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In Reply to: Yep....affectionately known as the krappa...nt posted by michael w on April 15, 2001 at 04:23:52:
The owner reviews on the Ren 90's (see www.audioreview.com - Product Reviews, Main speakers, i for infinity, scroll down to Ren 90's)speak for themselves.
I just recently bought a pair- a preowned pair that is, as this model isnt made anymore (1991-1995). And I can tell you, the other owners arent kidding, they are GREAT speakers!!
Infinity used to make the awesome Quantum models back in the late 70's- see site: www.bobbyshred.com/infinity.html I was interested in a buying a pair but being 20+ years old, I was concerned about the Parts replacement situation- so I opted fo the newer Ren 90's.
This model is truly a winner by Infinity. Not that well known and not that easy to find for sale- and I can understand why- look great (much better than the audioreview.com photo), sound great, etc- who would wanna sell theirs?
My Dad had a pair of Quantum 4's from the 70's through the mid 90's. They had no highs or mids to speak of. He finally replaced them with a pair of Aria 5-a's from Zalytron with a sub. No comparison. The Quantums were junk by comparison.
I can't help but wonder if dads systems were either damaged or misadjusted. I repaired a set of Q5's in 1985 which had the same problem. Cause: previous owner had a receiver (Technics) which did not do well with the Quantums low impedance. This forced the amp into clipping which generated a large amount of Emit fusing hf energy. This was a problem with the Q series design. That is why amplifiers with ability to handle the low impedance and have the capability to produce the desired SPL's were a must with Infinity speakers.
I have repaired/restored quite a few Infinity speakers dating from 1977 to 1983. I have found that these systems achilles heals were the Emits tendency to act as fusable links. Infinity delt with the problem in later designs by raising the crossover point, but they were still haunted by clipping "lesser" solid state amps.
Any chance you're in the New York area?? Hard to find a good audio repair shop here- I'm not kidding. Especially a place thats knowledgeable on the older Infinity models.
Have you done any work on the infinity Qb's? (3 way system: Emit, 4" mid & 10" butyl woofer). I have a pair of Qb's and they really sound great- better than a pair of RSb's I had for a short while- which is odd, as the RSb was the "improved" follow-up to the Qb w/ poly-p woofers. But sometimes Ive noticed when listening to music- the sound from the midrange becomes muffled in one speaker. It clears up and then becomes muffled again. Is this a problem with the mid driver or a faulty capacitor in the crossover circuit board or- as most people have said-the adjust pots in the back need cleaning. ?? Any advice you have to offer would be appreciated.
If you read my other post here, I have the Renaissance 90's. But the Qb's still look/sound excellent- so I couldnt part with them- When I have more room I shall set them up in a 2nd hi-fi system along with my collection of vintage Sansui & Pioneer receivers and amps. The Qb's are 4 ohms but the Sansui's & Pioneers are alright with them. The bigger Quantums might be more challenging- but my brother drove a pair of Quantum 3's with a Sansui AU-717 integrated amp (85W), no problems.
I'm driving the Ren 90's with a newly bought Odyssey Stratos. Its a very pleasing combination. I'm just concerned about the Parts situation for the future. Right now, the EMIM's used in the Ren 90's are down to the last few in stock and they sell for $330 each- Ouch!! I dont know if Infinity (HK) is planning to make just the membrane (diaphragm) available- which would be alot less $$- and usually its just that 'part of the part' that fails- based on my understanding- I believe it either develops an open or it gets scorched from excessive current.
I live in Western Ma. No, I haven't done any work on the Qb, but I am sure they aren't all that different. So far as muffled midrange, I would be inclined to check your mid driver for healthy connections from the crossover the the driver. If they are OK, then I'd get some good contact cleaner and shoot your level controls. If the problem persists, I would try disconnecting your midrange driver and swapping it with the one in the other QB (making sure you don't get the driver polarity reversed....very strange effect). If the sonic problem moves, you have found the culprit. If it remains it is surgery time. You need to get at the crossover and examine it for cold solder joints, broken lugs and so on. Also, check for any current limiting device protecting the mid driver. If present in the circuit, it could be responding incorrectly to the audio signal and partially muting the output. Barring these problems, then you need to look for damaged crossover components. If electrolytic caps are in the midrange section, they may be going bad (leaking etc...) given that the Qb probably was introduced around 1979-1980.
I have seen scorched EMITS (big brown-black burns in the kapton diaphragm), but not EMIMs. The few I've seen were damaged by poked holes courtesy of "junior" with a sharp writing implement, or a object made of steel getting into the slot and firmly contacting the diaphragm causing a break in the conductor(s). Breaks in the conductors can be repaired with Loctite brand rear window defroster repair paint. Obviously, if there is a hole in the diaphragm it needs to be patched first, then the paint applied with a fine artists paint brush (camel hair or red sable)
Feel free to e-mail me if you have further questions.
OK- Thanks for the all the helpful info, I really appreciate it. If I have some extra time this weekend I'll try and hear how the Qb's are doing and will keep in touch w/ you via email. Regards, Fred
Email me. I may be able to help out.
'The Quantums were junk by comparison'- Gee Des, Sorry to hear that your father's experience with them wasnt that good. I dont know why, because there are alot of other people Ive met online who absolutely love the sound of their 'ol Infinity Quantum models- which puts your opinion in the minority. Those EMIT tweeters were especially good in reproducing the highs so I am baffled by your complaint about them. What amp did your Dad use to drive the Q4's? Is it possible he underpowered them? If the Aria's are working out better for you/him, thats fine- to each his own 'Ya know, but none of those Quantum models were junk.
Ever look at the response of the Aria 5? While a good design (I respect Joe D'Apolito's work) the metal dome tweeter version has a HF peak, lending a brightening effect to the overall sound.
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