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j.baars
Joined: Jan 11, 2008 Posts: 16 Location: netherland
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Posted: Sat Sep 20, 2008 11:38 am Post subject:
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the resistor at 15 volts should be 350 0hms, use a 1 watt type .
the diode thingie is to keep the filament (heather) voltage aproxx. 0,7 volts.
I did use the antiparallel confg to make sure the filament is not burned when the powersupply is
accidently inverted when experimenting.
bye,
jeroen baars |
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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Posted: Thu Oct 30, 2008 6:36 pm Post subject:
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mr baars
was the mosfet chosen for it's particular attributed or can i substitute with another fet like mpf102. just wondering if you used that as you had it on stock or if it is crucial for the design
well im going to try this today, hopefully it works, ill post my results _________________ problemchild
melbourne australia
http://cycleofproblems.blogspot.com/
http://www.last.fm/user/prblmchild |
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j.baars
Joined: Jan 11, 2008 Posts: 16 Location: netherland
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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crashlander42
Joined: Oct 21, 2006 Posts: 292 Location: Orlando, FL (US)
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Posted: Sun Nov 23, 2008 11:55 pm Post subject:
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I breadboarded the tube VCA and am pleased with it's sound. It almost sounds filterish. It has a neat woosh. I added a mod to it that acts almost like an amount pot, but also changes the timber. It's actually Frequency Central's "HiGain" mod for his pentadriver with a 100k pot instead of a 68k resistor.
Really, this seems to act more like a PWM than a VCA, but it does the trick. Even with the original design.
Anyway. Here's a video. http://www.youtube.com/watch?v=3SxKiEdGgxo _________________ When they plug me in the lights go down in Hong Kong.
http://www.myspace.com/isaciongun
http://www.youtube.com/user/Crashlander42
My DIY stuff Flickr |
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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frequencycentral
Joined: May 25, 2008 Posts: 186 Location: UK
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Posted: Mon Nov 24, 2008 10:48 am Post subject:
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crashlander42 wrote: | I breadboarded the tube VCA and am pleased with it's sound. It almost sounds filterish. It has a neat woosh. I added a mod to it that acts almost like an amount pot, but also changes the timber. It's actually Frequency Central's "HiGain" mod for his pentadriver with a 100k pot instead of a 68k resistor.
Really, this seems to act more like a PWM than a VCA, but it does the trick. Even with the original design.
Anyway. Here's a video. http://www.youtube.com/watch?v=3SxKiEdGgxo |
That sounds most excellent! Seeing as how you mentioned it, here's the Pentadriver MkII with the high gain mod. It's posted elsewhere on the net ( I mostly hang out at the DIY Stompbox forum http://www.diystompboxes.com/smfforum/forums.html?topic=71381.0), but now it's here too.....
_________________ http://www.frequencycentral.co.uk/ |
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LektroiD
Joined: Aug 23, 2008 Posts: 1018 Location: Scottish Borders
Audio files: 2
G2 patch files: 2
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Posted: Wed Jan 07, 2009 12:05 pm Post subject:
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I'm quite interested in this, I wonder how easy or hard it will be to transfer to stripboard? Since I don't have an etching kit. |
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janvanvolt
Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany
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Posted: Mon Feb 23, 2009 8:00 am Post subject:
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HELP!
I am still having issues with my two built tubes.
They still do not work (as expected).
I am using this here: http://www.casia.org/modular/SF/tubevcf.jpg
(which the grounding of course) BUT:
a) if i turn input counterclockwise, i still have an input signal.
b) Resonance also does not work as expected.
I simply didn't get the "tube" sound at all, more or less a "passing" signal. _________________ Homepage - http://www.czmok.de
My dIY - http://diy.czmok.de
Film/Music - http://gfm.me |
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janvanvolt
Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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Posted: Sun Mar 01, 2009 7:23 pm Post subject:
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i got a couple dud 5672s in my batch
had you tried replacing them?
also are you sure your tube is orientated correctly?
it is really confusing with j.baars schems as he numbers them with a different orientation to the datasheets. you have to pay attention to the dot not the numbers. i think he said in this thread that he copied the numbering format from an old schematic but it is something to be aware of.
i havent made the filter but i have made the vca. i have a modded version with an input mixer, negative bias on the grid and output amping. the output amp can move the distortion more towards opamp distortion and not purely tube but i like the outcome. once i have properly tested it i will post the design. _________________ problemchild
melbourne australia
http://cycleofproblems.blogspot.com/
http://www.last.fm/user/prblmchild |
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janvanvolt
Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany
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Posted: Wed Mar 04, 2009 7:44 pm Post subject:
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Hi Luka,
a) the red dot is (hopefully) correct, it will be on the "upper" direction.
b) i have built two pcb's from this forum post, both are acting same strangely.
c) i can try to get other 5672 tubes... _________________ Homepage - http://www.czmok.de
My dIY - http://diy.czmok.de
Film/Music - http://gfm.me |
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crashlander42
Joined: Oct 21, 2006 Posts: 292 Location: Orlando, FL (US)
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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Posted: Thu Mar 05, 2009 3:32 pm Post subject:
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ill give the vcf circuit a go on my breadboard next week jan
ill let you know how i go.
i know that my vca didnt work first time when i used the initial layout but i think that was due to a bad etch and perhaps a bad tube. once i studied the circuit i decided i wanted to change it anyway.
One thing i was told by eric from metasonix in respect to the tube designs is that they need a negative bias on the grid. This circuit doesnt include that. He suggested -0.4v for the 5672. I have implement this into my vca design. I might try it when i breadboard the vcf and see if it makes a difference. _________________ problemchild
melbourne australia
http://cycleofproblems.blogspot.com/
http://www.last.fm/user/prblmchild |
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janvanvolt
Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany
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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Sun May 28, 2017 5:06 pm Post subject:
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Luka wrote: | quick questions
some of my friends are running on 12v supplies. will this be possilble for this module? |
I realised that the schematic is for 12V
Going to give it an etch |
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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Fri May 04, 2018 4:17 am Post subject:
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I want to etch a mean sucker vcf but I don't understand part of the schematic I have outlined in pink on the schematic (pictured under the layout below):
Specifically:
1. What does "Rx" mean? (alternately a fixed resistor?)
2. What is the dotted line between 'Rx or 1m Lin' that leads to 'input'. How do I connect this in a circuit?
3. What do the two slashes on either side of 'Rx 220k' after 'input' mean?
The pcb by Etaion (see green layout below for ease of reference) seems to match the schematic other than the 350r resistor which is for +15V and I will run it on +12V with a 275r resistor. If anyone can see any other differences please let me know.
Thanks very much.
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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Thu May 10, 2018 5:21 am Post subject:
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I realise that this probably means either 1m lin potentiometer or R 220K but can someone please confirm. |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
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Posted: Thu May 10, 2018 6:13 am Post subject:
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That is my interpretation too, select one of both options. _________________ Jan
also .. could someone please turn down the thermostat a bit.
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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Thu May 10, 2018 7:08 am Post subject:
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Thanks Jan
As you think so I will use 1m linear pot instead of 220k
Appreciate your help and will let you know how it works out |
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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Posted: Sat May 15, 2021 1:18 am Post subject:
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I've been trying to adapt this design to use an EF86 but didn't get far - it might be the difference between the tubes, or not using a FET at the cutoff end - could I just use a pot instead, as I don't need CV control right now?
I've just asked similar questions on the synthforum.nl thread as well, but had to google translate to Dutch so I hope I haven't inadvertently caused a diplomatic incident |
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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Posted: Thu May 20, 2021 4:20 am Post subject:
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I think I finally got it going with the ef86 - I put a pot on the two caps with centre going to ground and there's definitely some effect, turning a square wave into a saw for a start, and then the resonance can get really feedbacky, ranging from 60 - 150 hz... I definitely need to refine it but I'm happy that I finally got somewhere |
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Fernando
Joined: Dec 30, 2006 Posts: 286 Location: Barcelona & Emporda, Spain
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Posted: Thu May 20, 2021 7:10 am Post subject:
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Great! Post schematics and notes please!
Krupa wrote: | I think I finally got it going with the ef86 - I put a pot on the two caps with centre going to ground and there's definitely some effect, turning a square wave into a saw for a start, and then the resonance can get really feedbacky, ranging from 60 - 150 hz... I definitely need to refine it but I'm happy that I finally got somewhere :) |
_________________ Fer
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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Posted: Thu May 20, 2021 7:29 am Post subject:
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I'll try and do that, never done one before but it isn't very different to the original - my next plan is to try and use a dual pentode / triode with the triode replacing the transistor...
I'm glad someone noticed / is interested
Fernando wrote: | Great! Post schematics and notes please!
Krupa wrote: | I think I finally got it going with the ef86 - I put a pot on the two caps with centre going to ground and there's definitely some effect, turning a square wave into a saw for a start, and then the resonance can get really feedbacky, ranging from 60 - 150 hz... I definitely need to refine it but I'm happy that I finally got somewhere |
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Fernando
Joined: Dec 30, 2006 Posts: 286 Location: Barcelona & Emporda, Spain
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Posted: Thu May 20, 2021 11:36 am Post subject:
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It is very interesting. It worths getting deeper in tube filters/processors.
I'm specially interested in using tubes with low voltage/low cons. heaters:
5672 50mA@1.25V heater
6418 20mA@1.25V heater
2E35 20mA@1.25V heater
CV4092 a ruggedised 5672 w/ 20mA heater (expensive)
1Ж24Б 30mA heater
Krupa wrote: | I'll try and do that, never done one before but it isn't very different to the original - my next plan is to try and use a dual pentode / triode with the triode replacing the transistor...
I'm glad someone noticed / is interested :)
Fernando wrote: | Great! Post schematics and notes please!
Krupa wrote: | I think I finally got it going with the ef86 - I put a pot on the two caps with centre going to ground and there's definitely some effect, turning a square wave into a saw for a start, and then the resonance can get really feedbacky, ranging from 60 - 150 hz... I definitely need to refine it but I'm happy that I finally got somewhere :) |
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_________________ Fer
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