Joeweak!!

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michael.butler

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I need help. (as always)

I got a joemeek vcq3 a few weeks ago. It was out of the box w/ no adapter. Stupidly I didn't follow the advice of several who warned not to use the unit w/ any adapter other than the one it should come with. But here's the thing. I ran across an old Fostex 4 track adapter that seemed to work fine. In fact, I've been using the pre w/ that adapter quite frequently w/ great success, but, until today, none of the signals I've been sending have required phantom power. I've been micing amps w/ a 57 and using the line in for some bass tracks. It's worked fine. Plenty of hot signal and sounds great.

Today I was excited to try vox w/ it. Mic of choice was a large audio technica condenser (4035, I think....sharpest tool in my shed anyway..$500 mic). I powered up the 48 phantom...light comes on and everything. Problem is, I can't get a decent signal until both the drive AND output are up to about 5 o'clock, and, by then, there's so much noise, it sounds like the Pacific ocean!!

W/ all other pre's I have (dbx, presonus) this mic is hot, hot, hot.


So....is it possible that the adapter I'm using could be supplying plenty of power for all applications except phantom power? (Remember, the phantom light DOES come on when engaged).
It just seems strange that it works fine otherwise.

ANY words of wisdom would be greatly appreciated!!

Michael
 
TFR..but maybe I should rephrase...Any answers to these q's would be appreciated.

Thanks
 
michael.butler said:
maybe I should rephrase
Click to expand...

Maybe I can rephrase for you:

You know that writing in the manual you were talking about that gives you such good advice to use the right adapter?

Follow it.
 
Get the right adapter!

If not, and assuming that the vcq3 takes the same power as the mq3, you need an adapter that puts out 12 volts AC at one amp. That is, 12VAC@1.0A or 12VA.
Look on your Fostex adapter and see how it compares to these values, If it's DC, or the voltage is more than a volt or two different, it might not work well or work at all. If the amps are higher, that's OK. If the voltage is much higher, you might have already trashed something.

Good luck!
 
You're welcome, glad to help.

Also, if the current rating is less than 1 amp (say less than 900 ma because there is probably a fudge factor involved) it might not work well also, as it will try to put out the needed current and be unable, which will drag down the voltage also.

If you need an adapter, RS I think still has a system where you buy the adapter with the needed parameters and a separate connecter of whatever type needed to connect it to your device, for $10-$15.
 
seems like such a small thing - contacting the manufacturer and getting the right part. I am curious as to why you are so dead set against doing the obvious? It's not like you are going to improve the sound of the unit with a non-standard adaptor, and you could very well damage or even kill it! :confused:
 
The industry is clever about this. They specify specific adaptors for their own bits of kit which can only be used for the purpose intended.

Having an adaptor with the right plug, and the right voltage is only half the battle. You HAVE to have an a daptor with the correct current rating. If it is too high, it can fry the machine, if it is too low, then you simply wont be getting enough power into the product. With Printers, and video games this is usually not a problem, and you can get away with 100 mA here and there no bother. Musical equipment however is precision engineered to run with the correct current. Too little current running through your VC3, and ur correct, the phantom power wont work, nor will any of the other bits work correctly. An LED takes very little current to light up which is why the light is coming on. But the 48V required at the microphone is a different matter.

If the adaptor you are using has a higher current than required, it stand a good chance that you have fries the circuitry inside the VC3.

from the online VC3 handbook (europe version):

THE POWER SUPPLY.
An external 12V AC power supply provides the power for the unit. DO NOT ATTEMPT TO POWER THE UNIT FROM ANY POWER SUPPLY OTHER THAN THE ONE SUPPLIED WITH THE UNIT. Circuitry inside the unit converts the 12V AC into 14.5-0-14.5V and 48V DC supplies for the amplifiers and the phantom power.
Power rating is 5 watts.
Click to expand...

This doesnt tell you the current rating, but you should ring up JoeMeek to find out hwat it should be. You CAN use another adaptor as long as it is the same Voltage (12v AC) and current rating.....

I use a VC3 and have no problems, so it is unlikely to be the product.

Peace
 
NickHall said:
You HAVE to have an a daptor with the correct current rating. If it is too high, it can fry the machine, if it is too low, then you simply wont be getting enough power into the product
Click to expand...


NONONONONO........The current rating on an adapter is how much current the device can supply...It cant magically force more current through your device and damage it. Current equals voltage/resistance. If you have 12 volts, across a a 10 ohm load, you have 1.2 amps...Period...It doesnt matter if the adapter says it can suplly 100 amps, the device will only pull 1.2 amps. Thats why your clock radio doesnt explode when you plug it in to the same outlet as your TV. That wall plug may be rated at 20 amps, but the clock radio only pulls what it neads.

Now if the amperage on the adapter is too low, the voltage will drop, or the adapter will shut down/fry....but it cant be too high.

Ohms law...
 
With all due respect to some of your posts on using the adapters that come with the device, Most of the time those wall warts use such low quality componants that I think a self designed one would be an improvement over some of the trash out there.

None of the outside adapters are really designed for the products they only reach the required specs for them , so usually they will produce a little of that noise that you dont want.

The simple way to solve this is to aquire the correct replacement for the device, But designing one may be better. Id do some research and explore my options. but do make sure the specs are met, and It doesnt hurt to exceed the current specs by 20% but more may give you noise.
 
C'mon - this is not complicated. Bdgr is absolutely correct.
The wallwarts that come with most product are generic outsourced units that have the required specs, including the one with the Mq3. The device itself in most cases, including this one (Mq3), has a regulated power supply built into it - all it requires is the correct voltage at a rated current or greater, and a connector that fits into the device. In this case, since the required voltage/current is AC, the polarity doesn't even matter. (Some devices require DC voltage, in which case the connector has to be hooked up with the correct polarity.)

I don't know how different quality wallwarts would introduce different amounts of noise into the circuit (assuming they have the correct specs), since they are merely transformers, and the device's own power supply will remove the noise equally for all of them.

So Michael, all you need is a 12VAC transformer (wallwart) with a minimum rating of 1 amp (1000ma) - the current rating can be greater in any amount - and a connector that fits into the power jack of the vcq3, and you're in business.
 
A transformer,wheatstone bridge and a capacitor, and more capacidence makes a big difference when pushing the envelope.
 
darrin_h2000 said:
A transformer,wheatstone bridge and a capacitor, and more capacidence makes a big difference when pushing the envelope.
Click to expand...

???

I don't quite get your drift. The rectifier (bridge or otherwise) and capacitors are inside the vcq3, not in the wallwart.
 
Yes, a DC power supply will typically consist of a transformer (which is an AC only component), for voltage step-up, step-down or isolation; a rectifier to allow current to pass in only one direction; and large value capacitor(s) for initial 60/120Hz filtering (to smooth out the rectfied voltage.) Some power supplies only consist of this. Many others then incorporate a voltage regulator circuit to further keep the DC voltage level within specified parameters independent of circuit loading. In my (limited) experience I've not seen a DC wallwart that included anything but the transformer and diode rectifier - no capacitors (though it's possible to include these, but would make it much more bulky and there might be some heat dissipation issues).

In the case of the mq3 (and I am assuming the vcq3 which I believe is the same except for the current sensing inputs) the wallwart only contains the transformer - any other circuitry is inside the JoeMeek, so the only important specs are those of voltage and minimum current as noted previously, and any transformer matching these specs will be as good as any other to supply the vcq3.
 
Have you tried switching mic cables? I am assuming you checked the specs on the adaptor.


I am sure you have but just thought I'd throw out the mic cable issue.


F.S.
 
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