What "chipset" would you like to see in a Dim D PCB |
Original chips. They are still out there. |
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76% |
[ 39 ] |
Low voltage BBDs - easier to get, probably more noisy. Takes longer to design. |
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5% |
[ 3 ] |
Make a PCB that allows both options. Will be more expensive (more PCB area required!), and will take the longest to design. |
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13% |
[ 7 ] |
Not interested. (Who needs a Dim D? And isn't there another Dim D project on the way?!) |
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3% |
[ 2 ] |
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Total Votes : 51 |
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ognam
Joined: May 04, 2009 Posts: 7 Location: Berlin
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Posted: Tue Aug 24, 2010 10:33 am Post subject:
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jhaible wrote: | numbertalk wrote: | Hi JH,
The only trimmer I don't see any instructions on how to calibrate is the LFO Offs trimmer on the BBD board - what is this one exactly and how is this one set?
Thanks! |
This is for a symmetrical LFO shape at pin 7 of U14.
JH. |
Hi. I have sucessfully built a Dim D (thanks for this project!) and was searching for this answer. But how is the way to set this trimmer?
Another question:
Is there a way to adjust the BBD Bias without a Scope?
Thanx a lot!
Jonas |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Tue Aug 24, 2010 12:16 pm Post subject:
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ognam wrote: | jhaible wrote: | numbertalk wrote: | Hi JH,
The only trimmer I don't see any instructions on how to calibrate is the LFO Offs trimmer on the BBD board - what is this one exactly and how is this one set?
Thanks! |
This is for a symmetrical LFO shape at pin 7 of U14.
JH. |
Hi. I have sucessfully built a Dim D (thanks for this project!) and was searching for this answer. But how is the way to set this trimmer?
Another question:
Is there a way to adjust the BBD Bias without a Scope?
Thanx a lot!
Jonas |
Symmetrical shape means: Positive amplitude = negative amplitude.
Scope is recommended - no idea how to build stuff without a scope.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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ognam
Joined: May 04, 2009 Posts: 7 Location: Berlin
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Posted: Tue Aug 24, 2010 5:07 pm Post subject:
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Thanx for the answer. By the way, this machine sounds already fantastic. Finished it today and just did some listening tests. So, actually I would also be happy, leaving everything as it is... but, somehow I really would like to find out how to configure it the professional way. So, would it be possible that You describe the way to measure and adjust the BBD Bias and the LFO-Off for Scope beginners? I think it could be possible to use a Scope of a friend of mine... Thank You again! I will post some Pictures soon (I did a nice Front-Panel Layout
Cheers Jonas |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Tue Aug 24, 2010 10:33 pm Post subject:
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ognam wrote: | Thanx for the answer. By the way, this machine sounds already fantastic. Finished it today and just did some listening tests. So, actually I would also be happy, leaving everything as it is... but, somehow I really would like to find out how to configure it the professional way. So, would it be possible that You describe the way to measure and adjust the BBD Bias and the LFO-Off for Scope beginners? I think it could be possible to use a Scope of a friend of mine... Thank You again! I will post some Pictures soon (I did a nice Front-Panel Layout
Cheers Jonas |
My circuits normally are designed such that the nominal setting of trimpots is around center position, so it's likely that everything is close to optimal already in your circuit. BBD bias helps to prevent distortion - the right setting is such that there is no clipping for positive and negative parts of the audio signal. You set that by feeding a large signal and then adjust the cliping such that it occurs on positve and negative signal extensions equally - which ensures that you don't waste headroom for one side, and run into distortion on the other side in normal operation. - But if you don't hear any clipping, just leave it as it is - it's set up properly already.
Same for the LFO. If it's way off (with extreme offset tolerance of an opamp), you might hear a clock bleed thru if the BBD is modulated too low on one extension of the LFO swing. And same as above: if you don't encounter such a phenomenon, just feel happy and leave it as it is.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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ognam
Joined: May 04, 2009 Posts: 7 Location: Berlin
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Posted: Wed Aug 25, 2010 12:21 am Post subject:
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Ah... very interesting.
So "CMR" , "BBD-Bias" and "LFO-Offset" do all change the Offset of the Signal but in different positions of the circuit?
Just another question:
Why should the right pin of the "interf"-conector be disconnected when the input is not symmetrical (as described in sc_audio_balanced.pdf) ?
Normally I thought that it should be no problem to connect a non symetrical signal to a symmetrical Input... |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Wed Aug 25, 2010 1:05 am Post subject:
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ognam wrote: | Ah... very interesting.
So "CMR" , "BBD-Bias" and "LFO-Offset" do all change the Offset of the Signal but in different positions of the circuit? |
No. -
CMR adjusts the common mode rejetion of the balanced input.
The other two adjust the two (different) things I described above.
ognam wrote: | Just another question:
Why should the right pin of the "interf"-conector be disconnected when the input is not symmetrical (as described in sc_audio_balanced.pdf) ?
Normally I thought that it should be no problem to connect a non symetrical signal to a symmetrical Input... |
The right pin of the Interf connector is a control pin that changes the internal gain of the circuit, allowing the same (unity) gain for both balanced and unbalanced connection. See http://www.jhaible.de/subtle_chorus/subtle_chorus_main_board_sch_dwg2.pdf
Doesn't have anything to do with plugging an unbalanced output into a balanced input, which *is* ok. Just don't plug the balanced output of the Dimension D into an unbalanced input!
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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ognam
Joined: May 04, 2009 Posts: 7 Location: Berlin
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Posted: Thu Aug 26, 2010 2:28 pm Post subject:
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Ok, Thanks!
So for the CMR i put a sinus on both wires of the symetrical input and tried to adjust the remaining signal with R37 and R46. Curiously it just had no effekt on it. Its some kind of endless trimmer, so I even don´t know where is the middle-position... can you help?
Thanks a lot!
Jonas |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Thu Aug 26, 2010 2:53 pm Post subject:
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ognam wrote: | Ok, Thanks!
So for the CMR i put a sinus on both wires of the symetrical input and tried to adjust the remaining signal with R37 and R46. Curiously it just had no effekt on it. Its some kind of endless trimmer, so I even don´t know where is the middle-position... can you help?
Thanks a lot!
Jonas |
You may get the impression of having an endless trimmer, but you're actually at one end of its travel, and it just allows mechanical slipping (?) without any further change.
The right way to determine mid position, if in doubt, is using an ohm-meter.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24075 Location: The Netherlands, Enschede
Audio files: 277
G2 patch files: 320
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Posted: Thu Aug 26, 2010 4:29 pm Post subject:
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jhaible wrote: | The right way to determine mid position, if in doubt, is using an ohm-meter. |
I always was too lazy for that ... what used to work .. if you listen carefully .. there is a click when the thing reaches the end, every time it slips back. It does so on both ends, so you can count turns _________________ Jan
also .. could someone please turn down the thermostat a bit.
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thermionicjunky
Joined: Dec 07, 2006 Posts: 90 Location: san francisco
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Posted: Wed Sep 22, 2010 12:03 am Post subject:
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I finally received the panel and jacks yesterday for my simple chorus module using only the BBD board. I had the board populated three months ago.
I love this chorus.
I added an external modulation input using the pad for the main board LFO. I also added wet outputs so I can experiment with external processing before mixing with the dry signal. This is my first JH module. I just want to express my appreciation for the work that went into this project. |
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vtl5c3
Joined: Sep 08, 2006 Posts: 425 Location: PDX
Audio files: 13
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Posted: Sun Jul 17, 2011 9:19 am Post subject:
Subject description: Chorus Only Version? |
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Has anyone built the chorus only version? I'm thinking I'd like to give that a try. |
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whomper
Joined: Dec 15, 2007 Posts: 201 Location: Israel
Audio files: 2
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Posted: Sun Jul 17, 2011 11:12 am Post subject:
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Yeah, I have built a double chorus versions with only the BBD boards.
They sound amazing! I love them so much that I usually have them as the last step of an analog bass or lead sounds. Analog sequencers are also treated by them. _________________ Erez Yaary
Home Page: http://www.yaary.com
Buy my CDs at http://www.mellowjet.de |
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vtl5c3
Joined: Sep 08, 2006 Posts: 425 Location: PDX
Audio files: 13
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Posted: Mon Jul 18, 2011 7:18 pm Post subject:
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cool. thanks! |
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