[Tobiah]

I ordered a Jethead Phantom to see whether it would improve
the S/N used with my NT1-A's, and an M-Audio Fast Track
Ultra audio interface. I also have a 'dummy mic' as we
recently discussed, using the 150 Ohm resister soldered into
a male XLR connecter trick.

Given the dummy mic, the microphones, the interface, and
the Jethead which will arrive on Wednesday, how would you
go about deciding whether the Jethead is going to be able
to deliver clean enough gain that it surpasses and improves
my existing preamps. I know I could just listen, but it's
tough to pick out the noise in my residential bedroom from
machine noise.

How would we do this in science class?


Also, I was thinking of putting the Jethead between the mic
and cable, to avoid amplifying any noise the cable picked up
in between (yeah, balanced connection, but still).

Thanks,


Tobiah

[Phil Allison[_4_]]

Tobiah wrote:

I ordered a Jethead


** Its called a " Fethead " - dickhead.

Phantom to see whether it would improve
the S/N used with my NT1-A's, and an M-Audio Fast Track
Ultra audio interface.


** I can safely predict it won't.


I also have a 'dummy mic' as we
recently discussed, using the 150 Ohm resister soldered into
a male XLR connecter trick.

Given the dummy mic, the microphones, the interface, and
the Jethead

** Fethead.


which will arrive on Wednesday, how would you
go about deciding whether the Jethead is going to be able
to deliver clean enough gain that it surpasses and improves
my existing preamps. I know I could just listen, but it's
tough to pick out the noise in my residential bedroom from
machine noise.


** Machine noise ??

What have you got in there, a factory.



How would we do this in science class?


** Makers (like Rode) tests the background noise of condenser mics by either placing them in a vacuum OR in a silent chamber.

FYI a silent chamber is a thick walled, cast iron sphere with airtight door and XLR connectors fitted.


Also, I was thinking of putting the Jethead

** Fethead.

between the mic
and cable, to avoid amplifying any noise the cable picked up
in between (yeah, balanced connection, but still).

Thanks,


Tobiah

** Go away.

..... Phil

[PStamler]

On Monday, March 18, 2019 at 6:50:44 PM UTC-5, Tobiah wrote:
I ordered a Jethead Phantom to see whether it would improve
the S/N used with my NT1-A's, and an M-Audio Fast Track
Ultra audio interface. I also have a 'dummy mic' as we
recently discussed, using the 150 Ohm resister soldered into
a male XLR connecter trick.

Given the dummy mic, the microphones, the interface, and
the Jethead which will arrive on Wednesday, how would you
go about deciding whether the Jethead is going to be able
to deliver clean enough gain that it surpasses and improves
my existing preamps. I know I could just listen, but it's
tough to pick out the noise in my residential bedroom from
machine noise.

How would we do this in science class?

You'll probably also need an audio oscillator. It can be a cheap one -- even the Shure Oscillator in a plug will work (do they still make that?)

Here's one way. Set the oscillator to some mid-frequency, like 400 or 1,000Hz. Is your current interface still set from your last recording session? If not, set it to the gain setting you used (you did keep notes on that, right?) Set the oscillator to a low level and connect it to the interface input. Make sure it isn't clipping your DAW -- if it is, turn *its* level down; don't touch the interface's controls -- and note what level it's producing on the DAW. Let's say it's -15dBFS.

Don't touch the oscillator's controls. Also don't touch the interface's controls. Now plug your dummy plug into the interface's input and record a 30-second file. Entitle is "OLD". Connect up the new interface, and your doohickey if you're planning to use it, and plug the oscillator into it. Adjust the interface (not the oscillator) to produce the same -15dBFS level on the DAW. Good, now the new setup has the same gain as the old setup; plug the dummy plug into it and record another 30-second file. Entitle it "NEW". Compare the noise levels of the two files using an audio VTVM. If you don't have one of those, select a 10-sec segment of each file and increase its level 60dB. Do destructive edits here; save your files.

Loop the boosted segment of the OLD file; do likewise on the NEW file. Listen to each on headphones. One will probably be noisier than the other; the quiet one is the one to use for future recordings. Also look at the boosted segments with a spectrum analyzer, which many DAWs have. See what the two spectra look like; look for hum or any other discrete frequencies.

If you can't hear any difference, boost each of the segments a further 20dB, for a total of 80dB of boost. Save the results. If you still can't hear any difference, then there probably isn't enough noise difference between the two setups to justify spending money on the new one.

That's a relatively simple, though crude, way to compare the noise levels of the two interface setups when they are set for comparable gains. Save the dummy plug; it's your friend.

Peace,
Paul Stamler

[geoff]

On 19/03/2019 7:46 PM, PStamler wrote:
On Monday, March 18, 2019 at 6:50:44 PM UTC-5, Tobiah wrote:
I ordered a Jethead Phantom to see whether it would improve
the S/N used with my NT1-A's, and an M-Audio Fast Track
Ultra audio interface. I also have a 'dummy mic' as we
recently discussed, using the 150 Ohm resister soldered into
a male XLR connecter trick.

Given the dummy mic, the microphones, the interface, and
the Jethead which will arrive on Wednesday, how would you
go about deciding whether the Jethead is going to be able
to deliver clean enough gain that it surpasses and improves
my existing preamps. I know I could just listen, but it's
tough to pick out the noise in my residential bedroom from
machine noise.

How would we do this in science class?

You'll probably also need an audio oscillator. It can be a cheap one -- even the Shure Oscillator in a plug will work (do they still make that?)

Smartphone app maybe !

I have Signal Suite Pro on an iPod Touch (g4) - maybe one and only Apple
product. But many reasonably sophisticated sig-gen apps available now
for free on Android.

geoff

[geoff]

On 19/03/2019 8:19 PM, geoff wrote:
On 19/03/2019 7:46 PM, PStamler wrote:
On Monday, March 18, 2019 at 6:50:44 PM UTC-5, Tobiah wrote:
I ordered a Jethead Phantom to see whether it would improve
the S/N used with my NT1-A's, and an M-Audio Fast Track
Ultra audio interface.Â* I also have a 'dummy mic' as we
recently discussed, using the 150 Ohm resister soldered into
a male XLR connecter trick.

Given the dummy mic, the microphones, the interface, and
the Jethead which will arrive on Wednesday, how would you
go about deciding whether the Jethead is going to be able
to deliver clean enough gain that it surpasses and improves
my existing preamps.Â*Â* I know I could just listen, but it's
tough to pick out the noise in my residential bedroom from
machine noise.

How would we do this in science class?

You'll probably also need an audio oscillator. It can be a cheap one
-- even the Shure Oscillator in a plug will work (do they still make
that?)

Smartphone app maybe !

I have Signal Suite Pro on an iPod Touch (g4) - maybe one and only Apple
product.Â* But many reasonably sophisticated sig-gen apps available now
for free on Android.

geoff

Ooops - for 'maybe' read 'my'.

geoff

[[email protected]]

Also look at the boosted segments with a spectrum analyzer, which many DAWs have. See what the two spectra look like; look for hum or any other discrete frequencies.

+1 this is an important step.

A meter will respond to everything equally, your ears don't.

m

[Mike Rivers[_2_]]

On 3/18/2019 7:50 PM, Tobiah wrote:
I ordered a Jethead Phantom to see whether it would improve
the S/N used with my NT1-A's, and an M-Audio Fast Track
Ultra audio interface.Â* I also have a 'dummy mic' as we
recently discussed, using the 150 Ohm resister soldered into
a male XLR connecter trick.

Given the dummy mic, the microphones, the interface, and
the Jethead which will arrive on Wednesday, how would you
go about deciding whether the Jethead is going to be able
to deliver clean enough gain that it surpasses and improves
my existing preamps.

Your first though was correct. Just listen.

If I wanted to measure what it was doing (and indeed I'd do this if I
was writing a review of the product), I'd do something similar to what
Paul suggested.

First, connect the mic that you intend to use to the interface you
intend to use, and set the input gain on the interface so that you get a
good recording level. Do this in a quiet room, maybe waiting until late
at night to reduce stray noise.

Replace the mic with your dummy, and make a quantitative measurement of
the noise level. If you'd like to be more "classroom" about it, replace
the mic with a signal generator and adjust the generator output (not the
interface's preamp gain) to give you a steady tone at that level, and
then replace the generator with your dummy mic. Although you'll need to
make up a cable for it, I find that the function generator phone app
from Keuwlsoft works quite well.

Put your DAW program into the Record mode on a track and read the
meters. They may be below -80 dBFS, so if your program gives you the
option of setting the minimum level on the scale, do that accordingly.
The meters will be bouncing around, so take an eyeball average and write
it down. A more instructive procedure would be to use a spectrum
analyzer to see if there's anything there besides random noise - hum,
for instance. I like the DAW plug-in SPAN from Voxengo, but some DAW
programs have a spectrum analyzer built in, though, like Audacity's, the
scale is limited to reasonable music levels and won't show a small
amount of noise.

After you have a reference reading of the noise level without the
pre-preamp, put it in line ahead of the interface and again, adjust the
input gain on the interface to get back to your reference level - either
with a mic or a signal generator.

Now, plug your dummy mic back in and look at the noise level. If the
pre-preamp claims to have 25 dB of gain (and you can confirm that with
the same test setup) you won't find an improvement of 25 dB in
signal-to-noise ratio, but you should find some improvement. Don't be
surprised if it's less than 10 dB - molecules are going to move no
matter how good the specs look.



--
For a good time, call http://mikeriversaudio.wordpress.com

[Tatonik]

When I was considering one of these gain boosters several years ago, I
came across the results of some tests run by Jim Williams on a Fethead
and a Cloudlifter:

https://www.gearslutz.com/board/show...3&postcount=78

https://www.gearslutz.com/board/show...2&postcount=86

In another thread, he wrote of the Cloudlifter, "I did extensive Audio
Precision analyzer tests on those. They add 1 db of noise to the stew."

"EIN specs (if supplied) will tell you the base line. Use a Neve ring of
three and you get about -125 db EIN. The best designs can best that by 7
or 8 db. That will determine if a fet booster will help or not."

https://www.gearslutz.com/board/so-much-gear-so-little-time/1233178-cloudlifter-supposed-increase-signal-noise-ratio.html

[Tobiah]

On 3/18/19 5:55 PM, Phil Allison wrote:
Tobiah wrote:

I ordered a Jethead


** Its called a " Fethead " - dickhead.

I'm so sorry. It must suck to be you.

[Tobiah]

Smartphone app maybe !

I have Signal Suite Pro on an iPod Touch (g4) - maybe one and only
Apple product. But many reasonably sophisticated sig-gen apps
available now for free on Android.

geoff

Ooops - for 'maybe' read 'my'.

geoff

Ok, so "Smartphone app my"!

[Phil Allison[_4_]]

Tobiah wrote:

Phil Allison wrote:


I ordered a Jethead


** Its called a " Fethead " - dickhead.

I'm so sorry.


** Very sorry indeed - a sorry little dickhead.



It must suck to be you.


** LOL - ****wits like you suck 24/7.

Wot a jerkoff.


..... Phil

[Tobiah]

I got the Fethead today. I placed both NT1-A's in as close to the same
position as possible. I ran one through the Fethead, and the other
straight though into the preamps of my M-Audio Fast Track Ultra. I set
the non-Fethead gain to 100%, then set the gain of the Fethead mic to
match the best I could trying different sound sources and pink noise far
and close to the mics. Eventually I was satisfied that the meters were
responding identically.

Next, I traded the mics for two 150 Ohm dummy mics. The Fethead
produced audibly more noise. I applied same-gain normalization
to the two tracks, and here is the result, with the Fethead mic
on the bottom.

https://imgur.com/a/UwdLoII

So, it goes back. I could see it being handy with a portable
recorder that had horribly noisy preamps.


Toby