View Full Version : Realistic Optimus T-200 Speakers


zibzer
01-17-2010, 05:57 PM
Hello everyone. I purchased a month or so ago A set of Optimus T-200 Speakers from a guy. Knowing this was Radio Shacks flagship speaker I jumped at the chance to buy them.

They needed new grilles and I made some that look excellent. Also I replaced the electrolytic capacitors in them. They didn't sound as great as a TOTL model should so i dug into them a bit more. I noticed the woofers were wired out of phase on one cabinet and immediately swapped it in phase. There was a dramatic change in the sound-stage.

there are two 10" woofers per speaker wired in parallel with no crossover. The ones in the cabinet are labeled Radio Shack 40-1331 8 ohm. I have reason to believe these are not the original because I have seen on multiple sites that they should be 16 ohm each.

What my question is, what is the factory woofers model number? and what type of difference do you suppose it would make if I swapped to 16ohm OEM woofers rather than what i have?

thanks!

MarkAnderson
01-17-2010, 07:39 PM
In general, OE drivers are preferred since the speaker cabinets (presumably) were designed for those particular drivers. That's not to say, necessarily, that your current drivers don't sound as good or even better than OE - it's kind of a crap shoot, usually. If you like the sound of them, I'd leave 'em be, but be aware that your system impedance is now around 4 ohms. Pics?

zibzer
01-17-2010, 08:40 PM
here's some photos. They are bad quality my camera doesnt like low light photos

Smorgy
01-17-2010, 09:50 PM
I have a pair of these. The foam went bad on the original 16 ohm woofers so I bought replacements according to rat shack. The replacements were 8 ohms and I didn't know enough at that time, I just happily wired them in. Once I learned a little more, I wired them in series instead of parallel. The hot or blue wire to the positive of the first speaker then the negative of that speaker to the positive of the second speaker. The ground or black wire back to the crossover. I just taped off the other black and blue wire so they didn't touch anything.

At least the resistance is more than 4 ohms on that circuit. Then I decided to pull one of the woofers and just have one. I added a pair of passive radiators from polk monitor 7's that I picked up cheap. I put the fiberglass fill behind the live woofer and left the space empty behind the passive radiator. I liked this better and its a sure 8 ohms on the woofer circuit.

Check the tweeters - are they working? I use a paper towel roll to listen to each speaker. Mine were blown when I got them. I found a replacement pair online. Now I am thinking a pair of inverted dome tweeters from EPI might be better suited. The bass and mids are good on the T-200's but somewhat lacking in top end. (to my ears, anyway . . . maybe its my ears that are lacking!)

Nice cabinets on these, a bit big but well built. I like 'em! :thmbsp:

//Smorgy

zibzer
01-17-2010, 10:08 PM
I did the paper towel roll trick and appears like all drivers are working :banana:

i just checked the Radio Shack 1981 Catalog and it boasts the T200 as "our best sounding speaker ever" and is 20$ more than the venerable 4024 Mach 1 speakers. I suppose I found a good speaker set! and im glad i caught that the woofers were out of phase. Before I had to place my left speaker 6 inches closer to my sitting position to get a centered soundstage when someone would be singing. Now its straight from the center at equal distances from sitting position :thmbsp:

Im going to keep my 8 ohms wired the way they are until I find out what the origionals were, and possibly get something as close as possible... or Ill just continue to listen to music the way it is :music:

does anyone know how these would compare to a new set of decent speakers?

tiga
01-18-2010, 09:23 AM
I have the T-100 version of these and had to replace the woofers. They were originally 16 ohm as well - I removed them both and put in one 8 ohm woofer from an old set of Realistic MC-1800's that had a exact frequency range as the originals and a passive radiator from an old Polk monitor speaker. I removed enough of the fiberglass until it just came up to the PR. I'm surprised how nice it sounds - I thought of replacing the cone tweeter with a new dome but I actually like how this cone sounds right now. The bass is really smooth.

I'd also suggest cleaning your L-pad. I thought my tweeter was shot until I cleaned it and it came right back to life. There really isn't much of a crossover- just a capacitor and resistor at the l-pad I believe

Then nice thing about these speakers is the cabinets. Walnut veneer on all 4 sides. I'm going to hit mine with some Howards Restor-a-finish once it gets a little warmer outside. Good luck with yours.
Tiga

markshan
01-18-2010, 10:40 AM
The problem with changing the impedance of the woofers is that (if it is a true crossover network and not just high pass caps) the crossover frequencies all change. You will be left with either a hole in your mids or an overlap. I would see how it sounds with just one woofer wired to give the correct 8 ohm, and the other remaining in the cab but not connected (acting as a passive radiator). This would certainly be an easy experiment to try and may improve the sound.

The other question is (sorry if I missed it) were all four woofers replaced or just two? If only two, I would put one original and one replacement in each cab rather than both in one. That would bring the sound and the impedance closer to original.

markshan
01-18-2010, 10:47 AM
Don't forget that if you end up swapping drivers altogether, two 4 ohm in series is just the same resistance as two 16 ohm in parallel. That should help your driver options as there are several inexpensive 4 ohm Goldwoods on PE right now.

tiga
01-18-2010, 11:23 AM
I thought about doing this same thing. I remember reading somewhere that running woofers in series can be problematic. Does anyone know if there is any truth to that? If I didn't already have the 8 ohm woofer I was going to try that approach.

Don't forget that if you end up swapping drivers altogether, two 4 ohm in series is just the same resistance as two 16 ohm in parallel. That should help your driver options as there are several inexpensive 4 ohm Goldwoods on PE right now.

BruceRPA
01-18-2010, 01:45 PM
I have a pair that I bought new (back in 1981?). I replaced the rotted out foam surrounds a year or two ago and replaced the crossover caps at the same time. There is a thread somewhere about the project. I really like them and consider them to be one of the best sounding speakers that Radio Shack made.

It's a shame that your woofers are not the original although yours could very well sound just as good. Your replacement speakers are 8 ohms each so you will have to settle for either 4 ohm cabinets or 16 ohm cabinets. If you can replace them with suitable 16 ohm drivers you probably will get closer to the original specs and quality. Whether it is worth it or not is a judgement call that only you can make. If the existing drivers sound good to you, that is all that matters.

tiga
01-18-2010, 02:00 PM
Another option I considered was using two dual voice coil woofers. You can wire each in series bringing each to 16ohm, then wire in the cabinet in parallel.

At some point I'd like to try all these options on my t-100's and see what sounds the best. - I guess that's what makes this such a cool hobby.

zibzer
01-18-2010, 05:47 PM
thanks for the tips guys. i think first ill be cleaning the l pads. the only problem is that since ive swapped the woofers in phase ive been loving the sound and cant stop spinning the vinyl. :D . ill let you all know how it works out or if i can get a chance to do this or if i get any more info.

as of right now ive developed a slight problem with me right channel on phono :( im hoping its my reciever because im using my back up marantz 1530 right now as im waiting for parts for my 2230.

zibzer
01-18-2010, 06:50 PM
just a quick update. i replaced the stylus with my spare and im good to go :D

markshan
01-18-2010, 11:26 PM
You didn't say, is it a full crossover network with low pass coils or just high pass caps?

HomeBody
01-19-2010, 08:15 AM
I didn't know that a passive radiator was wired...that doesn't sound right, at all.

...I would put one original and one replacement in each cab rather than both in one. That would bring the sound and the impedance closer to original...
Plus One

At any rate, congrats on your T-200 score.
I have a pair on layaway, it'll be close to summer before I can take delivery of them.

zibzer
01-19-2010, 02:52 PM
they are all replacement woofers. all i saw in the crossover was a high pass and an electrolytic crossed between + and -. the woofers are directly in parallel. it has l pads but i havent removed them yet. actually while im talking about it im going to remove the l pads and let you know if there is anything back there other than pots.

zibzer
01-19-2010, 03:08 PM
no crossover in the lpads either. very simply made

markshan
01-19-2010, 11:19 PM
I thought about doing this same thing. I remember reading somewhere that running woofers in series can be problematic.
Most 4x12 guitar cabs are series/parallel wired. I can't understand why it would be an issue.

markshan
01-19-2010, 11:20 PM
I didn't know that a passive radiator was wired...that doesn't sound right, at all.

Huh?

MarkAnderson
01-19-2010, 11:40 PM
I remember reading somewhere that running woofers in series can be problematic. Does anyone know if there is any truth to that?

None.

MarkAnderson
01-19-2010, 11:41 PM
i didn't know that a passive radiator was wired...that doesn't sound right, at all.

huh?

+1.

Wildlifer
05-31-2010, 08:03 AM
Just had mine out to do a refoam. These are definately the original woofers from 1979. The info on the magnets is as follows:

Realistic
Woofer
40-2029
16Ω 30W
12A8 Japan

squarewave
05-31-2010, 09:47 AM
:banana:I thought about doing this same thing. I remember reading somewhere that running woofers in series can be problematic. Does anyone know if there is any truth to that? If I didn't already have the 8 ohm woofer I was going to try that approach.

There are people on this site way more knowledgeable than I, BUT, it is my understanding that as long as the woofers are electrically equal (read: same exact brand, model, impedance etc.) it's usually ok to run them in series (I have done it before w/no problems). Problems arise when two different woofers are used because they will interact electrically because of their dynamic physical differences: resonant frequencies and so forth. You could easily roast your amp from the wild swings in impedance from such a set up. Running in parallel avoids this problem but of course your amp will see a lower resistance according to Ohm's law. Be careful, and if in doubt ask here first, and somebody will step up and answer your question. Of course there are variations in a production run, so if you're a perfectionist you can bench test the woofers to make sure they are truly equal...depends on how deep down the rabbit hole you want to go. Happy listening!
P.S. If you do run two different woofers in series and "get away with it", they may only sound worse than each alone, but they will interact acoustically and electrically...

BruceRPA
06-01-2010, 12:35 AM
They are excellent speakers, especially if you like classic rock or simalar music. The T200s were the first pair of speakers that I refoamed and rebuilt the crossovers. The refoam job was easy using the kits from PartsExpress.