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Thread: switching balanced & unbalanced output on 388

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    switching balanced & unbalanced output on 388

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    I've always run the 388 master outs unbalanced as I can see in the schematics theres bunch of things going on to convert the master out to a balanced signal. I've always thought switching to balanced will degrade the audio path quality. However, I wouldn't mind strapping a comp or eq across the mix. That gear is balanced of course.

    I have a Radial Pro DI 2 which is a passive DI box, would this work better to make the conversion? Or for better quality would I be better off using a couple of Lundahl Problem Solvers? Maybe getting some good transformers and making my own box?

    thb Im not hearing a big difference when switching between balanced and unbalanced. Are the any test I could do that might reveal the differences?

    am I completely over thinking this?

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    Quote Originally Posted by mr.blisset View Post
    I've always run the 388 master outs unbalanced as I can see in the schematics theres bunch of things going on to convert the master out to a balanced signal. I've always thought switching to balanced will degrade the audio path quality. However, I wouldn't mind strapping a comp or eq across the mix. That gear is balanced of course.

    I have a Radial Pro DI 2 which is a passive DI box, would this work better to make the conversion? Or for better quality would I be better off using a couple of Lundahl Problem Solvers? Maybe getting some good transformers and making my own box?

    thb Im not hearing a big difference when switching between balanced and unbalanced. Are the any test I could do that might reveal the differences?

    am I completely over thinking this?
    Well "I" can't see from any schematics! I cannot see there could be much 'adulteration'? If an op amp there will just be another stage. If discrete a few more transistors or/and a transformer.

    I personally think Lundies or even Jensen traffs are a bit of an overkill for tape signals. The distortion levels of £20/$20 traffs from the likes of OEP are well below those of tape, where do you peak to? 3% thd? Bandwidth of '600-600Ohm' output traffs is not a problem because they are 1:1 and often bifiliar wound.

    In the esoteric would of digital recording a bog standard balanced INPUT is some 14dB noisier than an unbalanced one but since even the former come out below -100dBu not really a problem?

    A DI box is 10:1, not at all what you need.

    Dave.

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    The 'bunch of things' is very unlikely to introduce any problems, and I doubt if you could even hear it - probably a chip with differential output. If you are going into an analogue external device, that's degrading the signal far more than the balancing would, and if you select unbalanced out then you're not taking advantage of the signal to noise the desk has, and any gain makeup will be done at the processor, where it will have to make the gain up anyway. I've never heard anyone concerned about their mixer sounding worse when balanced - probably because they don't. The unbalanced external linkages would probably raise the noise floor more than if you run balanced, that's why people use it through choice.

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    The balance amp on the 388 is a +/-15V powered semi-discrete design with a discrete transistor output stage, and the input stage uses a 2041 opamp, which is considered a high output variant of the TL072. In my opinion I’d leave it alone and just use what’s in the 388. I’m not sure what you would gain by adding boxes in between the 388 and your downstream device.

    You might have said it already but what are you driving withbthe balanced out specifically? What device are the 388 outputs connected to?

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    You're not going to outthink the Tascam engineers. You've got a balanced output and a balanced input. Connect them, they were literally made for each other.

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    Err? They SAY "sarcasm is the lowest form of wit" and it seems to have done me no good!

    To be plain I would LOOOOOVE to see those schematics!

    Dave.

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    Quote Originally Posted by sweetbeats View Post
    The balance amp on the 388 is a +/-15V powered semi-discrete design with a discrete transistor output stage, and the input stage uses a 2041 opamp, which is considered a high output variant of the TL072. In my opinion I’d leave it alone and just use what’s in the 388. I’m not sure what you would gain by adding boxes in between the 388 and your downstream device.

    You might have said it already but what are you driving withbthe balanced out specifically? What device are the 388 outputs connected to?
    According to this: http://52ebad10ee97eea25d5e-d7d40819...JM2041D_DS.pdf

    The IC is a bipolar input device but seems to have the poor load drive capability of the '72 (hence the extra transistors). It seems an NE5532, better an LM4562 could be a drop in, the discrete kit scrapped and still get all the drive you need into 600 Ohms? NOT that anybody does that these days!

    But as you say Mr S, why bother?

    Dave.

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    If you really want good sound quality, why are you using cassette?

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    Quote Originally Posted by bouldersoundguy View Post
    If you really want good sound quality, why are you using cassette?
    Indeed, 78s with thorn needles are the New Black.

    Dave.

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    I mean, you're not going to hurt anything running the unbalanced output into a balanced input either, but balanced almost has to be better for noise. Not that you'll notice under the waterfall of tape hiss...

    A DI (as mentioned above) will attenuate the signal and add its own little bit of noise. You'll pick up less (bot not no) noise on the balanced run, but you'll have to turn that noise up more at the other end.

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