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ChristoMephisto
Platinum Member
Canada
1288 Posts |
 Posted - 05/05/2007 : 15:56:52
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Im tweeking my SD-1 again, as its my only pedal thats not OoP
I was looking at the schems for the od-1 and noticed it had a 0.0047uf at C2 to the input of the IC. With the 100K res at R4 this is one heck of a high pass/bass cut at 338Hz. Is that a typo? Do the OD-1 really have a 0.0047uf and 100k res? .047uf or a 10k maybe?
I intsalled a toggle to switch between a value close to sd-1 of 33.8Hz (all bass plus first octave) and the above found on the OD-1 schems.
Its not really a volume loss, but there is next to no gain. Midrangy n up, very very mild overdrive
If i apply the theory of adding more bass and gain like on the output of the drive (C3/R6)by halving the resistor and keeping the same freqency, will this increase the input. Or should i boost the gain/bass after in the same section of the circut (C3/R6).
tia |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/05/2007 : 16:31:00
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Hi ChristoMephisto
On my service Schematic, C2 = 0.018 and R4 is 100K
You must be working off the other .bmp schematic that is on the web.
it's the one that is drawn in Blue & Green with Red text & voltages.
Check your PM, I'll send you the one that i think your looking at as well.
It's a bit too late to go opening up the SD-1's
I do have a couple of PCB pics, of my latest one.
Hope it helps
Regards Dr. Bob 
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ChristoMephisto
Platinum Member
Canada
1288 Posts |
Posted - 05/05/2007 : 16:56:28
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My schem is the same, 0.018 gives you 88.5Hz, dropping it to 0.047 gives a hint of more bass at 33.9Hz (first octave is at 50Hz)
The service schem for the od-1 shows 0.0047uf at C2, same relative location on the sd-1 but uses a 0.018uf stock.
So im wonderng whats in the od-1
Probably need a new sd-1 in the future...nahhhh |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/05/2007 : 17:16:45
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Sorry Christo
I miss read your posting, I thought you were talking about the SD-1, I now see, that you wrote od-1 -- I missed it.
Anyway I sent you a heap of stuff on the SD-1
I just looked at the OD-1 service schematic, and C2 is shown to be 0.0047uf -- R4 100K.
I guess we'll have to get someone with an OD-1 to open it up & check.
I don't own an OD-1..
Regards Dr. Bob  |
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ChristoMephisto
Platinum Member
Canada
1288 Posts |
Posted - 05/05/2007 : 18:02:16
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Thanks for all the sd-1 stuff, had some of it.
My sd-1 is no where near a pretty on the inside
no rush, im still fighting with my clone |
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ChristoMephisto
Platinum Member
Canada
1288 Posts |
Posted - 05/06/2007 : 18:06:12
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Found my answer by looking at Pacafeliz's comparison on od-1s from 78 and 80. The answer is both. There is also other changes in comp values too. The '78 has a 10k/0.047 and the '80 has 100k/0.0047 both giving 338Hz at the input. The other changes are at R2, the '78 had a 220k, while the '80 had 470k giving the latter more impedance. Also at R13, the older one has a 10k compared to 100k, but im not sure what that does.
Im guessing the older one had more input but less impedance, and vice versa on the other. Still has a bass cut tho.
Wonder if that balances out like burnt fishsticks that are still frozen on the inside.
thx for the txt on the sd-1 mods dB, helped to figure out a few more mod points, but you gotta stop hijacking ppls threads
Thx Pacafeliz for the clear pics, very helpful!!
each one has its own stock values? Or replaced what was there originally? Any sound difference in the two?
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Edited by - ChristoMephisto on 05/06/2007 18:08:32 |
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OD-1 and SD-1 question
