Thanks! I have followed up on your site as requested.Modulart_JP wrote:You can contact me privately via my website.
I'm sure we'll figure out what's wrong.
a legend is back...System-700 in eurorack
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- wendallsan
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- Modulart_JP
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Hi, I'm building the oscillator which asks for a 453K resistor. Using standard values, I am able to make 454K by either 24K + 430K in series, or 470K + 13MΩ in parallel. Is 454K adequate for this, or should I try to source the exact resistor?
Also... Does anyone know a good source for the subminiature SPDT switches (as used on the VCO) at a reasonable price in the UK?
Also... Does anyone know a good source for the subminiature SPDT switches (as used on the VCO) at a reasonable price in the UK?
- Modulart_JP
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454K will do.
As for the SPDT switches, Farnell carry them:
https://export.farnell.com/multicomp/2m ... t%2Fsearch
Don't know if it's what you consider a good price though.
As for the SPDT switches, Farnell carry them:
https://export.farnell.com/multicomp/2m ... t%2Fsearch
Don't know if it's what you consider a good price though.
Thanks for this... I managed to find some from a company in Taiwan, just a case of waiting on shipping...Modulart_JP wrote:454K will do.
As for the SPDT switches, Farnell carry them:
https://export.farnell.com/multicomp/2m ... t%2Fsearch
Don't know if it's what you consider a good price though.
My next question is that 250pf capacitor... I have searched all over and cannot for the life of me find any, except those high voltage (>1KV) things used in power supplies, would these be ok, or should I use a 1000pf & 330pf in series to get 248.1pf? That's the closest I can get with standard values.
- Modulart_JP
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Thanks, I hadn't noticed the link initially.Modulart_JP wrote:Please refer to the Mouser cart.
The next problem is the LM301, Unfortunately I've now run out of my limited stock. I don't see them in the mouser cart (I have also tried Farnell, RS as well as smaller companies like Bitsbox). I can only seem to find them on ebay or aliexpress, so I'm doubtful of the authenticity. Have these been discontinued? Is anyone managing to get these in the UK?
- wendallsan
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I'm doing a build of several of these modules as well and have also had a bit of a challenge sourcing LM301's. I bought a bunch from China, and they all turned out bad, so apparently trying to score a deal on eBay is not the thing to do. I bought some OP07CPZ chips from Mouser in the US and these seem to have worked fine as drop-in replacements for LM301's in the modules I've tried them out in (including the mixer, the amp/E.F./integrator, S&H, and noise/ring mod modules). When my LM301's from China were causing problems, folks were telling me to replace them with 'pretty much any op amp' that had the same pinout, so it seems like the LM301 is not all the critical? If this is the case, I'd love to hear what acceptable subs could be used for folks having problems sourcing the LM301's. Also, the 3080's are a pain to find and are expensive to boot, which leaves me wondering if there are any acceptable replacements for those as well. I don't know enough electronics to know one opamp from another, other than looking at pinouts and curves in the graphs on the spec sheets for the IC's.LektroiD wrote:The next problem is the LM301, Unfortunately I've now run out of my limited stock. I don't see them in the mouser cart (I have also tried Farnell, RS as well as smaller companies like Bitsbox). I can only seem to find them on ebay or aliexpress, so I'm doubtful of the authenticity. Have these been discontinued? Is anyone managing to get these in the UK?
Here's a link to the OP07CPZ chips if anyone needs them:
https://www.mouser.com/ProductDetail/584-OP07CPZ
Currently building a whole mess of modules by Nonlinear Circuits. Troubleshooting a Nonlinear Circuits Sauce of Unce.
In a brief test I did a while back LM13700 worked fine in the 24db VCF, although I had to do some convoluted wiring up to check 'cos the pinout is very different.
Not a UK/EU supplier but Tayda say they have loads of LM301. I've bought some from them in the past, I don't remember having any trouble (not much of an endorsement, I agree)
The impression I get is that the LM301 is fairly rubbish so I don't think there's any need to buy anything fancy.
Not a UK/EU supplier but Tayda say they have loads of LM301. I've bought some from them in the past, I don't remember having any trouble (not much of an endorsement, I agree)
The impression I get is that the LM301 is fairly rubbish so I don't think there's any need to buy anything fancy.
- Modulart_JP
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You can buy them from me.The next problem is the LM301, Unfortunately I've now run out of my limited stock. I don't see them in the mouser cart (I have also tried Farnell, RS as well as smaller companies like Bitsbox). I can only seem to find them on ebay or aliexpress, so I'm doubtful of the authenticity. Have these been discontinued? Is anyone managing to get these in the UK?
They are available for sale in my shop.
Jameco has them too at a slightly better price.
- Modulart_JP
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It was spotted in this sale: http://www.rlmusic.co.uk/rlm3/roland-system-700/
It seems the original 708A had the 4-way switches hardwired to the various oscillators in the synth. Looks like someone had the creative idea to add sockets in place of the hardwiring. It's an interesting configuration having the switchable inputs if you're playing a live sequence and you want to route another source into the RM without repatching. I guess that's another feature that made the System 700 so unique.

It seems the original 708A had the 4-way switches hardwired to the various oscillators in the synth. Looks like someone had the creative idea to add sockets in place of the hardwiring. It's an interesting configuration having the switchable inputs if you're playing a live sequence and you want to route another source into the RM without repatching. I guess that's another feature that made the System 700 so unique.

- wendallsan
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This looks like fun. I immediately find myself thinking about this plus CV controlled switches for those inputs. I guess we could throw that together with a 708 and a couple 723's?LektroiD wrote:It's an interesting configuration having the switchable inputs if you're playing a live sequence and you want to route another source into the RM without repatching.
Currently building a whole mess of modules by Nonlinear Circuits. Troubleshooting a Nonlinear Circuits Sauce of Unce.
I was initially thinking of modding the 708, rather than filling the cabinet with switch modules. The only issue is the PCB covering the blank area of the panel, so no room for a switch. I'm now thinking of maybe a 2HP breakout panel and a couple of 4 way slide switches.wendallsan wrote:This looks like fun. I immediately find myself thinking about this plus CV controlled switches for those inputs. I guess we could throw that together with a 708 and a couple 723's?LektroiD wrote:It's an interesting configuration having the switchable inputs if you're playing a live sequence and you want to route another source into the RM without repatching.
- Modulart_JP
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Calibrating the 703F VCF... I see no change on any of the poles when I test at the points indicated. I have my scope set to 50mV and all pots fully CCW. I am grounding the scope from the socket ground. Each pole is giving zero reading on the scope but rotating the trimmers from 0-100k has absolutely no effect on the scope reading.
The filter appears to work as expected with an audio input, but I would like to calibrate the individual poles properly.
The filter appears to work as expected with an audio input, but I would like to calibrate the individual poles properly.
- Modulart_JP
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- Modulart_JP
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Set your scope to 5mV.I have my scope set to 50mV and all pots fully CCW.
Frankly speaking, it does not make a difference and I kept those trimmers for each pole to be thorough, stay true to the original schematics.
The truth is that many filters in other Roland synths have a similar filter and they did omit those trimmers.
I think they realized it was not worth it.
If you can do it, fine.
If not, don't bother...

50mV was already too noisy to see a decent signal. I had better luck with a multimeter set to mV, but even then the voltage was reading in the + at the lowest setting of each pole. It already sounds really nice, so if it's not vital, I'll leave it as is.Modulart_JP wrote:Set your scope to 5mV.I have my scope set to 50mV and all pots fully CCW.
Frankly speaking, it does not make a difference and I kept those trimmers for each pole to be thorough, stay true to the original schematics.
The truth is that many filters in other Roland synths have a similar filter and they did omit those trimmers.
I think they realized it was not worth it.
If you can do it, fine.
If not, don't bother...
I was looking at the manual and reading through the various modules, the Frequency to Voltage feature on the 714 looks interesting. Is this something that's likely to be looked at?
Also there is a two-channel phaser (720B) with a lot of really nice features, is this likely to be cloned in the near future?
Hi, I'm having a bit of difficulty with the 702 oscillator (so far I have built only one as I'm awaiting LM301s to arrive).
Firstly, the pitch is about an octave and a half too low, and I cannot calibrate it any higher, even when I set the range to 4 instead of 8, I still cannot get it to reach 440Hz. The scaling and range is perfect otherwise.
I am also experiencing something strange with the sync. When I run in a waveform, it sounds more like an atari punk console than a sync. I have attached an audio demonstration. Firstly set to W, then to S, then back to W with a different source frequency. I sweep through the pitch from 0-10 and back to 0 on each of the three examples.
Firstly, the pitch is about an octave and a half too low, and I cannot calibrate it any higher, even when I set the range to 4 instead of 8, I still cannot get it to reach 440Hz. The scaling and range is perfect otherwise.
I am also experiencing something strange with the sync. When I run in a waveform, it sounds more like an atari punk console than a sync. I have attached an audio demonstration. Firstly set to W, then to S, then back to W with a different source frequency. I sweep through the pitch from 0-10 and back to 0 on each of the three examples.
You do not have the required permissions to view the files attached to this post.
- Modulart_JP
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Great on paper, not so great in real life...I was looking at the manual and reading through the various modules, the Frequency to Voltage feature on the 714 looks interesting. Is this something that's likely to be looked at?
Nothing you can't do with 2x 711's.Also there is a two-channel phaser (720B) with a lot of really nice features, is this likely to be cloned in the near future?
Because this is what the 720 basically is...
To be exact, the 720 is 2x 711's with the addition of a frequency shift pot for each phaser.
Have a look at the schematics and you'll see that's something you can easily add to the 711.
You could make a break-out 4HP module you put between 2x 711's.
So far, what did you do to troubleshoot it ?Firstly, the pitch is about an octave and a half too low, and I cannot calibrate it any higher, even when I set the range to 4 instead of 8, I still cannot get it to reach 440Hz. The scaling and range is perfect otherwise.
What your scope shows you ?I am also experiencing something strange with the sync. When I run in a waveform, it sounds more like an atari punk console than a sync. I have attached an audio demonstration. Firstly set to W, then to S, then back to W with a different source frequency. I sweep through the pitch from 0-10 and back to 0 on each of the three examples.
The very last (and final) additions to the SYS-700 series are:
- 715 Multimode Filters (available by the end of this week)
- 717 Pulse Shaper (from the 717 Analog Sequencer), available as pre-order
- 717 Analog Sequencer: HUGE project, available as pre-order
Soon I will create a thread for that guy alone.

Nothing, other than checking over component values.Modulart_JP wrote: So far, what did you do to troubleshoot it ?
Which waveform is best to use to check frequency? It doesn't say which waveform output to use in the calibration procedure.
Also, what are the test points for, I have added test point terminals, but these are not mentioned in the calibration.
I'm at college through the week so I don't have access to my workshop, what in particular should i be looking for on a scope reading, and what scope settings?Modulart_JP wrote:What your scope shows you ?I am also experiencing something strange with the sync. When I run in a waveform, it sounds more like an atari punk console than a sync. I have attached an audio demonstration. Firstly set to W, then to S, then back to W with a different source frequency. I sweep through the pitch from 0-10 and back to 0 on each of the three examples.
So no 721 (2ch. Audio Delay)? If it's anything like the System 100m, the system 700 audio delay should be a really nice analogue stereo chorus.Modulart_JP wrote:The very last (and final) additions to the SYS-700 series are...
Last edited by LektroiD on Thu Sep 26, 2019 10:53 pm, edited 1 time in total.
- wendallsan
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Oh yeah, so you ARE gonna release a sequencer!Modulart_JP wrote:The very last (and final) additions to the SYS-700 series are:
- 715 Multimode Filters (available by the end of this week)
- 717 Pulse Shaper (from the 717 Analog Sequencer), available as pre-order
- 717 Analog Sequencer: HUGE project, available as pre-order
Soon I will create a thread for that guy alone.

I guess my pharmasonic builds are not done yet!

Will it be 12 steps like the original or something more 'typical'?

Can't wait to see what this will look like.

Currently building a whole mess of modules by Nonlinear Circuits. Troubleshooting a Nonlinear Circuits Sauce of Unce.