Acoustic Image has some nice new pics

I've just look at the pictures and read the tech. specifications. They say that the input impedance is 1 MOhm. First I thought it's a mistake, but the same is written at several different models of the new line of AI products. I'm very surprised by this fact, because the previous line of AI amps used to have 10 MOhm input impedance and that was the greatest advantage over other amps - GK MB's for instance. So is this advantage gone now???

 

Good eyes. While I didn't look all that hard at the specs before, I never really noticed it until you mentioned it, Jaromir. I wonder....
You would think they would keep the ultra-high impedance input. Again, that was one of their advantages over the competition. I suspected it might be a typo but after looking at Bob Gollihur's page, it says the same thing there, too.

This is from Bob's Acoustic Image page http://www.urbbob.com/accimg.html :

"Combination Jacks allow the use of a 1/4" or XLR input; input impedances are 1 megohm or 600 ohms based on jack chosen, separately buffered."

Hmmmm

 

I've discussed this new spec with Rick at length, and they are quite comfortable with their decision to go to a 1 megohm input impedance.

They tested many pickups using both a 1 and 10 megohm load, and concluded that differences, if material, were not favorable. For instance, with the Fishman Full Circle, they reported the difference to be subtle, and that definition suffered at 10 megohms. The Realist was bassier (and not in a good way) at 10 megohms. The only pickup with a more favorable result at 10 megohms was the Fishman BP-100. Rick also consulted with other industry figures during the research process.

Another factor is the propensity of higher input impedances to be noisier, especially as input jacks corrode or otherwise get dirty, exacerbating any scratchiness or crackling that can occur as a result.
I'm sure their decision can be debated by those in the 10meg camp, but both Rick and Paul at Acoustic Image are gigging double bassists, and you can be certain that the new models would not have gone to this new spec without serious testing and debate. I also less formally tested different pickups using 10 vs. 1 megohm loads a few years ago and concur with their result and decision.

 

Also surprised regarding the lack of the bright control while no change in the extreme high shelving start frequency of 10K for the treble control... per my post in the older AI Series III thread.

 

I had noted this 1 Meg Ohm spec awhile ago and asked
Kevin Kaufman about it (local BG luthier famous as bass tech for Jaco Pastorius, not to be a name dropper) he explained in techie terms what A. H. Bob wrote so eloquently. Basically saying it was "probably better for modern piezos such as the realist and F. C. " I have faith that A.I. has done the R&D toward improving the product and made the decsion after 'on the gig' tests. And since I got an e-mail from A. H. Bob letting me know that my Focus 3 2R is near shipping I'll try and compare it with a friends Focus 2 at some point.

I'm am wondering why AI didn't utilize the empty compartment on the Contra EX
(Where the head would go) . Seems like it would be nice to have it flip open for cable storage.

 

I'm pretty sure WW's are 1M ohm and have been for a while. They work fine. By the way, do you have contact info for Kevin Kaufman? Thanks.

 

Correct.... HI is 10 and low is 1megohm for series II.

 

I just noticed that the A.I. site also has the series lll manuals as pdf. available for download. Since I mentioned the CONTRA EX earlier, the new specs on it are that it's rated @ 300 watts (I think series ll is 250) comes with a gig bag and weighs 16 pounds. Now THAT'S something my spaghetti arms could handle while maneuvering a DB through the kitchen at a five star hotel or a parking lot/street side obstacle course!

 

Having a 10M input impedance following 10' of coaxial cable and a hi-Z pickup isn't a very good solution; you end up getting a lot of noise from the coax. It's always better to put the preamp as close as possible to the transducer, and run a low-Z interconnect.

A perfect example is the typical condenser microphone, which has an extremely high input impedance and near-inifinite DC resistance (the actual transducer is two conductors seperated by air) followed by a vacuum tube or FET preamp and transformer to drop that to something in the 150-600 ohm range.

 

I could see this noise being an issue in a recording situation, but live? What kind of noise are we talking about? Is this the only drawback?

 

From any movement of the cable, for one. The coax acts like a capacitive transducer and you get a lod crackling noise. You also lose a lot of highs.

 

My focus series lll 2R arrived today. (very happy, thanks Bob)! One thing I hadn't considered with the stereo 'chan 2' on-off is that if you're not connected to the house or using the balanced out you can use it as a mute for channel 2 only. Now off to the gig to try it out for real. Too bad it'll be on "XMAS JAZZ".

 

Any updates from happy (or not) recipients?

 

I was able to see and hear a Focus III the other day up at Low Down Sound, and I have to say, I'm not all hot and bothered about the current ethetics. I preferred the look/feel of the old one. Tonally, it sounded similar to previous AI heads I had heard (though it was driving a pair of Eden cabs, which I would not call a match made in heaven).

It's still a tidy little package, it's just that I was a little disappointed in its looks. The graphics on the front panel appear to be, for lack of a better term, a "fancy sticker", where they are applied to a seperate "sheet" which is then adhered to the front of the amp. I'm sure other amps do this, too, but it was pretty obvious in this case, and not as attractive as some of the units with the printing done right on the metal (plastic?) panel.

Tom.

Tom.

 

I picked up a Focus SIII and I like the way it looks. IMO it looks more like an "amp" than the old model which to me looks like a giant stomp box (but I think that one looks cool enough too). The stickers don't bother me at all - they are understated and well done and dont attract attention. It think it looks better than the gaudy golden Eden amps (although I like the sound of those). The new face plate is more fuctional in that if you have the amp up at shoulder level you can still read the dials.

Soundwise the Focus is brighter than I expected it to be. This is the first time I've actually got to play with the EQ of an AI amp. I find myself cutting the mids and treble quite a bit. So far I've only used in fairly quiet trio and duo settings and I anticipate using more mids and trebs when I get it out on a louder rock/pop gig. I love the clear tight sound it puts out. So far I'm very happy with it.

 

Those are valid points. I can see where lots of people might dig it. It just didn't "click" with me, visually (not that that's a big deal, though).

Tom.

 

I am very happy with my focus series lll 2R. But I can't really give it a full review because at the moment, I am between cabinets for DB. (I sold my LDS 1X8). Strangely; (and I am sure it will seem VERY strange for my brothers to the North) All my gigs since I got it have been outdoors. I used it with a jazz trio of electric keys/percussion and DB outside a large House (mansion) over on Palm Beach for a cocktail reception. I was pleased & it was easy to get the sound I wanted without fuss. All I can really say at this point is: considering the 'non-full range' cabinet I used ... it sounded great. BTW This was using a old very small 'one way' EV loaded 1x15 cabinet made by Jim Stinnett
http://www.jimstinnett.com/index_flash.html
I have two and bought them from Steve Bailey when he left Miami to become famous. I think they are from the "Walter Woods 100 watt / BP-100 and a little cabinet" gold standard days in the mid 80's

The next night. I used the focus lll an outdoor gig with the 2 small Stennett 1x15s with BG and I thought is sounded great for that too. Some of 'youse' guys on talk bass don't seem like it for BG but it worked much better than I thought. I am not a guy who wants to add ridiculous high treble for slapping so flat EQ was perfect. This Friday and Saturday are outdoors too. I blame the snow birds.