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Realistic Mach 2 mods

Well, start with removing the metal grills.... :)

Others have suggested that taking the light bulbs out of the crossover (jumpering their sockets) opens up the top end. I'd say experiment before soldering in the jumpers.

Of course, if the woofer foam is stiff, it should be replaced, and if it's actually damaged, do not operate the speakers until that repair is done.

As for capacitor count, here, let me look at this Mach 2 crossover I have sitting around....OK.

2 @ 4.7 µf
2 @ 8 µf
2 @ 2.2 µf

The 8s and the 2.2s are axial lead.
 
TheOctavist said:
So where to start guys? Modwise
Click to expand...

One member here just removed the metal mesh from the grills and kept the trim rings so that's an option.

Upgrading the crossover with poly caps is also a good start. Then I'd look into bracing & damping the cabs.

BTW guys, has anybody done any measurements on the Mach Two mids? I'm guessing it should be able to play lower than the Mach One horns. If I ever re-foam mine, I'll see how they work crossed at 1000hz.

I finally tried my RS dome mids in my 'Two's. On a quick listen it sounds pretty good but I had to turn the L-pads all the way down to balance them with the woofers & tweeters.
 
T/S specs, midrange

RickeyM said:
...BTW guys, has anybody done any measurements on the Mach Two mids? I'm guessing it should be able to play lower than the Mach One horns. If I ever re-foam mine, I'll see how they work crossed at 1000hz...
Click to expand...

F(s): 107
Q(ts): 0.861
Q(es): 1.701
Q(ms): 1.742
L(e): 0.175
V(as): 0.148
R(e): 4.8932
 
F(s): 107

With that low of a Fs, I wonder why RS didn't cross the mids at a lower frequency on the Mach Two's? I think it would have made for a better sounding speaker.
 
RickeyM said:
F(s): 107

With that low of a Fs, I wonder why RS didn't cross the mids at a lower frequency on the Mach Two's? I think it would have made for a better sounding speaker.
Click to expand...
My initial thoughts about it last night were the high crossover point for that tweeter. The present crossover points are 600hz and 6khz. The published frequency response for the tweeter (in the catalog) is 4khz-50khz.Honestly I feel that thing is more like a super tweeter than tweeter. I think running that mid where it is likely is the best compromise.

Going by VL's measurements of the Mach One, which VL claimed the Mach Two woofer was in the same ball part, VL suggested 600hz as an ideal crossover point for the woofer, but severely bad for the Mach One mid. So this cone mid is a more suitable match. Also, given the light duty cone I'd be hesitant to running it any lower.

One of the reasons I like the dome mid, 40-1281.
 
104_1320-M.jpg
:music:
 
The bulb also acts as a kind of crude compressor as the resistance changes with power in a sloppy and non-linear way. Old Urei studio monitors in the 80's had various 'car bulbs' in them - so the response changed radically with level, in a kind of slow and annoying fashion, no home play-out system ever would. :-( My advice; if you are not going to thrash the speakers, measure the bulb resistance cold and replace it with a power resistor of that value.. :-)
 
My Frankenmachs :p. the strath earn speakers are ass up at the moment , only the midrange drivers function. And since the mach midrange drivers need reforming ... I decided to put the strath earn mids in place of the mach mids. Required making the enclosure bigger, embiggening the mid driver/hole, turning the tweeters 90 degrees, and modifying the crossover. I recognize that I broke dozens of speaker design rules.....but to be totally honest, they sound spectacular. I mean jaw dropping good. That's all I care about really. No monetary investment, no big time commitment, and let's face it.. This is great fun. Oh yes soldered power resistors in to replace those wretched lamps. And modified the port tube...and have to turn the lpad all the way up to high for the mids and tweeters....but it all is coherent now. No gaps/breaks ..the last thing is to caulk the woofer basket and maybe brace the cabinet better.... And more batting. Then I'll be tackling one of mr jjs builds( a from scratch build...my first)
 

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You talking about adding damping to the woofer basket, to fight 'ringing?' I think the classic material for that is 'plasticine,' non-hardening clay-like modelling stuff. Get it at an arts and crafts place. Put it all over the basket.
 
TheOctavist said:
My Frankenmachs :p. the strath earn speakers are ass up at the moment , only the midrange drivers function. And since the mach midrange drivers need reforming ... I decided to put the strath earn mids in place of the mach mids. Required making the enclosure bigger, embiggening the mid driver/hole, turning the tweeters 90 degrees, and modifying the crossover. I recognize that I broke dozens of speaker design rules.....but to be totally honest, they sound spectacular. I mean jaw dropping good. That's all I care about really. No monetary investment, no big time commitment, and let's face it.. This is great fun. Oh yes soldered power resistors in to replace those wretched lamps. And modified the port tube...and have to turn the lpad all the way up to high for the mids and tweeters....but it all is coherent now. No gaps/breaks ..the last thing is to caulk the woofer basket and maybe brace the cabinet better.... And more batting. Then I'll be tackling one of mr jjs builds( a from scratch build...my first)
Click to expand...
That most certainly qualifies as FrankenMach. Wow. I'm thinking you need to change the resistor values. There is too much resistance, at present, which is why you are having to turn the L-pads up. Reason I'm suggesting going with a different value is it will permit you more flexibility in adjustments. Right now you are maxed out.

That is wicked looking, I'll give you that.

As for the caulking I have the same question, what are you doing with it? You don't need a good seal with the woofer, being a ported cabinet. But if you are attempting to deadening the woofer basket then Don hit the mark.
 
TheOctavist said:
Yes deadening woofer basket cabinet , port tube (outside) tweeter basket mid etc all metal parts. Now I don't know much about the tech stuff(I'm a hack ) but how to choose resistor values? http://www.avahifi.com/root/audio_basics/ab_pdf/ab1982.pdf
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What did you use? The old lamps work like varistors, however, as they degrade (since they're really a lamp) the resistance will go up, and will effectively reduce the output of the driver it is connected to. That is why there are people who recommend testing the resistance of the lamps, or simply replacing them.

Post what values you used.
 
Copa1934 said:
What did you use? The old lamps work like varistors, however, as they degrade (since they're really a lamp) the resistance will go up, and will effectively reduce the output of the driver it is connected to. That is why there are people who recommend testing the resistance of the lamps, or simply replacing them.

Post what values you used.
Click to expand...
I removed them completely. Now I just have to replace the tweeters and recap the crossover. can someone list the values of the caps for me? that midrange I used in the frankenmachs though in theory shouldnt work....absolutely sing. just stunning. Ive never heard vocals so clear.
 
TheOctavist said:
I removed them completely. Now I just have to replace the tweeters and recap the crossover. can someone list the values of the caps for me? that midrange I used in the frankenmachs though in theory shouldnt work....absolutely sing. just stunning. Ive never heard vocals so clear.
Click to expand...

See post 241, above. :)
 
Copa1934 said:
Hey wait, what's with the woofer?
Click to expand...

I bought my Mach Two's because they were cheap (sans woofers). I just happened to have a pair of over-the-counter RS 15's NIB. The mounting holes lined up but the baskets are a wee bit bigger than the original Mach Two woofers. Rather than make a mess trying to enlarge the openings for the woofers, mounting plates out of MDF were made. FWIW, those over the counter drivers ain't no slouch. They were played hard and loud with no signs of distress and were ready for more.
BTW, when I build the new bigger enclosures, the woofers will be countersunk so I can use the original trim rings :thmbsp:
 
DonQuixote99 said:
As for capacitor count, here, let me look at this Mach 2 crossover I have sitting around....OK.

2 @ 4.7 µf
2 @ 8 µf
2 @ 2.2 µf

The 8s and the 2.2s are axial lead.
Click to expand...

FWIW there are also pcb variations with all caps axial, and one with just the 4.7's axial. Counts and values are the same, but if you're wanting to replace like for like, you'll have to open it up and see what you have.
 
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