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Radial JPC did we expect too much (& a rotary encoder supplementary Q?)

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Radial JPC did we expect too much (& a rotary encoder supplementary Q?)

Postby hooty2 » Mon Feb 24, 2020 11:46 am

Hello,
I'm wondering if we asked too much of the JPC stereo Di to completely stop noise from a laptop?
The query is also prompted by another recent thread on the forum where the virtues of the ART DTI were extolled.

Q1: this is the main question:
At a small live acoustic gig last night, a DJ presented his soundscapes ambient dance music as a finale'.
He used headphone output for audio & we put a Radial JPC di (3.5mm stereo to x2 mono jacks) before running XLR's into a VDC snake & onto o1v mixer.
We swapped out new leads and used alternative 13Amp outlets & kept his power lead away from audio leads.

Awful crackly glitchety constant noise that he said happens often unless he uses an interface and always worse when battery is fully charged.

In the end his programme masked the noise & the set was anyway out of sync artistically with the session that preceded it, & the audience drifted out ...but it (the inability to stop the noise) was disappointing.
Should the JPC stop that?

Question 2: the rotary encoder on fx returns on the o1v leaps about and needs gentle fingers and patience...it can be cajoled to sit where we want it, bit it can't be used on the fly to vary the return.
There is a nut holding the thing in place...i cleaned around the stem to the pot but the issue is clearly deeper. I'm loathe to..&...not competent to pull the whole hood off....
Any thoughts on why the encoder behaves like this and the probable only solution?

cheers for indulging two queries (if you did:))
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Re: Radial JPC did we expect too much (& a rotary encoder supplementary Q?)

Postby Hugh Robjohns » Mon Feb 24, 2020 11:54 am

hooty2 wrote:Awful crackly glitchety constant noise that he said happens often unless he uses an interface and always worse when battery is fully charged.

I have a JPC and it's brilliant for that application.... but it can only ever sound as good as the headphone socket it's plugged into! I suspect had you plugged headphones in instead you would still have heard the same crackling noises. Nothing you can do about nasty power management noises on the internal sound card... I've found a simple USB D-A thumbdrive-style converter (one that works natively without drivers on both Macs and PCs) often works better -- and I take the headphone socket from that into the JPC.

Any thoughts on why the encoder behaves like this and the probable only solution?

Dirt on the encoder's internal workings. On a traditional analogue pot it would go noisy and scratchy. On a digital encoder you get erratic output data. Replacement is usually the only practical solution I'm afraid

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Re: Radial JPC did we expect too much (& a rotary encoder supplementary Q?)

Postby AlecSp » Mon Feb 24, 2020 12:02 pm

Hugh Robjohns wrote:I have a JPC and it's brilliant for that application.... but it can only ever sound as good as the headphone socket it's plugged into! I suspect had you plugged headphones in instead you would still have heard the same crackling noises. Nothing you can do about nasty power management noises on the internal sound card... I've found a simple USB D-A thumbdrive-style converter (one that works natively without drivers on both Macs and PCs) often works better -- and I take the headphone socket from that into the JPC.
Hugh is, as usual, right.
I, too, have had my fair share of noisy laptops when using their headphone outputs.

To help a little more on the subject of driverless USB D-A interfaces, even the cheap Behringer UCA202 (under £20) will give a far better sounding output than most if not all built in outputs on PCs/laptops. No drivers required.
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Re: Radial JPC did we expect too much (& a rotary encoder supplementary Q?)

Postby hooty2 » Mon Feb 24, 2020 12:11 pm

thanks for that (twice:))

i know what to do now, and i'm setting about doing it
regards
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Re: Radial JPC did we expect too much (& a rotary encoder supplementary Q?)

Postby Hugh Robjohns » Mon Feb 24, 2020 12:24 pm

Just one word of caution. I promote 'safe sound'... ;)

When I'm providing live-sound facilities I'm paranoid about maintaining galvanic isolation between the PA rig and anyone else's equipment on stage -- be that laptops, keyboards, or whatever. I don't want a phantom power -- or worse still, a mains power -- problem in my gear to damage/destroy the presenter/performer's gear. And equally, I don't want a problem with their gear causing damage to mine.

So I ALWAYS make sure there's something with an audio transformer between their gear and mine. That could be a DI box (active or passive), or a line isolator box, or an transformer-output interface... but there will always be something in the way to provide protection.

The only time I don't -- and it's not that often -- is where all the gear is my own or I otherwise know for absolute certain that it's completely safe, and I'm the only one doing the connecting!

Hence, the reason I use a thumbdrive DAC feeding the JPC. If I was to use a cheap interface with electronically balanced outputs I'd connect it to the stage snake via a line isolation box.

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Re: Radial JPC did we expect too much (& a rotary encoder supplementary Q?)

Postby AlecSp » Tue Feb 25, 2020 12:40 am

Hugh Robjohns wrote:Hence, the reason I use a thumbdrive DAC feeding the JPC. If I was to use a cheap interface with electronically balanced outputs I'd connect it to the stage snake via a line isolation box.
Quite! And again, why I quite like the UCA202 - just unbalanced phono outputs, so has to go into a DI box to get to my XLR inputs.

Though, true, some might take it direct into a line input - not me, though.
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