Anyone have the Elite Acoustics Stompmix 4?

[AeroUSA]

Originally Posted by lkingston

You know there is a noise gate right? I find very little self noise in the Stompmix4. I would guess that you are just hearing the noise in your pickup.

It’s not as noisy as this through my other systems. I will investigate today. Do you know if there is a way to perform a factory reset?

[lkingston]

Originally Posted by AeroUSA

It’s not as noisy as this through my other systems. I will investigate today. Do you know if there is a way to perform a factory reset?

Do you have the compressor dialed in? Compression will raise the apparent noise floor.

[lkingston]

Originally Posted by AeroUSA

My K&K guitar gets sufficient signal on all of the inputs but there is still more hiss that there should be.

Are you sure about this? Press the system button once to call up the input meters. With the guitar plugged into channel three or four, see what input level you are getting. The optimal input level is above the -12db line but not quite hitting zero. With either of my active pickup acoustic guitars, the signal is well below the -12db line and there is no way to bring it up without an external preamp.

This makes sense because it is line level TRS. Yes it works and it sounds ok, but it is below optimal levels and will lead to higher signal to noise and slightly grainy audio.

This is what I was complaining about in my post. My guess is that this is the reason for your complaint with hiss as well.

None-the-less, for my use of combining my guitar with the Bass9 generated bass and properly processing the separately, it is still the best option available in spite of this flaw.

[AeroUSA]

Originally Posted by lkingston

Are you sure about this? Press the system button once to call up the input meters. With the guitar plugged into channel three or four, see what input level you are getting. The optimal input level is above the -12db line but not quite hitting zero. With either of my active pickup acoustic guitars, the signal is well below the -12db line and there is no way to bring it up without an external preamp.

This makes sense because it is line level TRS. Yes it works and it sounds ok, but it is below optimal levels and will lead to higher signal to noise and slightly grainy audio.

This is what I was complaining about in my post. My guess is that this is the reason for your complaint with hiss as well.

None-the-less, for my use of combining my guitar with the Bass9 generated bass and properly processing the separately, it is still the best option available in spite of this flaw.

Yeah my K&K hits the middle line as it should and it’s a 1megohm impedance. Seems intended for K&K pickups! The hiss is because I am cranking the treble as I always do with the K&K but I guess it’s an aggressive high boost and I am boosting it a lot as I’m playing quietly at home.

[Cuki79]

Originally Posted by AeroUSA

The hiss is because I am cranking the treble as I always do with the K&K but I guess it’s an aggressive high boost and I am boosting it a lot as I’m playing quietly at home.

Sounds like thermal noise from the 1Mohm resistor... Not a good sign.

Things I would try:
1) The noise can come from the DC-DC convertor of the 48v Phantom power. High frequency switches produce digital noise. Turn it off. (ex: Soundcraft UI12-UI16 notoriously noisy)
2) The noise can come from a badly filtered power supply (same kind of digital noise). Try to use a pedal power bank like rockboard LT (which however does include a DC-DC converter too...). If the noise come from the power supply, best solution is 3x18650 cells. It deliver almost 12v and will be perfectly clean.
3) The noise can come the thermal noise of the 1Mohm resistor. Try increasing the level pot on the back of the unit. By chance it could be the analog gain stage placed before the ANalog-to-digital-converter. If it does not work, the only solution is to put a less noisy a preamp in front to improve the Signal to noise ratio. (Which annihilates the benefit of this pedal)

AeroUSA has successfully used TC helicon Play Acoustics for years now, so if he says the EAE digital pedal is noisy: I believe him.

Here is a quote from EAE website

2) Can I plug Passive Pickups directly into the StompMix4?
– No, StompMix 4 only support Active Pickups.
3) Too Much Hiss on the outputs?
– Make sure the GAIN level knobs for Chan 1 and Chan 2 are NOT at MAX.
– Reduce the MIX input level to be about 12 o’clock for each channel.
– Check for possible Ground Loops
– Make sure to use Active Pickups.
– Make sure output is “NOT” going into High Impedance Inputs on your Amplifier or PA system. Outputs from StompMix 4 should be connected to Line Inputs on the Amplifier or PA system.

* No passive pickups: Usually means no high-Z input or no analog preamp gain.
* The 4 first peace of advice are typical of a noisy unit (think headway 1st gen preamps)

I don't understand that:

– Make sure output is “NOT” going into High Impedance Inputs on your Amplifier or PA system. Outputs from StompMix 4 should be connected to Line Inputs on the Amplifier or PA system.

I understand than a High-Z input can be noisy because of the thermal noise on the high value resistor but if the input signal is at line level it should be hot enough to maintain a good signal-to-noise ratio. I am sure there are professional electronic engineer who can shed some light on that for me...

If the stomp mix 4 has no Hi-Z quality preamps, it is a small step up from Mackie DX4.

[AeroUSA]

Originally Posted by Cuki79

Sounds like thermal noise from the 1Mohm resistor... Not a good sign.

Things I would try:
1) The noise can come from the DC-DC convertor of the 48v Phantom power. High frequency switches produce digital noise. Turn it off. (ex: Soundcraft UI12-UI16 notoriously noisy)
2) The noise can come from a badly filtered power supply (same kind of digital noise). Try to use a pedal power bank like rockboard LT (which however does include a DC-DC converter too...). If the noise come from the power supply, best solution is 3x18650 cells. It deliver almost 12v and will be perfectly clean.
3) The noise can come the thermal noise of the 1Mohm resistor. Try increasing the level pot on the back of the unit. By chance it could be the analog gain stage placed before the ANalog-to-digital-converter. If it does not work, the only solution is to put a less noisy a preamp in front to improve the Signal to noise ratio. (Which annihilates the benefit of this pedal)

AeroUSA has successfully used TC helicon Play Acoustics for years now, so if he says the EAE digital pedal is noisy: I believe him.

Here is a quote from EAE website


* No passive pickups: Usually means no high-Z input or no analog preamp gain.
* The 4 first peace of advice are typical of a noisy unit (think headway 1st gen preamps)

I don't understand that:


I understand than a High-Z input can be noisy because of the thermal noise on the high value resistor but if the input signal is at line level it should be hot enough to maintain a good signal-to-noise ratio. I am sure there are professional electronic engineer who can shed some light on that for me...

If the stomp mix 4 has Hi-Z quality no preamps, it is a small step up from Mackie DX4.

Thanks! I do have the channel volume at max so I’ll try reducing that and it is a passive pickup but how come it seems to work well (plenty of gain and sounds good).

[jonfields45]

Originally Posted by AeroUSA

Thanks! I do have the channel volume at max so I’ll try reducing that and it is a passive pickup but how come it seems to work well (plenty of gain and sounds good).

Looks like you are headed in the right direction.

Any input buffer circuit will require biasing resistor(s) and low noise resistors are a good design choice (resistor noise power, along with a host of other variables, is proportional to value). Low impedance inputs are prefered for general immunity to high impedance noise sources (most noise sources). However there are plenty of good sounding 10M ohm input preamps on the market.

Thermal noise in an input bias resistor would be a sample defect in this day and age. You should return it for a replacement, if that resumes a place in the list of possible suspects.

I am no longer surprised by how cheap most power supplies are these days, even the ones shipped with name brand products. At the retail price points for common 9v wall warts I can't imagine they are really tested in manufacture and it is up to you to return the bad ones...

[lkingston]

Originally Posted by Cuki79

If the stomp mix 4 has no Hi-Z quality preamps, it is a small step up from Mackie DX4.

It has great preamps on channels 1 and 2 and TRS line level inputs on channels 3 & 4.

[MrErikJ]

Originally Posted by AeroUSA

My K&K guitar gets sufficient signal on all of the inputs but there is still more hiss that there should be.

Sean De Burca told me that the StompMix is more of a mixer than a "preamp" and that he runs his K&K through its blender preamp before it goes into the StompMix. He said that it's intended to work with powered pickups, so my inference is that it isn't ideal for passive pickups, unless you run them through a buffer of some sort.

I've been wanting to try this or the Orange Acoustic Pre to mix my Fishman Rare Earth Blend but, OMG, I gotta stop buying preamps.

[Groberts]

Originally Posted by AeroUSA

Yeah my K&K hits the middle line as it should and it’s a 1megohm impedance. Seems intended for K&K pickups! The hiss is because I am cranking the treble as I always do with the K&K but I guess it’s an aggressive high boost and I am boosting it a lot as I’m playing quietly at home.

K&K's need treble added. Not much getting around that.

[AeroUSA]

I wanted to update my findings so as to not mislead anyone.

So the Anthem and the K&K both have the same gain in Ch 3 and 4 (they both hit the middle line which is said to be ideal). There is hiss when boosting the treble too much but the Anthem only needs a slight boost at low volumes (it should need less at louder volumes).

The K&K does have a touch of noise in the background, probably because it's passive (it disappears when using the battery powered K&K preamp), I remember James May mentioning that this can happen with passive pickups into a preamp. When boosting treble from the external preamp there is no added hiss.

All in all the mixer seems to make an excellent preamp choice for active and passive pickups but a dedicated preamp allows even more control.

Is there anything specifically that I should talk about in my demo of this on my YouTube channel? Any ideas would be appreciated!

[lkingston]

One thing is that this mixer does something that seems to be common, but that I’m not crazy about:

It uses line level inputs, then allows you to compensate for the gain by adding up to 12db of extra gain from the individual mixer channels. If you look at mixer channel, the 12 o’clock position is 0db. All the way clockwise. With 24db ADC and DAC converters, this theoretically isn’t a big deal. Mackie does this and calls it “wide-z”. Behringer does this on the XR-12 and XR-16 line inputs. Korg does this on their KONNECT one piece PA.

I’m sure this approach saves money by reducing the number of preamps needed. I play fingerstyle guitar with no nails, and my guitar output is softer than most strummers. I find this approach to be a bit anemic, even with the mixer channel turned all the way up to 12db. It probably works ok for strummers.

[Cuki79]

Originally Posted by lkingston

:

It uses line level inputs, then allows you to compensate for the gain by adding up to 12db of extra gain from the individual mixer channels. .

Is it true for all four inputs when using jacks? If the 12 dB gain are digital it is a bit disappointing for me.

[rockabilly69]

Originally Posted by AeroUSA

I wanted to update my findings so as to not mislead anyone.

So the Anthem and the K&K both have the same gain in Ch 3 and 4 (they both hit the middle line which is said to be ideal). There is hiss when boosting the treble too much but the Anthem only needs a slight boost at low volumes (it should need less at louder volumes).

The K&K does have a touch of noise in the background, probably because it's passive (it disappears when using the battery powered K&K preamp), I remember James May mentioning that this can happen with passive pickups into a preamp. When boosting treble from the external preamp there is no added hiss.

All in all the mixer seems to make an excellent preamp choice for active and passive pickups but a dedicated preamp allows even more control.

Is there anything specifically that I should talk about in my demo of this on my YouTube channel? Any ideas would be appreciated!

Yeah talk about how you can only use the delay on one channel, which frankly is ridiculous for a stand alone mixer.

[lkingston]

Originally Posted by Cuki79

Is it true for all four inputs when using jacks? If the 12 dB gain are digital it is a bit disappointing for me.

Just for channels 3 & 4. Channels 1 & 2 have rather nice preamps.