NOW finished: Upgrading old diecast Realistic Minimus 11 speakers Part 2.5

Gentle reader,

Since I just put a few items on ebay, this morning, there has been a huge upsurge in folks visiting my humble blog. Thank you for looking. In fact, I suspect they are hoping I have gotten to doing a post about NASCAR die-cast cars. Be patient, please.

I like to keep busy while at home doing various things, obviously, since I tell you all about many of the things that I enjoy, and my wife tolerates. I do love her very much!

Today, I completed the conversion of the second Radio Shack Realistic Minimus 11 speaker to new Dayton Audio drivers and Infinity crossovers. The original post is here:

The Robb Collections: Upgrading old diecast Realistic Minimus 11 speakers

Below, you can see them in front of my fantastic Cerwin Vega LS12 speakers. 

Below is the second one I completed. It is in the right channel position.

Below is the first finished unit. occupying the left channel location.

There has been historically and some companies still build their speakers with what was coined: "Time Aligned Drivers". What that means is the voice coils (the actual coil that is wrapped with the fine wire and electrically moved by the signal from the music source) of each driver; woofer, mid-range and tweeter, are in the same vertical plane. In simpler terms, if one were to cut an entire Time Aligned speaker top to bottom, one would see the magnets the same distance from the back of the cabinet. 

The thinking is that the various frequencies of music from each driver should reach the listener's ears at the same microsecond. It seems Radio Shack's audio engineers were attempting this desire with the Minimus 11. This image shows how "horn loading" the tweeter pushes the tweeter back in the cabinet so that it's voice coil is vertically aligned with the woofer's voice coil.

Now, since ribbon tweeters do not have a voice coil, but these are occupying the same location as the original cone tweeters, it is close. I do not know whether they should be mounted like this or 90 degrees from it. They sound great like this!

I made this image large on the page so you could see how I bent each washer to align the washer with the face of the woofer's edge. I will do that to the other speaker as well and probably paint all eight washers black to blend in better. I haven't decided how to finish the rest of the speaker or whether to use the metal grilles.

LISTENING IMPRESSIONS

Last night, I was listening to some classic rock music, and had just flipped Firefall's first album over to Cinderella. It is one of their best songs and as is the rest of the LP very well played and recorded. Anyway, it was perhaps one minute in, and since my wife wasn't home, quite loud, when she walked in. She started singing along and I joined in. The point of this? I am very familiar with this music, so naturally chose it to test both speakers. Plus, I had JUST heard it last night through the Cerwin Vegas.

Of course, there was a lack of deep bass. No way a 5" woofer in a sealed cabinet can come close to a 12" woofer in a bass reflex cabinet. This I expected. Now, so far, I have only played two pieces of music. However, my overall impression is very favorable.

I do not have the knowledge or experience, nor the "golden ears" of some of my fellow music lovers/audiophiles. So, I have no idea if those white polyfil sheets I installed are "enough" stuffing or not. Nor do I have a way of knowing. Since the backs are removable, it's easy enough to swap it with the original fiberglass or add some more polyfill. 

Back to my impressions. I've never owned ribbon tweeters before and have to agree with the reviews that I read as to their presentation and smoothness. The sounds I heard were quite realistic overall and almost gave me a tingling feeling. Eyes closed, I could "see" the musicians. I am going to spend many hours auditioning these. These Dayton woofers are rated down in the mid-fifty Hertz area of bass. Far deeper than the original Radio Shack woofers. I chose them for that reason and that they are of the same efficiency level (88 dB @ 1 watt @ 1 meter) as the ribbon tweeters.

Today, I got eight new matching flat washers, bent them all the same, bead blasted them to remove the shiny rust-proofing and then spray painted them black. Replaced the old washers with the new and here it is. (I shot both, but the other one is out of focus.)

Now, I have "auditioned" these speakers for hours with various types of music and sources. They AMAZE me! I am hearing things that I never knew were there. The width, height and depth of the sound-stage is phenomenal! I could not be happier. 

Will I get rid of the Cerwin Vegas? No. Will I keep these? Yes, I have over a hundred dollars in parts alone and really love the way they sound. Also, the CVs have incredible efficiency. One watt by my meters is very loud. Thus, my 100 watt per channel power amplifier has plenty of "head room" to cover the crescendos. 

Thanks for looking,

Scott