New chorus pedal ? (Roland Jazz Chorus)

[V!N]

Hi guys,

I've been building pedals for a while now, and I have this great idea to put one of the best chorus effects I have ever heard in a pedal. The one on the second channel of a Roland Jazz Chorus.
http://www1.korksoft.com/~schem/newamps/roland_jazz_chorus.pdf

I am not that experienced yet that I can read a schem to know how to put things (still using parts-layout drawings). So reading just an effect out of a schem of an amp ? oh dear ..

But with a little help of you techs, I think we can make this a project many people would be interested in ! If not, I'll think about the zombie-chorus again. (There aren't many chorus-projects out there. )

greetz and thanks,

V!N

ps What a GREAT hobby we have  :wink:

[Thomas P.]

Cool idea!!!

I'm not one of the tech-guru's, to start with. But I saw that the chorus unit needs a MN3007 and a MN3102 :shock:  
This will be a really expensive journey...but to get the right tone... :wink:

Regards,
tomboy

[petemoore59]

The right half of the schematic ends...the page margin is cutoff.
 Even if I could, you picked a duzey. It does look like analog.
 After separating it from the rest of the other ckts [reverb dist and EQ etc] and finding out whether it's somehow dependant on them being there or providing a mod for thier absence, the only things left to do would be figure out the PS, and get the right level of signals for input and output of the efkt...very interesting prospect...
  But have you considered a Small Stone Intstead...maybe someone else wants to take a whack at this stone...whew...enough to make me twingey just looking at it...I guess anything's possible if Will's there!

[V!N]

Thank you for sharing my enthousiastm This sure would make a great pedal.

The PDF consists of two pages, some feller scanned both halves and didn't put them together.

I like the Small Stone, but it's not the sound I am looking for in a chorus.

[moosapotamus]

You mean... Small Clone... right? Small Stone is a phaser.

~ Charlie

[David]

If a schematic can be drawn and stupid-proofed, you bet your quad speakers I want to build it!!!!!!!!!!!!!!!!!!

[Rodgre]

Am I wrong? The JC chorus circuit is the same as the CE-1, isn't it? I thought the chorus in the amp, the Chorus Echo RE-501, and the chorus in the RS-09 were all the same circuit, no?

Roger

[Mark Hammer]

What makes the JC chorus effect sound so rich is not the chorus circuit itself, but how it is used.

The JC series of amps are stereo.  Each speaker has its own power amp.  When the chorus effect is engaged, one of the channels remains in real time and the other is time varied via the chorus sub-circuit.  

So, if you like the way it sounds, I suggest making yourself a stereo chorus (separate dry and wet outputs) and running them to two amps.

[ExpAnonColin]

Getting those delay chips would be more than a pain in the ass-it'd be a pain in the wallet, which is true of many choruses... I advise trying to imitate a small clone design with one with less-rare or less expensive delay chips, like the reticon series chips available on smallbear.

[V!N]

Thanks again for your replies. It's good to see some guru's are posting into this thread as well.



Another amp is indeed the best way for stereo effects, but I don't think that many like carying around all that stuff for sessions and gigs. Perhaps for an occasional recording, but that's it.

I have this idea to put in a dry/wet blend knob. Sorta like the left/right balance knob on our radios. This knob should work fine on both a single and a dual output pedal.



I see your point on the expensive chips. About $25 is quite normal, some stores even have them for over $50 each (!!!). But Donberg seems to have them for a price that is more than quite alright.

http://www.donberg.ie/descript/m/mn3102.htm
http://www.donberg.ie/descript/m/mn3007.htm

That is .. if these are the chips we are looking for ?

If not, a little googling should get us both the chips for less than $30. Quite an expensive project indeed, but to me, it's worth it !



I have tried the The Small Clone (or Stone ? the chorus thingy ..) at a store the other day, and it sounds a bit cold and 'metalized' to me, not that smooth, warm and rich. A great pedal, but just not the sound I'm looking for.
Or would a Clone Clone with NOS parts sound better than a new Clone ?



I have a feeling we realy can make this a great project !  

[Joep]

You can get them cheaper from SmallBear.

3,95 for the MN3102, 10,50 for the MN3007 and 3,50 shipping. I'm talking dollars here, so it is even less in Euro's!

Groetjes,

Joep

[V!N]

Ha Joep, kerel


Well, if those are the prices, I don't think money is an issue on this project. Sure, it will be more expensive than a Rangemaster, but cheaper than a Deluxe Mistress .. Kinda a middle of the road project.

[Preben Hansen]

Hi. As Mark says, it depends how the chorus is used. You can use a Boss CE-5 to get almost the same effect, with 2 amps connected to the pedal.
But:----- if you can get the other half of the schem you will se, that there is some sort of trigger function to the LFO of the chorus, comming from the speaker output.
There is also a 3 position switch, that selects the behavior of the LFO.

Just my comments for now.

Regards Preben

[Bluesgeetar]

I don't know if I can help but I would answer any questions abou the old CE-1.  I also thought it was the same circuit as in the Jazz Chorus amps and echo unit.  Almost forgot to add the obvious, I own a CE-1.  SO I can crack her open and answer any questions.  Also on Harmony-Central.com

Under effects reviews for CE-1  there seem to be a couple good suggestions for improvements to make her more suitable for guitar.

Suggestions from reviewers:

to replace the original 50 kohms pot with 250 kohm's one. I did it, and that's it.

ATTENTION! I SAY ATTENTION! LISTEN UP ALL YOU CE-1 USERS - I HAVE IMPORTANT INFO HERE - some of you may already know what i'm about to give out. ANY CE-1 CAN BE MADE TO PERFORM BETTER BY REPLACING THE
50k POT AT THE INPUT TO A 500k POT. THESE UNITS WERE INITIALLY BUILT
FOR USE BY KEYBOARD PLAYERS. THE 500k POT AT THE INPUT MAKES THESE UNITS MORE GUITAR FRIENDLY! YOUR GUITARS ARE EITHER 250k or 500k EQUIPPED - YOU SEE THE NEED NOW? I did this to mine and it made all the difference in performance for guitar usage. I know several pros who have done this as well - in fact, it's from them i learned this.

[Ben N]

I have this idea to put in a dry/wet blend knob. Sorta like the left/right balance knob on our radios. This knob should work fine on both a single and a dual output pedal.  

I used to do this with a Dano Cool Cat and an EB stereo volume/pan pedal set to pan between the two outputs.  I fed the outputs of the pan back to the same amp, as sort of a crude mixer.  Panned to the effected side it was a vibrato, and in the middle it was chorus.  As switch may give you all the flexibility you need.

But as far as getting the spacious sound of a stereo chorus (or a JC amp), there is no substitute for actual separation.

Ben

[V!N]

Come on guys, http://www1.korksoft.com/~schem/newamps/roland_jazz_chorus.pdf is a two page document ! Please scroll down to see the right halve of the schematic.

hm, another thing .. I thought you guys were talking about the little blue Boss-boxes, but I see it's the big grey chunk with controls very similar to the ones I had on my JC.


There was a profject somewhere online for cloning this deveice ?

And what was that little blue Boss-box that should be so amazing ?

(sorry, kinda new to chorus-thingies)  

V!N

[smallbearelec]

The MN007 and its companion clock driver MN3101 remain expensive, because neither is in production. What are available at reasonable cost are the low-voltage MN3207 and MN3102. Not as much headroom as rthe 15-volt parts, but adequate for guitar. A number of commercial pedals have used them. I have good stock of both, and, when they are gone, I will be able to supply Chinese-made pin-for-pin compatibles from Shanghai Belling. I have put a few parts in the hands of designers, and I hope that someone offers a nice DIY chorus just as Scott Swartz has done his 3208-based delay.

Regards
Steve Daniels

[Peter Snowberg]

Has anybody figured out what the feedback loop from the speaker to the LFO is?

It either makes the LFO faster, slower, or changes the phase. It seems like you could add this to a pedal with just about any compressor front end, so long as you LFO allowed for it.

-Peter

[puretube]

...envelope-following intensity (depth)...

[Khas Evets]

The blue pedal you were thinking of is the CE-2 (two knobs).