Help Somewhat Urgent!!! Components Question

[ComputerGeek]

Hey guys I need to order components to build the circuit below within the next two days at most. And I had a few questions about the circuit,

First off, I am trying to build this curcuit http://www.rcrowley.com/T12pwr.jpg mentioned in this thread, http://help.lockergnome.com/movies/p...pict73571.html . In addition I will be building this one as well. http://www.uneeda-audio.com/phantom/p48t122.jpg This will be used with a expensive vintage microphone, so i want the components to be as good as possible.


What Caps should I be using for this, Electrolytic, Tantalum, Ceramic, or Non-polarized?

What Resistors would be used in this application? Metal Film, Thin Film, Wirewound? And what kind of wattage should I look to get?

Any suggestions out of these?
http://www.digikey.com/product-searc...=0&pageSize=25

Also, in the thread the guy who made the circuit mentions, "The value of R3 (2K5 ohms) is just a rough guess. If you make it too low, you waste battery capacity in uselessly heating up D1 and R3. Conversely, if you make it too small, the voltage may droop under heavy load." Would you stay with the same value?

[budm]

Re: Help Somewhat Urgent!!! Components Question

What kind of MIC is it, electret?
You may want to read this first:

The diagram in your link may not applied to your MIC.
Carbon film 1%.
Cap: search for audiophile capacitor if you really want to spend lots of money.

[ComputerGeek]

Re: Help Somewhat Urgent!!! Components Question

What kind of MIC is it, electret?
You may want to read this first:

The diagram in your link may not applied to your MIC.
Carbon film 1%.

Ok Carbon Film Resistors, would going with more than 1% be wise, or just a waste? Any Brand that you would get?

In the article they mention this,
"The supply voltage is superimposed on the signal voltage and therefore needs to be exceptionally well filtered. In multiple microphone systems the mutual decoupling - the isolation that pre- vents the leaking of audio signals via the common supply rail - must similarly be of a high order."

Which is why I want to make sure the components are good!

I have a Sennheiser MKH-415T, it already has a bunch of circuits in it, but it needs the 12t power mentioned in the article to actually make it work.

http://www.ebay.com/itm/Sennheiser-M...-/200628406865

[budm]

Re: Help Somewhat Urgent!!! Components Question

1% or less will be good.
Audio coupling Caps, that is hard to say since some golden ears claim some caps (brands) are better than the other as far as the sound is concerned.
You want low ripple power supply as possible, otherwise the amplify will treat it as AC signal.
Panasonic FM for DC filter caps, with 0.1uf ceramic cap in parallel.

[ComputerGeek]

Re: Help Somewhat Urgent!!! Components Question

Do the three caps in the circuit act as coupling caps? If it was you what would you use?

So I should use polarized electrolytic? Or Tantalum in my somewhat rusty brain, I think I recall reading that Tantalum or Film are better for audio, or am I way off?

I was going to use http://www.digikey.com/scripts/DKSea...21847154107572 for D1? is that ok? 1N5242B seems to have a max power of 500mW, does that mean 1/2 watt resistors would be fine?

Would you mind pointing me to a link where I can read about what the different types of Caps and resistors are good for?

Edit: lol I just reread my last post, I meant "would less than 1% be better, or just a waste?

Edit Edit: Carbon Film are those vintage resistors right? AFSIK, digikey doesn't sell those, or did you mean thin film or metal film?

[rhomanski]

Re: Help Somewhat Urgent!!! Components Question

I think he meant metal film, 1%. I like KOA Speer myself. I've used tons of them. In every case that I have checked them, they are right on the money. Tighter than 1% even. Try here, http://ca.mouser.com/KOA-Speer/Passi...z0zlrrZ1z0wljo . For capacitors, I would recommend Nichicon PW series( UPW ) for power supplies and general purposes. 20% tolerance, with low impedance, and 105 degrees C. For the audio path I would recommend Nichicon KL series ( UKL ). 20 or 10 % tolerance, low noise ( low leakage ) with 85 or 105 degree temp. Those are what I use in all my audio gear. For semi conductors, I try to get Fairchild, but will use just about any brand for hard to get components.

UKL : http://ca.mouser.com/Nichicon/Passiv...z0zlbmZ1z0yp6m

UPW : http://ca.mouser.com/Nichicon/Passiv...z0zlbmZ1z0z7l5

[budm]

Re: Help Somewhat Urgent!!! Components Question

I am sorry, metal film for low noise.
http://www.eetimes.com/document.asp?doc_id=1278251
The coupling caps are the two between the Mic pin2 and preamp pin 2, pin 3 and pin 3.
For my own home use I use Panasonic FM with 0.1uf Ceramic in parallel for my audio coupling caps, since I do not have golden ear, if it sounds good to my ears then it's fine with me.
http://sound.westhost.com/articles/coupling-caps.htm

[ComputerGeek]

Re: Help Somewhat Urgent!!! Components Question

Ok, you guy's have helped out immensely, but I still have a couple questions?

1N5242B seems to have a max power of 500mW, does that mean 1/2 watt metal film resistors would be fine?

Both Nichicon KL and Panasonic FM are polarized, however from the links you sent me it would appear that I need to use either a bipolar (non-polarised) electrolytic Cap, polyester cap, or a Polypropylene cap for C1 and C2. Is this correct?

C3 can be polarized and doesn't nearly have to be as high spec. Correct?

Also, in the thread the guy who made the circuit mentions, "The value of R3 (2K5 ohms) is just a rough guess. If you make it too low, you waste battery capacity in uselessly heating up D1 and R3. Conversely, if you make it too small, the voltage may droop under heavy load." Would you stay with the same value?

And One last thing, in this circuit, http://www.uneeda-audio.com/phantom/p48t122.jpg the cap on the far bottom (would it be a filter Cap?), Would the voltage only need to be 15v or does it need to be 63v? And the resistors are 2210ohms correct?

[budm]

Re: Help Somewhat Urgent!!! Components Question

"C3 can be polarized and doesn't nearly have to be as high spec. Correct?" Right.

"a bipolar (non-polarised) electrolytic Cap, polyester cap, or a Polypropylene cap for C1 and C2. Is this correct?" Polypropylene will be best but will be very big body.

"1N5242B seems to have a max power of 500mW, does that mean 1/2 watt metal film resistors would be fine?" At 18VDC and 2500 Ohms in series to feed the circuit and the Zener Diode, there will be so little current flowing through the Zener at light load. Actually at 1/4W resistor will be fine. With 18V and Zener shorted out, the max current will be only about 7mA.

[ComputerGeek]

Re: Help Somewhat Urgent!!! Components Question

OK Great, Sorry I promise I'll stop pestering you soon, lol.

It is correct that I can't use a polarized Cap for C1 and C2 right?

Also, in the thread the guy who made the circuit mentions, "The value of R3 (2K5 ohms) is just a rough guess. If you make it too low, you waste battery capacity in uselessly heating up D1 and R3. Conversely, if you make it too small, the voltage may droop under heavy load." Would you stay with the same value?

And One last thing, in this circuit, http://www.uneeda-audio.com/phantom/p48t122.jpg the cap on the far bottom (would it be a filter Cap?), Would the voltage only need to be 15v or does it need to be 63v? And the resistors are 2210ohms correct?

[budm]

Re: Help Somewhat Urgent!!! Components Question

At 2500 Ohms (max power is only 0.12W) if circuit shorted out so nothing will really get hot at that low current, it not quite enough to bias that Zener diode, so at lower value, it will draw more current which will drain the battery faster. See how well the battery hold up with 2500 Ohms.
You can use polar caps will not hurt the circuit. Try both polar and non polar to see if you can hear any differently between the two kinds of cap and type.

"the cap on the far bottom (would it be a filter Cap?)," Yes, I would use 25V cap incase something goes wrong, 63V will be big.

[ComputerGeek]

Re: Help Somewhat Urgent!!! Components Question

At 2500 Ohms (max power is only 0.12W) if circuit shorted out so nothing will really get hot at that low current, it not quite enough to bias that Zener diode, so at lower value, it will draw more current which will drain the battery faster. See how well the battery hold up with 2500 Ohms.
You can use polar caps will not hurt the circuit. Try both polar and non polar to see if you can hear any differently between the two kinds of cap and type.

"the cap on the far bottom (would it be a filter Cap?)," Yes, I would use 25V cap incase something goes wrong, 63V will be big.

Perfect, I will venture to guess that I didn't explain very well about the second circuit, the second circuit is a converter from 48-52v phantom power to 12t power, instead of the battery operated one. Would that make any difference with your recommendation on the cap voltage? Since the other two caps are in the 48v I understand why they need to be 63v, but I was just wondering about the other one.
http://www.uneeda-audio.com/phantom/p48t122.jpg

Also, the resistors are 2210ohms correct? And the resistors could be a 1/4w with the 48v in that circuit too right.

[budm]

Re: Help Somewhat Urgent!!! Components Question

I see, the second circuit, so it is using the 48 Phantom from the mixer board to drop the voltage down, then those two coupling cap should be 63V.
And if the Zener shorted out for what ever reason, then that 2K2 can dissipate about 1W. So get 2W resistors (Metal Oxide-MOX).

[Khron]

Re: Help Somewhat Urgent!!! Components Question

According to the manual found here:

http://94.100.244.130/sennheiser/old_manual.nsf/resources/MKH_415_oNr_oDatum_Sp2.pdf/$File/MKH_415_oNr_oDatum_Sp2.pdf

It needs about 6mA @ 12v, so according to a couple zener calculators i've checked, something around 2k / 0.5w should be ok for the "input" pair of resistors.

Edit: It would be worth keeping in mind that, per standard, the 48v phantom power is (or should be) supplied through a pair of 6.8k resistors to pins 2 and 3 on the XLR connectors, so it's all current-limited "by default"

[ComputerGeek]

Re: Help Somewhat Urgent!!! Components Question

Which resistor are you referring too? Also, I have not been able to find 180ohm metal oxide resistors over 1W in stock anywhere, I have or order 500 or more and most places won't have them shipped to me until after 9/25. Would using 1/2 watt resistors be fine in the second circuit.


http://www.uneeda-audio.com/phantom/p48t122.jpg

Also, the resistors are 2210ohms correct?

[Khron]

Re: Help Somewhat Urgent!!! Components Question

As i said - per the standard, the 48v phantom power is supplied via two 6.8k resistors. That gives a max current of 48 / 6800 = 7mA, times two ('cause it's supplied to pins 2 AND 3 in the XLR), so a max absolute of 14mA.

You should be fine "even" with 1/4W (metal film) resistors, and the actual values don't need to be THAT exact. I mean, even in the mic's manual, it says it needs a current of "approx. 6mA"

The two caps on top indeed need to be 63v minimum, but the lower one (that's just filtering the 12v from the zener) is enough if it's a 16v one. Although, if you can spare the space, all three can be 63v (especially if you can get some price break on the caps ).