At4060

[antispatula]

what's up with this things "power supply?" I keep hearing it needs a AT8560 power supply. Why, does it have an unusual output connector or something? Do you need this thing for the at4060 to operate? Can you buy the power supply seperately? Thanks!

 

[scrubs]

Most tube mics run off of a separate power supply and connect via a 7-pin mic cable (not standard XLR). If you buy the 4060 new, from a reputable dealer, it should come with the power supply (see: http://www.zzounds.com/a--2676837/item--AUTAT4060). If you have one of these without the power supply, I would contact Audio Technica directly and ask if they sell replacements. Or, browse around e-bay.

 

[littledog]

If you buy a tube mic that works without an external power supply, chances are there is a compromise in the design. Tubes need a lot of voltage to work properly, and the 48V phantom power that condenser mics run on is not enough.

That's why good tube mics need an external power supply. The existence of a power supply doesn't necessarily guarantee anything about the quality of the mic, but I would be very suspicious of buying a tube mic that doesn't have one.

The 4060 is a very decent microphone.

 

[dgatwood]

If you buy a tube mic that works without an external power supply, chances are there is a compromise in the design. Tubes need a lot of voltage to work properly, and the 48V phantom power that condenser mics run on is not enough.

That's why good tube mics need an external power supply. The existence of a power supply doesn't necessarily guarantee anything about the quality of the mic, but I would be very suspicious of buying a tube mic that doesn't have one.

FWIW, AT did a phantom-only tube mic (the AT3060).

Don't know any reason you couldn't do a phantom-powered version of just about any tube mic design. The 10 mA provided by the current phantom power spec should be more than enough to drive a tube. That's 480W, and a single preamp tube shouldn't draw anywhere near that---maybe 150W on the high side of things, plus your capsule and other miscellaneous parts, but you shouldn't be even in the ballpark of 480W....

You should just need a DC-DC converter. It shouldn't be that hard to step 48VDC up to 125 or 160 or whatever the particular tube prefers....

Of course, why would a mic manufacturer use a $5 DC-DC board and a couple of caps when they can provide a whole separate power supply and make it look all impressive?

Sigh.

Edit: Crap. I miscalculated by orders of magnitude. 48VDC * 10 mA is 0.48W max. That puts the tube heater current of a single 12V tube beyond the capacity of any phantom power source by a factor of three. I'm a little confused how the AT3060 actually is able to function.

 

[scrubs]

The Gefell UM900 is also a phantom-powered tube. I don't think anyone is suspicious of that mic.

 

[mshilarious]

FWIW, AT did a phantom-only tube mic (the AT3060).

Don't know any reason you couldn't do a phantom-powered version of just about any tube mic design. The 10 mA provided by the current phantom power spec should be more than enough to drive a tube. That's 480W, and a single preamp tube shouldn't draw anywhere near that---maybe 150W on the high side of things, plus your capsule and other miscellaneous parts, but you shouldn't be even in the ballpark of 480W....

Ummm . . . that's 10mA, not 10A, so it's a mere 1/2W available whereas your usual 12A_7 tube heaters need to burn about 2W.

 

[dgatwood]

Ummm . . . that's 10mA, not 10A, so it's a mere 1/2W available whereas your usual 12A_7 tube heaters need to burn about 2W.

Yeah. I just noticed that. Still better than my previous miscalculation.

So how exactly does the AT3060 get away with running a 12AT7 under those conditions? If you starve the filament for current will it just require longer for the tube to get up to operating temperature?

 

[littledog]

The Gefell UM900 is also a phantom-powered tube. I don't think anyone is suspicious of that mic.

Actually, quite a few of us have been suspicious of that mic. When Stephen Paul was still alive I asked him to check into it and tell me exactly what was going on. No matter what it sounds like and whether or not it is a "legitimate" design, you gotta admit it is about the coolest looking mic ever built.

He said he would, when he got the chance. Unfortunately for the audio world, he died, so I never found out. But yeah, I'm still suspicious that anyone can pull that kind of design off without some sort of sleight-of-hand or sonic trade-off.

 

[mshilarious]

Yeah. I just noticed that. Still better than my previous miscalculation.

So how exactly does the AT3060 get away with running a 12AT7 under those conditions? If you starve the filament for current will it just require longer for the tube to get up to operating temperature?

It doesn't, it uses a 6418 mini-tube which only drinks 10mA @ 1.25V, just about perfect for phantom powering. I gotta start playing with that tube myself

Also if you starve a 12AT7 that bad (remember that is across two 6.8K resistors, so the voltage drop across the filament would be 1.2V), I'd doubt the tube would work at all.

 

[sdelsolray]

The Gefell UM900 is also a phantom-powered tube. I don't think anyone is suspicious of that mic.

The UM900 is one of the finest mics on the planet. It was the first to use a 48v phantom supply to power the tiny tube inside.

 

[BigRay]

Gefell is the greatest mic company in the world. I assure you that there were NO compromises in the design of that, or any of their microphones. Sonic wise, build wise, or any others....and sleight of hand.. that.a phrase that doesnt belong in the same sentence as Gefell. They are the absolute picture of Quality Control, Integrity, and Professionalism. all hand built there on site.
I am intimately familiar with pretty much all of Gefells new and old designs, and am a friend of their head engineer. He and I have talked many many times, and I assure you that the company is constantly looking for ways to RAISE the bar in terms of product quality, and to continue bucking the mass production copycat trend. People can be suspicious all they want, but the fact of the matter is, that there is nothing slight or compromised there...

Actually, quite a few of us have been suspicious of that mic. When Stephen Paul was still alive I asked him to check into it and tell me exactly what was going on. No matter what it sounds like and whether or not it is a "legitimate" design, you gotta admit it is about the coolest looking mic ever built.

He said he would, when he got the chance. Unfortunately for the audio world, he died, so I never found out. But yeah, I'm still suspicious that anyone can pull that kind of design off without some sort of sleight-of-hand or sonic trade-off.

 

[scrubs]

Actually, quite a few of us have been suspicious of that mic. When Stephen Paul was still alive I asked him to check into it and tell me exactly what was going on. No matter what it sounds like and whether or not it is a "legitimate" design, you gotta admit it is about the coolest looking mic ever built.

Yes, I suspect that it is totally badass. This is the mic Batman would use.

 

[Gus]

First if you are buying a tube microphone without a power supply AT4060(that needs a power supply) I would check if it was stolen.



Now people you need to think in terms of power for a phantom powered tube microphone. DC Power = voltage x current

transformers have the same power(- core wire etc loss) on both sides.

Take a small well designed switcher chip and down(fil) up(B+)convert the 5 to 10 ma at what ever voltage, voltage drop across the phantom is 3.4K x current drawn.

Calculate the power you can get.

lets guess .5ma in the tube and what voltage you want to have as B+ that will allow you to cal the power

Then look at small tubes and cal the power the heater needs

Add the power together and subtract some for loss in the DC to DC converter

Look at the current draw for the AT3060 and gefell for hints things like ma draw. AT3060 from the web site 48V at 3ma for about a 10.2V drop so we have about 37VDC for the B+ without using a converter. take away .5ma(guess) so now 37V at 2.5 ma for the fil 37V X .0025= .093watts not you need to look for fil voltage and current ratings for different tubes to see if it is enought. The AT3060 seems to be an electret so you don't need a capsule voltage supply

car radios had low voltage tubes

Ohms law is your friend, add the power math, look up some app notes for DC to DC converters and have some fun.

 

[mshilarious]

Look at the current draw for the AT3060 and gefell for hints things like ma draw. AT3060 from the web site 48V at 3ma for about a 10.2V drop so we have about 37VDC for the B+ without using a converter.

That's too high for the 6418, max rating is 30V and 15-22V is typical.

take away .5ma(guess)

That's the max rating.

so now 37V at 2.5 ma for the fil 37V X .0025= .093watts not you need to look for fil voltage and current ratings for different tubes to see if it is enough.

More than enough, you'd only need .0125W

The AT3060 seems to be an electret so you don't need a capsule voltage supply

Yes.

Overall that seems to make sense for AT's approach, I could trace the circuit but I'm lazy I'm thinking of a cheaper approach that doesn't involve DC converters. If you simply hook a phantom supply directly to a 6418 heater, that's just about the necessary current (a bit much actually). So divide off 15V for the plate, and perhaps you've got the cheapest tube mic on the planet Sure it wastes power but who cares?

Of course if you're dealing with an electret, that begs the question of why bother with a tube stage in the mic, but hey, tubes are fun

I've done a sketch & I've just ordered some 6418s, I'll post a schemo if it works,

car radios had low voltage tubes

Low plate, but the filament on 6GM8 still draws 300mA.

 

[Gus]

mshilarious

Fair reply. I was not sure what the AT uses I have read different tube numbers in the past on the web. Did you open one and see the number? Or maybe from the last post you own one?

I was posting in general about the idea of a tube powered by phantom. The .5ma guess is from looking at circuits and building a few.

I would guess the gefell might have a different tube and setup.

I am going to look for the 6418 info.

 

[mshilarious]

mshilarious

Fair reply. I was not sure what the AT uses I have read different tube numbers in the past on the web. Did you open one and see the number? Or maybe from the last post you own one?

Yeah I do have one, plus I've been thinking about the 6418 for a while, I have the datasheet but until today, no spare tubes to play with.

On paper, my 6418 phantom circuit yields 10V at the plate--a bit low, but within spec for the 6418--but I can't quite get enough current across the filament. It's close though, so I will build it and see

Datasheet is here:

http://tubedata.tigahost.com/tubedata/sheets/127/6/6418.pdf

 

[littledog]

Gefell is the greatest mic company in the world. I assure you that there were NO compromises in the design of that, or any of their microphones. Sonic wise, build wise, or any others....and sleight of hand.. that.a phrase that doesnt belong in the same sentence as Gefell. They are the absolute picture of Quality Control, Integrity, and Professionalism. all hand built there on site.
I am intimately familiar with pretty much all of Gefells new and old designs, and am a friend of their head engineer. He and I have talked many many times, and I assure you that the company is constantly looking for ways to RAISE the bar in terms of product quality, and to continue bucking the mass production copycat trend. People can be suspicious all they want, but the fact of the matter is, that there is nothing slight or compromised there...

Ray, I wasn't intentionally making any personal attacks on you or your friends at Gefell. The information about using tiny tubes explains to some extent how they've skirted the power supply issue, so that is good to know.

I don't necessarily share the same intensity of admiration that you have for Gefell as a company. This comes from personal experience with some of their mics, which I think are ok - but not, for me at least, blowing me away.(I own an 800 and a 70s). But also, from conversations with one of their engineers who insisted that it was impossible to make a well designed stable microphone diaphragm with a thickness of less than 6 microns. Since the world's greatest authority on ultra-thin diaphragms recently died, someone else (with more pure engineering knowledge than me) will have to take up the torch on that argument.

But the real question for me is, how do the tiny tubes sound compared to "real" tubes? Is it just a gimmick, or is there a real design consideration for using them? And if it is a really great idea, how come we are not seeing them in more microphone models?

I guess I won't ever know until I have the chance to work with the 900 myself, and I haven't yet had that opportunity. Which leads to yet another question of why, given how cool it looks, do so few studios seem to own one of them? I'd be interested, Ray, in your impressions of the 900.

 

[BigRay]

I see plenty of people on GS with UM900s. Everyone ive heard talk about them over there loves them..I guess a big reason that more people dont own one is due to cost constraints. They are quite pricey, and as with all of Gefell mics, the cost comes from top notch components and hand building..I have had the extreme fortune of using the UM900 on several occasions. My impression was that it is an EXTREMELY open, detailed microphone, with plenty of high end and fast transient response(not the case with a lot of tube designs). It still sounds tube-y(if I may say such a thing) but the effect is very, very subtle. IMHO, this is how it should be.If I did more solo vocal work, this microphone would no doubt be in my future. As I work with primarily orchestras and string quartets and the ilk, I dont have need for another vocal mic.

Ray, I wasn't intentionally making any personal attacks on you or your friends at Gefell. The information about using tiny tubes explains to some extent how they've skirted the power supply issue, so that is good to know.

I don't necessarily share the same intensity of admiration that you have for Gefell as a company. This comes from personal experience with some of their mics, which I think are ok - but not, for me at least, blowing me away.(I own an 800 and a 70s). But also, from conversations with one of their engineers who insisted that it was impossible to make a well designed stable microphone diaphragm with a thickness of less than 6 microns. Since the world's greatest authority on ultra-thin diaphragms recently died, someone else (with more pure engineering knowledge than me) will have to take up the torch on that argument.

But the real question for me is, how do the tiny tubes sound compared to "real" tubes? Is it just a gimmick, or is there a real design consideration for using them? And if it is a really great idea, how come we are not seeing them in more microphone models?

I guess I won't ever know until I have the chance to work with the 900 myself, and I haven't yet had that opportunity. Which leads to yet another question of why, given how cool it looks, do so few studios seem to own one of them? I'd be interested, Ray, in your impressions of the 900.

 

[Gus]

think I found a patent relating to the AT360.

http://www.freshpatents.com/Condenser-microphone-dt20051117ptan20050254671.php

 

[littledog]

Thanks for your reply, Ray. Perhaps it is a regional thing. I just never seem to come across them around my area. I don't think it is a matter of cost, because I see plenty of U47's, C12's, 241's, (as well as newer expensive mics like Soundelux, Korby, Lawson, BLUE, etc.) But I guess it is no surprise that a good place to find German mics would be in Germany!

Anyone else here used the UM900?

Any theories as to why no one else is using this design for high end microphones?