Discussion in 'Infinity Loudspeakers' started by pauljh, Mar 13, 2018.
I don’t suppose it would hurt anything for me to play pink noise for a few days.
Are audio gear and pickles the only things that get better as they get older?
I don’t know about pickles and audio gear but surely my memory does, doesn’t it?
‘Cause it damn sure isn’t my ears!
It's time for an update. I still have one original and one modified tower, and I'm going to leave them that way until a few more friends have a chance to A/B them and weigh in with their opinions. But that doesn't mean that I don't have more to share.
Here are the measured 3db down points for each crossover channel for the RS1 and the RS1b crossovers:
As you can see, the two crossovers are close. The upper EMIM doesn't go quite a low nor quite as high. The mid-freq tweeters also overlap less with the EMIM on the bottom, and the High-Freq tweeters on the top. The High-Freq and Rear tweeters are essentially the same. Note that these measurements don't account for levels, only the 3db down points of the crossovers.
I also measured the impedance for the RS1 tower and the RS1b tower:
Two comments. 1st) People who say that these speakers are amplifier killers with impedances going down to 2 ohms are wrong. They do go down to four ohms, but that's about it. Also, the phase angle changes are quite modest. 2nd) the major difference between the two is the hump at 1K Hz. If I had to guess, I'd say this was the level pot for the upper frequency EMIM (#3) added in the RS1b spec.
One more impedance measurement graph, this time of one of the bass towers:
This is a normal sealed box impedance curve with a peak at about 55Hz. This means that the bass towers will roll off at 12db per octave below 55Hz. When using the Infinity Reference Standard Crossover, the servo feedback circuit corrects this so the system is flat to 32Hz or so. When you see people saying they are using Rane or Dbx or other third party electronic crossovers with their RS1(a/b) speakers and reporting that it works great, they are people who don't like deep bass, or they aren't telling you the whole story. At the moment I'm using a Rane AC22B crossover, but I'm also using a convolution filter in the JRiver Media Center DSP engine to boost the bass below 55Hz down to 30Hz or so. Without this correction, the system was obviously bass-shy.
Just stopped into say the depth of knowledge shared here great. 90% is way above my pay grade but it is interesting to read none the less. Another ak'er and I were talking about it. His word is "Jelly" and I think I agree for lack of better words.
Those Infinity's in your room, which I think is fantastic btw, are in the right place and the end result here is something I would certainly love to hear. My music taste is all over the board and I'm not selling myself short here, with Jazz and Classical music I can only wonder how GOOD that would sound in that room.
It's time for the next chapter: the Reference Standard Servo Crossover.
As I mentioned in the first post, although my Infinity crossover worked, it was noisy, humming and buzzing. I tried various fixes, lifting grounds on amplifiers and such, but never got it quiet enough to listen to, so I eventually gave up and started using the RANE AC22B that had been lying around in a cabinet for 20 years. Since the RANE was professional gear with balanced XLR connectors, I used two Henry Engineering Matchbox IIs to connect the RANE to my Adcom 555 Mk II, and Mondial/Aragon 4004. It was dead silent and I was happy for several months.
But, I kept worrying that I was missing the true Infinity RS1 experience by not using the servo crossover. I started looking around on the Internet and found an article with some tips (Google for "For all Infinity RS-1B owners having problems with their active controller" and you will find the same article). It suggesting that hum problems could be traced to faulty grounds. "The shields on all the RCA jacks - between themselves and the circuit ground point; should measure less than 1 ohm." Well! my measurements were 45 ohms for the inputs, 8 ohms for the low pass jacks, and about 0 for the high pass jacks. Clearly, this was a potential source of my noise problems. The original RCA jacks were very cheap with fiber insulators to keep the circuit ground separate from the chassis. Over the years, the fiber washers compressed, and the connection between the ground lugs and the RCA jacks got less tight. Since fixing this required desoldering everything and then tightening the RCA jacks, I decided to order some new gold-plated jacks to replace the cheap originals. I had to enlarge the chassis holes to fit the new RCA jacks. While I was messing around in the crossover, I replaced the existing TL082 op amps with the later Infinity-recommended LN353N op amps.
Here is what the original crossover looked like:
And here it is with the sexy new gold-plated RCA jacks from China (installation required enlarging the chassis holes for the jacks).
This fixed the buzz in the midrange/tweeter towers, but there is still some minor hum in the woofers (there must’ve been some reason that Infinity added a hum balance adjustment pot to later versions of the crossover). I have decided to live with it, and I'll now get down to some serious listening.
Hey, watch it! You'll dry up the supply out there and increase prices!
The Nielsen Third Symphony is such a wonderful work. (Serious listening).
This seemed like a good idea at the time. It’s a good thing I’m not trying to fit this in an Infinitesimal.
Not very pretty, but upgraded to get rid of all NPE caps, upgrade all the film caps, replaced out of spec inductors, and upgrade the crossover to RS1b version.
Here’s mine from my RSIIb a few years ago. We used the same caps! See that big 200uf on the right. I used the 250v though.
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