Stereo delay / Vibrato

papaver · Posted: Fri Nov 16, 2012 1:29 pm Post subject: Stereo delay / Vibrato

HI!

Here working on a Pseudo stereo (1 in 2 outs) delay with modulation, an LFO. The Jellyfish.

It's capable of single delay lines, stereo lines, stereo expanding (just one repetition and very short but different delay times per channel), vibrato and stereo vibrato, something like reverb, and lots of weird noises.

The LFO is modulating the delay time and has triangle and square waves.

Theres is a fine control (time) for adjsuting the effect qhen doing some stereo xpanging.

Individual Dry and Wet controls for using only the effect when requiered (vibratos)

A switch for combine the two channels in a single output (parallel).

And that's it. I will do very easy to mount PCB's with directly to PCB pots. The photo is the first prototype. Still need the clear some errors.

I'm thinking to put a send/return into the delay for experimenting with other effects inside the fx. Just imagine some effects repeated with the feedback. Also thinking to put a CV in for control the delay time. Any thoughts?

Here a photo of the prototype and some demos. Just finished today!!!

http://snd.sc/ZZoetd

The controls are (in order): LFO Rate, Depth, Time, Fine, Feedback, Wet, Dry.

Any suggestions / comments?

I will do a batch of 50 PCB when finnished.

Still working on the centipede sequencer!

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papaver · Posted: Wed Nov 21, 2012 4:32 am Post subject:

Hi,

here is the schem. A bit of explanation:

The delays are based on the PT2399 chips. The circuit is very close to the one that appears in the datasheet. Diferences are some filtering changes, the independent dry and wet controls, and the switch (SW2 & SW4) that changes the feedback resistor. This switch select between infinite and non-infinite repeats and works different than the feedback pot.

LFO's are simple 40106 circuits with the add off NPN and a resistor that transforms the square wave to triangle wave. A switch (SW1 & SW3) is provided for select between the 2 wave types getting a wide variety of results. The modulation of the delay is thru a transistor working as a resistor. In this case I have take the same formula as one delay that is on the net (echobase) but the circuit is pretty simple. There are a lot of ways to do this. There is a website with many circuit examples for doing this.

The delay time is controlled by a 50k pot and a Fine 5k pot. This one is very usefull when adjusting the delays in stereo mode providing cool effects.

With Switch 6 is possible to send the second delay to output 2 or mix it with the first delay to the output 1. With this is possible to use the effect in mono and parallel.

Switch 5 active the effect on and off. In "off" mode a buffer sends the input signal directly to outs 1 and 2 without impedance issues.

And thats it! Smile

Maybe I will add a CV in and a send & return pair in the feedback. The S&R will be very simple as it will not have buffers but I thin that it can work with short wires.

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Uncle Krunkus · Posted: Wed Nov 21, 2012 5:13 am Post subject:

That looks like a really cool project papaver.
I've been wanting to do a similar thing with the MN series of BBDs for a long time, but haven't found a circuit I like yet. Crying or Very sad

One thing I would definitely recommend, is a swap over switch (DPDT) on the feedback lines straight off the wiper of the pot. So you can literally send one delay to the other one's feedback input, and vice versa, and back again. At slower delays, this sounds really nice.

papaver · Posted: Wed Nov 21, 2012 5:26 am Post subject:

Yep, with BBDs it will be better, but more difficult to design it!

Tomorrow I will try that switch. It seems like a very good idea. Thxs!

I think that the best point on this effect is the stereo vibrato on synth pads and guitars. It sounds superb. Boards of Canada sound with low cost equipment! Very Happy

analog_backlash · Posted: Wed Nov 28, 2012 5:27 pm Post subject:

Your demo sounds really good to me papaver.

I have to ask you, where did you get your PT2399s from? I've really wanted to play with these, but no one seems to sell them (in the UK). I've seen loads on eBay (mostly from the far-east), but I'm never that sure how trustworthy these sources are. It would be nice to hear a recommendation on his.

Gary

papaver · Posted: Thu Nov 29, 2012 1:19 am Post subject:

Hi!
Thanks. You can get the 2399 from many stores. Try this two ones:

http://www.musikding.de/advanced_search_result.php?XTCsid=a7aff851bd25d6e968958ff7757bf0d5&keywords=pt2399&x=0&y=0

http://www.taydaelectronics.com/catalogsearch/result/?q=pt2399

First is from Germany and the second from Thailand. Both are fine. The second one is cheaper and have a better service but it's vey far, so that's your choice.

Good luck!

analog_backlash · Posted: Thu Nov 29, 2012 5:29 pm Post subject:

Sorry, I forgot to thank you for replying. I've added those to my favourites for future reference. I think I might try the cheaper source first!

Gary

rumblin_cynth_rampo · Posted: Fri Nov 30, 2012 6:38 am Post subject:

In the UK you can also get PT2399 from Doctor Tweek's website

http://tinyurl.com/dyduo39

papaver · Posted: Tue Dec 04, 2012 6:10 am Post subject:

Have a problem here.

I'm finishing next the next PCB with the crossdelay (from UNcle Krunkus) the send and return jack and all the switches soldered directly to the board.

The problem is that the on/off switch is doing a pop sound when switched. I have put a 1M resistor to the output cap but the sound is there anyway. Maybe the leakage of the cap?

Any sugestions here?

papaver · Posted: Thu Dec 20, 2012 4:36 am Post subject:

Solved!

I have finished the next prototype and it works fine. No clicks or noises when switching.

The crossdelay function is really nice and open a world (thanks to Uncle Krunkus).

Added leds to the on/off switch and to the LFOs.

Waiting for the stereo jack connectors with switch for test the send and return feature.

Then I will restructure a little bit the position of the items, improve the filter section, make a final protoype and thats it!

News soon... Very Happy

papaver · Posted: Thu Dec 20, 2012 4:39 am Post subject:

A phone photo....

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papaver · Posted: Fri Feb 08, 2013 5:08 am Post subject:

Final design finished. Need o make the last prototype.

Next week will report.

Cool

Paradigm X · Posted: Fri Feb 08, 2013 7:23 am Post subject:

This looks like a cool project!

I have about 8 PTchips lying around too.

I just love Delays, especially grungy crap ones!

Will the final PCBs be professional ones? And what size is it, i.e. pot spacing etc.

Looks brilliant, put me down for 2 pcbs provisionally!

Many thanks, Ben

papaver · Posted: Mon Feb 11, 2013 4:30 am Post subject:

Hi,

thanks Ben.

Yes, the final PCB will be professional ones.

The Jellyfish fits well on a Hammond 1590 DD. I'm designing a case too. Anyway I will pñost the drilling template for ones that wanna do the case themselves.

So in the final design:

- I have added more filtering, lowering the cut frequency on the existing ones and adding two more filters per channel.

- The crossdelay function is implemented. You can see with Switch 7 (2 pole). When activated the feedback signal of delay one is sent to delay 2 and viceversa. This causes a nice effect similar to having to delays in series but a little more usefull as you can avoid part of the filters when the signal is going from one channel to the other.

- Finally I have not added the send and return section as it needs to be buffered and there is no more room in the PCB if I want to keep the things easy for the begginer DIYers (all the pots and switches are in the exact place and there is no need to run wires for this items).

- I have changed the modulation section. The old one was the same that there is in th Echobase delay. But this one have a problem that's when you turn up the depth knob you're increasing the resistance of the delay section, so you are increasing the delay time even if there is signal incoming. So if you have determined an usefull delay time and then you turn up the deph knob to create some modulation you are loosing the usefull time.

Instead of the PNP mod I have used a P-channel Jfet. This is very usefull and easy to implement. With the Jfet the resistance in the drain increases as the voltage on the gate increases too. The voltage on the gate have to be more positive than the voltage of the source. So as the source is grounded the input signal can not be below 0.

Using this method as you turn up the depth knob the delay time keeps in the same centered place.

- Added CV inputs. the CV input goes directly to the depth knob. It uses a switched jack so when a jack is plugged in the signal comming from the internal LFO is deactivated. It's important to keep signals from 0 to 9V here. The depth knob acts as a voltage divider for the incomming signals.

And that's it!

I'm correcting all the number and value mistakes and designing the final PCB, si this will come very soon... Smile

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papaver · Posted: Mon Feb 11, 2013 4:40 am Post subject:

Working on this also...

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Paradigm X · Posted: Mon Feb 11, 2013 5:13 am Post subject:

Cool, love standlaone boxes

Nice one.

Cheers, ben

papaver · Posted: Sun Feb 17, 2013 10:18 am Post subject:

Playing with some designs. Thoughts?

I have had no rights of the last jelyfish draw. this one has been specially drawn for the machine Wink

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Paradigm X · Posted: Sun Feb 17, 2013 1:48 pm Post subject:

Wow.

I missed the audio demos the first time, this sounds amazing. really cool circuit man. Cool

Im definitely going to have to grab a few of these..

cheers, Ben

papaver · Posted: Thu Feb 21, 2013 3:15 am Post subject:

Finall prototype.

This is woring very well. I'm happy with this!

demos soon!

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analog_backlash · Posted: Thu Feb 21, 2013 5:08 am Post subject:

Hi Papaver,

I really like this design and I have to build one some time. I finally got a load of PT2399s from Tayda, as you suggested. I'll probably try breadboarding a simpler design at first (e.g. the Deep Blue Delay), as a quick test to check the ICs (although I'm pretty sure that they're OK).

One question. You have used a 7805 in your circuit. Do you know if this is necessary, as I've seen 78L05s in other designs. I looked at the datasheet, but I couldn't find a typical power consumption value on it. It doesn't really matter, as I have both regulators anyway.

Thanks again for alerting me to Tayda - I bought quite a lot of other things there too. Very Happy

Gary

papaver · Posted: Thu Feb 21, 2013 11:42 am Post subject:

Hi Gary!

I'm using a 78l05, there is a mistake in the schematic. Rolling Eyes

I have mounted the PCB into a blank drilled cases and I have found some mechanichal problems. First, the switches are to high and there is no room for the alpha pots to appear outside. The second, again the switches puts the PCB to close to the bottom of the case and there is very little room for the jacks.

I need to find some super mini switches to replace the existing ones or find another solution.

So I think that this will take longer. Evil or Very Mad

Paradigm X · Posted: Thu Feb 21, 2013 12:10 pm Post subject:

Hi

If you look at hex inverters symple seq he uses what looks like the same pcb mount pots with some switches. Might be worth looking at that. I'm on my phone at the moment, ill have a look later.

I'd be happy to send you a few to try if you like?

Cheers ben

Paradigm X · Posted: Thu Feb 21, 2013 2:46 pm Post subject:

also, what are the dimensions of the pcb? im a big fan of the pactec pt10 (x0xb0x) cases, sloping too. Lots of room inside, and its mucheasier to twiddle a sloping box. they also do a smaller pt8.

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the small switches Hex inverter uses are;

papaver · Posted: Thu Feb 21, 2013 3:56 pm Post subject:

Thanks!

I think that mountain switches are a good choice. a bit expensive but good quality. I have to check if there are avaliable in DPDT and 3PDT and go for them in Mouser.

I'm not sure about the pactec cases, I want to keep a compact format and metal cases. But I have to look at the dimensions of the PT8, maybe it feets perfectly, I don't know.

anyway tomorrow will be a nice day to keep working on thiS!

analog_backlash · Posted: Thu Feb 21, 2013 4:58 pm Post subject: