1310 Clock Noise Improvement

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dslocum
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1310 Clock Noise Improvement

Post by dslocum » Wed Nov 03, 2010 10:27 am

Hi Folks!

For those who would like to improve the clock bleedthrough, you can return it and I'll make the change at no charge and return ship on my nickel.

If you are comfortable with a fairly simple part replacement and you'd like to try it yourself, you can either replace C9 & C10 with 1uf electrolytic caps (positive lead toward the 2399 chip), or simply parallel the existing caps on the bottom of the board, thus avoiding possible PCB damage when removing the existing caps. The caps are located off pins 7 & 8 of the 2399 chip.

This change will be incorporated in all future 1310's.

Please feel free to post here if you need help or have any other questions.

Here's a photo that Yves was kind enough to supply. Note that he elected to replace the caps with a box type non-polarized version.

Cheers!

Image
Doug Slocum
Synthetic Sound Labs
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"...this whole thing was started by a dream and a mouse." - Walt Disney
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Re: 1310 Clock Noise Improvement

Post by fac » Wed Nov 03, 2010 11:12 am

dslocum wrote:or simply parallel the existing caps on the bottom of the board, thus avoiding possible PCB damage when removing the existing caps. The caps are located off pins 7 & 8 of the 2399 chip.
This seems simple enough even for me. Could you provide a rough diagram of the procedure? (trust me, I would need it).

It's so ironic (and annoying) that I'm an EE working at the Department of Electronics in a university, yet I feel completely lost when it comes to analog electronics (and soldering, ugh). :ripbanana:

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Re: 1310 Clock Noise Improvement

Post by dslocum » Fri Nov 05, 2010 3:22 pm

fac wrote:
dslocum wrote:or simply parallel the existing caps on the bottom of the board, thus avoiding possible PCB damage when removing the existing caps. The caps are located off pins 7 & 8 of the 2399 chip.
This seems simple enough even for me. Could you provide a rough diagram of the procedure? (trust me, I would need it).

It's so ironic (and annoying) that I'm an EE working at the Department of Electronics in a university, yet I feel completely lost when it comes to analog electronics (and soldering, ugh). :ripbanana:
FAC,

Wow....

I've thought a lot about your request for some step-by-step instructions. I would rather not put myself in the position of having to guide someone through basic electronic soldering, etc.

If you are not comfortable with this electronic mod then I would respectfully request that you find someone that can do it, or return it so we can make change.

I'm very willing to help with this modification, but I'm not comfortable teaching basic soldering skills. Hope you understand!
Doug Slocum
Synthetic Sound Labs
www.steamsynth.com
------------
"I guess all the Forest Mims Radio Shack books I read finally paid off!"
"I ordered twice as many _______ as I thought I'd need, only to find out that I'm still less than half way to having enough."
"...this whole thing was started by a dream and a mouse." - Walt Disney
"Flatulence sounds aren't just for brass and reed instruments anymore, thanks in large part to Dr Moog." - Ockeghem

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THE ULTIMATE FIX!!!!!

Post by dslocum » Sun Nov 21, 2010 2:22 pm

Hi All,

It turns out those capacitor changes only masked a design flaw. (Yeah, maybe I'm nuts to admit I could actually make a mistake. :roll: )

I spent most of Saturday afternoon and today (been up since 6:30 AM) getting to the bottom of this. I was not going to let this get the better of me.

Well, about an hour ago, I found that two other caps were flipped around in the original design. This caused the delay chip some heartaches because DC was getting back to inputs that needed to be AC coupled. A new batch of caps are apparently fussier about reverse polarity than the ones used in my original design, so I didn't pick up on it.

Long story short, with no input it's DEAD quiet even at the longest delays. No more squealing. Woo Hoo!!!

If you'd like to return your 1310's for repair, we'll be happy to do so.
If you order another unit, we can cross ship and refund the sale price plus your shipping cost when received.

We want you guys happy. While it feels great to have found the problem, it's also quite embarrassing. :doh: :oops: :waah: :guinness: :party:
Doug Slocum
Synthetic Sound Labs
www.steamsynth.com
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"I guess all the Forest Mims Radio Shack books I read finally paid off!"
"I ordered twice as many _______ as I thought I'd need, only to find out that I'm still less than half way to having enough."
"...this whole thing was started by a dream and a mouse." - Walt Disney
"Flatulence sounds aren't just for brass and reed instruments anymore, thanks in large part to Dr Moog." - Ockeghem

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Post by Christopher Winkels » Sun Nov 21, 2010 3:39 pm

Hey thanks Doug, I was wondering if it was me. :oops: I'll have to send mine your way for an upgrade.

One other question: my 1310 appears to actually cause a pitch shift when both delay time and recirc amounts are set high. Is that a deliberate feature? This happens even when I'm not feeding anything into the CV input. It definitely has some uses, but I'm wondering if it can be defeated as well.

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Post by russma » Sun Nov 21, 2010 3:50 pm

Is this something I can fix myself? If so, which caps need to be reoriented? And, is this instead of, or in addition to, the earlier cap replacement solution?
Russ M.

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Post by dslocum » Sun Nov 21, 2010 4:27 pm

Christopher Winkels wrote:One other question: my 1310 appears to actually cause a pitch shift when both delay time and recirc amounts are set high. Is that a deliberate feature? This happens even when I'm not feeding anything into the CV input. It definitely has some uses, but I'm wondering if it can be defeated as well.
Chris,

Yeah, I've noticed that. Kinda slick, but not intentional. I'm pretty sure it happens over the entire range, but is more noticable at the slow end and with recirc high. It's probably due to the chip's internal clock being slightly modulated by tiny changes in the chip's internal voltage reference. Can't prove it and the data sheets for the chip s*ck.

So just bewteen you and me, it's a design _feature_, OK? :roll:

Any way your like to handle the exchange is probably just fine.

Regards,
Doug Slocum
Synthetic Sound Labs
www.steamsynth.com
------------
"I guess all the Forest Mims Radio Shack books I read finally paid off!"
"I ordered twice as many _______ as I thought I'd need, only to find out that I'm still less than half way to having enough."
"...this whole thing was started by a dream and a mouse." - Walt Disney
"Flatulence sounds aren't just for brass and reed instruments anymore, thanks in large part to Dr Moog." - Ockeghem

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Post by dslocum » Sun Nov 21, 2010 4:33 pm

Oh folks,

I've only got a couple 1310's asssembled right now, and due to the upcoming holiday, the dining room "module assembly table" has been reallocated for food. Imagine that! So if those are gone, I won't be able to build any more for cross ship exchange until this coming weekend.
Doug Slocum
Synthetic Sound Labs
www.steamsynth.com
------------
"I guess all the Forest Mims Radio Shack books I read finally paid off!"
"I ordered twice as many _______ as I thought I'd need, only to find out that I'm still less than half way to having enough."
"...this whole thing was started by a dream and a mouse." - Walt Disney
"Flatulence sounds aren't just for brass and reed instruments anymore, thanks in large part to Dr Moog." - Ockeghem

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Post by dslocum » Sun Nov 21, 2010 4:45 pm

russma wrote:Is this something I can fix myself? If so, which caps need to be reoriented? And, is this instead of, or in addition to, the earlier cap replacement solution?
Russ & any other DIYers,

The two caps are 1uf radial electrolytic (voltage can be any thing from 16v to 50v). They are marked C20 & C21 at the rear edge near the center of the board. Simply remove them and reinstall replacements in reverse polarity (+ goes to -, and - goes to +). Unless you're pretty skilled at PCB rework, I wouldn't recommend reusing the caps as removal might damage them internally. You could also use a non-polarized electrolytic.

I'd be more than pleased to mail out replacement caps to any brave souls.

EDIT----
I didn't answer your second question... I'd definately install this new mod first. The other mod couldn't hurt, but this one should be "the fix"!
Last edited by dslocum on Sun Nov 21, 2010 6:00 pm, edited 1 time in total.
Doug Slocum
Synthetic Sound Labs
www.steamsynth.com
------------
"I guess all the Forest Mims Radio Shack books I read finally paid off!"
"I ordered twice as many _______ as I thought I'd need, only to find out that I'm still less than half way to having enough."
"...this whole thing was started by a dream and a mouse." - Walt Disney
"Flatulence sounds aren't just for brass and reed instruments anymore, thanks in large part to Dr Moog." - Ockeghem

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Post by Christopher Winkels » Sun Nov 21, 2010 4:46 pm

dslocum wrote: So just bewteen you and me, it's a design _feature_, OK? :roll:
Works for me. :nana:

FYI to anyone interested, one great feature about the 1310 is the ability to do those great "three-on-four" echoes (the LFO is cranking out triplets while the 1310 is banging out fours) when combined with 7thDan's "fake delay" trick.

For more on what I'm talking about: viewtopic.php?t=24617&highlight=vanilla

The best part is that because one is a real delay and the other pseudo-delay they have different sounds that can't be achieved simply by feeding one delay into another. Good stuff.

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Re: THE ULTIMATE FIX!!!!!

Post by bwhittington » Sun Nov 21, 2010 7:38 pm

dslocum wrote:Long story short, with no input it's DEAD quiet even at the longest delays. No more squealing. Woo Hoo!!!
Doug is this fix about the clock noise on the delay pot or the squealing on the recirc pot? Or both?

I'd love to clean up the top end of the delay pot, but I'd really like the feedbacky squeal to stay. Would the first mod be more my thing? Or should I stick with the charmingly muddled original version? It looks like I'll be trading for a used 1310, so maybe I'll fix one and keep one as is. :)

Cheers,
Brian

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Re: THE ULTIMATE FIX!!!!!

Post by dslocum » Mon Nov 22, 2010 8:26 am

bwhittington wrote:
dslocum wrote:Long story short, with no input it's DEAD quiet even at the longest delays. No more squealing. Woo Hoo!!!
Doug is this fix about the clock noise on the delay pot or the squealing on the recirc pot? Or both?

I'd love to clean up the top end of the delay pot, but I'd really like the feedbacky squeal to stay. Would the first mod be more my thing? Or should I stick with the charmingly muddled original version? It looks like I'll be trading for a used 1310, so maybe I'll fix one and keep one as is. :)

Cheers,
Brian
Brian,

I'm mostly referring to the Delay pot. Some modules have the problem, others don’t. If you disconnect inputs and are experiencing a fairly loud whistle at the longest delays, then you might consider swapping it. If it’s pretty quiet and you’re enjoying the module as is, then I don’t think you’ll need to worry about it.

Note: there will always be some aliasing & artifacting at the longest delays, most pronounced with high frequency content inputs. Heterodyning.

RE: the feedback pot, I'm not sure what you mean by squealing. It should still feedback the same. Nothing changed there.

We're happy to work with you to make things right - your call.
Doug Slocum
Synthetic Sound Labs
www.steamsynth.com
------------
"I guess all the Forest Mims Radio Shack books I read finally paid off!"
"I ordered twice as many _______ as I thought I'd need, only to find out that I'm still less than half way to having enough."
"...this whole thing was started by a dream and a mouse." - Walt Disney
"Flatulence sounds aren't just for brass and reed instruments anymore, thanks in large part to Dr Moog." - Ockeghem

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Re: THE ULTIMATE FIX!!!!!

Post by VinceL » Tue Nov 23, 2010 7:20 pm

dslocum wrote: I'm mostly referring to the Delay pot. Some modules have the problem, others don’t. If you disconnect inputs and are experiencing a fairly loud whistle at the longest delays, then you might consider swapping it.
As Doug says, not all 1310's have the problem. I was figuring that I would need to send mine back to have the caps replaced. But, mine is fine. I can crank the Delay all the way to 10 with no input connected, and it is VERY quiet.

So, don't just assume that you need the mod to your 1310.

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Post by klstay » Tue Dec 21, 2010 12:27 pm

Got mine back last night from the modification and quickly mounted it and threw together something quick.

I gotta say I am very happy with the mod and how clean the longer times are now. I am also really enjoying the range of the CV input.

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Post by dslocum » Tue Dec 21, 2010 1:00 pm

Thanks Kevin.

Anyone else who wants to send their unit back, please don't hesitate to contact us. We'll make things right and pay shipping, even if you're out of the USA.

We love making synth modules, and we want to treat our customers as we would like to be treated.
Doug Slocum
Synthetic Sound Labs
www.steamsynth.com
------------
"I guess all the Forest Mims Radio Shack books I read finally paid off!"
"I ordered twice as many _______ as I thought I'd need, only to find out that I'm still less than half way to having enough."
"...this whole thing was started by a dream and a mouse." - Walt Disney
"Flatulence sounds aren't just for brass and reed instruments anymore, thanks in large part to Dr Moog." - Ockeghem

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