To share my thoughts regarding RGB trimpots, and this isn't strictly related to your device, just thinking out loud with like minded people to gain insight and ideas etc...
Personally I don't have preference to a triple gang pot due to intolerances as you have mentioned. Yes it's convenient but the trade-off is an imperfect colour balance which is significant.
I'm currently 'settling' on 3 x separate pots. The benefit being obvious, perfect control and the ability to cater to practically any output, be it lower or higher than 'average'. Yes a vast majority of arcade boards hover around a similar output, however there are exceptions, some very old boards have a weaker signal for example. The disadvantage as you point out, is the 'difficulty' of use and obtaining an even output. These factors are perhaps counteracted by the following:
- If 'most' arcade boards have a similar output, then the pots need only be set once and forgotten about. For boards that are out of the normal range, at least you have the means to adjust accordingly.
- Quite trivial to use a multimeter to match the 3 pots evenly. This can be performed prior to sale, so the end user in most cases need not worry about it.
A low tolerance fixed resistor is a great compromise between the above two methods, with the drawback that adjustment, if needed, may not be readily available.
One area I'd like to explore is digital potentiometers, controlled by tactile switches. I think having control over all 3 channels via a single set of switches may be quite convenient, but then I think sometimes I prefer the feel of analogue adjustment.
Once again, just chewing the fat to gain a different perspective, not stating that you need to change how you do things.
Personally I don't have preference to a triple gang pot due to intolerances as you have mentioned. Yes it's convenient but the trade-off is an imperfect colour balance which is significant.
I'm currently 'settling' on 3 x separate pots. The benefit being obvious, perfect control and the ability to cater to practically any output, be it lower or higher than 'average'. Yes a vast majority of arcade boards hover around a similar output, however there are exceptions, some very old boards have a weaker signal for example. The disadvantage as you point out, is the 'difficulty' of use and obtaining an even output. These factors are perhaps counteracted by the following:
- If 'most' arcade boards have a similar output, then the pots need only be set once and forgotten about. For boards that are out of the normal range, at least you have the means to adjust accordingly.
- Quite trivial to use a multimeter to match the 3 pots evenly. This can be performed prior to sale, so the end user in most cases need not worry about it.
A low tolerance fixed resistor is a great compromise between the above two methods, with the drawback that adjustment, if needed, may not be readily available.
One area I'd like to explore is digital potentiometers, controlled by tactile switches. I think having control over all 3 channels via a single set of switches may be quite convenient, but then I think sometimes I prefer the feel of analogue adjustment.
Once again, just chewing the fat to gain a different perspective, not stating that you need to change how you do things.
Potential clients can judge for themselves if they think it's an issue:
Other than that the video quality is pristine, I tested about 4 different boards so far (echo chan -> ossc -> datapath e1s capture card) and the video quality is pure and I never saw any color drifting or whatever was described earlier. I also did some audio comparisons with MAME and didn't detect any issues (although I'm no audiophile). I'm going to do some more captures this week with a variety of boards.
