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Realistic Mach 2 mods

dorsett33 said:
OK...my power/internet is finally restored. I picked up a pair of the 40-1281's from Epay based on Copa's recommendation in this thread. First thing I did was A/B the original midrange with the new 40-1281...WOW! Significantly better in terms of clarity, brightness and overall sound quality. The original midrange just doesnt hold up against these 40-1281's. Next thing I did was drill new holes and mount the new midrange. I used some general wood putty to fill in the old holes and will touch up with some black paint later tonight. Im opting to not use the speaker grill as I like the "sparkle" look of the new 40-1281's. If you get the chance...go for it and buy these 40-1281's and install them into your Mach II's. Nice upgrade using Realistic parts from the time without totally bastardizing the speaker. Pics to come very soon....
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Here goes.....
 

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Now positioning is a problem sometime. The first pic is where I try all speakers I get for myself or the ones I repair/upgrade. This is where my bar is going. The second pic is just extra stuff. Nothing is hooked up. The third pic is the surround sound stuff and there is a lot more in my shop. And this is just the basement. Hopefully by next summer almost everything will be gone. The Mach Ones I have sounded better is the same position and I haven't even touched them yet. No crossover work or anything. I agree with all that the mid is a big problem with the M2 and there three good suggestions (4 if you consider the Pyle PDMR5). I don't mind spending a little more but to my old ears the untouched M1 sound much better than the recapped M2. As soon as you hear the M1 you know the cabinet is too small for the woofer so I look forward to do all the mods. I'm not giving up on the M2 but I'm going to wait for a while to see if others try some of the mids mentioned.
 
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I would like to put a couple of those 40-1281's in MY Mach 2's, but don't see any on the auction site. Has all this chatter made them not-so-readily-available?
 
I don't know how old these 40-1281 mids are, but it seems to me there would be newer, better made dome mids that would sound great and be alot easier to get. I guess that is what an earlier poster was saying about Tang-band and Vifa. I'm okay with my Mach Two's not being 100% Realistic.
 
dorsett33 said:
Quick question: What Radio Shack speakers did those 1281's come out of new?
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I don't recall them being used in any RS speakers. I would question, of course, why they carried them, but honestly RS carried so many types of speakers for sooooo long, it doesn't surprise me that they carried this "type" of speaker for DIY speaker builders.

New for 1980 http://www.radioshackcatalogs.com/html/1980/h058.html

Optimus-27 used the 40-1283 introduced in the above catalog. So it's pretty accurate to say that some drivers were sold "off the shelf" that were used in RS brand speakers.

There are two pair listed currently, one pair very reasonable (even with shipping) the other ridiculous (but I have my doubts it has anything to do with our posts).

There are several PE dome mids I've checked out and thought would work, but my goal (mostly) was keeping it all RS. I see no harm thinking outside the box as the speakers available may sound as good or better, may handle more power, and likely will be available for less money. So my personal efforts were mostly proving you can get quality sound from RS speakers and or RS drivers, or combination thereof.
 
40-1281 mids

The only thing that gives me pause is that the power handling goes down to 40 watts http://support.radioshack.com/support_audio/doc40/40984.htm

The crossover network in the link only shows a first order, 6-db per octave crossover. Maybe a second order, 12-db per octave network (like the Mach Two's have) will keep the power handling at a higher level :scratch2:
Thoughts anyone?
 
RickeyM said:
The only thing that gives me pause is that the power handling goes down to 40 watts http://support.radioshack.com/support_audio/doc40/40984.htm

The crossover network in the link only shows a first order, 6-db per octave crossover. Maybe a second order, 12-db per octave network (like the Mach Two's have) will keep the power handling at a higher level :scratch2:
Thoughts anyone?
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If it's any comfort I fed them roughly 170 watts recently for maybe 15-20 minutes continuously. I have a feeling they handle more in a proper network. The rating is using strictly a cap. A network will also have a choke (attenuator), and then you have the bulb in-line, so I'm a tad more on the optimistic side. The original, as noted earlier, is rated less and I don't recall many (at all?) reported being blown. I'm sure someone has, but given the abuse many of these have been through, I'd think they would be blown left and right. The 1281, I'm pretty certain, has a larger VC and I know a heavier and larger magnet.

I'll know after more testing.
 
Copa1934 said:
If it's any comfort I fed them roughly 170 watts recently for maybe 15-20 minutes continuously. I have a feeling they handle more in a proper network. The rating is using strictly a cap. A network will also have a choke (attenuator), and then you have the bulb in-line, so I'm a tad more on the optimistic side. The original, as noted earlier, is rated less and I don't recall many (at all?) reported being blown. I'm sure someone has, but given the abuse many of these have been through, I'd think they would be blown left and right. The 1281, I'm pretty certain, has a larger VC and I know a heavier and larger magnet.

I'll know after more testing.
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http://www.parts-express.com/pe/sho...tm_content=299-414&utm_campaign=email110812_a anyone check these out? Look like another nice option. Not cheap but a lot of bang for the buck. Oh, as a mid replacement, of course.
 
I rescued a single poor pathetic...seen the wars...minimus 7 walnut. Sad cosmetics.
I rescued it out of pure love.
Then it dawned on me if the Min7 woofer would/could serve as a viable MR for this Mach thread?
 
Woofers re-foamed, the right sized rolls are from (nice)
http://www.simplyspeakers.com/radio-shack-speaker-foam-edge-repair-kit-mach-fsk-15mach2.html

Re-capped, (little tight on the 33uf, had to move off board)
http://www.parts-express.com/pe/showdetl.cfm?partnumber=027-114

Mid-ranges replaced , the foam looked OK- but was NOT
(could have re-foamed and still can) Could have found cheaper somewhere else.
http://www.parts-express.com/pe/showdetl.cfm?partnumber=292-202

And bulbs bypassed. SWEET!!!!!!!!!!!!
Thanks ev1 -Rick
 
I've just gotten a pretty much new/mint pair of mach iis, Tandy made. 1989. https://flic.kr/p/qHGjD6

https://flic.kr/p/qHtWdE

https://flic.kr/p/qHPw7J


The bass is phenomenal. The first pair of speakers I've had in which the bass is not only heard, but felt. However...I got these for 45 bucks and want to address a couple issues. I want to clean up the mids, and get some more energy up high..they are very low/low mid heavy. I'm not at all versed in soldering or the intricacies involved in modifying crossovers, although looking at the caps, it appears as though they will need replacing. They will need refoaming..etc. so my question is...as a neophyte. ..where should I start first? What is easiest to implement? And what can be done to get more highs? Also, is there a listing of all the cap values? Thank you.
 
I had 2 pairs, down to a single pair now. Gifted the other pair to my twenty something nephew who just bought his first since home. He loves them.

Saving the other pair for my twenty something daughter who I feel will be moving out in the spring. I have a Soundcraftsmen preamp/power amp setup waiting for that occasion (see signature). They are a fun party speaker to be sure.
 
Little black rubber squares on back of mids

Love this thread. My Mach 2's have brought me a great deal of pleasure over the years. I just replaced the surrounds on the mids. I noticed four little black rubber squares glued to the back of the paper cone. Each one is located beneath a metal basket strut. I removed them while I was cleaning off the old foam. Does anyone know the purpose of these little squares? Are they there as sonic dampeners? Perhaps they are there to prevent the paper cone from mashing into the metal basket if it should take a blow from the front. Should I reglue them back in? Here's a picture of the system; https://www.flickr.com/photos/jasonmcconnie/2329701393/in/set-72157606895763637
 
Not sure what those little black squares are for either.....I have enjoyed my Mach 2's for many years also :) (In fact they are playing as I write this) One thing I found, and everyones mileage may vary, but last month, I decided on a whim to remove the metal grills from the mid driver...Doing so, gave the Mach 2's a totally different, more open character for the better. I don't know if many have done this, but mine are now off for good. 4 Phillips head screws, and you are good to go. I'd be interested in hearing other Mach 2 owners impressions on this.
 
Conroy said:
Love this thread. My Mach 2's have brought me a great deal of pleasure over the years. I just replaced the surrounds on the mids. I noticed four little black rubber squares glued to the back of the paper cone. Each one is located beneath a metal basket strut. I removed them while I was cleaning off the old foam. Does anyone know the purpose of these little squares? Are they there as sonic dampeners? Perhaps they are there to prevent the paper cone from mashing into the metal basket if it should take a blow from the front. Should I reglue them back in? Here's a picture of the system; https://www.flickr.com/photos/jasonmcconnie/2329701393/in/set-72157606895763637
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I believe they are for dampening. I found a couple articles some time back. I and others have discussed this in this thread and other Mach two threads. I left mine intact.
 
I think the metal grill screens are cosmetic and can only do harm sonically. They will muffle the sound some amount, and they can always get a bit loose and buzz.
 
DonQuixote99 said:
I think the metal grill screens are cosmetic and can only do harm sonically. They will muffle the sound some amount, and they can always get a bit loose and buzz.
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:yes: The mach 2's are a much more "open" sounding speaker without those grills. The decency of the midrange driver has jumped up a few bars in my opinion, it really is a better unit in this application that I had thought it was with the grills removed.
 
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