ARP 1601 clone Build Thread

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finnurbjarna
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Post by finnurbjarna » Sun Jul 26, 2015 3:32 am

Sorry if I've missed this somewhere, but is everyone just using the schematic to match the resistor values to the silk screen?

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Kipling
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Post by Kipling » Sun Jul 26, 2015 4:03 am

finnurbjarna wrote:Sorry if I've missed this somewhere, but is everyone just using the schematic to match the resistor values to the silk screen?
Hi Finnur

Use the PDF file at the bottom of the first post (ARP 1601 Sequencer - PCB Rev 1 (round 1).pdf) - that has all the values as attributes for each component if you hover over them.

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Post by sduck » Sun Jul 26, 2015 9:16 am

I just used the parts list - sorted it by the part value, then just work your way down.

That hover over to display value thing doesn't work on my mac, and seems like an awfully convoluted way to find out where to put your 68K resistors (or whatever) anyway.
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finnurbjarna
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Post by finnurbjarna » Sun Jul 26, 2015 9:20 am

Thanks, John.

clicking accomplished what hovering couldn't.

I've put together a draft for a resistor key, attached, in case anyone else finds that useful.

There are a couple of discrepancies between the quantities in the Mouser BOM and the number I could find on the silk screen; I could only find 11x47K slots, 18x1M slots and no 649R slot.

All numbers, 1-241, were accounted for except for 124-128, which I failed to find.

Please feel free to correct/edit and re-post as you see fit. If I find any mistakes in it I will try and fix them straight away.

[EDIT] Already found a couple of errors, now corrected.
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Last edited by finnurbjarna on Mon Jul 27, 2015 6:01 am, edited 2 times in total.

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Kipling
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Post by Kipling » Sun Jul 26, 2015 11:17 am

There are some gaps in the component numbering. I kept to the original ARP numbering, which has several gaps, apart from the extra resistors for the LED droppers and the substitute for the Z20 resistor pack.

There are one or two amendments to the LED resistors. I'll post an amended pdf later.

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Post by finnurbjarna » Mon Jul 27, 2015 4:33 am

sduck wrote:I just used the parts list - sorted it by the part value, then just work your way down.
I see what you mean now. I hadn't actually discovered the different tabs of the parts list and thought the 'hover' technique or the diagram were the only way to see the values. :doh:

The list I've made is therefore pretty redundant but I have now checked it against the parts list and it all tallies. I can leave it up or remove it if it's just a distraction. :oops:

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Post by sduck » Mon Jul 27, 2015 11:30 am

I'm sure it'll be handy for somebody!
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Post by Suf-fuD » Mon Jul 27, 2015 11:33 am

sduck wrote:I'm sure it'll be handy for somebody!
I would definitely take the boat if available.

edit. Sorry wrong thread

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Post by finnurbjarna » Thu Jul 30, 2015 2:27 pm

I got my Mouser delivery and have slowly starting building. There's one bit of confusion: C30&C31 are listed as 5nF but the part that arrived is 4.7nF (Mouser 80-R82EC1470DQ50J).

:hmm:

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Kipling
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Post by Kipling » Thu Jul 30, 2015 2:37 pm

Capacitors generally have a fairly wide tolerance so 5 & 4.7 are pretty much the same. They typically only come in the equivent of E12 or even E6 resistor values and 5 isn't one of them.

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Post by gslug » Sun Aug 02, 2015 6:10 pm

It still needs the wooden ends and some paint, but my DIY boat turned out reasonably well.
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Post by Kipling » Mon Aug 03, 2015 6:49 am

Looking good - are you going to paint/powder coat it?

Finally got around to making some teak end cheeks for mine yesterday, only need to oil them now and it's finished.

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Post by gslug » Mon Aug 03, 2015 7:25 pm

I haven't decided yet. I'd prefer powder coating, if I can find somewhere willing to do it for a reasonable price.
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Post by finnurbjarna » Wed Aug 05, 2015 5:13 pm

Finished my build! Everything seems to be working very well...I implemented the recommended mod and there is no bounce issue with the start button.

Saving the calibration for a rainy day, since it all seems fine, and turning my attention to making some sort of wooden case...

Can I just say, this is a WONDERFUL sequencer and a brilliant project. Thanks so much for making it happen!

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Post by Broadwave » Thu Aug 06, 2015 12:40 pm

I was just installing the resistors when I noticed something a bit odd... It may not be anything, but it concerns R211 & R210 in the Quantizer A/B section.

R210 is 10k and R211 is 100k - I would have assumed that both quantizer circuits would have been identical.

I took a look at the original ARP schematics and they are indeed 10k & 100k respectively - But I've come across several similar situations with ARP schematics in the past.

I'd just like to know if anyone has noticed problems when calibrating the quantizers, and if this could be the reason?

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Post by Kipling » Thu Aug 06, 2015 2:57 pm

Yes I noticed that early on, and looked to the ARP PCB layout for confirmation, but that didn't help. In fact that made it worse as they've mixed up R204 and R211 on the PCB, but both are 100k so it didn't matter that much. So given that my guess is that R210 should be 100k too, but it works OK whether it's 10k or 100k and makes no difference to the calbration.

I was hoping to get a hi-res shot of a genuine 1601 board to see the colour codes, and also to solve the 1k/2.5k riddle for R217 & R218, but alas never got anywhere with that.

BTW R217/218 should be 1k in my opinion and are llisted as 1k in th the BOM - if you do use 2.5k you end up with the adjustment right up one end, i.e. with a resistance of less than 1k.
Last edited by Kipling on Mon Aug 10, 2015 1:16 am, edited 1 time in total.

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Post by finnurbjarna » Sun Aug 09, 2015 2:04 pm

I've had a bit more time to play around with the sequencer now, and what a brilliant thing it is. I'm using it with a Eurorack modular (I know...sorry, no TTSH!) and will try an post a video at some point.

Like I posted earlier, I've not had any issues with the Start-Stop button (I guess the mod works perfectly) but I am finding the Skip button a little bit temperamental, double-skipping as often as once every ten pushes. Any ideas?

I'm also sorry to say that the beautiful legend on the panel seems to be very easily damaged, even just by patch cables knocking against it, so some of the lettering on my unit has already started to disappear. Any tips for preserving it? Hairspray? Nail varnish? :despair:

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Post by satindas » Sun Aug 09, 2015 3:15 pm

finnurbjarna wrote:I'm also sorry to say that the beautiful legend on the panel seems to be very easily damaged, even just by patch cables knocking against it, so some of the lettering on my unit has already started to disappear. Any tips for preserving it? Hairspray? Nail varnish? :despair:
For printed panel protection I've been experimenting with frosted window film. It gives a great finish and its as tough as old boots. You can get it on ebay dead cheap :tu:
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Kipling
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Post by Kipling » Sun Aug 09, 2015 3:28 pm

finnurbjarna wrote:Like I posted earlier, I've not had any issues with the Start-Stop button (I guess the mod works perfectly) but I am finding the Skip button a little bit temperamental, double-skipping as often as once every ten pushes. Any ideas?
I'm not in a position to test it for at least a week, but try a 1nF cap across the skip button terminals similar to the start/stop mod and see if that makes a difference. I'll have a play when I get back in a week.

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Post by Altitude909 » Sun Aug 09, 2015 4:54 pm

Can someone explain the R226/R222 calibration to me? I followed the manual but I get 0v on both outputs and nothing changes when I adjust the pots

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Post by elmegil » Sun Aug 09, 2015 10:00 pm

finnurbjarna wrote:I'm also sorry to say that the beautiful legend on the panel seems to be very easily damaged, even just by patch cables knocking against it, so some of the lettering on my unit has already started to disappear. Any tips for preserving it? Hairspray? Nail varnish? :despair:
I will have to check my panel for this sort of thing, as I haven't built yet, but I typically protect hand-made panels with a coat of clear matte spray paint. I expect from your description that I may do that with this one as well.

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Post by duff » Mon Aug 10, 2015 12:01 am

Altitude909 wrote:Can someone explain the R226/R222 calibration to me? I followed the manual but I get 0v on both outputs and nothing changes when I adjust the pots
If you patch from the quantized outs do you hear quantizing happening as you slide the pitch sliders up and down?

If not then what is happening on the I quantized outs?

If you do then I would guess you aren't following the instructions quite right. The goal of them being to get the sequencer to 'hang' on step 1 so you are reading the quantized pitch cv with the slider 2 octaves up.
To check the obvious, when you are reading the voltage:
Is the step 1 led lit?
Is the step 1 slider fully up?
If you adjust the step 1 slider does the voltage at the quantized out change?
You could set it to run and reset on step 2 which should also result in step 1 cv staying on the output as require to calibrate. If you try this do you get the expected values?

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Post by Altitude909 » Mon Aug 10, 2015 6:19 am

duff wrote:
Altitude909 wrote:Can someone explain the R226/R222 calibration to me? I followed the manual but I get 0v on both outputs and nothing changes when I adjust the pots
If you patch from the quantized outs do you hear quantizing happening as you slide the pitch sliders up and down?

If not then what is happening on the I quantized outs?

If you do then I would guess you aren't following the instructions quite right. The goal of them being to get the sequencer to 'hang' on step 1 so you are reading the quantized pitch cv with the slider 2 octaves up.
To check the obvious, when you are reading the voltage:
Is the step 1 led lit?
Is the step 1 slider fully up?
If you adjust the step 1 slider does the voltage at the quantized out change?
You could set it to run and reset on step 2 which should also result in step 1 cv staying on the output as require to calibrate. If you try this do you get the expected values?
I get nothing out of quanitized outs regardless of what I do. Looks like I have some debugging to do

*edit.

For the record, there is an LM301 in the bom, looks a lot like an opamp :P

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Post by finnurbjarna » Mon Aug 10, 2015 10:40 am

elmegil wrote:I will have to check my panel for this sort of thing, as I haven't built yet, but I typically protect hand-made panels with a coat of clear matte spray paint. I expect from your description that I may do that with this one as well.
That sounds like a very good idea - I will give that a try.

@Satindas Thanks you also for your solution - I just worry that I would never be able to neatly cut out slits for the sliders :hihi:

I will also stick a 1n cap on the Step switch and report back.

There was one other thing I forgot to mention; when Reset is pressed, the pitch from the first slider is not re-triggered. Is that a design feature?

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Post by Kipling » Tue Aug 11, 2015 2:33 am

Altitude909 wrote: *edit.

For the record, there is an LM301 in the bom, looks a lot like an opamp :P
The quantiser output stages use the LM1458 dual Opamps. The LM301 is in the comparator.

The Opamps are some of the few components that use the -15V power rail so check you have the correct voltages on both rails.

Also check that you have used the correct switching sockets and that for the few critical ones that use the switch contacts, they are passing the signals through to the quantisers when no plugs are inserted. To test this patch the A Seq out to the A quantiser in and similar for the B channel and check for output on the quantisers again.

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