

Moderators: Kent, luketeaford, Joe., lisa
wow that looks stunningly accurate, brilliant! Can I ask you some questions? I have a lotACME wrote:I also built myself a Module Board. This is only one Part of my JP8 replica.. All ICs in the filters (HPF /LPF) are original from Roland. The other BA662 are also clones from the openmusiclabs schematic. For this I have designed my own pcb.
Here comes my last copy.:
dikkietrom wrote:I am somewhat surprised and confused about the dac's, I always thought memory was 12bit or 14bit but it is 8bit on the controller for pot data and 12/14bit on the interface for key cv. The 8 bit is a discrete ladder.
Btw it is not 32 sh but "only" 23 per dac throug 3x8-channel multiplexers, I have no clue about the s&h refresh rate, the z80 has 8mhz clock.
Anyways the voice scheme is annotated with original references now, the original scheme has some missing references but that can be recalled from the board layout. Found one more wrong junction in the kicad scheme. In hindsight it was not so bad that I had to go over it a few times cause I found mistakes that otherwise might have been unnoticed.
I am going to take a little break. Looking forward to replicate the component placement.
Ok cool, can you verify my resistor analysisACME wrote:dikkietrom wrote:
wow that looks stunningly accurate, brilliant! Can I ask you some questions? I have a lot
Feel free to ask me, I also have a lot of questions.
Markus
Do not worry about these resistors. Instead, just use 1% metal film.dikkietrom wrote:Ok cool, can you verify my resistor analysisACME wrote:dikkietrom wrote:
wow that looks stunningly accurate, brilliant! Can I ask you some questions? I have a lot
Feel free to ask me, I also have a lot of questions.
Markus
There are 3 types on the board
- R25G, user groove suggested carbon 1/4 watt 2% On board pics I see red band at the location so I go with carbon 1/4 watt 2% as suggested.
- Carbon R25 , carbon 1/4 watt, gold band on pics > carbon 1/4 watt 5%
- Metal Film RB25FX, 1/4 watt, brown band > MF 1/4 watt 1%
Did you came to the same conclusion?
By lowering the discharge resistor values?dikkietrom wrote:@ACME : I tend to agree, how are the 3310's working out for you? Were you able to check some differenes with an IR3?
JP4 discrete ADSR, the question is how can we get decay time to 1ms instead of 14ms. Attack is actually 0.6ms vs 1ms
Thanks good to know it does not matter much to you, I will go for 5% for the sake of it.ACME wrote: Do not worry about these resistors. Instead, just use 1% metal film.
Markus
Can you eleborate the nonlinearities cause I don't understand since the env is by definition expo.ACME wrote: The 3310 have some differences on the top end times. They must be compensated by an external circuit to match the R01. There are some nonlinearities in the middle, but the R01 shows this behavior too. Otherwise, the 3310 provides a clean envelope.
Thanks, I see no page numbers but could find them on the module controller. There is indeed a 10k vs 4.7k diff between them. I also cannot get these simulated so I have no clue yet about the clock speed which would say something about the actuall difference between tom's pic and this approach.KSS wrote:Look at the upper left corner of page 23 of JP-4 service notes. The differences between the A clock gens and D,R clock gens are your clues and cues.dikkietrom wrote:JP4 discrete ADSR, the question is how can we get decay time to 1ms instead of 14ms. Attack is actually 0.6ms vs 1ms