Just bought an Oberheim OB8....wow!

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Floss
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Just bought an Oberheim OB8....wow!

Post by Floss » Sat Oct 19, 2013 6:47 am

This things sounds so beautiful!

Question:

one voice is alot lower in volume than the other 8. what do I do?

Sounds, it has virtually no sounds. I wanna load via Wav. but Im afraid i will decalibrate my synths, as I have heard it can do! or does it not matter, or does someone with a well calibrated Obie post a wav of their factory bank?! thanks

When I tune the synthh, it shuts off voices 5, and 6, but when I turn them on they are in tune. What gives?

Thanks for your help, really want to start creating with this synth!

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Re: Just bought an Oberheim OB8....wow!

Post by radek tymecki » Sat Oct 19, 2013 8:53 am

congratz, massive synth! you can load via casette it wonr decalibrate synth! when one voice has lower volume check panning pots on the right side of the synth. anyway... try to tune it with service manual. should help

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Re: Just bought an Oberheim OB8....wow!

Post by Bitexion » Sat Oct 19, 2013 9:08 am

Nah a WAV wouldn't decalibrate the synth in any possible way, it's just a recording of the pulsewidth modulated signal that get sent via cassette anyway. You can load WAV files directly from your computer even, don't need a cassette tape deck and tape. Just plug the computer's output to the cassette input on the synth, and experiment with the correct output volume level until the synth accepts it.
I have done this successfully with several 80s synths with cassette input. I could switch soundbanks in my Juno-106 in a few seconds by playing different WAV files into it from my computer.

You can't break anything, if the synth doesn't recognize the sound file, it doesn't do anything at all.
Videogames of the 80s were usually using the same data transfer method to load from cassette storage device into the computer. It's just a modulated square wave. You can hear the whole signal as it transfers since it's in the audible Hz range.

I've spent many hours listening to screeching cassette load sounds from my C64, as games would usually take several minutes to load, and so the "loader music" phenomenom came around, as coders made a song for us to listen to while waiting for the game to load, and usually a nice picture to look at. If the tape player was somehow uncalibrated after long use, the games wouldn't load and you'd have to recalibrate the tape read head with a tiny screwdriver..
In some cases, the loader music became more famous than the actual game itself. The cassette will just play back the same few seconds of screeching sounds as the WAV file will.

It is the exact same method used to transfer patches to a synth. And you can use any audio source as long as it goes into the cassette input on the synth, and have the correct WAV files. I've found collections of banks as WAV files on lots of websites with google.

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Re: Just bought an Oberheim OB8....wow!

Post by Floss » Sat Oct 19, 2013 11:03 am

Okay will try this this afternoon! It has nothing to do with my pan knob... I have stereo outs. I also don't have the tape so can I do via my sound card?? Thanks for the speedy reply

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Re: Just bought an Oberheim OB8....wow!

Post by Bitexion » Sat Oct 19, 2013 11:22 am

Yes you can do it via your sound card, like I said. Just get an output from your PC to the cassette input on the synth, play the wav file in mediaplayer or whatever. When you find the right output level the synth will register it and load the patches.

The cassette tape/player itself was just another means of playing the audio signal into the synth. You don't need that.

You probably have to set the synth in some kind of "receive" mode, manual should tell that.

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Re: Just bought an Oberheim OB8....wow!

Post by Floss » Sat Oct 19, 2013 11:38 am

Thnx!

And the lone voice that's quiet?

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Re: Just bought an Oberheim OB8....wow!

Post by Floss » Sat Oct 19, 2013 3:13 pm

Judging from the replies No one knows why the Obie is shutting off voice 5 and 6 after tune

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Re: Just bought an Oberheim OB8....wow!

Post by Z » Sat Oct 19, 2013 4:07 pm

Could be a bad CEM3310 or CEM3340.

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Re: Just bought an Oberheim OB8....wow!

Post by synthroom » Sat Oct 19, 2013 8:16 pm

Probably bad chips, like Z says, but you could pulling the voice cards and swapping their positions to confirm it is the cards.
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Re: Just bought an Oberheim OB8....wow!

Post by Floss » Sun Oct 20, 2013 5:22 pm

Okay is there a mode where I can confirm which one is being triggered. Also 3340 are voice chips. How do I get about hearing the affects or know which 3310 I'm dealing with ? :(

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Re: Just bought an Oberheim OB8....wow!

Post by Bitexion » Mon Oct 21, 2013 11:11 am

Isn't there a row of lights that light up when a voice is triggered? Then you can clearly see which voice isn't playing by retriggering a single key until it cycles to that voice.

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Re: Just bought an Oberheim OB8....wow!

Post by synthparts » Mon Oct 21, 2013 1:07 pm

Yes there is an LED on the voice boards next to each voice that lights up when triggered... You can also adjust the pan pots to figure out what voice is playing if you don't wanna open the lid...
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Re: Just bought an Oberheim OB8....wow!

Post by adhmzaiusz » Mon Oct 21, 2013 8:54 pm

synthroom wrote:but you could pulling the voice cards and swapping their positions to confirm it is the cards.
The OB8 has two voice cards, and one has a terminator on it which tells the synth which card is which. You need to also switch a jumper near the header to test this method, but swapping chips is way more practical.
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Re: Just bought an Oberheim OB8....wow!

Post by Floss » Tue Oct 22, 2013 1:11 am

Sorry for all the dumb questions but how do I know which voice card to start with. I am assuming there are 16 cem 3340s...?

And the 3310( that's not a voice chip..)

Thanks for all the replies

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Re: Just bought an Oberheim OB8....wow!

Post by Z » Tue Oct 22, 2013 2:11 am

There are EIGHT voice boards in the OB-8. When you open the synth, you'll see four voice cards on the right and there will be four more below them. The top four are on a hinged PCB that you'll have to unscrew to get to the bottom four.

Each voice card has a red LED that illuminates when that voice is being triggered by the synth. If you're confident enough to trouble shoot your own synth, you can start swapping known working CEMs with CEMs on the faulty voice card.

I am not that confident and prefer to have my tech work on $2500+ synthesizers.

EDIT: Sorry, I confused the OB-X / Xa's innards with the OB-8's. adhmzaiusz was correct, that there are only 2 voice boards, but each voice board has all the components for a single voice arranged in a rectangle in a fashion similar to individual voice boards of the OB-X / Xa.

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