Apex 460 capacitor change?

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Apex Power Supply

Actually its real easy to rebuild the supply. Besides, I've got most eveything in the junk box.
I'm also looking at taking out the zeners. They are in there to keep the output from going over 200vdc. I'm guessing here. There are 4 22 mike caps@400volts. The sims says there is a 300 plus volt overshoot at turn on. so the zeners are helping to protect the tube and capsule from over voltage. By using a choke-cap-choke-cap supply the voltages will stay below 200 or so. Typically you want to use caps in a acending order. IE: 2ufd- choke 4-ufd choke 10ufd. That last cap can be a high grade film cap NOT electrolytic. We hate those electrolytics. Rembmber the PS IS IN the signal.
There iis a 1000puff cap just after the bridge to shut the noisey diodes...Cut that guy out after installing the good low noise diodes. (I tried Cree silicon carbides in other preamps with good results but the crees slam shut like a screen door on a summer day. The slamming is like a hammer hitting the transformer...not good. So if you use the crees a bigger tranny is in order. I use snubbers as a matter of course to kill ac line noise. But becareful here cause if the snubber is not sized correctly it will make to PS soft and you will lose dynamics.
 
Yeah,

I should have done some math before saying that. I'd imagine a super pimped 460 would probably cost around $550 or so. I have a Nady TCM1050 (same circuit, larger body and head-basket, as most folks know) and it's probably gonna have around $600 in it by the time I'm done, with all the different stuff I've tried.

But in the end I don't know that I'll even use it that much more than say, an AT 4047. We'll see. It's still too damn bright.

Even w/ Peluso CEK347 (if that's what I even have, who knows?) a Peluso 47-style Xformer (who knows what this is? It's probably just an el cheapo Chinese tranny. Looks surprisingly close to the original. I'm beginning to wonder. ) Auricap for C8, 56V zeners, GE 6072 tube. I upgraded all resistors, and other caps, even replaced the el cheapo lytics in the p.s. w/ Nichicons, removed the cathode follower. Next step is to put a black gate back in for C6 which I don't have in there right now. I'll give it the full run-through, but in the end I don't know if it'll really be worth all the hassle.
 
Putting the Black Gate in at C6 and a film back at C7 I think is necessary with the cathode follower removed. It made a HUGE difference with the low end on my 1050. Like yours, it was way too bright before.

Craig
 
Jonk said:
Even w/ Peluso CEK347 (if that's what I even have, who knows?) a Peluso 47-style Xformer (who knows what this is? It's probably just an el cheapo Chinese tranny. Looks surprisingly close to the original. I'm beginning to wonder. )
Click to expand...

A good quality transformer, like the Cinemag replacements for C12 or U47 are both dual-bobbin design, instead of the single bobbin design of the original chinese transformer. If there are no windings or winding form around the outside of the metal-leaf core, then it is probably a single bobbin transformer.
 
Try using the Non Polarized BG...(The Red ones)

If you do use the NP BG at C6 you do not need C7 as the NP BG as a bypass. The BG are good caps and do not need to be bypassed. (Less is more)
If your mic sounds hot try using some NOS Allen Bradly resistors...2 watters at R7...I like to use resistors in parallel that are smack dab in the signal path.

Also C8 the output cap will have a very heavy influnce on the overall sound...The BEST film caps are Mundorf. And better yet..."Vcaps" ...they are an outrage $$$$ BUT oh my!!!...500 hour to get settled in and sound right.
To shorten the breakin time a use a signal generator set to 5 or 6 volts at 1000hz or so place the cap in parallel with a resistor (Brown Black Orange) and let is simmer for 10 days.

I don't know how the get a Vcap inside the mic body...but one would need to remove the the PC board. Same with the Mundorfs.

Gotta go just got a shipment from Doug Oade... Fostex FR-2LE Field memory recorder...Finally!


Phil
Santa Fe
 
voltage ?'s

For C7, what's the voltage rating? I only have a Dave Thomas schematic, with C6 and C7 removed.

Also, for C8, is anyone going as low as 200V? It would be convenient for Auricap.
 
Stock C7 is 63 volts BUT

The cap it is bypassing is rated at 25v. Sooo most any low voltage cap will be fine...My measured voltage at the cathode of stock mic was 2 volts +/-...


The Auri cap will do the job but make sure not to nic the cap with your soldering iron...The Solen caps and Auricaps do not have a sense of humor when it comes to melts in their bodys. :eek:
 
https://img267.imageshack.us/my.php?image=xformerle1.jpg

This is about the best pic I could get w/ my camera, but can anybody tell if this is a dual bobbin transformer?

You can't really see the windings but they go all the way around the transformer. They're underneath the white outside material, and I can see them on all four sides when I look down into the teeth.

How do auricaps respond to bludgeoning? The corner of mine has been smashed a tiny bit from the tight fit.
 
Hi all,

I'm sure that this is common knowledge for some, but what wattage are the planar resistors?

I was told to try a different value for R10, but have no idea what wattage to get.

Thanks,

Lucio
 
If you are referring to the 1Gigohm resistor, with that high of a resistance the wattage could be anything.
 
Auricaps...and others

Plastic caps are plastic. They sound plastic and they are microphonic. That why we love the paper in oil stuff. But if the big stuff wont fit...plastic it is. The nic wont hurt much but its best if cap can be isolated. Typical I'll hang the cap so its not touching anything. :p
 
Phil Townsend said:
Plastic caps are plastic. They sound plastic and they are microphonic. That why we love the paper in oil stuff. But if the big stuff wont fit...plastic it is. The nic wont hurt much but its best if cap can be isolated. Typical I'll hang the cap so its not touching anything. :p
Click to expand...

Paper in Oil caps exhibit the least amount hysteresis and are the most linear. This is the main reason that they are chosen for their "sound" as they distort the signal the least. Poly foil caps are fairly linear as well. Electros exhibit fairly obvious hysteresis and are horrible for sound.

Just thought I would add that. :)
 
Phil Townsend said:
Actually its real easy to rebuild the supply. Besides, I've got most eveything in the junk box.
I'm also looking at taking out the zeners. They are in there to keep the output from going over 200vdc. I'm guessing here. There are 4 22 mike caps@400volts. The sims says there is a 300 plus volt overshoot at turn on. so the zeners are helping to protect the tube and capsule from over voltage. By using a choke-cap-choke-cap supply the voltages will stay below 200 or so. Typically you want to use caps in a acending order. IE: 2ufd- choke 4-ufd choke 10ufd. That last cap can be a high grade film cap NOT electrolytic. We hate those electrolytics. Rembmber the PS IS IN the signal.
There iis a 1000puff cap just after the bridge to shut the noisey diodes...Cut that guy out after installing the good low noise diodes. (I tried Cree silicon carbides in other preamps with good results but the crees slam shut like a screen door on a summer day. The slamming is like a hammer hitting the transformer...not good. So if you use the crees a bigger tranny is in order. I use snubbers as a matter of course to kill ac line noise. But becareful here cause if the snubber is not sized correctly it will make to PS soft and you will lose dynamics.
Click to expand...

Not sure I agree with this. So long as the power supply delivers clean, steady voltages and filters well I'm not sure you're going to improve anything. The zeners and regulator make sure the DC voltage is level and smooth. The biggest improvement to me would be increasing the value of the smoothing and filtering caps to reduce noise. Do you think the zeners are adding too much noise?

Gus, are you around to add to this?

How about Marik?
 
Good power supply...Bad Power Supply

The test of a Good Power Supply is simlpe...
How does it sound.

The sims are mostly right. But that have been times when the sims say good and ears say no.

My modded suppies are way better than the stock in every area. Upper, lower, slam, dynamics.

Download the sim from Duncan Amp and run the numbers. Then let you ears do the work.
 
One more thing

Adding more caps to the PS will smooth the voltage BUt there is a price to be paid...It tends to make to sound muddy...You lose dynamics. Its easy to hear this. That why you get better results using chokes and caps. But chokes cost money and electrolytics are cheap. If you use chokes you can reduce the total ufd in the supply. The power supply is in the signal path!
 
Resistor wattage?

mbrebes said:
If you are referring to the 1Gigohm resistor, with that high of a resistance the wattage could be anything.
Click to expand...
Yes, that's the one. I was told to try dropping that down to 100M to get a more U47ish sound (which is the size used in the U47 schematic) because the 1KM is allowing too much current to pass through, or something like that.

Is there a way to test to see what the wattage is or what's needed?

This mic is a Nady TCM1050 with a CEK-47 capsule, Cinemag 2480 and a 3.3uf Black Gate in C8 for a trans coupling cap. Cathode follower still there also because I read that it makes the output react more like the V14 tube. I dropped C4 from 1000pf (.001uf) down to .01uf (which is the same size as the U47 schematic shows) and it definitely thickened the low end. But it's still too bright sounding, brighter than my modded Apex with a CEK-12 capsule.

Also on the Apex, dropping the zener diodes down to 56v made a huge difference by pulling the upper mids back and making it fuller sounding, but for some reason, dropping the voltage in the Nady power supply made the sound brighter and thinner. The Nady ps also had 2 different zeners, one 1N4762 (82v) and one 1N4764 (100v), which works out to 182v. The Apex had 2 1N4761's (75v) for 150v. But even when I put 2 75v in the Nady it was still brighter than with the original zeners. That's changed since I dropped the .001uf to .01uf. Now it's more consistent when changing zeners.

I guess the circuit has more to do with the sound characteristics than I realized.

Thanks,

Lucio
 
Apex and Zeners

There are the 2 100 volt zeners in series across the output of the PS.
In my HO the ONLY zeners one can use that would make no noise are the 6.8 volt guys...sooo if one is bent on using them...6.8 / 200 = 29.4 zeners! Not going to happen here...
"A better idea"...he says reaching for The well worn GE Essential Characteristics book...page 22. Hows about a pair of OA3 (glow discharge diode voltage regulators) 105 volts each...hooked in series and yu got 210 volts Then place a small shunt cap across the series pair and wala clean transparent and Noise free DC. The cap wants to be .1 mike, no more...Mundorf film.
But then check the noise across the zeners with your scope and see if its worth the trouble.
My ears say it is...
but then after all that work, just maybe, it better be.

Did I talk about removing the solid state diodes and putting in a 5AR4 for the B+..no?

Never mind...
 
I discovered today that, while the layouts are the same for the Apex and Nady power supplies, there are different values one some parts.

For instance, the Apex has 2 1000uf caps at C9 and C10, where the Nady has 10,000uf caps in the same spots!!! Also, the Apex has a 1uf electrolytic at C7, where the Nady has a 2200pf mylar. I know that the zener diodes in the Apex are 1N4761's in both D5 and D6 (150 volts), but the Nady has one 1N4762 and one 1N4764, respectively (182 volts).

I know that changing the zeners makes a big difference, but what about the others? Anyone have a clue?

Lucio
 
I'm looking at the Apex schematic for the power supply and I don't see a C9 or a C10 anywhere. C7 is a 1000uF 25v.

Are you looking at the right schematic? Where did you get the Nady schematic?

Can you post it?
 
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