/media/QUASI-USER-GUIDE.pdf
heres schems for their minimix which has similar preamp design and may be easier to read (mod1 mod2 and mod3 are also similar)
https://www.allen-heath.com/media/MINIMIX-MANUAL.pdf
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