Optimus Pro LX5II Loudspeaker- Vintage Audio Review Episode #93

In this episode I discuss the REALISTIC (Optimus) Pro LX5II loudspeaker, as well as basic measurements of the speaker itself.
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00:00 Introduction
02:11 Top & Rear views
02:28 Impedance Measurements
03:47 Frequency Response
06:32 Listening/ Comments

[@evanleebodies]

I've just replaced the foam surrounds on my pair of LX5's with one slight difference. Instead of replacing the surrounds with foam, I've opted to use rubber surrounds. Let me tell you folks, the bass response is way better than before. I put this down to the stiffnes of foam vs rubber. I bought both foam and rubber surrounds off EBay and was able to make a side-by-side comparison before replacement, the rubber surrounds were way more pliable so on they went.

[@vintageaudioreview]

Thanks for sharing your experience. I will check with my friend and see what surrounds he used when he did his- I am guessing regular foam. If he gets another pair maybe he will try to find rubber ones.....

[@stuartwiner7920]

I have a set of the LX5's, which are fine for a kitchen radio. The magic may have been lost from sitting for 20+ years. With the ribbon tweeter rolling off at 10K hz+, it's really not audiophile. I may toss them. They're all metal, so they'd go in the recycling.

[@vintageaudioreview]

It is possible that there was something wrong with this pair after all of this time, but probably not worth the effort to get them repaired. They could be used as "sacrificial speakers", ones you hook up an unknown amp/receiver to find out if it works.

[@hitechrr]

I have 2 lx5 and 2 lx5II. I still use them today. I just upgraded a crossover in all 4. I also had to refoam all.

[@vintageaudioreview]

Glad to hear they are working well for you. Did the crossover upgrade help much ?

[@hitechrr]

I think it cut the Tweeter more. It had a 2.2 ohm resister in the tweeter circuit. I may have to remove it. I still have more testing. I bought them new at RS. I also have 2 pair of acoustic research AR16 speakers that I bought new years ago. I would also like to set up my AR turntable, but I have nowhere to store the records. I just replaced my 25 year old Sony receiver with a Denon avr X6700h

[@vintageaudioreview]

@@hitechrr I would not be happy if the upgrade made things worse. I did see there was a crossover mod for them but did not check into it as that was not going to happen with these. Not familiar with the AR16 speakers- hopefully they are not as power hungry as the AR9's

[@claddagh1000]

Bought mine in 1999 and still have them

[@ManFromLaBamba]

Thanks for measuring this speaker: it is one of odder bookshelves of its time, combining a very conventional bass reflex design using a mediocre realistic mid woofer, but using the then rather esoteric ribbon tweeter by a narrow market company rather than the realistic/radio shack mall mass market…and pretty cheap stuff generally. So it’s wonderful to have a review of these. I believe these lineaum ribbons are do-pole, radiating as much sound to the back as to the front. The ribbon is suspended between the cylindrical things, with nothing behind or in front of it. Dipoles are usually VERY affected by room placement and the material of the back wall. It is very possible to get reflections off the back wall that cancel frequencies radiating forward (or the opposite, adding to them). Usually they want to be many feet away from back or side walls. The upside in principle is a wide and very open and fast soundstage that envelopes the listener somewhat. Though some beaming can occurs depending on crossover etc. And they can be very tricky to measure. I wonder if some of the roll off might be room cancellations due to dipole. Or just room placement. Dust and years of grime can also reduce performance of ribbons because they have so little mass. However cleaning them is not something for the amateur. Then again these were never top end speakers. Though some buy them on eBay just to get the tweeters for a diy build. Most who buy them to keep intact say that one really should just replace the midwoofer unit entirely with an inexpensive but much better driver rather than bother refoaming. The improvements are marked apparently as the mid woofer driver was never a match for the tweeter, a cheap one to compensate for the relatively costly tweeter.

[@vintageaudioreview]

Thanks so much for all the info on this speaker. You seem to be very knowledgeable. My friend who refoamed them does a lot of refoaming so that is his 1st choice. I put the speaker towards the center of the room in the same spot I measure other speakers, so I think the rolloff is real, plus the high end sounded rolled off as I mentioned and for listening, they are placed more towards the wall- maybe a foot away.

[@ManFromLaBamba]

Well I was researching ribbon/amt tweeters a while ago and these little things are so cheap on eBay. Never ended up buying one though.

[@vintageaudioreview]

@@ManFromLaBamba Guess some folks like them after modifications- I appreciate your commenting.

[@jamiethornton6101]

You just nailed something most people don't know. The tweeter you want will say Linaeum on top of it. These say Optimus. Linaeum made the original ribbon tweeters for Radio Shack and they were great! This model the Optimus Pro LX 2 optimus has a much cheaper ribbon tweeter. I don't know how hard they are to find, but if you could find one of those original lines; you can really hear the difference on the high ends. I loved mine for rear surrounds for years. Sadly the size of the cabinet was just really too small for the size woofer on those. IMO. The foam issue is another thing.