Ibanez - SD9M Sonic Distortion mods  [schematic]

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Ibanez - SD9M Sonic Distortion mods

Postby rocket512 » 22 Mar 2012, 23:04

I am interested in the differences between the vintage SD9 and the new "modded" version by Ibanez.
Is the circuit like the original one if the MOD an GAIN switches are off?
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Re: Ibanez SD9M Sonic Distortion Mod

Postby SGJarrod » 22 Jun 2012, 19:04

This is also something that I am interested in. I was getting ready to order parts to use the SD9 PCB that I have had laying around for yrs and ran across the new version on the web. From the videos it appears the high gain setting is the normal SD9 setting, but to my ear the normal old school SD9 is more inbetween the settings on the mid switch.

Anyone got ideas on these Mods?
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Ibanez - SD-9M - Sonic Distortion Modified

Postby aionios » 15 Jun 2014, 13:20

I noticed there weren't any schematics available for the Ibanez SD9M (2012 reissue) or any documentation on how it differed from the regular SD9. I particularly just wanted to find out what the switches do.

Well, when I opened it up, I found good news and bad news. The bad news is that there are two 4558 op amps and only 3 transistors, which means the differences are a bit more than just a couple of toggle switches on the front to switch out a component or two, so it will probably need a full trace - or at least a very thorough checking with Dirk's schematic of the original SD-9. The good news is that Ibanez is using Molex-style connectors for everything, so it was really easy to pull the board out without having to desolder anything at all.

So: I have great photos and a full visual trace of the circuit. I haven't had time to work up a schematic yet, so I thought I would post my progress here in case anyone wanted to take a shot at it.

Here's the PSD: https://www.sendspace.com/file/r5oque

Everything is done with layers - the front, the back (mirrored), each individual net, and the labels - so you can turn them on and off as needed.

Here's the component side of the board:
http://i1249.photobucket.com/albums/hh5 ... ligned.jpg

Here's the trace side of the board, mirrored to match the component side:
http://i1249.photobucket.com/albums/hh5 ... ligned.jpg

And here's a flat trace of the component side of the board, if you don't have Photoshop to look at the better one above:
http://i1249.photobucket.com/albums/hh5 ... -trace.jpg

In addition to the photos, here are the offboard components.

Input jack board: jack input -> 47n capacitor -> 47k resistor (Yellow, Violet, Orange) -> PCB "In" connection
There's also a ceramic capacitor marked "47" (47pF) after the resistor, going to ground.

Pot board: The 6-pin connector in the bottom-left corner of the board has the following connections. (numbered so the bottom pin to ground is "1")
1 Ground (green dot)
2 Vol 2 (blue dot)
3 Tone 1 (white dot)
4 Tone 3 (orange dot)
5 Dist 2/3 (brown dot)
6 Dist 1 (gold dot)

On the pot board itself:
Vol 1 -> 1k resistor -> ground
Tone 2 -> Vol 3

Output jack board: 330pf capacitor (code 331) to ground immediately before the output jack

The one thing I still need to do is to pull out C5, the teal bipolar capacitor, and measure it. The sleeve on the capacitor was cut just perfectly before the "uF" marking so it's impossible to read. If someone had another SD9M I'm sure the cap would be readable - just unlucky on my part!
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby aionios » 16 Jun 2014, 00:17

C5 is a 1uF bipolar capacitor. First draft schematic coming soon.
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby aionios » 16 Jun 2014, 01:17

Here's the schematic. I left off the power section and FET switching, but from initial glance the power section is pretty well the same as the SD9 and the FET switching should be the same as well (but isn't needed for true bypass). I didn't double-check anything, so this should be considered entirely unverified, but it should be pretty easy to cross-check it with the trace I posted earlier.

Image

The major change is the addition of the op amp gain stage between IC1A and the clipping diodes. I haven't played an original SD9 but I imagine this would change the sound a fair amount - hardly just a "modded" version. The gain switch is pretty intense, actually. I'm not too crazy about it. A little too much metal, even for an already high-gain pedal. I thought the Mids switch was pretty useful and made it a bit more Tube Screamery. A lot of people think the Mids switch is too drastic, so it'd be pretty easy to play around with the values of C10 and C11 to get a better balance - maybe two 47n's would be better.

The second half of IC2 is used to buffer the dry signal for switching, as in the original, so for a true-bypass version you might want to use it to buffer Vref per Dirk's suggestion.
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby Chugs » 16 Jun 2014, 09:01

Thanks for the schematic.

I presume C12 and R17 should be connected to the non inverting input of IC2B?
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace  [schematic]

Postby aionios » 16 Jun 2014, 11:37

Yep, you're right. Good catch. It's been updated:
http://aionelectronics.com/wp-content/u ... ematic.png

And sorry the first one was so small! I thought it would show the full size version if you saved it or viewed it by itself but it did not. The one above is a bit more legible :)
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby Dirk_Hendrik » 16 Jun 2014, 17:56

Like :D
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby aionios » 17 Jun 2014, 00:19

Unbelievable - the second one was just as small as the first one. It's supposed to be around 2200px wide. Try the above link one more time - it should actually be readable now. Sorry for making all of you get out your glasses!
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby Chugs » 17 Jun 2014, 09:00

Thanks, it is indeed bigger now. :block:
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby mirosol » 19 Jun 2014, 22:45

Thought i'd draw a layout for the circuit, so here you go. As suggested, i used the remaining half of an opamp as a buffer for vref. One could take a third switch for clipping diodes pretty easy.
Unverified for now.
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby Dirk_Hendrik » 22 Jun 2014, 08:31

With some 2nd thoughts while spending some time.. :blackeye

- The input buffer suddenly changed transistor P/N?
- The photo's show a FET, the schem doesn't?
- The photo's show a 4v7 Zenet, the schem doesn't.

How accurate is the schem really?
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby Dirk_Hendrik » 22 Jun 2014, 13:07

Ah I see. Not at all:

so this should be considered entirely unverified,
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby alexradium » 22 Jun 2014, 14:25

Dirk_Hendrik wrote:With some 2nd thoughts while spending some time.. :blackeye

- The input buffer suddenly changed transistor P/N?
- The photo's show a FET, the schem doesn't?
- The photo's show a 4v7 Zenet, the schem doesn't.

How accurate is the schem really?
the 2 fets are switching the outputs,classic Ibanez.
Zener is part of the led supply.
It was stated by original poster he left off switching and power circuit.
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby Dirk_Hendrik » 22 Jun 2014, 18:40

As I answered myself already. ;)

Have a full version in the make. I don't like ommissions. Ommissions take time in repairs.

For now my main frown remains:
When looking at the schematic I do not see an input capacitor. Since this box is mecahnically switched but not true bypass this does not result in a Pop. nevertheless, non-popping of a full setup has come to rely on the DC decoupling of the other devices in the FX chain since the input gives a 4.5 volts loading in the device that preceeds this pedal in the signal chain. I do consider this a defect in the design.
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby tube-exorcist » 22 Jun 2014, 20:53

Dirk_Hendrik wrote:..... Have a full version in the make. I don't like ommissions. Ommissions take time in repairs.
.......

How true.
Dirk_Hendrik wrote:For now my main frown remains:
When looking at the schematic I do not see an input capacitor. .......

I think you missed this in the first post:
aionios wrote:......
In addition to the photos, here are the offboard components.

Input jack board: jack input -> 47n capacitor -> 47k resistor (Yellow, Violet, Orange) -> PCB "In" connection
There's also a ceramic capacitor marked "47" (47pF) after the resistor, going to ground.
......
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby aionios » 22 Jun 2014, 20:56

The input capacitor (47n in the schematic) is actually located on the input jack PCB, along with the 47k resistor. So the wire going to the board is actually the R2/Q1 junction, and those first two parts can't be seen in the photos.

Also, the input buffer transistor is actually a 2SC3198 rather than a 2N5088. Shouldn't matter since it's just a buffer, but wanted to mention it!
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby Dirk_Hendrik » 23 Jun 2014, 20:03

I couldn't care less for the transistor type for an emitter follower. Unfortunately there's some willing to discuss the sonic differences for days. Just as well there's some who are in the opinion that when one traces a circuit the trace shouls be as correct as possible. Changin transistor type in such a situation already suggests pure laziness. "It doesn't matter electronically so why bother". I tend to be of the 2nd camp. When you do something push yourself to do it accurate. Leave your own engineering opinions for a later stage.

Which leaves 2 capacitors which are unidentified on the board photo's and have a value in the schem. Since the schem is unverified and does contain errors...

here's my go based on the info provided so far...
Ibanez_SD9M.pdf
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby tube-exorcist » 23 Jun 2014, 23:02

Dirk_Hendrik wrote:.....
Which leaves 2 capacitors which are unidentified on the board photo's and have a value in the schem. Since the schem is unverified and does contain errors...

Thanks for you effort. Output pulldown resistor is a 100k (instead of 1M). :wink:

Cap values:
aionios wrote:C5 is a 1uF bipolar capacitor.

and from the draft schematic the other cap is a 10n . This matches with the SD9.
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Re: Ibanez SD9M (Sonic Distortion Modified) guts + trace

Postby Dirk_Hendrik » 24 Jun 2014, 06:52

Thanks. Though i already corrected that 1Meg. Seemingly not.

As that 10n. That's what I suspected but I did not really trust that draft.
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