Infinity 2000A Hybrid Electrostatics

[hakka26]

Picked up a pair of these at a moving sale last month for $5 includng stands. Planning to fully audition them end of this month. Seems like all drivers are working though difficult to be sure of all panels. Anyone have any experience with these?

[Titanium Dome]

Looks like they've been "customized" with some putty.

The original spec (from a reliable source):

[hakka26]

Actually, I believe it is Bluetac and was used by Infinity to alter mass and sound. 35wpc rating is the minimum. If all goes well I might have some space to at least put them side by side and give a better listen.

[Tom Brennan]

Those are interesting. Are the tweeters firing out the back?

[hakka26]

THe tweeters fire to the front but the box is open to the rear also. Grill cloth covers the rear opening.

[Hoerninger]

Lots of information you can find here:
http://www.infinity-forum.de/2000A.html
(Was looking for Infinity Servo Static 1, an old love ;) only for one afternoon)
____________
Peter

[fs41]

Hey there,
Nice score!
I was bitten by the 2000A bug about 4 years ago. I've been searching and slowly collecting info on these speakers the best I can, but as you might have found, there isn't much out there.
From what I've found there was differences in the model throughout production. One big difference was the midrange driver. I can't recall what the make of the unit that is in your speakers, but in my opinion it was inferior to the Phillips unit (identifiable by tan cone, cloth surround, and black whizzer cone) that came in my 2000A's. I have had the opportunity to hear both and the difference was, well, big. Other differences I've seen are: rear plate with different binding posts, knobs, and lettering, as well as the woofer being either surface mounted or 'let-in' flush to the front baffle.

The tacky rings ARE a factory installed ring that was used to voice the driver to the cabinets. My theory on this is: The cabinets are of a resistive damped design, ala the huge wad of damping material inside both the main cabinet and the midrange compartment. Since the boys in the factory couldn't really install the material exactly the same every time, the damping characteristics of each cabinet/woofer system would be inherently different ultimately affecting the sound of the speaker. The ring enabled them to voice each speaker closely to the rest or to a spec so they would all (hopefully) sound the same and achieve the desired frequency response. Interestingly enough though, the pair that I use were consecutive serial #s, and the damping material in each weighed the exactly same. I went in and fiddled with the stuffing for quite some time, trying to get it as evenly ditributed, until I was able to get both of my cabinets voiced together nicely, without the ring! It was a lot of messing around, but it was winter, I was bored, and it kept me out of the pub for a couple weeks. I fully believe the result was better than the original factory voicing, marked by amazingly well tamed bass I can only describe as 'fudgesicle'.

Now here's a catch-22 in the design of these speakers. The crossover and high voltage bias supply are installed on the back of the plate housing the inputs, controls, etc. The only way to access it is by removing the woofer and pulling out a lot of wadding, which is going to change the sound of these speakers once you put everything back. Here's a tip: If you go inside these speakers, plan on making a new mounting arrangement for the rear plate so that it is outboard of the cabinet, instead of trapped internally. There is a fuse in the bias supply which may need replacement sometime, and the midrange pot and tweeter setting switch will need cleaning sometime. After all, these speakers are nearly 40 years old!

The tweeter panels were made by RtR, which is actually in business, but hasn't made electrostatic stuff in a long time. Finding replacements is difficult. The high voltage transformer is an odd value that isn't really available either. A simple way to check if each one is running is to just use something like a paper towel tube and your ears. Tune into white noise on an unused radio frequency and listen to each panel through the tube. Also, the rear cover for the tweeter tunnel is removable if you wish, just pry on it a little. Makes for an eye catching view through the panel array. Another check you might want to do is: while playing white noise, unplug both speakers power cord at the same time. The panels will continue to produce sound for several seconds as the bias supply caps drain. Listen to see if one fades faster than the other. This may indicate a drift in component values that could lead to trouble.

The most important factor in getting these speakers to really sing (like most speakers) is having an amp that is right for the job. These speakers are a solid 4ohm load and not very voltage sensitive (inefficient), which some amps wont tolerate very well. I've tried a couple small low wattage tube amps, and they simply didn't have nearly enough snort to get the Infinitys to come alive. Stepping into solid state, a 35 watt amp (such as a Marantz 2235 receiver) doesn't have the mettle either. A 70 watt Marantz 4270 gets them going. An amp over 100 watts comfortable with a 4ohm load and with a high 'damping factor' really gets these going. If yours are working well you will definately be able to hear their ability to truly reproduce 30hz and below! I like the bass of these speakers more than any other I've heard, but it took all that fussing with them to get that far.

If you like doing some tweaking, these might offer a lot of enjoyment. Be aware that one of the failure modes of these speakers is they may catch fire if, say for example, the internal line or HV wiring were to rub and short. I'm long past that fear, and leave mine plugged in constantly to a proper line conditioner and avoid on/off cycling. Maybe it will help the power supply last longer, maybe not. I also installed some stretchy plastic mesh (like those net sacks for oranges) over the crossover/HV supply to keep the stuffing away from the electrical components just to be safe(r).


So what equipment will you be auditioning these with?

fs41

[SEAWOLF97]

My bud picked up 1 of these. It also had the clay like stuff on the woofer. Since only had 1, he parted it out. Got about $175 on feeBay.

We played it for a bit. Actually sounded very good.

[hakka26]

fs41,
Thanks for the additional info. I am planning to run an Onkyo TX-8500 through them. I was hoping to free up some space last week but plans fell through.

[fs41]

Have fun! Looks like the Onkyo should run them well.

Looks like I also forgot to mention that you will probably also want to play with elevating them, spacing them apart, and out from the wall. The first time I hooked mine up they were on the floor, a foot away from the wall, about six feet apart and they stayed that way for a while because they imaged so well in the little room I had them in. I've moved a few times since then, and every room required a different elevation, but low always seems to be good.

If you're not getting really good imaging you may need to adjust their positions. Don't worry about the non-mirror imaged design of the cabinets. They will 'come out of their boxes' so to speak when you find the sweet spot for positioning. Also make sure the mid and tweeter controls are matched, as this will throw things off as well. Tweeters are pretty straight forward, I'd just leave them on protect or normal, NEVER +3db. Mids are a little more difficult, but you can set them with a mono FM signal off your receiver. Set both speakers on the floor with just enough space to sit between. Play the mono signal, listen closely to the mids and adjust the control while sitting right between them (I think you can reach around each speaker and manipulate both controls simultaneoulsy). Once you have them set where you think they are both equall in output, make a small tickmark where the knobs for the mid controls are pointing. This will just be a sort of benchmark to see if the controls of each speaker are operating uniformly to each other. You can also use it to adjust to taste later on, and always have somehwere to come back to that you know they are outputting equally. These suckers are old, the pots may not track perfectly to each other, and as pots go, they don't look like anything too fancy anyway. They may also require a little cleaning as well.
Also, the plugs for the HV supply aren't polarized, so you might want to play with plugging them in both ways to see if one way is more silent. I noticed a small difference on mine and wrote 'FAT' on the applicable blades.

I hope they impress! Have fun and please post results!
fs41