bobby S

looking for mods. on an ORBAN 622b "paramedic" EQ
« on: July 07, 2005, 07:20:47 PM »
Hey Folks, my First post here.

I am looking to do some mods. on an ORBAN 622b "paramedic"  :grin:  EQ,  but cant find any schematics .  Can anyone point me in the right direction please.

also, if anyone has any mods. for this box already, that would be great.

I wil  remote the PSU, and replace front end,  And make a relay hardwire bypass for it.

I may clean it up , but I like as it sounds. so wont screw with it too much.

lastly, R there any good EQ P 1a (pultec)  DIY projects floating Around?

best
Bobby Summerfield


[email protected]

Vince Poulos
Speck Electronics
www.speck.com

edanderson

re: orban 622 mods
« Reply #2 on: July 07, 2005, 07:45:02 PM »
after getting and thoroughly reading the manual, you could search the rec.audio.pro newsgroup using http://groups.google.com for posts by scott dorsey regarding modding the 622.  

i don't think orban gear has been much discussed here, but you should use the search function to see.  you'll certainly find some info on that other eq you mentioned.  also try reading the "meta" threads.

ed

bobby S

looking for mods. on an ORBAN 622b "paramedic" EQ
« Reply #3 on: July 07, 2005, 08:44:21 PM »
Vince & Ed,

Thank you,  grabbed the PDF

Best

NewYorkDave

looking for mods. on an ORBAN 622b "paramedic" EQ
« Reply #4 on: July 07, 2005, 09:45:02 PM »
If you like how it sounds already, why do you want to modify it?

It's not state-of-the-art now but it was a good EQ in its time, and is still very usable. (I'm a broadcast engineer and have a high opinion of Orban gear in general. I also happen to have a 622B of my own  :grin: ).

But I'll be a nice guy and post Dorsey's note on mods for the 622B, just to save you the trouble of having to find it.

Quote

Scott Dorsey wrote:
Orban 622 A/B
-------------

C3 and C5 are DC blocking caps for the input.  Replace them with jumpers.
If you're worried you might be connecting to devices with DC offset, use
good 1uF film caps.

Replace C701 and C702 with 1000 uF axial electrolytics.

Replace C703 and C704 with 47 uF radial electrolytics, preferably
Panasonic type FC.  These caps are more critical than C701 and C702,
especially in terms of ESR.  Use good caps.

Replace all tantalum capacitors remaining with Panasonic EF-series
tantalums.  Bypass all caps directly in the signal path (C407, C409,
C411) with film caps.  It might help to bypass C415 although I cannot
tell any difference on that one.  You can eliminate some of these caps
if you're willing to live with pops when you switch filters in or out;
since this is a problem in some applications I don't do this.

Clean all the pots with Cramolin and make sure they turn easily and freely
without any grinding feeling.

Remove all the ICs on the main PC board and install sockets, except for
IC601 which is only used in the overload indicator.  Use machined-pin
sockets.  The OPA607 will work fine in all of these sockets, as will
probably most other high-performance singletons.

Don't touch any of the ceramic caps or the silver-mica caps, which are
fine by themselves.

Give the system a listening check to make sure it's okay and that all the
work was done well.  Make sure to turn all the filters on when doing this.

Now comes the fun part.  IF the unit you have isn't full of epoxy potted
modules, you will see eight little daughter boards.  If it's full of epoxy
potted modules, proceed to the last step.  If you see the daughter cards
exposed, however, you are in luck.

Desolder all the daughter cards and remove them.  This really, really
helps to have a desoldering station, but you can do it with a manual solder
sucker if you are very careful and very patient.

Desolder the metal-can 4558 op-amps from the daughter cards and solder on
8-pin DIP sockets, machined-pin of course.   Underneath the boards, add
a 22 pF NPO or COG ceramic capacitor between pins 1 and 2 of the top chip,
and then one between pins 6 and 7.  On the lower chip (the one farther from
the number 10 screened on the board), you only need to add a capacitor between
pins 1 and 2.  These are compensation caps which are required for stability.
The Panasonic ECU-S-1H1055CB is fine.

Do not add supply decoupling caps.  The grounds on those boards aren't
very stiff and supply decoupling caps can actually cause more damage than
good in a lot of cases.

Now solder the daughter cards back onto the main PC board.

You should now be able to use OP275s in this circuit and it should remain
stable.  Don't use the 2604.

If you like, you can replace all of the mylar box caps in the EQ networks
with polystyrene or polypropylene caps.  The Panasonic polypropylenes sound
fine to me although many folks are gung-ho about Wimas.  I don't bother
replacing the ones on the lowest frequency filter bank either, but you can
if you want.

Last step: Power it up, test it out, and see what it sounds like.  THEN
run the alignment procedure listed on page 7 of the manual.  Do not skip
this.

wiz1der

looking for mods. on an ORBAN 622b "paramedic" EQ
« Reply #5 on: July 11, 2005, 02:44:29 PM »
Quote from: "[email protected]"
ftp://ftp.orban.com/622/


It's asking for a username and password? Anyone know what this is?

Thanks

kiira

looking for mods. on an ORBAN 622b "paramedic" EQ
« Reply #6 on: July 11, 2005, 02:49:11 PM »
Quote from: "wiz1der"
Quote from: "[email protected]"
ftp://ftp.orban.com/622/


It's asking for a username and password? Anyone know what this is?

Thanks


probably "anonymous"  and password: <your_email_address>

 it didn't ask for name/passwd from me so if ya really can't get it I'll give you an url for it on my server.

-k

wiz1der

looking for mods. on an ORBAN 622b "paramedic" EQ
« Reply #7 on: July 11, 2005, 02:55:55 PM »
Quote from: "kiira"
Quote from: "wiz1der"
Quote from: "[email protected]"
ftp://ftp.orban.com/622/


It's asking for a username and password? Anyone know what this is?

Thanks


probably "anonymous"  and password: <your_email_address>

 it didn't ask for name/passwd from me so if ya really can't get it I'll give you an url for it on my server.

-k


The login screen keeps popping back up with the password gone like it wants a new one. I tried my hotmail addy, and my ISP email addy, none worked.

wiz1der

looking for mods. on an ORBAN 622b "paramedic" EQ
« Reply #8 on: July 12, 2005, 10:13:10 AM »
Thanks Bobby, I got it.

 

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