Butta's 3630 secret recipe

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chrissugar

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I remember at the old place there was a discussion about the fact that the gate circuit is doing something wrong and that gate signal makes the audio part to distort. I think it was sugested a mod with cutting a jumper to remove the gate signal from the circuit. Any ideas?

chrissugar
 
Without looking at the schemo or a unit, what's wrong with the diodes already there?
Is the socket change just to beef-up the contact area?
Are the 1u 50V added or do they replace something?
BTW It was always the low ratios that sounded particularly orrible, any improvement there?

Questions questions I know, it's just that I have one to mod that's not here. Cheers.
 
I have one of these, I've been waiting for a mod to come along which is beyond the "cut the gate links" or "swap the op-amps", this sounds potentially worthwhile.

I had wondered if the PSU might be better served with a more traditional outboard ±xxV DC PSU, instead of the (inherently more ripply and higher impedance) single-secondary-winding-doing-everything method...

Keith
 
Hey buttachunk,
I just did a recording/mix session and the bass player brought his own Alesis 3630 that was modded virtually the same way you described.
I have to tell you I was sceptical.....but wow...it really did sound very good. I'd recommend it to anyone.
Cheers,
Freddy G
 
I modified my 2 with the black lion mod, sans the super quality opamps. The thing really comes to life with a few little component upgrades! In my mods I used the fast recovery diodes that matt suggested in the psu - I guess the stock ones are just not going to cut it when the new components are in there or something - I did not question it - for like 45 cents, I was not gonna let that stand in the way of the intentions of the modification.

The results are friggin amazing - I could not even believe it. So so smooth, and no more pumping!
 
[quote author="mike_relay"]sweet! I just got one of these.. Hopefully Scott won't see this mod and want to keep it for himself... :roll:[/quote]

Well, you're gonna have to actually come pick the damn thing up before I get a little too curious... :twisted:

(plus this mod ought to take care of that little power supply problem you were going to have to fix!)
 
i cant believe that i built two 1176's before taking on my 3630.

now, let me get this right. we are replacing the existing wall-wart power supply with in IEC plug?
can you please post an internal photo, so i can grasp what we're doing ? i should point out we're 240VAC down here . . .

do you also cut the jumpers to the gate to remove it from the circuit? (the 'tape op' mod)
[edit - sorry, my bad. i see in a comment above that the gate is still in circuit]

i'm thinking i might try disabling the gate and popping in the 1uf caps first and see where that leads me. any thoughts?

looin forward to hearing from you'se.

chris.
 
i'm thinking i might try disabling the gate and popping in the 1uf caps first and see where that leads me.
I want to do it alike, first add those caps and then have a listen. I won't stop there (time permitting), but I'll definitely first have listen after adding those caps.
I can't almost believe this, did Alesis simply forgot about adding those two caps ?!

Thanks Butta for posting this summary :thumb:
 
Butta,

thanks so much for this Recipe! I have a Phonic PCL3200 comp/lim/gate that looks pretty much identical to the Alesis 3630. Does anyone know if it the same?

thanks,

ANdyP
 
drpat,

I am not refering to the distortion trimming, but to the 1k CV port input resistor. In the G-SSL to get the true compression ratios, with DBX2001's, you need 5k6 in parallel, and with 208x's you need 220R in series, if my memory serves me. Nothing is needed with 205x's. I was just wondering if something similar is applicable here too to preserve the correct ratios?

ANdyP
 
Hello, new born alesis fans!
Yes-- that 1uf cap is added-- that is what makes the biggest difference to the RMS detector.
Alesis has read the AN already...IF you have a REV C pcb then the RMS correction is already onboard (1µ50v from pin2 to -15V like in mine :shock: )
I didn't know that this is NOT the prob in my 3630...

So i have to go right to the psu section in front of me.
4x 1N4001 (butta, do you work for alesis meanwhile? its a 400x type already!) in there -> 1N4004 (laying around)
2x1000µF25V"wisdom" (C4,C5 on pcb)-> 2x3300µF 25V Sanyo laying around
2x1000µF16V wisdom (rear)-> 470µF Panasonic FC 100V
TLxxx already -> OPA 4227
(i am wondering if i can use 404 here, hehe, having some of them laying around!!!)
bigger psu and round connector is already in use

must go to work now...back in the evening. posting what happened to sound... :grin:

Martin
[/quote]
 
:grin:
a little bit sad they made the first revision without proper reading :wink:
even more because they pushed this unit out in masses!
i change the diodes anyway. a matter of 2 minutes...

Just wanted to tell that alesis finally came to the same conclusions like you (or should i say they did at least some of the bugfixes) , so there's definately something to it!

i want to thank you very much, i already packed it in the outer corner of the "maybe later" pile of boxes :wink: ...now it's gonna be reactivated!

I totally agree with you that the combination of psu and rms detection flaws (or "bugs") must be, what made this unit so less desirable sounding despite of the "feature overkill".
I'm very curious about the sound when the box is back in the rack...
(a bit of dbx crossed with fo*usrite red...that sounds just too good to be true :thumb: )

fantastic mod work by you :thumb:

Martin
 
Sooo, the first test is done!
I reactivated the noise gate and was curious if it is of use now. First impression: It IS. It's a quite musical unit also! :shock:
I fed program material only thru the alesis.
(fiddling around with my electribe patterns for half an hour now to get new rhythms with the gate! thats purely fantastic :shock: . That's what it should have been in the first. a creative tool floating your mind with ideas. i remembered getting bored of all the pops and clicks i got last time using it :? . now everything is fine, i had a hard time trying to get something *not* musical out of it! can't let my hands of it. :cool: )
the compression is very clean and smooth (still fascinated by sound and new freedom of parameter setup :shock: , yes i'm having a hard time to find anything bad sounding now.)
Awful at drums percussions and bass. clean with natural samples. and a cool "blue-red" shadow of vca color....gimme 3 hours more and i am willing to make product management tours for alesis :grin:

butta, you have won a kind of jackpot. cleaning up the psu based on your mods was definately turning the 3630 into a production tool for me.

i can't take it. incredible metamorphosis...
no, i'm not drunk.
just listening to the new sounds...

(have i forgotten to mention that the right out is not working anymore?hmmm...i have to reopen it, i must only turn it off...ehem :? . i think thats the problem, i can't, there's too much music at the moment to do that. :grin:
i was about to sell it. now i'm looking for another one to buy...)


thank you very much.

Martin
 
Just want to tell i found the error in the dead channel (bad opamp :idea: ).
Replaced it (and by accident read in the meta-> external links that i'm not the only one who likes the sound of burr brown opa4227 in this circuit :grin:, my favourite drop in replacement in other units also).
Everything fine again under heavy usage for some weeks.

I also read about adding tantalums at the rectifiers.

Can anyone tell me about the advantages of that or maybe suggest a value?
I'm not really familiar with tantalums, just know that the old types had some disadvantages that are not noticable in newer types...
:?:

Kind regards

Martin

(btw: i made a small but maybe useful mod if you deal with argus eye customers - removed the "3630" with AXE after shave :grin: in 2 minutes, the Ales*s logo /*no silkscreen*/ carefully scraping with a cutter knife within 3 minutes of time from the front panel... :razz: )
 

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