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Download 222A Manual

PLS: If anyone has any other upgrades modifications etc gladly I added here, will be useful for all of us:-) Also if notice any error or misspellings please let me know.

Email 261fm(at)

Thank you
XFon 261fm.

A “Must” and Potential modification’s

A must modifications
. All Orban 222A units from first to last year of production no matter what SN #, all have two slight mains hum problems, I and other technicians check lot of 222A units (about 15 pieces) we see that all suffered from the same hum problems definitely it is a design miss?!! rather than just one faulty 222A enhancer. Its very strange that NON of users around the world don’t notice it that, neither the factory report it with some supplements upgrade revisions as Orban factory uses to add on his service manuals.

If on all outboard equipment’s before your main processor exist any slight mains hum then this all adds up. Actually on real world, if one unmodified 222A is ahead of an 8100/xt2 then its hum is magnified by approx. 20+db by the 8100A1 AGC when the gain makeup reaches its max.
To listen/check/notice the hum problem on yours 222A do the following.Suppose that your 222A is already on air alone or ahead of any processor.

On a dead air tune in with your fm tuner, turn-up the volume of headphones or monitor’s, first listen carefully on Fm Stereo reception & then on Mono, at Fm Stereo reception you should notice the mains hum at your on air, at Mono that low mains hum must minimized or disappeared, the hum you listen on Fm Stereo reception comes from your 222A, to ensure that simply pull-out the AC power of 222A.

Personally I notice that hum problems immediately as an 222A connected ahead of my 8100/xt2 before some years, after lot of unsuccessfully attempts to locate the source of the problem,  fortunately comes friend Paul, he is very clever, curious & passionate with electronics and is very skilled with Optimod’s especially with 8100/xt2, my friend Paul from UK (info “at” finds the cure of hum problems on 222A and do some interesting upgrades modifications on 8100/xt2, also finds and eliminate the “6Khz beat tone, whistle” noise which is heard on a dead air at Stereo “only” reception on all Optimod’s  8200 (greetings Paul:).

That two hum problems are, one at MONO audio chain which is not so serious, and second at STEREO (L-R difference) audio chain is most serious because easily can heard on a dead air. At MONO the hum comes from a ripple at out of negative regulator -15V if you scope the out of 7915 can be see the ripple, and second at STEREO (L-R difference) hum comes from inefficient GND of PIN 3 on IC7, if you scope the TP5 which is the L-R VCA out, then easily may see the mains ripple.

Procedures to eliminate the hum noise. Remove the unit from AC mains, remove both upper and bottom plates, For elimination of hum at MONO, locate at PWS section the IC51 (7915) solder a short jumper wire from pin 1 of IC51to E17 (center tap GND of transformer).


For elimination of hum at STEREO, locate the IC7 (5532) near of balance out modules, solder a short jumper wire from pin 3 to E26 GND is between of L & R input cables E1,2,3,4. Both above mods will make your 222A more quieter.  


Potential modification’s

Here some proposes to lower the input noise level and how add some of StereoMaxx’s extra effects? on your standard 222A.

Lowering the noise level of input. Standard 222A use NE5532 as input IC’s, his noise figures become worsen with variation of driver resistance i.e. mixing console or any other outboard unit between 222A & mixing console, so noise figures on this old workhorse 5532 depends much from what R see on his input. For substantially reduced noise replace IC1,2 & 7 with OPA2134.  


To check the noise figure on your standard 222A just set your scope to 5mv per division at TP6 and easily may see lot of noise, also on TP6 may see the difference on noise level between NE5532, OPA2134 & OP275 or other IC of your preference. Today with the great evolution on audio IC there are exist some not so high priced IC’s with much better sonic and dynamic results, one of the best IC used by many modern upgrades designers are that of Texas Instruments/Burr Brown OPA2134, JFET input, very low noise figures with any variant of drive resistance, excellent sonically character.

Another better replacement of NE5532 is the OP275 by Analog Devices that is one with strange scheme Bipolar and JFET, designed especially for Hi End audio use, sonically sounds better, warmer & smooth on my ears than of cold and dark OPA2134, so you may give it a try. Now if you like the sonic character of NE5532 and wish to keep it, its better to replace that old Signetics or Philips IC which is the two favorites vendors of Orban factory with the same type of 5532 by that of Texas Instruments NE5532(A) the (A) sign means that version of 5532 is selected and verified for lower noise also TI NE5532 sounds much better of Signetics or Philips.

Give some of StereoMaxx’s on your standard 222A

Be aware, with the following mod's your MONO will suffer.
As describe above on my results & opinion, 222A & StereoMaxx are the same on overall way of treatment but with major differences on final “fake” widened result of stereo image due the use of “digital delay” on L-R products (222Ais superior here due non use such “baggy” “kitsch-y” tricks) also StereoMaxx expand stereo image on unnecessary 50Hz-18Khz range & 222A due his pure design only at region of 900Hz-4Khz where is and the usefully stereo information, for that and other reasons I like Bob’s design:) (if expand the 20-20khz region of L-R then expand and lots of garbage:( Any way for those who wish to add on his 222A some “impressing” “garbage” which gives that popular “wow factor”, here some potential mods.  

To open the freq. range of L-R products, thus the stereo image locate the C6 (470pf) on IC7, that C is connected from pin1 to pin2 of IC7 and limits the high freq. results thus the HF contains of L-R products, replace that 470pf with an 47pf. This mod gives on 222A half of
StereoMaxx “baggy” effect.

To add an delay on L-R products as on StereoMaxx, is not so easy job as the above mod but maybe want to try this, many users make it with good results and especially without any by-products as noise etc on StereoMaxx. Cut the PCB trace from TP5 which is the out of IC7 actually is the out of L-R VCA which going on R10 & R12 of IC1a & IC2 which is L-R, L+R adder/buffers and add between one Phase Rotator circuit similar that of used on input of any broadcasting processor (look at below given scheme). The Phase Rotator circuit act as x1 buffer on L-R audio levels so no worry for any trouble, his effect is good enough on stereo width image because his phase rotation is depended by the freq. that scheme by its self as all Phase Rotator circuits add some delay “echo”, if you use more of there or six cascaded such given circuits then the delay on L-R products is longer.  For IC you can use and here OPA2134, the indicated tolerance for grounded capacitor is for rotation freq. under of about 400hz, (vocal low region) for higher freq. use smaller tolerance, freely you can experiment to catch your preferred results.

Phase Rotator with buffer

That’s all folks, I don’t have any other modification. You play enough, now its time to restore yours 222A at his original state:)

ADVICE: DO NOT try to give some appeal of today digital toys on your old analogue units, leave it as IS in PEACE, if you want to play with digital toys then go to buy one. DON’T try make your analogue unit a horribly “Frankenstein” unit.