Peavey Spectrum Analog Filter

[clintrubber]

By accident:

"The Classic Sound of the Moog Ladder Filter"

http://www.uaudio.com/webzine/2008/august/index4.html
(note the text gives incorrect pat#, but the pic will correct it)


More info & links than you can handle..., please post summary

 

[clintrubber]

Got myself one of these now, including a leaky battery as pictured in Nate's pics  
Please allow me some rambling about it, maybe other owners have something to say in return.

Mine doesn't have the 'round font' style as in Nate's pics, no idea if that's more recent or not.
EPROM-version is 1.01 IIRC.  

Nice box, using just the VCA-section is cool as well.

Too bad it doesn't self-oscillate across the complete filter-range, I understood
this is a 'property' of the Moog-ladder. I'll think/search if there's a fix for this.

If anybody ran into a schematic in the meantime, please tell.

If a listing of the factory-presets exists that'd be of interest as well.

BTW, given the common complaint of people about MIDI-controlled filters
having poor 'resolution' (assuming 128 possible values here),
I was surprised to read that the Peavey only even uses just 64 possible values for the various parameters.
At least this is what the manual suggests.

So far I've only noticed 'stepping' on the resonance-knob, but there it's pretty noticable indeed.


Bye,

 Peter

 

[JohnRoberts]

I believe I know the guy who designed that.. (lives in Oz).  IIRC it was well regarded by users at the time but like several Peavey midi products a little too hip for their mom & pop store distribution and entry level brand image, so didn't sell well...

JR

 

[MartyMart]

I believe I know the guy who designed that.. (lives in Oz).  IIRC it was well regarded by users at the time but like several Peavey midi products a little too hip for their mom & pop store distribution and entry level brand image, so didn't sell well...

JR

It's a shame, that situation "hounded" many of the PV digital products and some were FAB !
I think that the "standard matt black" look compared to Korg/Roland didn't help either, there was a
joke once about the PC1600 coming "carpet covered" like a speaker !!
That was a very cool product too, I sold about 12 into the BBC electronic workshop before they got axed :-(
MM.

 

[clintrubber]

I think that the "standard matt black" look compared to Korg/Roland didn't help either,

Must indeed admit that boxes like this Spectrum A'Filter & say the DPM-SP don't look very spectacular.

But a bit boring looking box with good stuff inside, no problem, especially when they
pop up cheap years later 

I like the look of those zig-zag light-grey knobs though, it's nice to have direct access to most functions.
Got a Waldorf filter as well & while that box looks a lot better it has less knobs & requires to step through six layers.

Bye,

  Peter

 

[MartyMart]

Yes, more "knobage" is always good, the Access Virus is great for "Knob factor" !!
Wonderful sounding synth too.

MM

 

[clintrubber]

Too bad it doesn't self-oscillate across the complete filter-range, I understood
this is a 'property' of the Moog-ladder. I'll think/search if there's a fix for this.

The Oakley filter came to mind (also a Moogish ladder LPF). I recall a user-selectable resistor to enable/prevent
self-oscillation when hitting the resonance knob. I went for oscillation, but need to check if it does so across the whole freq-range.

I believe I know the guy who designed that.. (lives in Oz). 

If his name pops up, would he be the best point to start for a schematic ? or do you give me any chance when asking via the official route ? (Peavey themselves; IIRC there was some kind of $10 schematic service somewhere)

Thanks,

  Peter

 

[JohnRoberts]

That's one reason I didn't give his name... I wish to remain friends. (I notice Martin already shared his first name, so now you have a first name and a country.)

I don't keep schematics for the vast majority of the gear I designed over the years, and I get PMs or emails all the time. He is no longer working with Peavey

I would definitely try peavey service. If schematics exist they are the likely primary source.

JR

 

[clintrubber]

That's one reason I didn't give his name... I wish to remain friends. (I notice Martin already shared his first name, so now you have a first name and a country.)

Perfect, I understand & will try Peavey directly.

Regards,

  Peter

 

[clintrubber]

[quote author="natek"] or upload it to the group email!

I vote for that latter option  :wink:

The GroupDIY Gmail account:

Go to http://www.gmail.com
Username: groupdiy
Password: thelab

Thanks,

 Peter
[/quote]

Have a problem attaching files, is there a max-size ??
Blue bar gets stuck near almost-complete then fails to finalize attaching.
Splitting in smaller parts does not help, same error-mechanism: attachment failed.

???

 

[clintrubber]

[quote author="natek"] or upload it to the group email!

I vote for that latter option  :wink:

The GroupDIY Gmail account:

Go to http://www.gmail.com
Username: groupdiy
Password: thelab

Thanks,

 Peter

Have a problem attaching files, is there a max-size ??
Blue bar gets stuck near almost-complete then fails to finalize attaching.
Splitting in smaller parts does not help, same error-mechanism: attachment failed.

???
[/quote]

Solved, uploaded, done, stuff available.
Needed a Flash update to be able to upload a file. Ridiculous ! 

I'm out now, let's see if I can buy a bread at a bakery without having to have shoelaces of the correct thickness.

Enjoy,

  Peter

 

[clintrubber]

Solved, uploaded, done, stuff available.

So now let's see if we can get this thing to self-oscillate over the complete filter-range.
Relevant part is on Page 4, but mods for this are obviously complicated a bit by the programmable nature of this box (the resonance pot is not directly 'in circuit'). I'll have a further look, but please join.

Bye,

  Peter