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OBERHEIM OB-Xa
Old 29th January 2013
  #1
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Gringo Starr's Avatar
 
🎧 10 years
OBERHEIM OB-Xa

I'm just wondering what the reliability of these synths are. Are there any potential nightmare repair issues? Can't find certain parts or something???

Also, are there different revisions? Certain serial numbers I should avoid or look for?

And I know it's a matter of personal taste, but where does the OB-Xa rank amongst the OBX and OB8 and the Xpander in your opinion?
Old 29th January 2013
  #2
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clusterchord's Avatar
 
🎧 15 years
mine has been fairly stable over last 8 years. however.. this means some mandatory operations are done. i did them in few stages over the yrs not all at once.


1 you have to completely re-cap the machine, noise floor drops. and on this peticular analog (not on all) there was subtle restoration of transients and high end. however, its even more important bcs of stability of tuning. i had it go out of tune constantly until i did that.

2 in time i couldnt set the pitch trimmers on voiceboards exactly where i wanted as they are a) low resolution b) 30 yrs old.... so replace the vco1 and vco2 and if you want filter v/oct trimmers with nice multiturn ones

3 take out all the logic and CEM chips and clean their legs from black crap that gathered there over the yrs. contact can give you problems. tho i never had this issue on obxa, but had and still have on obx.


bottom line, i find the stuff about obxa is fairly known, and all together its easy to repair. i NEVER had a CEM chip die on me, in all CEM machines i have or had. insanely overblown out of proportion. use nice protected outlets for your analogs. good grounding etc.


and a tip in use: OBXa has relatively low signal output compared to JP8 or OBX etc. of all the analogs i got, it absolutely loves going into a nice discrete preamp with transformers (like my Great River NV). i usually drive the transformer into sat a little bit. it gets the colour of the synth closer to those old records (where it went thru a lot of that in tracking and finally end on tape), by softening the buzz of the CEMs a tad. another thing i do, if im not going to use a sound for more than 4 poly, i disconnect the upper voicetray... voila!! the signal becomes 6dB stronger and bigger.. its all nice subtle variations u use during tracking stage.


it will be burried with me. nuff said.
Old 29th January 2013
  #3
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maisonvague's Avatar
 
🎧 10 years
Well, I've had my OB-Xa for about seventeen years and he's about to go in for his first service in all that time! Recently one of the voice cards started failing the auto-tuning routine and so gets switched off automatically turning my eight-voice Obie into a seven-voice. So I'm using the occasion to have my tech give him a complete overhaul (recapping, etc). I restored the keyboard myself a couple of years ago with all new bushings, etc. A fresh Pratt-Reed action can feel really good (though it's hard to imagine, I know).

Basically it's been solid as a rock! Never had any serious problems with it. Mine is a later model with 8-voices and 120 patch memories. I would recommend getting an 8-voice model because outfitting four or six-voice models with more cards can be costly.

As for ranking it against the OB-X, OB-8, etc. I'll leave that for others who have stronger opinions on the matter. I don't. Each has his strengths and weaknesses, but they're ALL excellent instruments. Basically you can't go wrong with any of them.
Old 29th January 2013 | Show parent
  #4
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maisonvague's Avatar
 
🎧 10 years
Quote:
Originally Posted by clusterchord ➑️
another thing i do, if im not going to use a sound for more than 4 poly, i disconnect the upper voicetray... voila!! the signal becomes 6dB stronger and bigger.. its all nice subtle variations u use during tracking stage.
Brilliant! Never thought of doing that! The Xa has the lowest output of any of my synths. Up until recently, the only high-grade pre-amp I had was a UA Solo 610. But a little tube goes a long way... so I finally broke down and got some better solid-state preamps than the ones on my Mackie . Haven't tried them yet with the Obie, but I intend to.
Old 29th January 2013
  #5
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PeteJames's Avatar
 
🎧 10 years
I love my OB8 a lot - very warm and lush. Has some nice extra features such as triangle and an extra LFO. Stays in tune great and had midi. OB's can have quite stiff pots - my filter cutoff and master tune and pwm are a lot tighter than the others so watch out for that. I quite like it for bass too if you transpose the keyboard down an octave gets the floor shaking nicely! Go for it!
Old 29th January 2013
  #6
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clusterchord's Avatar
 
🎧 15 years
yeah, and the stringy droney sounds it makes... especially with looong release tales, with voices melting one into another...or dense chords.. 8 voices is a must..
Old 29th January 2013 | Show parent
  #7
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clusterchord's Avatar
 
🎧 15 years
Quote:
Originally Posted by maisonvague ➑️
Brilliant! Never thought of doing that! The Xa has the lowest output of any of my synths. Up until recently, the only high-grade pre-amp I had was a UA Solo 610. But a little tube goes a long way... so I finally broke down and got some better solid-state preamps than the ones on my Mackie . Haven't tried them yet with the Obie, but I intend to.

yeah, besides that you can also try turning all the 4 voice pans to the one side, and use that output. cant remember now, but i think i got some extra dB that way as well. im using Great River for my solid state, and its god given for just about any signal i fed into it. synths love it. voices and bass guitars too. i recorded some violins and clarinets also.. amazing.
Old 29th January 2013
  #8
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javd007's Avatar
 
🎧 5 years
I had an OB-xa last year and sold it. It broke on average once a month. It was horribly unreliable. I would be afraid to use it. I would try to only use it when i really needed a specific sound. It wasnt a synth to just turn on and jam with. I sold it for that reason. since then i bought an OB8 and it is now my favorite synth. It is UBER reliable. i just turn it on and jam. It gets turned on on average 6 times a day. Its been rock solid thus far. Now onto the sounds: The OB8 is a tad different than the XA. The Xa had a more (squelchy?) resonance. The Xa sounded a bit more loose on the tuning. So that could mean fatter? But I dont want to say fatter because its really not. Hard to explain. The Xa also had a slightly faster attack. Having said that the OB8 is wayyyyyyyy more versatile. It can produce many more sounds. It also has a great arpeggiator, midi, voice panning on the outside, lfo midi sync, it is lighter and much more reliable. The OB8 sounds more like a modern day synth. The OB8 can do modern trance sounds, the Xa sounded a bit more late 70s- early 80s. The OB8 sounds a bit more 1985-today. I hands down recommend the OB8 over the Xa. Good luck!
Old 29th January 2013
  #9
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LNerell's Avatar
 
🎧 10 years
OBXa's had between 4-8 voices and no midi. The early models only had 32 patch locations, later ones had 120 and should have a little placard saying so. Their was no factory midi so any midi kit is 3rd party, some are better then others.

As far as where does it line up with other Oberheims, hard to say. It has less parts then an OBX, more then an OB8. Those three are the most similar, the Xpander/Matrix 12 is a different beast. I had an OBXa for over 25 years and I enjoyed it every time I used it. Still wish I had it now.
Old 29th January 2013 | Show parent
  #10
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maisonvague's Avatar
 
🎧 10 years
Quote:
Originally Posted by clusterchord ➑️
im using Great River for my solid state, and its god given for just about any signal i fed into it. synths love it. voices and bass guitars too. i recorded some violins and clarinets also.. amazing.
Sounds awesome. I've had such good experience with the Solo 610 (mostly on vocals) I decided to try out some more UA gear and got a 4-710d. So far the only synth I've tried recording through it is my Prophet-10. It sounds absolutely gorgeous in the TRANS settting (100% solid-state) and pretty good on the tube setting as well. The 1176 style compressors on that unit are a nice touch, though limited. I'm a recent convert to using specialized preamps for synths. I used to not care or see the point. That all changed the first time I heard my Little Phatty going through the 610.
Old 29th January 2013
  #11
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Gringo Starr's Avatar
 
🎧 10 years
Thanks everyone. There's one for sale in my area. I read that it's very similar to the Prophet 5 which I have so I might pass. Maybe an Xpander would fit better with the P5. I would like a really good Oberheim. Though I do have a Matrix 1000 which I love. :-)
Old 29th January 2013
  #12
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javd007's Avatar
 
🎧 5 years
Gringo get an OB8 ... Trust me on this. I have a p5 and I love my OB8 more!
Old 29th January 2013 | Show parent
  #13
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maisonvague's Avatar
 
🎧 10 years
Quote:
Originally Posted by Gringo Starr ➑️
Thanks everyone. There's one for sale in my area. I read that it's very similar to the Prophet 5 which ...
...which is completely untrue (even for rev3s)! You shouldn't believe everything you read.

They are similar in only the most superficial way. My Prophet-5 has shared a keyboard stand with my OB-Xa for years and I can assure you their character is as different as night and day.

You'll often read stuff about "CEM overlap" and other such nonsense, but you take even the most basic things like the fact that the OB-Xa is bi-timbral and has a switchable 2-pole/4-pole filter and you've got enough of a reason to justify having both an Xa and a P-5 in my book.

I would agree, however, that if you're looking for maximum contrast the Xpander would be the way to go. And forget about "Matrix overlap" with your Matrix-1000!!! Similar in name and theory only!!!
Old 29th January 2013 | Show parent
  #14
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flat's Avatar
 
🎧 10 years
Quote:
Originally Posted by clusterchord ➑️
yeah, and the stringy droney sounds it makes... especially with looong release tales, with voices melting one into another...or dense chords.. 8 voices is a must..
Stop rubbing it in

Even though my OBXa is currently 4 voice, the pure CEM growl & sizzle is sometimes breathtaking, even when used monophonic. Its a pleasure to play & own. I honestly have no gripes with it, (although it is physically huge).

You really can't go wrong with an Xa, if you find a decent serviced unit. They are probably the best value analogue Polysynth available atm, and easily on par with JP8 and P5 as a quality high end flagship synthesizer.
Old 29th January 2013 | Show parent
  #15
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maisonvague's Avatar
 
🎧 10 years
Quote:
Originally Posted by flat earth ➑️
Stop rubbing it in


Still haven't ponied up for more voice cards, he?

To be honest, I play my Xa most often in dual mode. While that wouldn't be as much fun, of course, on a four-voice, the point is I can usually get by with only four-voices in the majority of my arrangements. What's more, four-voice unison is much more practical than eight-voice unison when playing the Obie monophonically. Only rarely do I have a need for eight-voice unison on a synth with such beefy oscillators (for example, the solo for Synthpop's Alive heh).

HOWEVER... like clusterchord said... well, I won't repeat it. Just pony up, dude! Life's too short!
Old 29th January 2013 | Show parent
  #16
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flat's Avatar
 
🎧 10 years
Quote:
Originally Posted by maisonvague ➑️
... well, I won't repeat it. Just pony up, dude! Life's too short!
Just when I had convinced myself I could live with 4 voices, and am trying to muster MiniMS20 funds lol

However, 4 OBXa voice cards at todays prices is just too much for me. Sometimes you just have to appreciate what you have.
Old 29th January 2013 | Show parent
  #17
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maisonvague's Avatar
 
🎧 10 years
Quote:
Originally Posted by flat earth ➑️
Sometimes you just have to appreciate what you have.
I couldn't agree more and presume you know I wasn't being entirely serious!

Coming to grips with compromise is an essential ingredient for balance and harmony and avoidance of conflict.

Regarding the MS-20 Mini, I'm determined to get one, if for no other reason than to give that sad little KORG fish more company!
Old 29th January 2013 | Show parent
  #18
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flat's Avatar
 
🎧 10 years
Quote:
Originally Posted by maisonvague ➑️
I couldn't agree more and presume you know I wasn't being entirely serious!
Maisonvague, you are one of the most down to earth, logical & mellow people on this forum. Of course I knew.

Quote:
Coming to grips with compromise is an essential ingredient for balance and harmony and avoidance of conflict.
Amen. Sig worthy.

Quote:
Regarding the MS-20 Mini, I'm determined to get one, if for no other reason than to give that sad little KORG fish more company!
β€œThe man who follows the crowd will usually get no further than the crowd. The man who walks alone is likely to find himself in places no one has ever been.” Alan Ashley-Pitt
Old 29th January 2013
  #19
Lives for gear
 
🎧 10 years
i wouldnt expect any obxa (or especially obx) to be fully operational and reliable at this point in time without a good servicing from a tech who's very familiar with these and the problems they typically have. that said, i havent heard about any problems our buyers have had with the obxas or obxs we've sold, but we have always put a great deal of time and money into servicing them first. if you have one and it keeps breaking down, it would probably be a good idea to give it a full overhaul to correct their common points of failure.
mini
Old 29th January 2013 | Show parent
  #20
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DesolationBlvd's Avatar
 
🎧 5 years
Quote:
Originally Posted by Gringo Starr ➑️
Thanks everyone. There's one for sale in my area. I read that it's very similar to the Prophet 5 which I have so I might pass. Maybe an Xpander would fit better with the P5. I would like a really good Oberheim. Though I do have a Matrix 1000 which I love. :-)
The only overlap between Prophet-5 and OB-Xa is when you have the resonance down and the OB's filter in 4-pole mode (e. g. brass).

Matrix-1000 actually overlaps more with Prophet-5 than with other Oberheim synthesizers, because it only has 24dB/oct filtering.


Quote:
Originally Posted by maisonvague ➑️
Only rarely do I have a need for eight-voice unison on a synth with such beefy oscillators
Wait, are you trying to do unison with both oscillators on? I prefer 1 oscillator x 8 over 2 oscillators x 4 for big unison.



Quote:
Originally Posted by javd007 ➑️
I had an OB-xa last year and sold it. It broke on average once a month. It was horribly unreliable. I would be afraid to use it. I would try to only use it when i really needed a specific sound. It wasnt a synth to just turn on and jam with. I sold it for that reason. since then i bought an OB8 and it is now my favorite synth. It is UBER reliable. i just turn it on and jam. It gets turned on on average 6 times a day. Its been rock solid thus far.
Have been having problems with mine since August - at first it was tuning and panel issues, but then it fell comatose one day. Finally pinpointed it to the power supply board and the -5V bridge rectifier - which I then goofed up trying to replace as the "legs" on my replacement bridge rectifier were too big.

I almost find myself wishing I had just gone with OB-8.

From what I've read, the -5V bridge rectifier is a weak spot on the OB series (X and 8 too). It's just that 8 doesn't have the other points of failure.
Old 30th January 2013
  #21
Lives for gear
 
🎧 10 years
Soundwise the non-MIDI Oberheims (OB-Xa, OB-X, OB-1, SEMs) have that "classic" dirty sound with a unique girth. The MIDI Oberheims starting with the OB-8, Xpander, Matrix sounded cleaner with each progressing model but more modulation options. The camps seem evenly divided between the two.

If you find an OB-Xa that doesn't have all eight voice cards, extra voice cards are very expensive and do not show up often on the used market.

Is an OB-Xa reliable? In the hands of a competent tech, yes. Three common problems are blown 4xxx CMOS ICs, aging caps and trimpots, and bad power supplies. Oberheim stuffed them with early RCA CMOS ICs which did not have overvoltage protection, and a design error in the OB-X/Xa made them vulnerable to being blown (OB-8 fixed the error). Aging electrolytic caps do dry out, and tantalum caps on the power rails (not in audio circuits) MUST be replaced. Power supply issues include underspec'd bridge rectifiers. A competent tech can make an Oberheim last a long time.

Only once did I lose CEM3310 in my Memorymoog in the twenty plus years I have owned it, I attribute that to a rare power transient. None of my other CEM based synths lost any.
Old 30th January 2013
  #22
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javd007's Avatar
 
🎧 5 years
Maybe a well serviced OBXA is reliable. I wouldnt take the chance. Mine was literally that bad. Voice problems, tuning problems, power supply problems etc.. It was a joke. Sounded great though. But then again so does the OB8.
Old 30th January 2013
  #23
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dougt's Avatar
 
🎧 10 years
The big reason to go for 8 voices is so you can use layer mode and layer 2 patches and still have 4-note polyphony. I still have a few complete OB-Xa voice cards available...
Old 30th March 2014
  #24
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Firechild's Avatar
 
🎧 10 years
How to find the serial number

I recently bought a OB-Xa and everything seems to be just fine. The filter envelope attack time differs a bit between all voices , differs more the longer attack time you set of course but I think it is in acceptable range.
However the output is kind of low so I am thinking it is one of the earlier 120 program units but unfortunately the serial number sticker on the back is removed/lost/gone. Is there another way to find the serial number?
Reading the service manual two resistors were changed eco#136 to boost the output level , so in case I have an earlier unit it may be possible for a tech to do the mod ?
Old 30th March 2014
  #25
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maisonvague's Avatar
 
🎧 10 years
Sorry, but I'm not sure if the serial number is recorded anywhere else on the instrument. As for the envelope times, they differ on mine as well but only between the upper and lower voice boards and not the individual voices. In other words, one set of four voices has one set of times, the other four voices another. The difference is a bit too much for my tastes, and is something I've been meaning to have fixed for years but just haven't gotten around to yet. Mine also has a low output level. So I usually run it through a good quality solidstate preamp to add some gain.
Old 31st March 2014
  #26
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Firechild's Avatar
 
🎧 10 years
Yes, mine has analog glide for sure. The seller told me so and when playing unison + portamento the voices will not reach the target note at the same time
However it is kind of a cool feature... :D
Old 31st March 2014
  #27
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dougt's Avatar
 
🎧 10 years
Another way to date it is to look for the board rev letter. For example the top processor board should say 1504 followed by A, B, etc up to G for the latest ones...

Also the voice boards should all have a production date on them. The earliest boards I have are from January 1981 and are beige colored instead of the usual green...

The back panels on the earliest OB-Xas look like the OB-X with just the large Oberheim sticker no "OB-Xa"...
Old 31st March 2014 | Show parent
  #28
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ionian's Avatar
 
1 Review written
🎧 10 years
Quote:
Originally Posted by Firechild ➑️
when playing unison + portamento the voices will not reach the target note at the same time
My OB8 does exactly the same thing. Did the OB8 have analog glide or digital glide?

Regards,
Frank
Old 31st March 2014 | Show parent
  #29
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Firechild's Avatar
 
🎧 10 years
Quote:
Originally Posted by dougt ➑️
Another way to date it is to look for the board rev letter. For example the top processor board should say 1504 followed by A, B, etc up to G for the latest ones...

Also the voice boards should all have a production date on them. The earliest boards I have are from January 1981 and are beige colored instead of the usual green...

The back panels on the earliest OB-Xas look like the OB-X with just the large Oberheim sticker no "OB-Xa"...
Thanks , good info.
I decided to go for a Kenton midi kit today as Encore is out of stock. However there is a user that got even lower output level after Kenton MiDi installtion. Is there a risk for that?
Old 31st March 2014
  #30
SEED78
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something has always sounded less polite about he Xa to me in demos than other OB synths of that era - I'm drawn to it because of that.
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