BAJA Korg CX3 Rotary Effect

snoof · Post by **snoof** » 03 Oct 2007, 15:15

bajaman wrote:Hi snoof
Adjustable ramp times for the bass/treb(fast for the horn, slow for the rotor)
NO - it is the other way around - the horn spins slightly slower than the drum
bajaman

I think you misunderstood, I was speaking of "ramp up times", not "top speed". The time it takes the horn to get up to speed on a real leslie is very fast, as it is very lightweight. The drum takes quite a bit longer to get to speed, as it is larger and heavier. Again nice work on this!

snoof · Post by **snoof** » 03 Oct 2007, 15:24

one thing on the Brake idea; on the a real Leslie, where the horn and rotor stop spinning has a big influence on the sound. The horn could stop facing you, or it could be 180 degrees off axis, same with the rotor. This effect is magnified when micing the cab. What would be cool is if the effect could stop and hold at whatever notch that the phase shifting is at at the specific time you hit the switch. Is that even possible??

bajaman · Post by **bajaman** » 03 Oct 2007, 19:57

Hi Doug, Dave and Snoof
I would never post this project (or any further projects) on DIYstumpboxes site because the air is way too corrosive over there

Even the slightest mention of this site gets Aron's back up - watch out for the backlash

Nevertheless, the project is freely provided for all to peruse, build and enjoy, as with any other projects I place on this great forum. it is my way of returning to the DIY community something useful for all the information I have received over the past few years from many folks on this and other forums.

Thank you for your observations Snoof. Sorry, I misunderstood your post re ramp up speeds. I will investigate the mods you have suggested in due course - they may be possible to implement easily. i will advise when I get some free time to study it further.

cheers
bajaman

markm · Post by **markm** » 03 Oct 2007, 21:42

DougH wrote:Funny... I created a new acct at diystomp and tried to post a link to this thread, since it is a cool diy project. But I guess the link to this site is outlawed or something as the url kept getting scrogged... Bizarre...

You can't link to anything here from there.
If if you could do it, it would be pulled quickly.

bajaman · Post by **bajaman** » 04 Oct 2007, 00:36

perhaps one could link to an intermediary site, that links to here then.
But why do we need any more trolls

grolschie · Post by **grolschie** » 08 Oct 2007, 08:50

Sounds very very good.

steve · Post by **steve** » 08 Oct 2007, 14:56

RE: A Brake Function.

I have a Rotosphere, and with the brake function engaged, it gives you a truly nice drive. Quite pleasant!

alteredsounds · Post by **alteredsounds** » 09 Oct 2007, 22:17

bloody hell! I'd love to be able to build and hear that, wayyy beyond me but all credit to you dude!

bajaman · Post by **bajaman** » 09 Oct 2007, 23:51

bloody hell! I'd love to be able to build and hear that, wayyy beyond me but all credit to you dude!

Thanks mate - but it really is not that difficult to build - just a lot of parts and time involved. It is always here when you feel up to it - plus, there are going to be some updates and modifications made to it in the not too distant future.
cheers
bajaman

Goop_buster · Post by **Goop_buster** » 10 Oct 2007, 00:32

bajaman wrote:perhaps one could link to an intermediary site, that links to here then.
But why do we need any more trolls

Could pages that transforms links (to shorter ones) like this work ?

http://www.shorturl.com/
http://miniddl.com/
http://tinyurl.com/

vanessa · Post by **vanessa** » 10 Oct 2007, 21:16

Great job Steve!

Thank you!!!

-Van

analogguru · Post by **analogguru** » 20 Oct 2007, 06:30

Nice job, but found this here:

https://www.diystompboxes.com/smfforum/ ... ic=62108.0

Dear Community--

I couldn't figure out why all of these flew out of the Cave within days, and then someone told me that a DIY project that required three of them had been posted. We have had to send e-msjs to a number of disappointed customers and return funds.

A request from your chief Bear: If you plan to post a DIY build around an obscure, obsolete part, even if it is on my Stock List, Please Check Availability With Me! Supply of these things is never unlimited, and it can become impossible to find more when everybody and his brother is calling brokers to see what is still on the shelves.

Regards
SD

maybe the adaption to MN3207 wouldn´t be bad....and stereo VCA ?

analogguru

bajaman · Post by **bajaman** » 20 Oct 2007, 06:43

Hi Gottfried
Good to see you back on deck

my goodness - there was only two TDA1022 ICs in my project - how did he get three??
I have found other stores with TDA1022 ICs though.
When I get time I will redesign ( probably next year) this project to use PT2399 digital chips, and include a brake function etc.
cheers
bajaman

bajaman · Post by **bajaman** » 20 Oct 2007, 06:46

Perhaps an adaptation to use the MN3002 - unfortunately it is noisier than the TDA1022 and that is already noisier than the MN3004.
bajaman

bajaman · Post by **bajaman** » 20 Oct 2007, 07:03

Hello again
i just checked the data sheets - the MN3207 is a 5 volt positive device, however the MN3007, which still appears to be still widely available and is 12 volts negative supply and over 80db signal to noise ratio,will slot straight in to the board - being a 8 pin dip it will only occupy half of the MN3004 footprint BUT pin 1 and pin 1 are the same - the other pins then fall into place perfectly ( ie: 5,6,7,8,9,10 are not used)
I will give it a try and report back
cheers
bajaman

bajaman · Post by **bajaman** » 20 Oct 2007, 11:13

I tried a pair of MN3007 chips in my unit - because they are 1024 as opposed to 512 stages (MN3004), I think the clock pulse speed will have to be halved or is that doubled??,because there seems to be a little too much - too deep an effect.
I must admit not knowing a lot about the 4046 phase locked loop cmos clock pulse generator, but I think the capacitor (1n5) between pins 6 and 7 may need to be halved, or is that doubled to clock the MN3007 at a lower frequency , or is that a higher frequency??
Anyone more knowledgeable please feel free to help here.
Clearly , the MN3007 is a much better replacement for the MN3004, than the TDA1022 or MN3207 - it is a low noise device and fits the board layout without any modification to the tracks, and it aoppears to be easily obtainable ( I just bought 20 from an Ebay store posted by Modman for US$25.)

cheers
bajaman

pz · Post by pz » 20 Oct 2007, 11:47

to get the same delay time from 1024 stage bbd as from the 512 you'll have to double the clock frequecy. I didn't try this circuit yet and don't know what is the clock frequency range. If it goes far beyond 100kHz i'd add a buffer in each clock line (3 paralleled 4069 inverters for example, or PNP+NPN based driver) to avoid smoothing out the square clock signal due to capacitive character of the bbd's clock inputs.
Some mosfet driver chips could also be used.
The less stage BBD (like 512) allows to use lower clock frequencies to
obtain short delay and saves some additional circuits like clock drivers.
Probably that's why 512s are sometimes used in flanger projects.

bajaman · Post by **bajaman** » 20 Oct 2007, 22:06

Hi pz
Thanks for your info regarding clock frequencies - according to the 4046 datasheet, the maximum vco operating frequency is 12MHz when using 4.5v supply.The VCO’s operating frequency is set by three external components connected to the C1A, C1B, R1 and R2 pins.
These three components are 1n5 for the capacitor and 68k for both the resistors.
It is a bit difficult to tell the centre frequency of the vco from the datasheet, because examples plotting C1 and R1 against frequency are only provided for 4.5v and 6v operation. The 4046 in the Korg circuit runs of 12v. As far as I can tell the centre frequency appears to be in the 100KHz to 200KHz range with 12v supply rail - I was thinking of doubling the 1n5 capacitor - trying a 3n3 for example or maybe halving the two resistors from 68k to say 33k would be a better option. What do you think

cheers
bajaman

analogguru · Post by **analogguru** » 21 Oct 2007, 06:40

For doubling the clock you need to half the 1n5.

The clock-frequency limitation doesnt óccur in the 4046, it is determined by the BBD.

analogguru

bajaman · Post by **bajaman** » 21 Oct 2007, 09:40

Hi AG
Thanks - so a 750pf capacitor should give me the same sound with a MN3007 as the 1n5 with the MN3004. Should I expect any improvement or otherwise or just the same quality of sound?
cheers
bajaman

BAJA Korg CX3 Rotary Effect [documentation]