ISA ONE's noise when cranked up

[Ximo]

This happens with every pre.

You need to look into gain staging. Do you really need +80 or even +60db of gain to record what you are recording? Opinions vary but as a general rule people will hit the converters well below 0db (-20db to -10db) so unless you are recording a pin drop you shouldn't really need to set the pre to its maximum volume. There is a lot of info here and on other sites about gain staging.

[superwack]

FYI - when a mic pre is not seeing the proper load (ie it doesn't have a mic plugged in to it) it will amplify its internal electronics noise, RF, etc. thus skewing your results!

If you connect a 50 ohm resistor across pin 2 & pin 3 of the mic input (better yet wire up an XLR barrel with a resistor) you will load the pre correctly and get a better idea of the noise but, as mentioned above, there will be noise in any pre all the way up,

You can also try a 150 ohm replicate a dynamic mic

[Manfrensengensen]

Are you sure you're not going thru a preamp on the interface as well..

Usually an XLR to TRS is required to go line level in on an interface.

[guitarboy94]

I had problems with my Isa ONe as well and had to return it. I was getting serious preamp hiss when driving my SM7b starting at around 45DB. I think there might be some quality control issues going on at the Chinese factroy with the ISA ONE line. I had a previous ISA ONE several yeas ago that was as quiet as a mouse, however.

[mowmow]

Originally Posted by Ximo

This happens with every pre.

You need to look into gain staging. Do you really need +80 or even +60db of gain to record what you are recording? Opinions vary but as a general rule people will hit the converters well below 0db (-20db to -10db) so unless you are recording a pin drop you shouldn't really need to set the pre to its maximum volume. There is a lot of info here and on other sites about gain staging.

Yes, I do need 60dB+ for my SM7b If I want the level to go around -12dB on DAW. I didn't notice this noise until I use SM7B. I hope mine is not broken.

[mowmow]

Originally Posted by superwack

FYI - when a mic pre is not seeing the proper load (ie it doesn't have a mic plugged in to it) it will amplify its internal electronics noise, RF, etc. thus skewing your results!

If you connect a 50 ohm resistor across pin 2 & pin 3 of the mic input (better yet wire up an XLR barrel with a resistor) you will load the pre correctly and get a better idea of the noise but, as mentioned above, there will be noise in any pre all the way up,

You can also try a 150 ohm replicate a dynamic mic

If I connect some dynamic mic, I see the noise plus the room noise that is picked up by mic. Amount of the noise doesn't change.

[mowmow]

Originally Posted by Manfrensengensen

Are you sure you're not going thru a preamp on the interface as well..

Usually an XLR to TRS is required to go line level in on an interface.

Thankx for checking but it is hooked up to one of the line inputs. It doesn't change the amount of the noise no matter which line input I connect to.

[mowmow]

Originally Posted by guitarboy94

I had problems with my Isa ONe as well and had to return it. I was getting serious preamp hiss when driving my SM7b starting at around 45DB. I think there might be some quality control issues going on at the Chinese factroy with the ISA ONE line. I had a previous ISA ONE several yeas ago that was as quiet as a mouse, however.

I hope this is not the same case.
Anyone else see the same amount of noise when its +60dB and +80dB?
It is funny that I don't see or hear any noise when I crank up the pre on interface.

[melway]

I own two ISA one pres and do not experience this issue. I briefly owned an MXL MPAC before purchasing the ISA, and the MXL had a far higher noise floor that prompted me to ship it back. You shouldn't be dealing with excess noise with the ISA.

[mowmow]

Originally Posted by melway

I own two ISA one pres and do not experience this issue. I briefly owned an MXL MPAC before purchasing the ISA, and the MXL had a far higher noise floor that prompted me to ship it back. You shouldn't be dealing with excess noise with the ISA.

Are you saying that even with +80dB, you don't see any noise on analyzer or hear any hiss?
If this is true, I have to contact my dealer.

[melway]

With everything cranked you're going to hear noise, some hiss, hum, etc. but I've used the ISA at high levels and didn't think the noise was a factor. And directly compared to another subjectively noisy preamp, thought the ISA was pretty quiet. In this price range, it's not going to be silent with 80db of gain applied. But if you're getting obtrusive noise up to that point, there might be a problem with the unit.

[guitarboy94]

Originally Posted by mowmow

Are you saying that even with +80dB, you don't see any noise on analyzer or hear any hiss?
If this is true, I have to contact my dealer.

Again, you might have an issue with yours. Mine most certainly had an issue. My guess is that a batch of ISA ONES have some defective chips, caps, etc. It's a terrific preamp and you shouldn't get any noise at 60db. My old one was dead quiet.

[mowmow]

Thanks a lot guys.

I noticed this problem when I go 96K with dynamic mic.
All I saw above 20K was a noise floor which kind of discouraged me.

I sent those analyzed pictures to Forcusrite to see if it is normal behavior.
I'll report back when I get a reply.

[mowmow]

I Just wanted to report you that I just got the reply from focusrite rep and he explained that he got the same kind of test results as mine. Therefore mine is not broken, it is just a normal behavior.

[audiotech]

Originally Posted by mowmow

I Just wanted to report you that I just got the reply from focusrite rep and he explained that he got the same kind of test results as mine. Therefore mine is not broken, it is just a normal behavior.

Maybe his is also broken. Now if he checked out two or three units and said they are all acting very much the same way, then I would feel much better about his findings. This is very much the same as finding a lot of noise in high ISO settings on digital SLR cameras. You just have to know what is normal for the amount of gain that is used.

Dennis

[Lights]

I have two ISA-One pres here at the moment. One I just purchased and one from a much earlier run. I will compare the two and your results and let you know.

However I wouldn't be surprised of there is some noise at the top of any pre's gain range. The ISA has a much wider gain range and therefore you can run it at the same level as many other pres and still have lots of headroom. Even with a gain-hungry SM7, I never pushed it to the point that I was getting audible noise from the preamp.

[garyboy2024]

Like others have said, there's no need to record so hot. Keep your peaks no higher than -10db (or even lower) in your DAW. You'll be glad to have this headroom later in the mix and it won't be asking so much of your preamp.

[mowmow]

Originally Posted by Lights

I will compare the two and your results and let you know.

Thank you! This will be great.
If you can, try capture the pictures and post them so we can all see them and compare.

[Lights]

Here are the results:

First of all, I have a brand new ISA-One and one built in 2009. Both performed identically.

Second, I'm seeing the exact same noise profile as you when the preamp is turned all the way up (gain and trim). When I turn the gain all the way up and the trim down to 0, I see nothing in the meters but can hear a slight hiss. At normal operating levels I hear nothing at all.

For comparison, I cranked a GAP73mk2, which has roughly the same gain range as the ISA-One. Attached you will see a completely different noise profile, but noise nonetheless. Again, when this preamp is used at normal operating levels, there is no audible or visible noise at all.

I can easily record even a gain-hungry mic like the SM7b on both of these preamps with no noise, which is more than I can say for just about any other pre I've seen.

I think the moral of the story is that you buy a preamp with lots more gain than you need, because when you crank any preamp to the end of the knob, there will be some noise. And the ISA-One is one of the cleanest, lowest-distortion preamps out there.

[dickiefunk]

Originally Posted by Lights

Here are the results:

First of all, I have a brand new ISA-One and one built in 2009. Both performed identically.

Second, I'm seeing the exact same noise profile as you when the preamp is turned all the way up (gain and trim). When I turn the gain all the way up and the trim down to 0, I see nothing in the meters but can hear a slight hiss. At normal operating levels I hear nothing at all.

For comparison, I cranked a GAP73mk2, which has roughly the same gain range as the ISA-One. Attached you will see a completely different noise profile, but noise nonetheless. Again, when this preamp is used at normal operating levels, there is no audible or visible noise at all.

I can easily record even a gain-hungry mic like the SM7b on both of these preamps with no noise, which is more than I can say for just about any other pre I've seen.

I think the moral of the story is that you buy a preamp with lots more gain than you need, because when you crank any preamp to the end of the knob, there will be some noise. And the ISA-One is one of the cleanest, lowest-distortion preamps out there.

Interesting results. Looking at this it would appear the PRE73mkII has less noise than the ISA One?

I've just been reading the noise specs of the ISA One and ISA TWO and the EIN is -125db on ISA One and -127db on ISA TWO?

[mowmow]

Originally Posted by Lights

Second, I'm seeing the exact same noise profile as you when the preamp is turned all the way up (gain and trim). When I turn the gain all the way up and the trim down to 0, I see nothing in the meters but can hear a slight hiss. At normal operating levels I hear nothing at all.

Thanks for the test!

So the first picture is the result with +80db using impedance set to Isa 110 am I right? Higher impedance setting will result more noise.
You know what, it looks almost the same as my first picture but mine is 9db louder for some reason. The tail of yours is at -69db where mine is at -60db.
I'll test again when I go home.

[mowmow]

OK. I just realized that it could be a lot of things that noise levels on analyzer can change. For example, pan raw setting, where the analyzer is inserted etc.
To avoid confusion, the analyzer should be inserted to input channel, not master channel. This way can avoid the confusions of pan raw setting.

So this is my update.
The analyzer is inserted in input channel.
ISA ONE is at maximu level (+80db)
Impedance is at ISA110
using it as mono track on reaper.

[Lights]

Yes, I had it in ISA 110 impedence and the GAP73 was set to Low-Z.

The GAP73mk2 and the ISA-One are both very low-noise preamps. The ISA-One produces more hiss than the GAP73 when fully cranked and the GAP73 produces more low-frequency hum as you can see from my pictures.

But that almost doesn't matter because aside from cranking them with no mic attached to look at them in an analyzer, they are as close to noiseless as any preamp on the market at their normal operating levels and they both have WAY more gain than most other preamps, so you will probably never need to use that last 15% of their gain range.

You have to listen to the quality of the sound, how much distortion is added at normal volumes. Even when I have the ISA-One's gain all the way at max, there's nothing on the signal meter--it's only when I also crank the trim to +20 that I get that result. And when used in normal operating range for a microphone (which is the application that uses the most gain), the ISA-One is crystal clear. The GAP73 imparts more color. I did a shootout of both of them and compared them both with different impedence and gain settings (since you can crank the input on the GAP and turn down the output to get more color, and the ISA-One has 4 different impedence settings). I tested them both with a Shure SM7b and a Stellar CM-6. In the end I'm very impressed with both.

Counter-intuitively, i chose to pair the ISA-One with the CM-6 and the GAP73mk2 with the SM7b. Both have more than enough gain for the SM7b, but I liked optimizing for the nice clean sound of the ISA-One paired with the modern clean sound of the CM-6, and the "warmer" harmonic distortion of a "relatively cranked" GAP73 on the SM7. Of course, I record both microphones on a stereo track and then blend the two. See: Dual Mic for Vocals... how close in phase do they need to be?

[nosebleedaudio]

Originally Posted by mowmow

OK. I just realized that it could be a lot of things that noise levels on analyzer can change. For example, pan raw setting, where the analyzer is inserted etc.
To avoid confusion, the analyzer should be inserted to input channel, not master channel. This way can avoid the confusions of pan raw setting.

So this is my update.
The analyzer is inserted in input channel.
ISA ONE is at maximu level (+80db)
Impedance is at ISA110
using it as mono track on reaper.

That looks about right to me at 80dB of gain...Plus or minus a few dB's..
You need to do these tests with a 150 Ohm resistor across Pin 2 & Pin 3 like mentioned.. A Dynamic mic WILL make them look worse...Room noise will be on top of the Pre's noise..

A 150 Ohm resistor has a noise of -131dB, add 80dB of gain and you raised it to -51dB...With no accounting for the Pre's noise floor, See how this works..

[mowmow]

Originally Posted by Lights

You have to listen to the quality of the sound, how much distortion is added at normal volumes. Even when I have the ISA-One's gain all the way at max, there's nothing on the signal meter--it's only when I also crank the trim to +20 that I get that result. And when used in normal operating range for a microphone (which is the application that uses the most gain), the ISA-One is crystal clear. [/url]

Yes, I agree. ISA ONE is like distortion free. That's where I feel this unit is professional. It is very reliable and get the same result everytime.

[mowmow]

Originally Posted by nosebleedaudio

That looks about right to me at 80dB of gain...Plus or minus a few dB's..

Thanks. This comment mekes me feel better.
I can't think of a situation where I need +80dB of gain so I really don't have a problem but I can see the noise floor visually which made me nervous.

Originally Posted by nosebleedaudio

You need to do these tests with a 150 Ohm resistor across Pin 2 & Pin 3 like mentioned..

How do I do that? Do I need some special instruments to do this?
Or do I just connect some mic cable in mic input which I already have.

[nosebleedaudio]

How do I do that? Do I need some special instruments to do this?
Or do I just connect some mic cable in mic input which I already have.[/QUOTE]

Yes, will need a 150 Ohm metal film resistor across Pin 2 & 3, and a 20KHz filter..To measure accurately..
I put up a test a while back for another reason but will show noise level expected from a GOOD Mic pre with a -128.5dB EIN, ISA One has -126dB if i recall...

Mic pre Noise test with/with out mic.

[Lights]

I don't know if this matters but i tested it with both no mic plugged in, and my Stellar CM-6 plugged in but with the power supply off. Same results both ways.

[the C.L.A.]

One interesting thing I noticed yesterday is that the noise of the peak at 6 kHz is correlated between the mic pre and the DI. If you match the noise levels and flip the phase on the mic pre those peaks get cancelled out.

I'm not a tech. So what does this tell us? Does this noise peak possibly come from the power supply?