Hi all, id like to make a few custom SNES RGB cables. i currently have all the cabling needed but going though scart. Since i only play snes i figured id simplify, have some fun, and at the same time make the lengths i want for a clean install. i crimp BNC fairly regularly at work so the cable making part will be easy, but was hoping to have a few questions answered heres what im working with: Super Famicom 1chip-03 w/ Voultars THS7374 board SNESmini w/ Voultars THS7374 board JVC DT-V1910CGU XRGB-mini Framemeister feeding my civilian TV id like to make: direct SNES AV connector to RGBs BNC and a mono audio RCA (JVC has only a mono RCA input) direct SNES AV to framemister 8pin mini din my questions: 1: to make mono audio feed is it as simple as wiring pins 12 (right audio) and 11 (left audio) together? 2: with voultars board are caps (220uf 6.3v?) still needed on the RGB lines? if the caps are needed can anyone recommend ones that are small enough to fin inside a nintendo multiout housing? 3: is a resistor (330ohm 1/4w?) needed on the CSYNC line? on both consoles voultars board the TTL strap is NOT bridged. any harm in adding the resistor anyway? 4: what, if anything, do i connect to the framemiester pin5 to on the snes AV multiout? thanks! for reference
Check out this page for more info on @voultar 's RGB amp. http://retrorgb.com/snesminiths7374.html Voultar has done the hard work for u. The amp board has the option for 220uF low pass filters if u bridge the LPF solder point. Don't add any more caps or u will reduce the overall capacitance and lose the benefit of a low pass filter. If u want a 75ohm friendly CSYNC signal, leave the TTL strap unbridged. Don't add more resistors or u will drop the signal voltage level further and your frameister may not pick up the signal. As for audio. Some sources advise against wiring both audio outputs together for mono. Just wire left audio and see if your games have a mono sound selection. Pin 5 on the frameister doesn't seem to be needed as if firmware 1.03.
thanks for the reply i dont see any mention of the 7374 low pass filters working as a 220uf cap? on that page or anywhere really. this stuff is above my head but could you elaborate? heres the spec sheet http://www.ti.com/lit/ds/symlink/ths7374.pdf
My mistake, I thought 220uF caps were on the board. If u look at the datasheet it states the 7374 has low pass filters built in. As 220uF caps are used to act as low pass filters, they are no longer needed here.
That's not correct at all. The 220uF acts (together with the 75ohm termination inside the TV / scaler) as a high pass filter with very low cut off. It's used to preset the signal but not neccessarily needed. The low pass filter inside the THS7374 in contrast is a 6th order Butterworth low pass filter and used for DAC reconstruction (transmitter side) or to reduce noise added during transmission (receiver side). Depending on your setup you can bypass these low pass filters. This is the case if your setup is completely of analoge nature or if your digital receiver has it's own low pass filter (anti-aliasing filter: e.g. OSSC, some mode of the FM). Some capture cards don't have low pass filters at all prior to ADC sampling and thus produces aliasing effects if the signal is not filter at transmitter / console side.
Ah, my mistake. Thought I read that 220uF cap acted as low pass filter. Thank you for the clarification. Ignore my previous post.
An RC circuit acts like a LPF if you take the output over the capacitor. If you take the output over the resistor - as it is done here - you got the “inverse”, i.e. you get a HPF.
thanks for jumping in borti so 220uf 6.3v cap should be added for good measure would these be alright? https://www.mouser.com/productdetail/74-293d227x96r3c2te3 or https://www.mouser.com/productdetail/647-tvx0j221mad could you take a second to address my mono audio question? ive been using one of the below to make mono on the JCV DT-V19 input but any chance of damaging something?
http://www.rane.com/note109.html The link above will explain y (pun very intended) you should not do that. Y cables and adapters are made for splitting rather than summing. By using them to sum, you end up causing each channel to drive the impedance of the other. Figure 2 on the page shows a simple passive mono summing circuit. Just replace the TRS connector at the input with 2 RCA connectors that have their ground leads tied together. As far as the specific values of summing resistors (the 475s on the schematic) go, that is dependent upon the output impedance of the source.
