Roland - AS-1 Sustainer

bajaman · Post by **bajaman** » 30 Nov 2007, 10:34

I wonder - did Roland corp buy the boards from colorsound - they look just like those vintage colorsound tracks - even got the board color right too - damn good clone, but which one sounds the best - the Colorsound unit has a 100n for it's input capacitor

- hmmmmm
bajaman

sosodef · Post by **sosodef** » 30 Nov 2007, 10:40

The colorsound looks cooler thats for sure. How about a bajasound

make it do more than just sustain get the compress to work!

bajaman · Post by **bajaman** » 30 Nov 2007, 10:41

the BMP came first and Colorsound "stole" it from EH

I thought it was designed for Steve Hackett by the Colorsound people - but apparently he did not like it that much - my recollection is that EHX started production of their BMP a year or so later than the Jumbo Tonebender - I could be wrong here though - my recollection of that era is that there was some very nice LSD and Cannabis around.

bajaman

analogguru · Post by **analogguru** » 30 Nov 2007, 10:51

I believe Roland could be the first, cause later the stompboxes were named Boss.

Then the Supa-Series appeared first in the Mid-70´s, before (1972/73) the Colorsound compressor was called "Sustain-Module" and was FET-based.

The Colorsound Supa Sustain pcb´s looked like this:
http://files.muziq.be/pics/colorsound_s ... in_003.jpg
or this:
http://files.muziq.be/pics/futuristicso ... in_002.jpg

analogguru

bajaman · Post by **bajaman** » 30 Nov 2007, 10:53

The colorsound looks cooler thats for sure. How about a bajasound make it do more than just sustain get the compress to work!

Easy

Unfortunately feedback type compressors do tend to be a bit erratic in their operation, because the LED shines on the LDR which lowers it's resistance, which lowers the gain stage amplifier, which lowers the drive voltage to the LED, which means the LED does not shine as brightly, which means the LDR increase in resistance, Which means the gain stage amplifier increase in level , Which means the LED driver amplifier increases the LED intensity, which means the LDR decreases in resistance, which means ....... well, i think you get the picture - the compression is far from smooth, especially when you take into account the flickering action of the LED itself - this tends to get magnified and shows up in erratic compression. Even the Demeter compulator has an erratic compression response on extreme settings. Nevertheless, this type of feedback AGC can give a quite useful sustain - which is why both the Colorsound and the Roland units are called Sustainers and not compressors.
A limiter works in a quite different manner. Here the signal is sense at the input BEFORE the gain stage - it is a feedforward design. perhaps feeding the Supa Sustain into a limiter will give you a more realistic compression effect perhaps

bajaman

bajaman · Post by **bajaman** » 30 Nov 2007, 10:57

The Colorsound Supa Sustain pcb´s looked like this

Hey

i wonder if Mike Fuller has seen that way of mounting the circuit board and pots - he should sue colorsound for stealing his IP - those devious Brits

bajaman

aelick · Post by **aelick** » 16 Feb 2009, 14:20

I was wondering if someone could let me know what LDR from Small Bear would work for this. I would like to try and build this but I'm unsure of which one to buy.

aelick · Post by **aelick** » 14 Mar 2009, 17:24

This my first attempt at doing a strip board lay out. I was hoping that someone could have a look at it and point out if there is any mistakes.

neldom · Post by **neldom** » 15 Feb 2011, 05:07

Hey Fellas,
Just wondering if anyone would have any ideas what I could check here.
I just got one of these sustainers for free, because of course it's not working.
When you engage the pedal there is a very noticeable volume drop and of course only the output pot has any effect.
You really have to hammer on the strings even with humbuckers to get the led to light, and get the voltage up over 0.5v.
I have checked Q1 and Q2 and the voltages seem okay with the base about 0.5V higher than the emitters.
Just wondering if you know what a fellow might check next?
Thanks.

mdame · Post by **mdame** » 08 Mar 2011, 02:54

So could you take power for an indicator LED from Q2 for a kind of input meter... like on some preamps... Use a 2 color LED similar to the diamond compressor?

I am actually looking at the Colorsound schem.

mictester · Post by **mictester** » 11 Feb 2012, 15:06

I messed with the bias values in the first stage, and got the collector of Q2 to Vcc/2. I put the thing on to Vero:

You might need to all a 100pF capacitor from the base of Q1 to ground (gets rid of AM radio reception) and some LDRs need a 100 - 220 pF capacitor across them to minimise distortion. If assembled into a fully light-tight box, with the LED pointing straight at the LDR, the sustain is amazing!

Nocentelli · Post by **Nocentelli** » 11 Feb 2012, 16:09

Am I right in thinking any low-ish gain npn would do for those 2SC1815s? Like 2N3904 or 2N2222?

teleK · Post by **teleK** » 11 Feb 2012, 17:24

Ill test out the 9v design soonish. Any chance for a schem just so I know whats going on? or was there just some value tweaking?

teleK · Post by **teleK** » 11 Feb 2012, 19:42

Also, as long as im at it, why not just use a ldr/led in a vactrol or something instead of having to adjust it and have it be so partial?

mictester · Post by **mictester** » 12 Feb 2012, 00:07

Nocentelli wrote:Am I right in thinking any low-ish gain npn would do for those 2SC1815s? Like 2N3904 or 2N2222?

You need a fair bit of gain from the Darlington pair, but trying out various transistors, almost anything seems to work OK. The one I built this afternoon with two BC182L (same pinout as the 1815) and that works fine. I've also used MPSA13A darlington transistors to save board space!

The two transistors in the input audio side of things need to be low noise types. I'm lucky enough to have a lot of BC109Cs but I've used 2N5088s with good results.

The changes to make the thing bias well at 9V are to increase the collector resistor for Q2 up to 27k (was 22k) and the lower part of the Q2 emitter potential divider needs to be increased to 3k9 (was 1k8). The LDR really isn't too critical - I've used ORP12, RPY58A, and some cheap Chinese unmarked things I got from Hong Kong on Ebay all with equal success. The colour of the LED doesn't matter either - just don't try to use a modern low current / high brightness type.

Try this one out - you won't be disappointed!

mictester · Post by **mictester** » 12 Feb 2012, 00:10

One last point - the input impedance is quite low for modern standards, so my most recent builds have an FET source follower impedance conversion stage before the Sustain pot.

mictester · Post by **mictester** » 12 Feb 2012, 01:49

teleK wrote:Also, as long as im at it, why not just use a ldr/led in a vactrol or something instead of having to adjust it and have it be so partial?

If you look at the schematic and the layout, you'll see that there's an LED and an LDR. These are surprisingly uncritical!

Nocentelli · Post by **Nocentelli** » 12 Feb 2012, 08:18

Cool, many thanks mic! I've got bags of BC109c and I'll try out a MPSA13 for Q3+4.

ansil · Post by **ansil** » 20 Feb 2012, 11:19

this circuit is a nice fuzz sound without all the extra parts. i built one for a friend about six months ago. i found the device to be too exttrme between mud and bright but again good fuzz

BMS1971 · Post by **BMS1971** » 11 Apr 2022, 08:52

I was wondering if an NSL32 could be use for the LED/LDR pair...

Ben

Roland - AS-1 Sustainer [schematic]