Realistic Mach One Upgrade/Update - diyAudio
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Old 3rd October 2009, 04:49 PM   #1
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Default Realistic Mach One Upgrade/Update

I just found a pair of Realistic Mach One's (40-4024a) locally for $50. Thought what the hey, I'll try them out. Got them home, they don't sound too bad, but I know that they have 30 yr old caps inside that are probably all used up.

Just took the woofer off to look at the crossover.

It has three inductors (I'll probably leave those....)

two resistors - "2 (ohm symbol) K" and "8 (ohm symbol) K"

two bipolar capacitors - "50V 22(u symbol)F" and "50V (u symbol)F"

one yellow capacitor (two individual ones in a case) - "2.2 +/- 10 250V (then a K ?)"

My question, with the horns, is there timing issues related to the volt rating? I'm thinking that I'll replace the resistors with metal oxide ones and all three caps with Solen Fast caps (Metallized Polypropylene) rated at 250V, unless that can cause unwelcome issues.

Also another question, should cleaning the l-pads suffice, or are new ones needed?

Any ideas other ideas?
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Old 3rd October 2009, 06:01 PM   #2
Ron E is offline Ron E  United States
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Inductors are probably fine, if they have small iron or ferrite cores they may cause a bit of distortion at higher powers.

The yellow cap may be a mylar cap if it is axial and a bit oval.
The volt rating affects nothing, 50 volts is enough for a 300W/8 ohm amp
Film caps can sometimes sound a bit brighter than 'lytics.

The L-pads may not need cleaning, I wouldn't mess with them unless they are scratchy.
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Old 3rd October 2009, 07:12 PM   #3
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A little research and found the crossovers to be 800hz for the woofer, 800-8000hz for the mid horn, and 8000hz with the tweeter.

Is it a good idea to use different caps in different locations?
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Old 4th October 2009, 10:22 PM   #4
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So any ideas on what caps to use where?
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Old 5th October 2009, 06:33 PM   #5
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you got a good deal on these. radio shack made good speakers back in the day. the mach ones keep their value and so do the newer mach two speakers. as long as the walnut vineer is in good shape you get one heck of a deal. You may want to test the caps to see i they are still working. a lot of people buy these then they dont end up using them often. the mach one speakers put out so much sound that it was hard for people to use them in apt buildings. people would get nocks on the door saying turn it down. I used to have the mach two's and wish i still had them. Now i own a house and could use them. I sold them even thoe they sounded great because the lady under me kept b*&ching to the leaseing office.
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Old 5th October 2009, 09:44 PM   #6
Face is offline Face  United States
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Quote:
Originally Posted by dmongrain View Post
So any ideas on what caps to use where?
Replace with the same uf's, don't worry about voltage.

http://www.parts-express.com/dayton-...capacitors.cfm
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Old 5th October 2009, 10:01 PM   #7
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Quote:
Originally Posted by dmongrain View Post
So any ideas on what caps to use where?
The white Mundorfs are well made and are modestly priced. I have used them in several projects so far with good results. Usually under 1% tolerance on my meter. You have piqued my curiosity now about changing out the electros in mine mainly as a conservative replacement/tune up than anything else; I'll add them to the next parts order.

Quote:
Originally Posted by Jason_1976 View Post
the mach one speakers put out so much sound that it was hard for people to use them in apt buildings. people would get nocks on the door saying turn it down.
There's this thing called a volume control.....
I use mine in an apartment.
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Old 5th October 2009, 11:12 PM   #8
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There's this thing called a volume control.....
I use mine in an apartment.

My issue was I turned the volume control to high and was shaking things off the walls in other apartments. I know the match two's use a lamp as a fuse. I could watch it light up as the bass hit. They were an xmas gift from my mom and dad. my mom still has two pair of these but she needs me to replace the foam on the woofers. I received my set after my mom got tired of me playing with her stereo.

now as for the mach one speakers there are two versons of them. ones with rubber surrounds are older and bring in more money on ebay and the rubber seams to last forever, and then they came out with ones with the foam that falls apart in 20 years. the catalog numbers are almost the same. I think the one kind adds a letter behind it but i can't remember what is what.
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Old 5th October 2009, 11:42 PM   #9
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Originally Posted by Jason_1976 View Post
now as for the mach one speakers there are two versons of them. ones with rubber surrounds are older and bring in more money on ebay and the rubber seams to last forever, and then they came out with ones with the foam that falls apart in 20 years.
Mine are the early rubber surround version and I am the second owner since new. The foam ones often do rot, but according to one of the excellent speaker repair firms near here, they have replacements.
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Old 6th October 2009, 12:32 AM   #10
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I had a pair of these new when I was 17 years old for about a month (sold them for beer money ). I didn't have anything decent to drive them at the time but boy, they were cool!

Still are.
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