[sdiy] Boss/Roland Dimension C/D differences

Mon Apr 17 18:13:23 CEST 2006

Hey Seb,

I have no idea what the difference in sound would be (that's part of the reason I want to build the D).  Seems I've read somewhere that the Dim C may be a bit more 'agressive' in mode 4 than the D.  'Agressive' is a relative term here - they key to these devices is subtlety that blends into the sound itself.  

I love my Dim C - I mean I *absolutely* love it.  It's exceedingly hard to resist running everything through it.  It's dead-nuts quiet, which is miraculous, considering there are two BBD clocks modulated anti-phase to each other.  The thing about it is, unlike a 'normal' chorus, the Dim C becomes more of a 'part' of the sound, rather than an effect modulating the sound.  It's very hard to describe.  It often blends in so effectively, it's easy to forget that it's there - until it's bypassed, then you realize what it's doing.  Usually that is in Modes 1 and 2.  Mode 3 is a bit more overt, and Mode 4 is even a bit more overt - more jangly, for want of a better description.  For me, I find I use Mode 3 the most.

For mono to stereo conversion, the effect is nothing short of beautiful.  It's not a 'smack you over the head' kind of thing, it's a sense of expanded space, which I imagine is the reason the effects are called 'Dimension'.  For Mono output (with the C), the effect is kind of like adding more VCO's to a single VCO, if that makes any sense.  You know something's there, but the characteristic cyclical modulation of a 'normal' chorus is greatly reduced.

I can only imagine the Dimension D, by putting in more wet signal per channel, but not more cross-mixing, probably exands the stereo field a bit.

I put LFO frequency and depth pots on the Dim C.  I also put the mode switches on it.  I use an additional switch to select between the mode switches or pot control.  To be very honest, I very, very rarely use the pots.  Those Roland Engineers so truly found the sweet spots, it's uncanny.  I did put CV control on the delay lines, and I do use that more often than the pot switches.  The Dim C can be turned into quite the little mangler using external CV control, as well as provide some nice effects by mixing LFO sources.  With the D, I'm aiming at keeping it as 'original' as possible in function, with perhaps the exception of seeing if I can give it a mono output like the Dim C has.

The D uses MN3007's, whereas the C uses MN3207's - the MN3007's right away are going to provide quite a bit more headroom.  I really haven't had any problem getting a good level out of the C, though one has to be a bit careful about input signal - I've got an input buffer and attenuator on mine which handles things pretty well.  The D would not require that.

One very interesting thing about the modulation - it's not a 'smooth' modulation at all for each delay line - it sounds almost like pulse or trapezoid modulation.  One delay line sounds very sick by itself, but when it's added with the other delay line, the transformation is amazing.  I recorded a sample of the effect - it starts out with the dry signal, then the same signal in Mode 4, mono in/mono out, then the same signal again, only with one delay line.  Sicko!  It's at the very bottom of the page here:

http://mypeoplepc.com/members/scottnoanh/birthofasynth/id9.html

Under the link 'Dim C One Hand Clapping'.

Thanks for the Dalbani tip!

Cheers,
Scott

-----Original Message-----
>From: Seb Francis <seb at burnit.co.uk>
>Sent: Apr 17, 2006 9:54 AM
>To: Synth DIY <synth-diy at dropmix.xs4all.nl>
>Subject: Re: [sdiy] Boss/Roland Dimension C/D differences
>
>It's interesting that you say the mode 4 is different between the 2.  I 
>wonder which sounds 'better' (subjective term that!)
>
>The Dim D was released in 1979 and the Dim C not until 1985, so perhaps 
>they had refined the sound in this later edition - but more likely it 
>was changed either to tailor more for guitars or to get component count 
>down.
>
>I am toying with the idea of adding fully variable controls to set the 
>chorus parameters, but then again half the beauty of the Dim C/D is that 
>the sound is 'just right' without having the play around.  Perhaps 5 
>buttons would be good - including both mode 4s from C & D.
>
>Seb
>
>
>Scott Stites wrote:
>> Hi Seb,
>>
>> I've been slowly circling the Dimension D myself lately, intending a build.
>>
>> Some differences between the two:
>>
>> The Dimension D provides stereo output of either a mono or stereo input.  The Dimension C provides stereo or mono output of a mono input (my Dim C has been modified to provide stereo inputs as well).
>>
>> The Dimension D will certainly have scads more headroom.
>>
>> >From what I can tell, the two produce Mode 4 differently.  In the Dimension C, Mode 4 is just another LFO frequency/depth combination.  The Dimension D appears to use the same LFO frequency/depth as Mode 3, but instead changes the amount of direct wet signal to each channel, without modifiying the crossfeed delay level.
>>
>> The Dim D uses a boatload of HA1457 preamp IC's, that are (over here anyway) nearly pure unobtainium.  There's a PNP in the output section that is also difficult to find here (though the NPN can be acquired quite easily). 
>>
>> I'm interested in building a Dim D, but I'm going to have to do some part substitutions.  The one thing I'd really be prone to try is a mono output mode, implemented in the way it is done in the Dim C.  The mono output on the Dim C is a fantastically wonderful thickening agent.
>>
>> Cheers,
>> Scott
>>
>>
>>
>>
>> -----Original Message-----
>>   
>>> From: Seb Francis <seb at burnit.co.uk>
>>> Sent: Apr 17, 2006 7:17 AM
>>> To: Synth DIY <synth-diy at dropmix.xs4all.nl>
>>> Subject: [sdiy] Boss/Roland Dimension C/D differences
>>>
>>> Well, 1 project almost wrapped up, so it's time to start on another :)
>>>
>>> I want to build a clone of the Roland SDD-320 "Dimension D".  I have the 
>>> schematics of the Dimension C guitar pedal but I can't find the 
>>> schematics of the Dimension D anywhere.  I'm wondering if it's worth 
>>> buying the service manual from Roland, or should I just work from the 
>>> Dimension C schematics .. are these things essentially the same?
>>>
>>> I know the Dimension D has stereo line level inputs as opposed to mono 
>>> guitar level input, and it has LED level meters.  But I'm not sure about 
>>> any other differences?  Would anyone care to share the schematic of the 
>>> Dimension D input stage?
>>>
>>> TIA,
>>> Seb
>>>
>>>
>>>
>>>     
>>
>>
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