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I'm trying to figure a bit out about the DX27s. As with the DX21
it has chorus, but then again, the DX27 and the DX100 do not, even
though they share the same main PCB.
According to
the DX21 uses a Panasonic MN 3209 as a chorus. But on my DX27s I
could only find a MN 3204, which also is a BBD, but with 512
stages (instead of 256 on the MN 3209).
That would mean the chorus should be slightly different - fine
for me.
Unfortunately I was not able to find good images of a PCB of DX27
or DX100, now I really wonder if IC 12 is populated on a DX27/100.
I do have a PDF here called "DX27 - DX100 Overall Circuit
Diagram", but according to that, IC 12 is a memory chip... But the
chip numbers in that diagram have nothing to do with the silk
screen numbers on the PCB anyway.
Does anyone have a good picture of the PCB with the area around
IC 12/13?
Cheers, Florian
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A chorus circuit like that is based around a BBD chip and a clock generator.? In this case, MN3204 is the BBD and MN3102 provides the clock.? There also one or two fixed filters, made with op amps or transistors.
It seems the MN3207 + MN3102 combination is more common, which was used in the original Boss CE-1 design, but they used transistors for the rest of the circuit, which makes it harder to follow:
I found a page with the combination you have, but the example schematic has been spoiled by photobucket.? If you save the image, or use View Imager in Firefox, you can see it without their banner, but you have to squint to make much out:
Maybe you can see a more detailed version if you register and log in.? The datasheets for the chips should have example circuits too.
- Andy
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Hi Andy,
thanks for the explanation. I was roughly aware how a BBD could
be used for a chorus effect, I was mainly surprised that the DX27s
would use a different chip than the DX21, both from the same year.
But I'm starting to think that the engineering team of the DX27s
and that of the DX21 were disjunct groups anyway, particularly
since the DX21 has a switch mode power supply and the DX27s a good
old transformer.
But my question was primarily geared towards the differences of
the 27/100 to the 27s. I would really like to know, if IC12/13
(and related components) are populated in a DX27/100 board.
Cheers, Florian
On 25/05/2020 22:49, AndyHornBlower via
groups.io wrote:
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Show quoted text
A chorus circuit like that is based around a BBD chip and a clock
generator.? In this case, MN3204 is the BBD and MN3102 provides
the clock.? There also one or two fixed filters, made with op amps
or transistors.
It seems the MN3207 + MN3102 combination is more common, which was
used in the original Boss CE-1 design, but they used transistors
for the rest of the circuit, which makes it harder to follow:
I found a page with the combination you have, but the example
schematic has been spoiled by photobucket.? If you save the image,
or use View Imager in Firefox, you can see it without their
banner, but you have to squint to make much out:
Maybe you can see a more detailed version if you register and log
in.? The datasheets for the chips should have example circuits
too.
- Andy
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On Mon, 25 May 2020, Florian Heer wrote: I'm trying to figure a bit out about the DX27s. As with the DX21 it has chorus, but then again, the DX27 and the DX100 do not, even though they share the same main PCB. Interesting. I knew the DX21 has a simple Chorus effect, but I didn't realize the (rare) DX27S also has a Chorus effect, unlike the DX27 and DX100. I have SysEx dumps from the 8x24=192 factory presets in the DX27/DX100 ROM, I have analysed them, and none of them have the CHORUS effect bit enabled in the VCED/VMEM data. I have also analyzed the 4x32=128 factory presets, and 14 of them have CHORUS switched on in the preset factory data: BellsBells Cheeky Clear Clav Easy Clav Easy Synth Fuzz Clav Good Vibes PercoPiano PickPluck PowerBrass Richstring Squeezebox Templegong Tube Bells So now I am wondering: does the DX27S have the exact same factory ROM presets as the DX100 and DX27, without CHORUS effect applied by default to any of the presets? Or do some presets have this Chorus effect switched on by default to use the DX27S chorus effect? -- MT
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On 26/05/2020 10:17, Martin Tarenskeen
wrote:
Interesting. I knew the DX21 has a simple Chorus effect, but I
didn't realize the (rare) DX27S also has a Chorus effect, unlike
the DX27 and DX100.
Rare? Then I must have been lucky, got it for very little money.
It also has a port for a foot volume controller.
I
have SysEx dumps from the 8x24=192 factory presets in the
DX27/DX100 ROM, I have analysed them, and none of them have the
CHORUS effect bit enabled in the VCED/VMEM data. I have also
analyzed the 4x32=128 factory presets, and 14 of them have CHORUS
switched on in the preset factory data:
Intruiging. I have just checked it on my DX27s, and at least
BellsBells
Cheeky
have the chorus set to "on".
So
now I am wondering: does the DX27S have the exact same factory ROM
presets as the DX100 and DX27, without CHORUS effect applied by
default to any of the presets? Or do some presets have this Chorus
effect switched on by default to use the DX27S chorus effect?
According to the documentation, a DX27 will not dump a voice as
chorus=on. I guess (but I haven't read out the ROM) that the
presets are all the same, but DX27/100 will only dump them
according to their capabilities. But that is just from the
standpoint that it would be quite an unnecessary effort to create
different voice roms.
Cheers, Florian
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On Tue, 26 May 2020, Florian Heer wrote: According to the documentation, a DX27 will not dump a voice as chorus=on. I guess (but I haven't read out the ROM) that the presets are all the same, but DX27/100 will only dump them according to their capabilities. That would be strange. It wouldn't hurt if the Chorus=On bit would be set in the sysex data, even for a DX27/DX100 that doesn't have a chorus effect. The bit would simply be ignored. -- MT
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On 26/05/2020 14:40, Martin Tarenskeen wrote: On Tue, 26 May 2020, Florian Heer wrote:
According to the documentation, a DX27 will not dump a voice as chorus=on. I guess (but I haven't read out the ROM) that the presets are all the same, but DX27/100 will only dump them according to their capabilities. That would be strange. It wouldn't hurt if the Chorus=On bit would be set in the sysex data, even for a DX27/DX100 that doesn't have a chorus effect. The bit would simply be ignored. I would have thought the same, until I saw that note in the DX27 manual. But for a dump the data needs to be processed anyway. At least in the DX21 firmware each voice only uses 49 bytes. Unfortunately I don't have a DX27/100 rom for comparison. Cheers, Florian
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Hi Michael, On 26/05/2020 15:54, Michael Whocares wrote: Does this help? thanks a lot, that is great. But from a first check, the DX21 firmware and that of the DX100 are completely different. In the DX100 the rom starts with code and ends with the voices, in the DX21 it's the other way round. Also the DX100 uses only 43 bytes per voice, so no simple direct comparison between those two. And that although they use the same MPU (HD63B03XP in DX21 and HD6303XP in DX27S),only difference is the speed of the processors. Okay, now I have a reason to desolder the rom from my DX27s and read that out... Unless someone has the firmware of the DX27s? Cheers, Florian
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On Tue, 26 May 2020, Michael Whocares wrote: Does this help? I have checked the voicedata in the file you attached: None of the 192 patches have Chorus enabled. MT
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On 26/05/2020 19:32, Martin Tarenskeen wrote: On Tue, 26 May 2020, Michael Whocares wrote:
Does this help? I have checked the voicedata in the file you attached: None of the 192 patches have Chorus enabled. How do you interpret the voice data from the firmware? Maybe I don't need to desolder my ROM after all... Cheers, Florian
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On Tue, 26 May 2020, Florian Heer wrote:
On 26/05/2020 19:32, Martin Tarenskeen wrote:
On Tue, 26 May 2020, Michael Whocares wrote:
Does this help? I have checked the voicedata in the file you attached: None of the 192
patches have Chorus enabled.
How do you interpret the voice data from the firmware? Maybe I don't need to desolder my ROM after all...
The total size of that bin file is 32768 bytes (0x8000) I checked the file with a hexeditor. The voicedata start at address 0x4da0 Each voice uses 67 bytes ( = the first 67 bytes of the 128 bytes VMEM voice parameter bulkdump format, up to the 10 bytes that contain the voicename. You can find detailed description of VMEM format in the DX100/21/27 etc. manual. Many of the unused or reserved bytes in these 128 bytes are used in the later models, from TX81Z and DX11 to YS200 and V50. ) There are 192 patches. 192 x 67 = 12864 bytes After that, starting at address 0x7fe0, there are 32 bytes ending the file. 67 + 12864 + 32 = Address | Size --------|--------- 0x0000 | 19872 firmware data 0x4da0 | 192 * 67 = 12864 bytes voicedata 0x7fe0 | 32 bytes ========|========+ 0x8000 | 32768 bytes Does that help ? MT
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On 26/05/2020 22:03, Martin Tarenskeen wrote:
On Tue, 26 May 2020, Florian Heer wrote:
How do you interpret the voice data from the firmware? Maybe I don't need to desolder my ROM after all... The total size of that bin file is 32768 bytes (0x8000)
I checked the file with a hexeditor.
The voicedata start at address 0x4da0
Each voice uses 67 bytes ( = the first 67 bytes of the 128 bytes VMEM voice parameter bulkdump format, up to the 10 bytes that contain the voicename....
THANK YOU! Yes, I meant to shout, 'cause I'm an idiot. My Hex editor showed me a length of 43 between starts of voice names. Now that I wanted to check what you described, I finally saw the length was in hex. Okay, yes, 67 bytes do make sense - all it needs, no Pitch EG available. 43 just didn't make any sense, so I suspected it to be neither VMEM nor VCED... Cheers, Florian
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I saw in the Service Bulletin No.: E-396 (Date: May, 1987) that there is (at least) a firmware ROM update from V1.1 to 1.2
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AndyHornBlower
Michael Whocares