Infinity Renaissance 90 questions

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.

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I own a pair in blonde oak. They are beautiful and sound incredible. Female voices on them are so good that the realism is down right scary.
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Timpany, thanks for sharing your technical experience with the Ren 90's. As most fans of these speakers would know, there are basically no reputable critical reviews to be found online, and therefore no lab reports etc..you're relying on Infinity's semi-technical white paper; so I and i'm sure many other Ren 90 owners would appreciate your comments.

I was interested in your comment that planar driver impedance remains constant with varying input & your point that this is otherwise a source of non-linearity with cones as one of the technical achievements of the Infinity/Watkins woofer was how the secondary motor was only allowed to operate in the low bass region where the impedance was much to high anyway, thus flattening the impedance peak at resonance and lowering it to a correct level (which provided a less reactive load with less phase shift, thus largely eliminating non-linearity in a cone design).

Also picking up on your comment about the difficulty of achieving coherancy in a 4 way speaker design, Infinity appear to have gone to great lengths to design a unique cabinet and grille which virtually eliminated resonance and diffraction and provided unimpeded and ideal dispersion of the musical signal. If Infinity didn't achieve quite the level of coherency as ML's CLS2, then in a single, conveniently placeable tower, they got bloody close!

Yeah, I was telling Mum the Rens sold for $8000 here way back when & I should land my pair for about $4100 with shipping/fees included, so still a good deal.

Melbguy1

ps: I'll keep a note of your your request to hear the Rens once my system is finally complete. By the end of next year, I plan to add to my existing JVC/Vimak front end with a Reference 3 pre-amp, Ca-2200, AR/Jorma cables, Running Springs filter, SRA platforms & new maple cabinet.. "Phew!"

Melbguy + others

IMO the only real shortcoming of the emit tweeter is the narrowing dispersion at very high frequencies. This results in a rolloff of high frequencies above 10KHz at > 25 degrees off axis and a rising response - on axis. For this reason the amount of 'toe in' becomes very critical in achieving the right tonal balance which makes then Ren's more of a 'one person' speaker because the sweet spot is very narrow. I have experimented (in the past) with ribbon super tweeters (sitting on top of the cabinets) to supplement the dispersion above 10Khz but I found that it was best to cross over (via a passive network) just above 10KHz, but the additional crossover introduces time alignment complications which can take plenty of listening time to fully optimise. However I was able to acheive excellent results using Raven R1's as super tweeters with a first order crossover at 10KHz. This made the horizontal dispersion really wide and gave the treble more 'air' creating an even bigger soundstage. Unfortunately the trade off was poorer vertical beamwidth (due to the distance between the EMIT and the Ravens) and this made listener height more critical. However I did persist with this setup for some time because it worked better in my room. I'm now using Raal ribbon tweeters which sit on top of the cabinets and the EMITs are no longer connected. This avoids the interactions between tweeters but the larger distance between the EMIM and the Raals does reduce the vertical sweet spot. I will probably (ultimately) go back to using the EMITs with the Raals purely as super tweeters because the EMITs IMO are better than all of the pure ribbon tweeters I've tested in the low range (2 - 6 KHz). The Ravens in particular are very poor performers below 6KHz where they sound very thin and dynamically very lacking. They are a very over rated tweeter IMO but they do work well as super tweeters due to the 50KHz BW and performance above 10KHz is pretty good.

FWIW I'm about to embark on an upgrade of the caps in the Watkins woofer crossover. The bass is sounding a little bit spongy these days which makes me think that the caps are lossy and need replacing. I will provide feedback to this thread on the outcome of that upgrade in the hopefully not too distant future. I do have the schematic but getting the correct value caps from a reliable manufacturer might be a challenge.

Here is a link to the Ren 90 crossover schematic. I would advise downloading this while it's available. Note there is an error. The 5 ohm resistor in series with the EMIT should read 0.5R.
http://www.kalman.org/RENAISSANCE%2090%20x-over.pdf

Timpani