September 10, 2019 at 1:19 pm #6833
I built the D’Lay and it worked OK from the start, but I thought it needed some improvements. The first thing I noticed was the Level control needed to be cranked all the way to hear the effect. I soon noticed that the parts list calls for R14 to be 68K while the schematic calls for a much more logical 33K (I will probably lower it more to 22K). I was also unhappy with the resolution of the Time pot when adjusting short delays, so I substituted an A100K log taper pot which improved things significantly. I then changed R9 from the specified 1K to 6.8K since the delay time is virtually undetectable with only 1K to ground on pin 6 of the PT2399. This provides a much more usable range in the shorter delays that I tend to use versus the long delays that I don’t.September 10, 2019 at 5:23 pm #6837
The Build Notes discuss several options for controlling the output level. Changing R13 to 68K when using TR2 should give plenty of gain to achieve unity level using TR2. If R13 is 22K and TR2 is used, you will not be able to reach unity level until TR2 is fully CCW.
The published parts list calls for R14 to be 22K. R13 is listed as 68K. The Build Notes suggest R14 should “try 22K to 33K if needed.”
Changing the TIME pot taper from a B100K to a A100K is certainly a personal preference. Likewise changing R9 from 1K to 6.8K will provide more emphasis on the shorter delay range. The Build Notes discussed the delay time relationship of the resistance values of R22 as well.since most users seem to be more concerned with achieving longer delay times rather than the shorter ones.September 10, 2019 at 8:44 pm #6840
I see now that I was using an older version of the build document. The new one does correct the value discrepancy of R14 and also makes note of the value range it should be within. And I don’t have an issue with the overall output level of the effect, I just had an issue with the level of the wet signal versus the dry which is taken care of by correcting R14’s value which, again, on my old build doc was listed as 68k on the parts list rendering it rather weak. Thanks for alerting me to the updated build doc! Had I looked for that first, I could have saved myself some time. But it’s always good to exercise your electronics knowledge when scratch-building electronic devices.
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