Double Bass iamp200 and infrasonics

[Mike Dimin]

DRURB
I just got off the phone with iAMP designer, Gary Gibilisco (the one that you probably should have spoken with first). Gary's name is listed as the amp contact on the EA page and wants to do everything he can to help. His email is [email protected] and I urge you to email him.

Well, I have to stand corrected, sort of - although John was technically correct that Iamps do not have a subsonic filter. All Iamps are designed with a very steep rolloff starting at 20hz. At 4 hz there is absolutley no response from the amp.

The anomolies that you mention have never been a problem for the very many DB users that use EA gear. The problem could be very many things that have little or nothing to do with the amp. One thing that it very well might be is a low frequency feedback caused by the physical relationship from the bass to the speaker.

Regardless of the problem, Gary was very interested in working out a solution. I suggest you contact him directly ASAP. If there needs to be a modification to the amp, Gary is always willing to do it.

I am sorry if I came off as abrasive or confrontational. There are too many posts, here at TB, where people jump to conclusions w/o investigating the issue first. Having a company, like EA behind you, that a) cares about your problem and b) will go out of there way to fix it does not justify the rash judgements of too many who know way too lillts (not meaning you DRURB)

Mike

 

[Mike Dimin]

BTW,
The study of "infrasound" is ususally reserved for:

sounds that, "Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation"

and

"Infrasound sometimes results naturally from ocean waves, avalanches, earthquakes, volcanoes, and meteors. Infrasound can also be generated by man-made processes such as explosions, both chemical and nuclear."

Now, I wouldn't mind having a nuclear DB

 

[junglebike]

Interesting discussion. My own datapoints:

1. Using my old EA iamp800 combo, going straight from my fishman full circle I also experienced those huge speaker cone excursions -- I probably noticed this too late, though (it's hard to see the cone on the EA cab). My 12" woofer also blew out on that amp in a matter of a couple of months (replaced under warranty, combo sold shortly therafter). Running through a Fishman Pro Platinum Bass set flat, I got no such excursions -- I assume that the Fishman had a high-pass filter.

2. Using my current Acoustic Image Focus through a Schroeder 1210, I also experience huge cone excursions with my FFC piezo. However, this is easily remedied by selecting the AI's built-in HP filter -- of course, you can't use its notch filter, but I never need that anyway.

 

[drurb]

DRURB
I just got off the phone with iAMP designer, Gary Gibilisco (the one that you probably should have spoken with first). Gary's name is listed as the amp contact on the EA page and wants to do everything he can to help. His email is [email protected] and I urge you to email him.

Well, I have to stand corrected, sort of - although John was technically correct that Iamps do not have a subsonic filter. All Iamps are designed with a very steep rolloff starting at 20hz. At 4 hz there is absolutley no response from the amp.

The anomolies that you mention have never been a problem for the very many DB users that use EA gear. The problem could be very many things that have little or nothing to do with the amp. One thing that it very well might be is a low frequency feedback caused by the physical relationship from the bass to the speaker.

Regardless of the problem, Gary was very interested in working out a solution. I suggest you contact him directly ASAP. If there needs to be a modification to the amp, Gary is always willing to do it.

I am sorry if I came off as abrasive or confrontational. There are too many posts, here at TB, where people jump to conclusions w/o investigating the issue first. Having a company, like EA behind you, that a) cares about your problem and b) will go out of there way to fix it does not justify the rash judgements of too many who know way too lillts (not meaning you DRURB)

Mike

Mike--

Thank you, it was very kind of you to check into this for me.

 

[drurb]

BTW,
The study of "infrasound" is ususally reserved for:

sounds that, "Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation"

and

"Infrasound sometimes results naturally from ocean waves, avalanches, earthquakes, volcanoes, and meteors. Infrasound can also be generated by man-made processes such as explosions, both chemical and nuclear."

Now, I wouldn't mind having a nuclear DB

No disagreement that these describe characteristics and the study of infrasound. In matters acoustic, I do tend to use the correct technical terms. Frequencies below the audible region are infrasound, those above it are ultrasound. Speeds below the speed of sound are subsonic, those above it are supersonic. Likewise, frequencies of light below visible are infrared, those above are ultraviolet. It all keeps the planets in line.

 

[drurb]

DRURB
...
The anomolies that you mention have never been a problem for the very many DB users that use EA gear. The problem could be very many things that have little or nothing to do with the amp. One thing that it very well might be is a low frequency feedback caused by the physical relationship from the bass to the speaker.

...

Mike

Well, just a bit of clarification. The problem occurs even standing far from the amp and just touching the string. Not much room for feedback but I will do as you suggested and contact Gary.

 

[LowNote]

Just a quick side note to this discussion. One of the reasons that the Schertler StatB "pickups" sound so good, to me at least, is that the little power source/preamp box that it comes with includes a filter to take out the low frequencies. I use a StatB on my good bass, a Full Circle on my Eastman hybrid, and a Rev Solo on my East German ply bass that I keep in Scotland. The eq settings required to get my sound--fat bass but very punchy--think shape of notes as cubes with eased edges instead of spheres (if that makes any sense to anyone but me)--is very different between these pickups. I have to roll off the bass on the Rev Solo and Full Circle and can leave it basically flat on the StatB when played through AI amps. My New Yorker doesn't have the HiPass filter but the Focus does, and I get the sound I want when using the Focus by using the Hi Pass filter as well.

I hope that you have a good experience with the Gig Pro. I too bought one based on Talkbass comments with the hope of tightening up the sound of my Eastman with the Full Circle. While the High Pass filter works fine on the Gig Pro, I just couldn't get it to sound as good as going through the preamp section of both of my AI boxes and intend to sell it when I return to Los Angeles at the end of November.

Erik Hansen
Los Angeles

 

[drurb]

...

I hope that you have a good experience with the Gig Pro. I too bought one based on Talkbass comments with the hope of tightening up the sound of my Eastman with the Full Circle. While the High Pass filter works fine on the Gig Pro, I just couldn't get it to sound as good as going through the preamp section of both of my AI boxes and intend to sell it when I return to Los Angeles at the end of November.

Erik Hansen
Los Angeles

Thanks for the info. You said you "just couldn't get it to sound as good as going through the preamp section of both of my AI boxes." As good as what? I'm a bit confused.

 

[LowNote]

I like sound of the AI preamp sections better than the sound I got going through the GigPro into the affects return, bypassing the amps' preamp section. I brought the GigPro with me to Scotland, where I am now, and tried it with the Rev Solo on my ply bass into an old GK MB150. With this setup I also found I could get a better sound without the GigPro.

 

[fdeck]

No disagreement that these describe characteristics and the study of infrasound. In matters acoustic, I do tend to use the correct technical terms. Frequencies below the audible region are infrasound, those above it are ultrasound. Speeds below the speed of sound are subsonic, those above it are supersonic. Likewise, frequencies of light below visible are infrared, those above are ultraviolet. It all keeps the planets in line.

Wow, you even got it correct by saying "frequencies" and not "wavelengths." Don't tell me you are an optical engineer too?

 

[Chris Fitzgerald]

[Invalid or Expired Link Removed]

 

[drurb]

I like sound of the AI preamp sections better than the sound I got going through the GigPro into the affects return, bypassing the amps' preamp section. I brought the GigPro with me to Scotland, where I am now, and tried it with the Rev Solo on my ply bass into an old GK MB150. With this setup I also found I could get a better sound without the GigPro.

Thanks for the clarification. What about the Gig Pro into the "active" input of the pre-amp. If I end up with the Gig Pro as my solution, that will be how I figured I'd use it-- or maybe it would be better in the effects return. Hmmmm.

 

[drurb]

Wow, you even got it correct by saying "frequencies" and not "wavelengths." Don't tell me you are an optical engineer too?

Well, this made me chuckle because I was about to write "wavelengths" and switched because "frequencies" was really correct in context. Nope, not an optical engineer but did teach the stuff to undergrads at a big-ten university. Thanks for noticing!

 

[drurb]

Thanks to the dialog that was facilitated by Mike Dimin, I heard from Gary Gibilisco, the designer of the iamp. He seems completely committed to making this right and solving my problem. He suggested that I return the amp to them for evaluation (at EA's expense).

I really can't ask for much more than that. I feel confident that a solution will emerge and I'll let you all know via this thread.

Two points for the guys at EA!

 

[Aleph5]

Well, this made me chuckle because I was about to write "wavelengths" and switched because "frequencies" was really correct in context. Nope, not an optical engineer but did teach the stuff to undergrads at a big-ten university. Thanks for noticing!

Not to pick too fine a nit, but all of the optics engineers I've known would have used "wavelength," and most cringe when they hear electrical types use "frequency" when referring to light. Maybe I don't get the "in context" part.

 

[drurb]

Not to pick too fine a nit, but all of the optics engineers I've known would have used "wavelength," and most cringe when they hear electrical types use "frequency" when referring to light. Maybe I don't get the "in context" part.

Well, wavelength and frequency are, of course, reciprocally related. In the case of light, one can get to the other via "c" the speed of propogation of electromagnetic radiation. When speaking about electromagnetic radiation, we usually do speak in terms of wavelength, per se. Thus, microwaves, short-waves, long-waves, etc. The context of my post was that for "frequency," one uses the prefixes "infra" and "ultra" to refer to those outside a pre-defined region. In the case of my post, the pre-defined regions were sound and light.

After my example of infrasonic and ultrasonic vibrations referring to frequencies of sound below and above the audible range, respectively, it was more consistent to say that infrared and ultraviolet refer to frequencies of light below and above the visible range, respectively. It benefitted from parallelism.

I could have said that wavelengths of light shorter than about 400 nm and longer than about 700 nm are infrared and ultraviolet respectively. It was cleaner to leave the reciprocal out of things.

You are correct, however, that such references to light are almost exclusively in terms of wavelength. Indeed, I have never given a lecture to students in which I referred the the various frequencies of light. I have, however, often discussed the wavelengths that correspond to the different frequencies of sonic vibration in air.

 

[Tbeers]

Just a quick side note to this discussion. One of the reasons that the Schertler StatB "pickups" sound so good, to me at least, is that the little power source/preamp box that it comes with includes a filter to take out the low frequencies. I use a StatB on my good bass, a Full Circle on my Eastman hybrid, and a Rev Solo on my East German ply bass that I keep in Scotland. The eq settings required to get my sound--fat bass but very punchy--think shape of notes as cubes with eased edges instead of spheres (if that makes any sense to anyone but me)--is very different between these pickups. I have to roll off the bass on the Rev Solo and Full Circle and can leave it basically flat on the StatB when played through AI amps. My New Yorker doesn't have the HiPass filter but the Focus does, and I get the sound I want when using the Focus by using the Hi Pass filter as well.

I hope that you have a good experience with the Gig Pro. I too bought one based on Talkbass comments with the hope of tightening up the sound of my Eastman with the Full Circle. While the High Pass filter works fine on the Gig Pro, I just couldn't get it to sound as good as going through the preamp section of both of my AI boxes and intend to sell it when I return to Los Angeles at the end of November.

Erik Hansen
Los Angeles

In response to the Stat-B comments... there is definitely some truth to that. I don't know what it is, but I have never had to turn bass down or use a filter of any sort with the Stat-B. Leaving bass flat yields the perfect response from that frequency range. Having said that, I find the midrange on the Stat-B to be goofy and difficult to manage. That characteristic alone will eventually cause me to move on to something else....

 

[panos]

+1 for the Gigpro. A very useful tool.

1) There are 2 weeks i use it. I bought it also based on comments from Adrian Cho and flatback. It does an excellent job cuting the excesive low frequences (i mean from open E to open A or even B) when i boost the general volume.
I have the impression (just only impression) that the trim filter of Gigpro is better than the high pass filters of Focus, or at least more friendly. I connect the output of Gigpro in the active input in order to have access to the preamp section of focus, even though i'm getting also good results if connecting it to effects return.
But i can't tell what exactly happens with infrasounds, i don't think i've noticed such a phenomenon. The user's guide says that this low cut filter is adjustable from 27Hz to 200Hz.

2) There is a second issue very important to me. Using the Gigpro (with my RS, also tested and verified with my older Bassmax), i'm getting the mid frequences significantly more warm and pleasent, without the piezo thonk. This allows me not to cut down the midrange as i did in the past. I heared from someone that the class A electronics amplify the even harmonics of sound, eliminating so the unnatural harmonics of piezo pickups. Maybe DRURB could comment about this.

 

[drurb]

I heared from someone that the class A electronics amplify the even harmonics of sound, eliminating so the unnatural harmonics of piezo pickups. Maybe DRURB could comment about this.

Well, whoever said that is incorrect. He/she is confusing the amplification of any harmonics created by the source (the piezo element) with harmonics created by overdriving or distorting the pre-amp stage.

First, I am not aware that piezo elements create objectionable (odd-order) distortion products. Suppose for the sake of argument that they do. Whatever they are, they will be amplified by ANY pre-amp-- class A, class B, op-amp, whatever.

The difference in the types of distortion produced by different amplifier classes becomes an issue for musical amplification when those circuits are overdriven. That's the last thing I figure folks want to do with the Gig Pro.

It is the even-order distortion products created by overdriving many vacuum tube circuits that many guitar players love.

 

[panos]

First, I am not aware that piezo elements create objectionable (odd-order) distortion products. Suppose for the sake of argument that they do. Whatever they are, they will be amplified by ANY pre-amp-- class A, class B, op-amp, whatever.

OK, now it's clear to me.

And, about infrasounds, taken that the low cut filter starts working at 27Hz (as the manual says), i'll wait with interest what will do with infrasounds. I hope that you'll get a good result.