Low pass filter and its issue... [Solved]

Questions and Answers concerning the spectralis!

Moderator: Jörg Schaaf

Low pass filter and its issue... [Solved]

Postby acemonvw » Thu Mar 28, 2013 3:27 am

Update: Please see the following links for Radikal Technologies fix to this issue (I have performed this fix and it works as described):
viewtopic.php?f=2&t=2758&start=60#p20139
http://www.joergschaaf.de/wordpress/spe ... -repair-i/

So, everyone knows that the 24db filter doesn't open up all the way, but I thought I'd do a simple visual so you can see how different it is from the other filter or no filter at all.

Here's what the direct output of a single oscillator (saw wave) holding C4 note looks like:
Direct output.png
Direct output.png (139.46 KiB) Viewed 6144 times


Here's what the same oscillator looks like going through the 12db LP filter with NO resonance:
MM filter no-res.png
MM filter no-res.png (140.4 KiB) Viewed 6144 times


Here's what the same oscillator looks like going through the 24db LP filter with NO resonance:
LP filter no-res.png
LP filter no-res.png (138.42 KiB) Viewed 6144 times


As you can see... there is a MASSIVE difference between the two filters.

I also looked at what happens when you add resonance to the two filters, but I can't post them here (max of 3). I'll try to post them elsewhere.

It would be so cool to be able to open the filters more, but "adjfltr" doesn't actually help at all.
Last edited by acemonvw on Tue Feb 23, 2016 8:35 pm, edited 2 times in total.
User avatar
acemonvw
 
Posts: 1212
Joined: Fri Mar 18, 2011 8:28 pm
Location: Minneapolis, MN

Re: Low pass filter and its issue...

Postby acemonvw » Thu Mar 28, 2013 3:36 am

Here's what the same oscillator looks like going through the 12db LP filter with resonance:
MM filter with res.png
MM filter with res.png (143.09 KiB) Viewed 6144 times


Here's what the same oscillator looks like going through the 24db LP filter with resonance:
LP filter with res.png
LP filter with res.png (134.19 KiB) Viewed 6144 times


So there you have it! The 24 dB filter needs some work...

:roll:
User avatar
acemonvw
 
Posts: 1212
Joined: Fri Mar 18, 2011 8:28 pm
Location: Minneapolis, MN

Re: Low pass filter and its issue...

Postby jizzmaster2000 » Thu Mar 28, 2013 7:20 am

Nice work, as a guess I'd say maybe the filter adjust sets the keyboard tracking ?
Jeremy
Melbourne
jizzmaster2000
 
Posts: 258
Joined: Fri Jan 13, 2012 9:59 pm
Location: Melbourne

Re: Low pass filter and its issue...

Postby acemonvw » Fri Mar 29, 2013 2:39 am

Yeah, I have no idea... maybe?

It kinda sucks. It must be a physical problem with the units, like the analog filters just can't open wide enough or something.
User avatar
acemonvw
 
Posts: 1212
Joined: Fri Mar 18, 2011 8:28 pm
Location: Minneapolis, MN

Re: Low pass filter and its issue...

Postby jizzmaster2000 » Sat Mar 30, 2013 9:07 pm

Yeah, I read a post from Jorg where one Spec he had sounded different (filter response) from another.
I'll try and find it.
Here it is.
"it's possible that you are right. My own Spectralis has the same issue. I meanwhile realized that based on the analogue circuitery and tolerances on parts the Spectralis synths are not sounding totally equal. A customer in the US brought that in about one and a half year ago when he bought his second Spectralis. He had a Spectralis 1 from the early beginning and bought a Spectralis 2. He then realized that his first unit had a more warm and smooth sounding analog board. He wanted to have the same sound on the new Spectralis. I told him to exchange the two analog boards (the analog board is the same on both editions). We checked then both machines again and figured out, that the older board's 24db Lowpass filter opened not the same like the new board. We maybe should change the measuring a little bit to control the high end of the filter."

So can Jorg give us the circuit diagram of the filter or tell us what components are involved to fix this please.
Jeremy
Melbourne
jizzmaster2000
 
Posts: 258
Joined: Fri Jan 13, 2012 9:59 pm
Location: Melbourne

Re: Low pass filter and its issue...

Postby pizzatime » Fri Apr 05, 2013 7:14 pm

it's annoying but really not that big a problem and you can work around it to some extent.. I think for a bigger problem is not being able to split the filters or A-Synth oscillators to different outputs..
pizzatime
 
Posts: 49
Joined: Thu Feb 14, 2013 9:15 am

Re: Low pass filter and its issue...

Postby acemonvw » Fri Apr 05, 2013 7:31 pm

pizzatime wrote:and you can work around it to some extent


How so? Other than to just use the MM filter when you really need to modulate Cutoff/Res...
User avatar
acemonvw
 
Posts: 1212
Joined: Fri Mar 18, 2011 8:28 pm
Location: Minneapolis, MN

Postby pizzatime » Fri Apr 05, 2013 7:47 pm

Hi,
Obviously it is not ideal but is it often really essential to modulate the LP filter to fully open? If not then mixing a tiny bit of direct signal to suit works in most cases?
I don't know.. of course you might need something different.. for example I'm not bothered about overdub now as I find it easier to record in midi sequences but it really bugged me a while ago.. I don't even think there should be a computer editor let alone wanting it.. not bothered about more fx..
If you need to modulate the filter fully open it would be a real pain.. it pissed me off then I forgot about it!

We should try and push this beast to the limit instead of pontificating about things that would only make a tiny difference to our music..
pizzatime
 
Posts: 49
Joined: Thu Feb 14, 2013 9:15 am

Re: Low pass filter and its issue...

Postby pizzatime » Fri Apr 05, 2013 7:55 pm

I didn't mean that as any critisism as I think it is all really interesting.. I just mean it is sometimes hard not to get obsessed about things that don't make a huge difference - I do it all the time - every day - wishing for new features or swapping bits of kit then I have a good session and think what the fuck was I thinking all this time just get on with it man!
pizzatime
 
Posts: 49
Joined: Thu Feb 14, 2013 9:15 am

Re: Low pass filter and its issue...

Postby acemonvw » Mon Apr 08, 2013 2:00 pm

pizzatime wrote:I didn't mean that as any critisism as I think it is all really interesting.. I just mean it is sometimes hard not to get obsessed about things that don't make a huge difference - I do it all the time - every day - wishing for new features or swapping bits of kit then I have a good session and think what the fuck was I thinking all this time just get on with it man!


Yeah, it was more of an exercise than a complaint I suppose. It was cool to see the differences in action, despite being somewhat annoyed by its presence. I had a lot of fun tinkering with this analyzer and changing pitch, waveforms, adding FM, etc. It was neat to see the display morph. Being someone who is not a physicist, sound designer, engineer, or whatever else causes people around these synth forums to know so much about synthesis... I was entertained for a short while.
User avatar
acemonvw
 
Posts: 1212
Joined: Fri Mar 18, 2011 8:28 pm
Location: Minneapolis, MN

Next

Return to Helpdesk

Who is online

Users browsing this forum: Google [Bot] and 1 guest

cron