SSF Stereo Dipole filter

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MossGarden
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Re: SSF Stereo Dipole filter

Post by MossGarden » Thu May 28, 2020 9:41 am

rafyc wrote:
Thu May 28, 2020 8:14 am
NoLegs wrote:
Wed May 27, 2020 5:49 pm
Spread just shifts the frequency of the secondary peak of that channel of the filter in relation to the frequency of the primary peak of that channel. At 12 o'clock it will line up with the primary peak, if you move spread clockwise it will be at a higher frequency than the primary, and if you move it counter clockwise it will be at a lower frequency.
MossGarden wrote:
Wed May 27, 2020 5:57 pm
rafyc wrote:
Wed May 27, 2020 4:44 pm
Does SPREAD is the same fonction than RADIATE on Qpas or SPACING on moog mattriarch ?
Spread offsets the second filter on each side from your frequency setting. It differs from the qpas because you have full independent v/oct control of both filter cores per side with the two controls, they share a resonance. With qpas the radiate control pushes and pulls both filters at once with the main freq pot offsetting them. The SD will act more like four independent filters than qpas will allow. There are pros and cons to both, personally, I prefer the filter to be as openly mouldable as possible, I think SD wins that game. It ultimately means you can have two completely independent sides who can just ignore each other, or be combined in a stereo setup. Four independent filters in any paired combination of series/parallel routing, summed in mono or broken out in stereo. Super flexible and completely open to your interpretation/need at the time. It’s also fully resonant, so 4 voice OSC with all the FM inputs ever, slew limiting and lfo capabilities that qpas can’t do. Qpas is still an amazing filter though. Different but similar beasts.
Ok thanks !
Now i only have a low budget headphone so cant figure out well but i notice no stereo effect with spread on SD. Offset doest not move the panning on SD while on Qpas it's obvious.
Not sure i could acheive this by routing SD output on a external panning module.
You need to patch either the two Pole outputs for dual stereo filters or patch both dipole outputs for quad stereo filters. They need hard panning l+r for fully wide stereo imaging, of course you can narrow it to fit a mix. The spread controls will make changes in the L or R channel, not move across the whole stereo image

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Re: SSF Stereo Dipole filter

Post by NoLegs » Thu May 28, 2020 10:26 am

Also make sure you are running the both dipoles in parallel and not series if you are looking to hear a stereo effect by modulating spread.

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Re: SSF Stereo Dipole filter

Post by rafyc » Thu May 28, 2020 11:43 am

[/quote]
MossGarden wrote:
Wed May 27, 2020 5:57 pm

You need to patch either the two Pole outputs for dual stereo filters or patch both dipole outputs for quad stereo filters. They need hard panning l+r for fully wide stereo imaging, of course you can narrow it to fit a mix. The spread controls will make changes in the L or R channel, not move across the whole stereo image
Ok so i tried. Its hard panned.

Spread only works in Dipole mode.
I can hear a difference but it's quite the same goal as changing frequency knob.
It's not obvious for me but dont see an interest for that Spread fonction...

I'm a bit disappointed i returned Qpas and bought Dipole thinking spread fonction would have change stereo image.
I need a stereo filter for a mono synth who dont have a filter (Lyra8) and give more stereo imaging ...
Shop will kill me if i return again this one for the Qpas i just sent back. :bang:
Last edited by rafyc on Thu May 28, 2020 11:47 am, edited 3 times in total.

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Re: SSF Stereo Dipole filter

Post by rafyc » Thu May 28, 2020 11:44 am

NoLegs wrote:
Thu May 28, 2020 10:26 am
Also make sure you are running the both dipoles in parallel and not series if you are looking to hear a stereo effect by modulating spread.
For me with this setting it's only changing one or an other channel so not stereo (both)

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Re: SSF Stereo Dipole filter

Post by scragz » Thu May 28, 2020 12:42 pm

rafyc wrote:
Thu May 28, 2020 11:43 am
Ok so i tried. Its hard panned.

Spread only works in Dipole mode.
I can hear a difference but it's quite the same goal as changing frequency knob.
It's not obvious for me but dont see an interest for that Spread fonction...

I'm a bit disappointed i returned Qpas and bought Dipole thinking spread fonction would have change stereo image.
I need a stereo filter for a mono synth who dont have a filter (Lyra8) and give more stereo imaging ...
Shop will kill me if i return again this one for the Qpas i just sent back. :bang:
Spread isn't stereo spread, it's spread of the two poles on that single filter. It only works in dipole mode because that's....the filter with both poles enabled.

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Re: SSF Stereo Dipole filter

Post by scragz » Thu May 28, 2020 12:44 pm

Easiest way to get stereo effects is to put the FM LVL attenuverter left on one and right on the other, then send bipolar LFO into the ST-FM input.

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Re: SSF Stereo Dipole filter

Post by cptnal » Thu May 28, 2020 1:58 pm

scragz wrote:
Thu May 28, 2020 12:44 pm
Easiest way to get stereo effects is to put the FM LVL attenuverter left on one and right on the other, then send bipolar LFO into the ST-FM input.
I was about to call you out thinking the attenuators only affected their own channel's FM input, but I just tried it and you're damn right. Nice trick! :tu:

The Lyra-8 is eight voice polyphonic BTW, rafyc. Hence the name. I use my Stereo Dipole with the Lyra-8 a lot, for exactly the purpose you're talking about. Chill, stick with it and it'll reap rewards. :cloud:

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Re: SSF Stereo Dipole filter

Post by NoLegs » Thu May 28, 2020 2:29 pm

rafyc wrote:
Thu May 28, 2020 11:44 am
NoLegs wrote:
Thu May 28, 2020 10:26 am
Also make sure you are running the both dipoles in parallel and not series if you are looking to hear a stereo effect by modulating spread.
For me with this setting it's only changing one or an other channel so not stereo (both)
I think I understand now. You would need to modulate spread on both sides if you want both sides to spread to change at the same time. Spread does not mean stereo spread, it means spreading the poles on that specific channel.

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Re: SSF Stereo Dipole filter

Post by MossGarden » Sat May 30, 2020 11:45 am

Thought this needed to be here, SD just out of shot doing some very heavy lifting! Love it


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Re: SSF Stereo Dipole filter

Post by rafyc » Sun May 31, 2020 5:45 pm

scragz wrote:
Thu May 28, 2020 12:44 pm
Easiest way to get stereo effects is to put the FM LVL attenuverter left on one and right on the other, then send bipolar LFO into the ST-FM input.
In fact very nice ! I thought FM was frequency modulation for craziness and fizzy glassy effect.
Definitely not a module for beginners...
MossGarden wrote:
Sat May 30, 2020 11:45 am
Thought this needed to be here, SD just out of shot doing some very heavy lifting! Love it

Nice stereo effect ! I'm waiting Arbhar !!

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Re: SSF Stereo Dipole filter

Post by Gyroscope » Tue Jun 02, 2020 4:26 pm

Does anyone know if it's possible to just buy a black faceplate? I wrote to SSF and haven't heard back yet.

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Re: SSF Stereo Dipole filter

Post by DMR » Mon Jun 08, 2020 9:13 am

Are each of the 4 filter cores 6 dB, or 12 dB? IE if you run all four peaks serially in low-pass mode, does that generate a 24 dB or 48 dB response?

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Re: SSF Stereo Dipole filter

Post by MossGarden » Mon Jun 08, 2020 9:31 am

DMR wrote:
Mon Jun 08, 2020 9:13 am
Are each of the 4 filter cores 6 dB, or 12 dB? IE if you run all four peaks serially in low-pass mode, does that generate a 24 dB or 48 dB response?
They're 12db filters, so a single side in serial LPF mode will give you a 24db response

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Re: SSF Stereo Dipole filter

Post by DMR » Mon Jun 08, 2020 11:29 am

MossGarden wrote:
Mon Jun 08, 2020 9:31 am
DMR wrote:
Mon Jun 08, 2020 9:13 am
Are each of the 4 filter cores 6 dB, or 12 dB? IE if you run all four peaks serially in low-pass mode, does that generate a 24 dB or 48 dB response?
They're 12db filters, so a single side in serial LPF mode will give you a 24db response
Thanks!

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Re: SSF Stereo Dipole filter

Post by NoLegs » Mon Jun 08, 2020 1:38 pm

I believe you can then patch the dipole output of that side into the opposite side, put that side in serial as well and you will have a 48db response.

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Re: SSF Stereo Dipole filter

Post by MossGarden » Mon Jun 08, 2020 2:37 pm

NoLegs wrote:
Mon Jun 08, 2020 1:38 pm
I believe you can then patch the dipole output of that side into the opposite side, put that side in serial as well and you will have a 48db response.
yes you can absolutely do this

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Re: SSF Stereo Dipole filter

Post by sbergen » Sat Jun 13, 2020 7:12 am

I just got mine this week, and there's something strange going on with low resonance settings, unless I seriously attenuate my input signals. I couldn't find anything about expected signal levels in the manual, so I'm wondering if this is normal or not?

TL;DR: Any input past 4V P2P seems to cause strange results around the cutoff frequency.

The way I reproduced/debugged this is:
  • Self-oscillating Filter 8 (to get the cleanest sine I can get) into attenuator
  • Attenuator through scope channel 1 into Stereo Dipole
  • Stereo Dipole output (any output!) through scope channel 2 to headphones
  1. Tune the Stereo Dipole cutoff to the same frequency as the sine being fed into it
  2. Turn all resonance controls to minimum, input drives to minimum, select HP, parallel mode
  3. Increase input level from attenuator and observe results
Everything works fine until the input is at about 4V P2P, after which it starts adding this buzzy sound, which is clearly visible on the scope, as an almost wavefolder-like waveform. This reproduces on all filter cores, which makes me wonder what's going on...

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Re: SSF Stereo Dipole filter

Post by kpreid » Sat Jun 13, 2020 11:06 am

For what it's worth, mine does exactly the same thing. Here's a sine at 4 Vpp, 6 Vpp, and 8 Vpp; red trace input, green trace POLE-A output; high pass mode.
scope.png
I see the same waveform if I keep the input amplitude low and turn up the DRIVE knob, so this isn't a different phenomenon than the intended drive control. There's also a small amount of distortion (squashed peaks) on the LP output.

This does seem a bit early to be distorting; e.g. Doepfer suggests 10 Vpp for audio signals.
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Re: SSF Stereo Dipole filter

Post by sbergen » Sat Jun 13, 2020 11:32 am

kpreid wrote:
Sat Jun 13, 2020 11:06 am
For what it's worth, mine does exactly the same thing. Here's a sine at 4 Vpp, 6 Vpp, and 8 Vpp; red trace input, green trace POLE-A output; high pass mode.
Thanks, that looks just like mine! So at least I'm not the only one with a module that does that :)

I'll ping SSF through their website to see if we could get an official take on this...

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Re: SSF Stereo Dipole filter

Post by analogPedagog » Sat Jun 13, 2020 3:36 pm

So if you have the stereo and individual resonance controls set all the way down - it actually produces this effect and you will notice that it goes away when you keep the channel res controls down and move the stereo resonance back towards center (0V).

This is because turning the stereo resonance control below center adds a different kind of ‘inverted’ resonance effect when both channel resonance controls are down low.

In practice, the stereo resonance control should be set to the middle position, when using the individual channel resonance controls, and then you can use the stereo res control to add/subtract from those settings.

But yes, that effect is totally normal and a characteristic of the design.

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Re: SSF Stereo Dipole filter

Post by sbergen » Sun Jun 14, 2020 2:27 am

analogPedagog wrote:
Sat Jun 13, 2020 3:36 pm
This is because turning the stereo resonance control below center adds a different kind of ‘inverted’ resonance effect when both channel resonance controls are down low.
Thanks! I did read about the negative CV in the quick start guide, but thought that the end result would have been just a "dead zone" in the controls, and not this "inverted" resonance.

Instead of a honeymoon period with new gear, I usually have more of a cross-examination phase, where I try to find out everything possible, both good and ugly. The reason I started measuring this was that I found it hard to get a really smooth sounding response out of the filter. I still find it impossible to dial in setting that wouldn't have something "extra" going on around the cutoff frequency (which can also be seen in an FFT analyzer), but time will tell if this really matters in practical use or not. I'm just being hyper critical right now :)

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Re: SSF Stereo Dipole filter

Post by NoLegs » Sun Jun 14, 2020 2:48 am

sbergen wrote:
Sun Jun 14, 2020 2:27 am
analogPedagog wrote:
Sat Jun 13, 2020 3:36 pm
This is because turning the stereo resonance control below center adds a different kind of ‘inverted’ resonance effect when both channel resonance controls are down low.
Thanks! I did read about the negative CV in the quick start guide, but thought that the end result would have been just a "dead zone" in the controls, and not this "inverted" resonance.

Instead of a honeymoon period with new gear, I usually have more of a cross-examination phase, where I try to find out everything possible, both good and ugly. The reason I started measuring this was that I found it hard to get a really smooth sounding response out of the filter. I still find it impossible to dial in setting that wouldn't have something "extra" going on around the cutoff frequency (which can also be seen in an FFT analyzer), but time will tell if this really matters in practical use or not. I'm just being hyper critical right now :)
Ok

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Re: SSF Stereo Dipole filter

Post by escargot » Tue Jun 30, 2020 11:31 pm

how do you modulate the filter with an enveloppe and have the equivalent of an enveloppe amount control? EG out into ST FM IN and attenuator(s)?

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Re: SSF Stereo Dipole filter

Post by NoLegs » Wed Jul 01, 2020 12:13 am

escargot wrote:
Tue Jun 30, 2020 11:31 pm
how do you modulate the filter with an enveloppe and have the equivalent of an enveloppe amount control? EG out into ST FM IN and attenuator(s)?
Yes, you would attenuate with the ST-FM CV control.

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Re: SSF Stereo Dipole filter

Post by daphnid » Wed Jul 01, 2020 12:21 am

MossGarden wrote:
Sat May 30, 2020 11:45 am
Thought this needed to be here, SD just out of shot doing some very heavy lifting! Love it

Sounds lovely.

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