Legendary Optimus Pro LX4 Speakers. Trying New Twisted Pair Speaker Cables. And More.

October 30, 2018

#282

Gentle reader,

I'm 62, but I don't feel that old and most people say I look ten years younger. Yesterday, my youngest turned 30. So that makes all of them in their thirties now. Wow. But I digress....

Ever since buying and installing a pair of woven Kevlar woofers from a pair of these Radio Shack Optimus Pro LX4 speakers, I've wanted to get my hands and ears on a pair of LX4s. 
eBay has been e-mailing me when they show up. This pair were posted by the original owner. 

He literally found them on his bookshelf. They had been sitting for YEARS. He started the bidding at $40.00 or make and offer. So, I offered $30.00 and he countered with $35.00. Sold.

This is a panorama photo made from two shots made from standing up behind this desk which I am typing this. It shows the book/diecast cars shelf in a rare state. Empty on top. (It isn't empty now, it's covered with cameras and lenses I have on eBay right now: rfcollectin | eBay 

In the corners are my Cerwin-Vega LS-12 speakers each with one of the LX4s and one of my restomodded (you read about them here!) Minimus 7W speakers. Each guarded by a member of The Dark Side.

Here is what is above them. The BOSE 301 Series V speakers Nancy bought for me years ago. (That is her in three pictures on the wall). She was hoping that I would stop using the big speakers in the living room. I didn't. But once I did set them up, first in the family room and later the listening room and finally in here. They surprised the heck out of me by sounding so good! Who knew? Well, BOSE fans for one.

To answer the question that I know was burning in your head, "How is he driving four pairs of speakers?" Above is your answer. Of course, you read about me fixing up this 1987 Sanyo-built Fisher RS-1035 classic stereo receiver here. And I told you about that Fisher cassette deck that runs on 19 volts AC. And that Yamaha  RX-496 receiver that was missing two small knobs. I paid more for the knobs than the receiver!

You remember how I converted the Fisher to three-way binding/banana posts, right? Well, here it is "in situ" as no one says in Latin. Because no one actually speaks Latin.

And here are the new cables that I mentioned in the subject line of this article.

Here's a close-up of them plugged into the Yamaha. And below is a comparison to the ones I have been using for many years.

Well, it seems that this is a good place to start the article with these cables. 

The blue and silver ones were put out by American Bass. You can imagine the type of customers they serve. Well, I don't think the eBay seller mentioned the brand name of the cables. I needed large gauge cables to run speakers from the living room all the way through the attic to this room, many years ago. It was a 100 foot reel and it was less than fifty dollars. They worked great. They are 12 gauge.  
The less colorful ones are the new ones. I was hesitant to buy them because I did not like a 1/ meter pair of RCA cables that I tried from the same company: KnuKonceptz. Weird misspelling thing going on here. They too are 12 gauge.
But, the on-line reviews I read were all favorable and since American Bass doesn't seem to make the twisted ones anymore, I bit. I bought fifty feet via Amazon and it came direct from the manufacturer.  

KnuKonceptz states that the wife is oxygen-free copper that is "tinned". I do not "tin" wire ends like some do. I know solder is extremely conductive or else every electronic thing we take for granted would not work. 
There are LOTS of TINY wires in each wire in the cable. How they tin them, I do not know. 
The "umbilical cord" cables as Nancy calls them, I found out are aluminum, aluminium for my British readers. With the copper conductor being "CCA" copper-clad aluminum. So THAT explains the color difference.

As a result, I switched the positive terminal from the silver wire to the blue covered one. Since is speaker wire/cable the negative is ground and has little actual current and no music going through it.

FUN FACT: A WIRE contains ONE conductor with insulation. Now standard "zip cord" like lamp wire and inexpensive speaker wires DO contain two conductors, bus since each is separate and they are not further contained by outer insulation, they are WIRES.
A CABLE contains two or more conductors within the entire assembly. Like CAT-5 cable, telephone cable, twisted-pair speaker cable, in-wall AC power cables. Understand?

Another FUN FACT: Plastic or metal tubular vessels AKA: Pipe or Tubing, even though they may be made of the exact same ingredients (plastic or metal) have different names. How?
IF the vessels are part of a larger object that can MOVE, car, train, boat, ship, every tubular vessel no matter how large or small are called TUBES. So, it is exhaust tubes, not pipes.

IF the vessels are part of a larger object that can NOT MOVE, house, shed, building, tunnel, every tubular vessel no matter how large or small are called PIPES. So, it is drain pipes, and supply pipes. Now,  a garden hose, I suppose if it is....oh, never mind!

Back to the subject of wires and cables. Below are all cables. Nut not just any cables. All were sold by Radio Shack as their top of the line RCA interconnect cables.

Top to bottom are the last of the line ones called "Gold Series". The only gold are the tips and they are no better quality than the cheapest ones out there. The insulators appear to be metal crimped to cables. But are in fact just plastic.
Middle ones are the original top-of-the-line Gold Series and are much better made. They even have "Signal Direction Flow" arrows on them and ferrite cores near the "exit" ends. They are great cables and if you see some for sale, buy them and try them.
Bottom ones are the last that I saw in our local store. Called "Auvio", a clever combination of audio and video. They have the same insulators (since they are metal, do they really insulate?" as the large original cables, but have actual terminals similar to the grey (or is it gray?) ones.
The Auvio ones sound better than the gray ones at the top. I hold them in reserve for testing a new component. 

Above is a closer view of the originals and the wannabee "Gold Series". The one on the very left are not the Auvio models, this is an older photo.

BACK to the new-to-me LX4 speakers. Firstly, yes, that is an actual word, I have had a pair of LX5 speakers which have the 360 degree Linaeum ribbon tweeters on top of their cabinets. The mid-woofer foam surrounds were bad and rather than try to replace them, I did some research and found a pair of mid-woofers recommended by Radio Shack speaker fans as a good replacement at Parts Express. Parts Express: Speakers, Amplifiers, Audio Parts and Solutions

LX4 speakers are meant to be listened to on their sides. As you can plainly see, the woofers are the same. The tweeters are: "Dayton Audio AMT Mini-8 Air Motion Transformer Tweeter 8 Ohm", and are SUPERB.

Spring terminals, how do I hate thee, let me count the ways.... Well, the only good thing about these are that they will accept banana plugs, not the tubular Nakamichi ones that I prefer, but standard ones that kind of look like straight bananas. I bought sixteen of those to use on the new KnuKonceptz cables. 

The reflex port, which extends almost the entire way to the front of the cabinet, and larger cabinet make a HUGE difference in bass output over my smaller creations. HUGE. 

They drove a terminal into one of the posts (usually a crossover board would be screwed to the four posts) to anchor the output side of the capacitor and attach the positive lead to the ribbon tweeter.

So, who can tell me the correct translation of "2.7K 250"? Seriously, I'd like to know. I know they are non-polarized capacitors, but don't remember the lingo.

Above are three views of the terminal cup and minimalist crossover used in the LX4 speakers. 
Note the insulation is not fiberglass or polyfill. But is more like carpet padding. I'm sure Radio Shack speaker engineers chose it for a reason, so, if and when I upgrade the crossovers, I will leave it in place.

Here is the woofer removed. And another closer look at the insulation and the crossover in place.

I have not measured the exact depth of the port, but this picture gives you an idea that it goes deep.
 
OK, I've shown you the LX4s, inside and out. And the new speaker cables which are sending music to them and my RM7W "Restomodded Minimus 7 Walnut" speakers.

How do they sound? Well, first, I listened to the LX4s one with a silver/blue cable and the other with the KnuKonceptz. I set it to mono and played test CDs which I am very familiar with. I swung the balance back and forth. Of course, it would have been better to have both of them stacked on the middle of the shelf to try and eliminate any room character influences. But I did not think of that until just now.
So, I really cannot detect any difference between the two companies products. Same size, same gauge, same design. Since I have been impressed with the American Bass for years, this means that the new ones are AS good as the old ones.
Then, I wired all four up with the new cables all from the Yamaha receiver. And placed them thus:

"Ebony and Ivory...." the speaker's guards. Remember that song, Michael Jackson and Paul McCartney?

Yes, I see the old cable here. This is an older picture too. 

Using A/B switching via the Yamaha receiver, the differences were significant at both ends of the audio spectrum. I have not tried test tones yet, but by ear, the LX4s have substantially deeper bass than the littler speakers. A fact caused by the engineers establishing their desired goals by cabinet and port design and tweaking. 

Ported speakers, if the ports are on the front, tend to have more bass output than similar sized woofer in sealed enclosures, since the ports are supposed to reinforce what comes out of the forward movement of front side of the cone with what comes out of the rearward movement of the cone. The port(s) is designed to delay the rearward movement air wave by one-half cycle so that it exits at the exact second the next forward movement of the cone occurs. Understand?

Secondly, the Linaeum ribbon tweeters do not reach nearly as high as the Air Motion Transformer models do. It is a significant difference. But being as old as I am I rotate the treble all the way to the right. To others, the AMT tweeters might sound too bright.

My solution is this: Play all four at the same time. Some feel one should not play pairs of different speakers at the same time thinking that they detract from each other. And they may be correct. Well, in this case, the woofers are identical. The tweeters are different, but both are non-traditional: Ribbons verses cones or domes. Different types of ribbons for sure. But the same type.

Combined, they sound fantastic! It all comes down to that with ANY change in your stereo or surround system. How do YOU feel about what you are hearing? Does it cause fatigue after a while? Do you find yourself grinning? Factors like that.

I fully expect some of you will put your thoughts on screen (no paper here) and give me your opinion. That is fine. Will you change my mind Not likely. Should you live near enough to come over and listen yourself, come on over. I'd be glad to share my systems and music with you.

Of course, if you read all the chapters covering the multiple steps I went through to modify my Minimus 7Ws AND you are able to find a pair of LX4 speaker's woofers AND buy a pair of LX4s, then you too can replicate my testing with your own room and system. The YOU can write about it. 

I hope you enjoyed reading this article. It is a joy for me to write about things that I have and activities that I've been involved in. Your comments are welcome, here below, or on FaceBook. Those left here will be answered when I see them. I am not notified if someone comments.

Scott

October 30, 2018
#282