Infinity Renaissance 90 questions

I have actually built external crossovers for my Renaissance 90 EMIT tweeters using Mundorf SIO caps and copper foil inductors. There was quite a jump in efficiency and I had to slightly alter the tweeter amp gain to compensate. For single amp drive you could pad the EMIT with a slightly bigger resistor (0.5 > 1 ohm).
The main benefit of the upgraded crossover was improved dynamics. I also modelled the crossover frequency response in LT spice and found that there was a 2.5dB peak at 2.3KHz. I was not surprised to see this because I had always thought that they were a bit too forward in the presence range. I have heard that there were changes made to the crossovers during the Ren 90's lifecycle that corrected this but I'm not 100% sure. However, the Ren 80's are using diferent values and do have a flatter crossover response when modelled.
I subsequently modded my crossover values to achieve a response +/- 1dB from 1Khz to 20KHz. To do this correctly you need to change a 33uF cap in the EMIM crossover to 30uF and also insert a 0.22R in series with the cap. When I did this mod I also noticed that the 10 year old 33uF electrolytics had expanded slightly at each end. I replaced them both with Blackgate 30uF 50V NPO electros and there was an immediate audible improvement. The MF seemed more pure and imaging was much more accurate. The other fine tune necessary is to add a 1uf in parallel with the 5.6uF pp film cap in the EMIT crossover. Both of these changes combined will result in a much smoother sounding upper mid range and a far more seamless transition from EMIM to EMIT.

More recently I have disconnected the EMITS and am using Raal pure ribbon tweeters which sit on top of the Ren 90's. This also necessitated some fine tuning of the crossovers but the result is really stunning. I have also designed a DC bias system for the tweeter crossover so that both SIO caps are voltage biased at 33V DC.
The main improvement from the Raal tweeters stems from the much wider HF dispersion and far more extended treble, but they also seem cleaner, less grainy and sweeter sounding, but then again they are also very expensive. IMO the EMITs used in the Rens are a very good tweeter and with the 2 component changes mentioned above the response will definitely be flatter.

Hi Timpani, I was really interested to read that earlier run Renaissance 90's had a 2.5db peak at 2.3Khz. Interesting! That does support Infinity's motivation to introduce later revs of the crossover. That also put a smile on my face as the pair I bought were late-manufacture/late sale examples which would have had the later x-over, thus not requiring mods for (hopefully) a long time to come. It would take a very skilled audio engineer to do in a couple of weeks what Infinity spend hundreds of hours to perfect, so on reflection, i'm happy to laave it well alone.

Melbguy, If you're completely happy with the tonal balance then it's good advice to leave them alone.

FWIW I'm using a 10 year old Meridian 557 to drive the Woofers, Mid Bass's and EMIM's and I designed and built my own amp for the tweeters because I couldn't find anything commercial with the smoothness and refinement I was after. The EMITS can sound a bit metalic with some SS amps and my own design - using a mosfet output stage with bipolar drives in CFP configuration results in a very sweet fluid treble while the gutsy Meridan gives me the dynamics and control from the mids and down to the sub bass.

I find the Ren 90's a tour de force when it comes to 3d imaging. I'm yet to hear another large speaker that can present a 3D image the way these can.

That's an interesting set up on your Rens Timpani. Speaking the obvious, but smooth watts are very important for the Emits! I can certainly understand the popularity of running a ss amp on the Watkins & tube power for the highs, but I feel that running separate amps for lows/highs creates phase issues and (personally) I feel using tube amps introduces microphonics which muddy the sound of highly revealing speakers like Rens.

What interested me about your hand-made tweeter amp was how similar in concept it sounds to Classe amps which employ Jfets in the input stage, Mosfets in the driver stage & Bipolars in the output stages. It's certainly rewarding and exciting to invest in that level of amp, but more fun if you can design and build your own!

Incidentally, I have a friend who is an Infinity sceptic. He actually sold a smattering of Infinitys back in the 90's (eg: IRS Epsilon), but he never heard Renaissance 90s. His common line is that Infinitys "lack coherancy". His favorite speakers are ML's, and in fact he tried to persuade me to buy a pair of CLS 2z's off him recently. I felt they had inherent weaknesses in that they are absolutely reliant on an add on subwoofer & good room acoustics. My response to him was "just wait till you hear the Rens!"

Re the phase issues, yes you are correct and my adapted tweeter crossover uses some conjugate matching to minimise the sharp phase transitions. Infinity's are not everyone's choice and your friend may have a valid point, however, the issue of coherence can be minimised with careful attention to speaker placement and the right choice of a listening room. Any 4 way speaker will need more distance to generate a coherent wave and the ren's are no exception. One big advantage of planar drivers is that the impedance is flat and resistive not only within but also well outside the operating range, so passive crossover design is far easier to get right and can be achieved without RLC networks that rob efficiency and introduce other side effects. Planar driver impedance also remains constant with power which is a source of non linearity with cones or domes. Every design has strenghts and weaknesses and the 90's are not perfect but they really don't do anything very wrong and what they do very right is difficult to live without once you have lived with them for a while. BTW from my brief experiences with Classe amps I think they are an excellent choice for the Ren's but I'm sure you will hear improved dynamics when you upgrade to the CA-2200. I would like to hear that setup. BTW I live in Sydney and bought my Ren 90'S new back in 1995 from Audio Excellence. The RRP at the time was $7999 but they gave me a nice discount. I have owned many other speakers including B&W 801 but these are my fav.