Does the QPAS have an ADC in it?

Cwejman, Livewire, TipTop Audio, Doepfer etc... Get your euro on!

Moderators: Kent, luketeaford, Joe.

User avatar
KSS
Super Deluxe Wiggler
Posts: 5833
Joined: Mon Jan 25, 2016 7:28 am

Re: Does the QPAS have an ADC in it?

Post by KSS » Tue Apr 27, 2021 12:25 am

studioutopia wrote:
Mon Apr 26, 2021 9:41 pm
- The distrust that certain manufacturers breed by gooping black epoxy all over a PCB to hide a.... let's face it... a really simple overdrive circuit (ARP did this too, if I remember correctly, to obscure a ladder filter design?)
No, they didn't. You're repeating a myth. Oft-repeated by others before you, but still not true.

There never was lawsuit and ARP did *not* use epoxy in their sub modules to hide anything. I've talked about this numerous times but I will keep doing so because as you say there's still people out there who believe things which aren't true.

ARP's designers -actually Tonus at the time- came from the US defense industry and the US space race of the 60's. Where it was common to embed circuits into submodules for thermal stabilization, resistance to thermal and mechanical shock and to provide a known sub-circuit 'block' which could be easily replaced when necessary. Having been tested and qualified individually. One company they worked with back then for their 1005 Modamp ring modulator potted sub-module still exists and is still making potted circuits and modules this way for industry and military use. Hybrid circuits in Massachusetts.

You still see this in the Audio Discrete Op Amp DOA modules plugged into API lunchbox modules. Where it is done for the same reasons listed above.

The idea that ARP-Tonus was hiding their use of a ladder filter is hard to maintain when you look at the facts. First, that moog was also using ARPs patented dual-voice keyboard at the time. <--That's why there was no lawsuit.

But more immediately obvious is that the ARP2500's 1006 Filtamp module, seen here in a view that requires one screwdriver and two screws removed to see.. Is quite clearly the moog ladder. You don't have to be an expert or need any great experience to see the four red capacitor rungs and quad red-topped matched pair transistor sides of the ladder on this PCB! The detail photo shows the same ladder arrangement but with tan capacitors 'rungs' and only one side of the transistor pairs painted red.

And here's the kicker. This module was in production and out in the world a year before the 2600 arrived with its potted sub-modules including the 4012 moog ladder filter. If they truly wanted to hide their use of the ladder, wouldn't this ladder be hidden??

PLEASE DO share this widely and with the authority of truth! It's time to put an end to these easily proven as false old narratives. And we have the power of the internet to make it better. Or to make it worse. Please help spread the word. The designers deserve not to be labelled unfairly.
------------------
The small 1" sq. potted sub-module seen here is the exponential CV generator for the filter. It has two temperature sensitive resistors inside and several transistors whihc would also be affected by temperature changes. It is potted in epoxy to keep all of these separate components at the same temp and to slow any ambient temp changes impact on this frequency critical portion of the circuit. It is not part of the ladder of the filter. The mechanical stability gained comes along for the ride since the temp concerns are the primary reason to pot this part. But the Filtamp was also available in a linear type. Which meant they only had to swap out this expo module for the linear type to change and fulfill that filter order. Mfrs didn't use potted modules to hide! They had good reasons to do so which had nothing to do with hiding anything. Like quickly changing a filter type from linear to exponential to match an order.
Attachments
1006-PCB-detail-NLS.JPG
1006-Filtamp-CompSide-VG.jpg
Treat utility modules as stars instead of backup singers.
Treat power supplies like Rockstars instead of roadies!
Chase magic sound, not magic parts.

User avatar
notmiserlouagain
Ultra Wiggler
Posts: 813
Joined: Thu Feb 23, 2012 11:04 am
Location: Hamburg
Contact:

Re: Does the QPAS have an ADC in it?

Post by notmiserlouagain » Tue Apr 27, 2021 4:11 am

VERY interesting, KSS! :tu:

Regarding there´s even the STG ´Post Law Suit VCF´
So fake news was even before the www :zombie:

Do you know why ARP dropped the topology?

btw. cannot help myself, the module´s so sweet looking!
He who eats with most pleasure is he who least requires sauce.
Xenophon

User avatar
KSS
Super Deluxe Wiggler
Posts: 5833
Joined: Mon Jan 25, 2016 7:28 am

Re: Does the QPAS have an ADC in it?

Post by KSS » Tue Apr 27, 2021 4:49 am

Alan Pearlman was always bothered by their use of the ladder. He wasn't the only one, but business is business, and they did have the 'hole card' of moog using their patent. Alan described when Bob came to talk to him about it in the Bright Sparks movie.

So once they could develop something different -and after their name had been established- they developed the 4072 and 4075 used in later 2600's and explorer-omni's, respectively. It's based on a quad norton amplifier LM3900 <--which is also all over Serge and other designs in the same time frame.

But their use of the ladder was well known by moog well before the 2600s shipped. Bob M did get kinda mad about it, but was red-faced when it was pointed out that his own company was doing essentially the same thing to ARP that he was complaining to Alan P about. You don't have to take my word for it, both men have sat for interviews which can be watched to show both sides. The 1006 module -and 952 KBD- sit as witness to the truth.

User avatar
notmiserlouagain
Ultra Wiggler
Posts: 813
Joined: Thu Feb 23, 2012 11:04 am
Location: Hamburg
Contact:

Re: Does the QPAS have an ADC in it?

Post by notmiserlouagain » Tue Apr 27, 2021 4:52 am

KSS your word is good enough for me, after reading so many of your posts!
The 4072 (which I build in the yusynth version) is one of my most beloved filters...
He who eats with most pleasure is he who least requires sauce.
Xenophon

User avatar
studioutopia
Wiggling with Experience
Posts: 487
Joined: Wed Feb 19, 2020 9:28 pm
Location: Toronto, Canada

Re: Does the QPAS have an ADC in it?

Post by studioutopia » Tue Apr 27, 2021 9:48 am

KSS wrote:
Tue Apr 27, 2021 12:25 am
studioutopia wrote:
Mon Apr 26, 2021 9:41 pm
- The distrust that certain manufacturers breed by gooping black epoxy all over a PCB to hide a.... let's face it... a really simple overdrive circuit (ARP did this too, if I remember correctly, to obscure a ladder filter design?)
No, they didn't. You're repeating a myth. Oft-repeated by others before you, but still not true.

Thanks for the clarification! I will share this.

User avatar
suitandtieguy
Hammond King
Posts: 3388
Joined: Sun Feb 03, 2008 11:50 pm
Location: Chillicothe IL USA

Re: Does the QPAS have an ADC in it?

Post by suitandtieguy » Thu Jun 10, 2021 2:08 am

notmiserlouagain wrote:
Tue Apr 27, 2021 4:11 am
Regarding there´s even the STG ´Post Law Suit VCF´
So fake news was even before the www :zombie:
the side of the module clarifies that there wasn't room on the front panel to call it "Post Ambiguous Legal Action Filter"

also there absolutely was legal action taken, but it didn't get to the lawsuit phase.

obviously they weren't even hiding the use of the filter.
http://suitandtieguy.com
http://stgsoundlabs.com
http://knobcon.com
suboptimal wrote:... if it's music you want to make with your modular, STG should be in your system.

BlinkyLights
Ultra Wiggler
Posts: 994
Joined: Wed Feb 13, 2019 12:16 am

Re: Does the QPAS have an ADC in it?

Post by BlinkyLights » Thu Jun 10, 2021 2:20 am

I love my STG one to bits.

natureclubcassettes
Veteran Wiggler
Posts: 723
Joined: Thu Jun 23, 2016 3:59 pm
Location: chicago

Re: Does the QPAS have an ADC in it?

Post by natureclubcassettes » Thu Jun 10, 2021 5:43 pm

KSS wrote:
Tue Apr 27, 2021 12:25 am
studioutopia wrote:
Mon Apr 26, 2021 9:41 pm
- The distrust that certain manufacturers breed by gooping black epoxy all over a PCB to hide a.... let's face it... a really simple overdrive circuit (ARP did this too, if I remember correctly, to obscure a ladder filter design?)
No, they didn't. You're repeating a myth. Oft-repeated by others before you, but still not true.

There never was lawsuit and ARP did *not* use epoxy in their sub modules to hide anything. I've talked about this numerous times but I will keep doing so because as you say there's still people out there who believe things which aren't true.

ARP's designers -actually Tonus at the time- came from the US defense industry and the US space race of the 60's. Where it was common to embed circuits into submodules for thermal stabilization, resistance to thermal and mechanical shock and to provide a known sub-circuit 'block' which could be easily replaced when necessary. Having been tested and qualified individually. One company they worked with back then for their 1005 Modamp ring modulator potted sub-module still exists and is still making potted circuits and modules this way for industry and military use. Hybrid circuits in Massachusetts.

You still see this in the Audio Discrete Op Amp DOA modules plugged into API lunchbox modules. Where it is done for the same reasons listed above.

The idea that ARP-Tonus was hiding their use of a ladder filter is hard to maintain when you look at the facts. First, that moog was also using ARPs patented dual-voice keyboard at the time. <--That's why there was no lawsuit.

But more immediately obvious is that the ARP2500's 1006 Filtamp module, seen here in a view that requires one screwdriver and two screws removed to see.. Is quite clearly the moog ladder. You don't have to be an expert or need any great experience to see the four red capacitor rungs and quad red-topped matched pair transistor sides of the ladder on this PCB! The detail photo shows the same ladder arrangement but with tan capacitors 'rungs' and only one side of the transistor pairs painted red.

And here's the kicker. This module was in production and out in the world a year before the 2600 arrived with its potted sub-modules including the 4012 moog ladder filter. If they truly wanted to hide their use of the ladder, wouldn't this ladder be hidden??

PLEASE DO share this widely and with the authority of truth! It's time to put an end to these easily proven as false old narratives. And we have the power of the internet to make it better. Or to make it worse. Please help spread the word. The designers deserve not to be labelled unfairly.
------------------
The small 1" sq. potted sub-module seen here is the exponential CV generator for the filter. It has two temperature sensitive resistors inside and several transistors whihc would also be affected by temperature changes. It is potted in epoxy to keep all of these separate components at the same temp and to slow any ambient temp changes impact on this frequency critical portion of the circuit. It is not part of the ladder of the filter. The mechanical stability gained comes along for the ride since the temp concerns are the primary reason to pot this part. But the Filtamp was also available in a linear type. Which meant they only had to swap out this expo module for the linear type to change and fulfill that filter order. Mfrs didn't use potted modules to hide! They had good reasons to do so which had nothing to do with hiding anything. Like quickly changing a filter type from linear to exponential to match an order.
KSS, great knowledge here. You totally made this thread worthwhile!

User avatar
KSS
Super Deluxe Wiggler
Posts: 5833
Joined: Mon Jan 25, 2016 7:28 am

Re: Does the QPAS have an ADC in it?

Post by KSS » Thu Jun 10, 2021 6:15 pm

Thank you.
Unfortunately, Marc Doty has continued to push both of these false narratives in his recent ARP video for Reverb. Maybe if enough people complain they will re-shoot that part or at least offer an onscreen footnote or correction? I did add a corrective comment to the Matrixsynth post where I saw the video.

User avatar
thetwlo
Super Deluxe Wiggler
Posts: 5147
Joined: Wed Apr 16, 2008 4:05 pm
Location: SF Bay area

Re: Does the QPAS have an ADC in it?

Post by thetwlo » Thu Jun 10, 2021 9:42 pm

if it sounds good it is good. But of course they should be honest about it.

User avatar
oilpanic
Wiggling with Experience
Posts: 299
Joined: Mon Sep 18, 2017 4:27 am
Location: Petaluma CA

Re: Does the QPAS have an ADC in it?

Post by oilpanic » Thu Jun 10, 2021 11:24 pm

I’m glad someone brought up hocus pocus because there is def some of that in Qpas.

Post Reply

Return to “Eurorack Modules”