cdmccul
New Member
Thanks! I just posted "Hi! New from North Dakota!" rather than clouding up this thread.
My new mids should arrive tomorrow, along with a bonus pair of tweeters she sent me... I'll post up what I get, and await discussion.
Realistic Mach 2 mods
- Thread starter bre's dad
- Start date
Thanks! I just posted "Hi! New from North Dakota!" rather than clouding up this thread.
My new mids should arrive tomorrow, along with a bonus pair of tweeters she sent me... I'll post up what I get, and await discussion.
cdmccul
New Member
So my new mids arrived. The cones, as mentioned in past parts of this thread, are gooey and sticky. I want to clean them up without damage, but began to wonder... If the stuff is sticky outside (but not running down the speaker frame), what are the odds it might have gotten sticky and run down into the voice coil?
What's the recommendation to mitigate the goo? I was thinking of dusting with talc, or graphite. Just something to firm up the goo, and keep dog hair from sticking to it. I have used talc to make an old fridge door handle rubber grip stop being sticky in a rental I had once. Certain rubbers will break down with oils, as get sticky and gooey.
Ideas?
What's the recommendation to mitigate the goo? I was thinking of dusting with talc, or graphite. Just something to firm up the goo, and keep dog hair from sticking to it. I have used talc to make an old fridge door handle rubber grip stop being sticky in a rental I had once. Certain rubbers will break down with oils, as get sticky and gooey.
Ideas?
DonQuixote99
just give me some truth
Graphite will be a better look. And there are cones with graphite in the composition even. Never heard of talc cones.
Of course what you're planning on doing (and probably did ages ago now) will be sonically neutral either way I expect.
SHK
New Member
Hi guys, just acquired a pair of Mach Two's on the previous weeks and i must say that in general, i like them.
But i also noticed that lack in the midrange department... so here i am. Yes i know i came late in that Mach Two's party.
I've read this entire thread, and also some others here on Audiokarma and i found it very interesting what you did to your speakers.
I have a question...
Do someone managed to get a better sounding midrange, or even an excellent sounding midrange (with the original white driver) by changing the crossover frequency(ies) only ? I understand that this driver can cross at a lower frequency than stock crossover points since it has a somewhat low Fs, so do someone experimented with this ?
I'm asking because on the previous pages it seems that most people went with totally changing the driver, plus or minus modding the crossover, which in any case move the stock crossover point since the new driver itself have a different impedance than the original one.
The Mach i got are in excellent shape, near mint shape, and have never been modified by the previous owner. I took a look inside the cabinet to validate that. They have been refoamed for both the woofers and the mids by a professional, that's the only treatment they got. Those are great looking speakers !
Anyway thanks in advance for any inputs in regards to the original mid driver / XO points relation.
SHK
But i also noticed that lack in the midrange department... so here i am. Yes i know i came late in that Mach Two's party.
I've read this entire thread, and also some others here on Audiokarma and i found it very interesting what you did to your speakers.
I have a question...
Do someone managed to get a better sounding midrange, or even an excellent sounding midrange (with the original white driver) by changing the crossover frequency(ies) only ? I understand that this driver can cross at a lower frequency than stock crossover points since it has a somewhat low Fs, so do someone experimented with this ?
I'm asking because on the previous pages it seems that most people went with totally changing the driver, plus or minus modding the crossover, which in any case move the stock crossover point since the new driver itself have a different impedance than the original one.
The Mach i got are in excellent shape, near mint shape, and have never been modified by the previous owner. I took a look inside the cabinet to validate that. They have been refoamed for both the woofers and the mids by a professional, that's the only treatment they got. Those are great looking speakers !
Anyway thanks in advance for any inputs in regards to the original mid driver / XO points relation.
SHK
SHK
New Member
The manual hints that the crossover points on the Mach Two are at 800 and 6000. Made some expectations by looking at the crossover schematic and guessed the low pass and high pass frequencies. Draw the lines and it's somewhat close. Got 840 and 4850. I'm getting interested to move down the high pass filter on the midrange a bit so it would cross at 650hz approximately, and maybe then move up the low pass and get that 6000hz to see, or somewhere between 5000 and 6000.
I know i'm risking the drivers, they are only 40watts from what i read, but i'm tempted. Ah they are ferro-fluid so that helps.
But at the same time i think i never read of someone who destroyed those mids, but the fuses instead. And as a B-plan i think i found a nice driver as an alternative.
Still thinking about it, but should order the parts soon.
I know i'm risking the drivers, they are only 40watts from what i read, but i'm tempted. Ah they are ferro-fluid so that helps.
But at the same time i think i never read of someone who destroyed those mids, but the fuses instead. And as a B-plan i think i found a nice driver as an alternative.
Still thinking about it, but should order the parts soon.
SHK
New Member
in the meantime // some news...
i started working on my Two's with some parts that i did have in hand, slightly altering the values to not change too much of the original slope curves on the midrange...
At first i wanted to take a manual measurement of each driver impedance response so it could enlighten my choices of the parts to order. But bad luck, my digital multimeter has died. So i've ordered a new one from china since im on a budget side, still waiting for it to arrive. For the frequency responses, i dont have any tool so im just assuming the drivers choosen by Realistic present an enough flat response, then draw the impedance responses in the future when i get the multimeter, and build around that.
But back to what i was saying first, i've (re)drawn the actual crossover shematic, altering it a bit with some parts i already have here, and i already hear a big improvement over the original setup. Here it is by the way...
And here is what i changed for my first test...
Notice the most important part, change the polarity of the midrange at the driver terminals.
It might be a mistake done by the company when the speaker entered the production phase.
I re-used the same 8uF parallel capacitor to make the serie 15.5uF total capacitor.
I listen to them with both L-Pads set to flat.
I'll leave this as-is for the moment until i receive my DMM.
If anyone want to try it, or still if anyone want to share any inputs, idea.......
SHK
i started working on my Two's with some parts that i did have in hand, slightly altering the values to not change too much of the original slope curves on the midrange...
At first i wanted to take a manual measurement of each driver impedance response so it could enlighten my choices of the parts to order. But bad luck, my digital multimeter has died. So i've ordered a new one from china since im on a budget side, still waiting for it to arrive. For the frequency responses, i dont have any tool so im just assuming the drivers choosen by Realistic present an enough flat response, then draw the impedance responses in the future when i get the multimeter, and build around that.
But back to what i was saying first, i've (re)drawn the actual crossover shematic, altering it a bit with some parts i already have here, and i already hear a big improvement over the original setup. Here it is by the way...
And here is what i changed for my first test...
Notice the most important part, change the polarity of the midrange at the driver terminals.
It might be a mistake done by the company when the speaker entered the production phase.
I re-used the same 8uF parallel capacitor to make the serie 15.5uF total capacitor.
I listen to them with both L-Pads set to flat.
I'll leave this as-is for the moment until i receive my DMM.
If anyone want to try it, or still if anyone want to share any inputs, idea.......
SHK
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SHK
New Member
On my previous post i have mentioned what was my first attempt at modding the loudspeaker.... you can scratch this.
Now that i had the time to play further with it, i finally get really pleasing results (to my ears). I consider the mod is done. (well for now / with the equipment & ressource i do have in hands)
I will post the mod tomorrow...
Now that i had the time to play further with it, i finally get really pleasing results (to my ears). I consider the mod is done. (well for now / with the equipment & ressource i do have in hands)
I will post the mod tomorrow...
SHK
New Member
My Mach Two mod
Here is a schematic with the changes that i have made to the loudspeakers shown in red.
The 4.3 ohms resistor is an additional component. Everything else is stock value. I have upgraded every capacitors to be metalized polypropylene. No shorting of lamp bulbs, and no mods made to the cab yet.
Here is an example of my modded crossover...
The metalized-prop caps being larger in size, i had to drill new holes into the pcb for the 20uf cap, and there was no way i could fit the 33uf cap & the 4.3ohms resistor onto the actual board, so i went with the idea of a small interconnect board that i can screw just next to the main x-o pcb.
(new holes on pcb)
And here what it looks like once installed into the speaker...
The last thing to do is to invert polarity of the midrange driver. The simplest way to make this is at the driver terminals.
So now the brown wire goes to the big leg (+) terminal
The sound has improved alot. I would say this is sounding much more natural now. Everything is more coherent, detailed, lively, yet smoother. I'm listening to them all flat, at the L-pads on the speakers and on the amplifier also.
Try it. I bet you will like your MachTwo more than ever after this one.
Here is a schematic with the changes that i have made to the loudspeakers shown in red.
The 4.3 ohms resistor is an additional component. Everything else is stock value. I have upgraded every capacitors to be metalized polypropylene. No shorting of lamp bulbs, and no mods made to the cab yet.
Here is an example of my modded crossover...
The metalized-prop caps being larger in size, i had to drill new holes into the pcb for the 20uf cap, and there was no way i could fit the 33uf cap & the 4.3ohms resistor onto the actual board, so i went with the idea of a small interconnect board that i can screw just next to the main x-o pcb.
(new holes on pcb)
And here what it looks like once installed into the speaker...
The last thing to do is to invert polarity of the midrange driver. The simplest way to make this is at the driver terminals.
So now the brown wire goes to the big leg (+) terminal
The sound has improved alot. I would say this is sounding much more natural now. Everything is more coherent, detailed, lively, yet smoother. I'm listening to them all flat, at the L-pads on the speakers and on the amplifier also.
Try it. I bet you will like your MachTwo more than ever after this one.
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anachrophile
New Member
Hello, all. New-to-Two guy here. I have watched this thread for years as I contemplate finding enough time to "do something" with a pair of Mach Twos that I picked up for $32 at an antique store. Long ago I had new woofer surrounds put on by Russell Coco in Baton Rouge, who is exceedingly good at that sort of thing (I used to do this myself). I listened to them lightly and they were OK (I'm not fussy). Some time ago, I got hooked on large acoustic suspension speakers. Not the 2 cu-ft ones you see in the Avatar but ones with 4 slightly smaller drivers in a single cabinet, as Winslow Burhoe pioneered with his EPI1000. I built something like that using Smaller Advents (8 cubic feet but not omnidirectional as Burhoe prescribed...these have an in-the-box resonance of about 35 Hz, but that is another story...also a hint to where this Mach 2 project will go). So anyway, what to do with these odd Mach 2 speakers with the single huge woofer and that ridiculously tiny cabinet? After the new surrounds, I measured the drivers with my woofer tester. Free air resonance is 22 Hz, Qts is 0.60 plus or minus about 0.01 for the pair. DC resistance about 6.4 Ohms. My Vas reading was nonsense, but these other data are fairly consistent with what Parts Express claims for the replacement Mach 1 driver. I think you can use the PE numbers reliably, so let's take Vas as 12.1 cubic feet. The graph below shows resonances beyond about 500 Hz. So...the woofer should be crossed over low, placing the midrange at risk. We can put up with a woofer crossed too high, lower that crossover and play them fairly quietly with the stock midrange, or blow the midrange up and replace with a better driver, as many above have discussed. My current plan is to put new surrounds on the midrange and see how long it lasts. The TS values do suggest that the driver works OK in either sealed or ported boxes, but either way it should be a LARGE box (think refrigerator if you want critically damped). So my current plan is to open these Mach 2's on the top, invert them, and set them on top of some gutted Cerwin Vega cabinets, similarly opened on their tops. Total volume should be 6 or 7 cubic feet. This is expected to give an in-the-cabinet resonance point of <40 Hz with Q ~ 1. Maybe fcab will be a bit lower than a Large Advent.
Some of you may like these Woofer Tester graphs.
>>>Mach Two Driver alone (new surrounds). The other was almost identical.
Here's a Mach Two in its standard, ported cabinet: peaks at 7Hz and 62 Hz, with broad saddle minimum at ~20Hz. I don't know enough about crossovers to decipher the mid- and high-frequency response, but crossover points of 850 Hz and 5700 Hz would not surprise me.
Some of you may like these Woofer Tester graphs.
>>>Mach Two Driver alone (new surrounds). The other was almost identical.
Here's a Mach Two in its standard, ported cabinet: peaks at 7Hz and 62 Hz, with broad saddle minimum at ~20Hz. I don't know enough about crossovers to decipher the mid- and high-frequency response, but crossover points of 850 Hz and 5700 Hz would not surprise me.
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SHK
New Member
Hi anachrophile ! Welcome and good luck with you upcomming mods 
Just a suggestion here, before going to open the cabs and make some huge and irreversible mods of this magnitude to what i found to be (and this is just my personal opinion here) a really great looking speaker... are you sure you did put enough time listening to them and pinpoint what you like and don't, or what they're doing great and where they could be better?
My father still has his two pairs of Larger and Smaller first generation Advent that i always loved, but i visited him and had the opportunity to re-listen to them recently and i think the 3-way MachTwo's are in another league sonically.
When your mids will be restored, do yourself a favor... just don't only put them back in their cups, but also take the time to slightly mod the crossovers for testing sake. At least at the high-pass filter for the midrange driver. That would be to only change the two 4.7uf capacitors for a single 22uf cap. For testing purpose you can choose the bi-polar electrolytics like the ones at part-express, they're just a few cents. And reverse the polarity. You might be impressed....
On another note, the software you are using for driver measurements... is it able to save the results in a .text or .zma file ?
Are you also planning to take similar measurements for the midranges in free-air once they will be refoamed? And so for the tweeter driver?
I would be interested if you could generate those files and post it here or in PM to help further investigate and fine tune the mods....
When i'm was modding mine i did it only with a multimeter in hands. I found the Fs of those mids to be... 95hz. the other unit was 96hz. Awaiting if you can confirm this....
Thanks and let us know when you re-audition your speakers and if slightly modded.
SHK
Just a suggestion here, before going to open the cabs and make some huge and irreversible mods of this magnitude to what i found to be (and this is just my personal opinion here) a really great looking speaker... are you sure you did put enough time listening to them and pinpoint what you like and don't, or what they're doing great and where they could be better?
My father still has his two pairs of Larger and Smaller first generation Advent that i always loved, but i visited him and had the opportunity to re-listen to them recently and i think the 3-way MachTwo's are in another league sonically.
When your mids will be restored, do yourself a favor... just don't only put them back in their cups, but also take the time to slightly mod the crossovers for testing sake. At least at the high-pass filter for the midrange driver. That would be to only change the two 4.7uf capacitors for a single 22uf cap. For testing purpose you can choose the bi-polar electrolytics like the ones at part-express, they're just a few cents. And reverse the polarity. You might be impressed....
On another note, the software you are using for driver measurements... is it able to save the results in a .text or .zma file ?
Are you also planning to take similar measurements for the midranges in free-air once they will be refoamed? And so for the tweeter driver?
I would be interested if you could generate those files and post it here or in PM to help further investigate and fine tune the mods....
When i'm was modding mine i did it only with a multimeter in hands. I found the Fs of those mids to be... 95hz. the other unit was 96hz. Awaiting if you can confirm this....
Thanks and let us know when you re-audition your speakers and if slightly modded.
SHK
70's Rockfan
Rough N Ready
I'm going to build one crossover and compare them
side by side , one original and one new crossover.
side by side , one original and one new crossover.
SHK
New Member
Good luck on your next mods guys.
As for me, i am still amazed with those. I'm listening to different kind of music : folk, classical, prog-rock (modern & old), metal.... anything i throw at my Twos just sound superb! It might just be my final speaker set. In fact i'm asking myself : why spending more money when i already have that sound quality...
I'm having another project since last september that is on standby. I'm was planning to do the VLmod to a pair of Optimus 5B that ive got for free. But in the meantime i just keep listening to the Twos more and more and continue to be amazed... The plan is still, one day, to compare the 2 modded pair of speakers.
Have a great day.
As for me, i am still amazed with those. I'm listening to different kind of music : folk, classical, prog-rock (modern & old), metal.... anything i throw at my Twos just sound superb! It might just be my final speaker set. In fact i'm asking myself : why spending more money when i already have that sound quality...
I'm having another project since last september that is on standby. I'm was planning to do the VLmod to a pair of Optimus 5B that ive got for free. But in the meantime i just keep listening to the Twos more and more and continue to be amazed... The plan is still, one day, to compare the 2 modded pair of speakers.
Have a great day.
DonQuixote99
just give me some truth
I think I would say the VL mods much improve the Optimus 5Bs, but they don't put them into the Mach 2 territory at all. If you like the Mach 2s, the VL mods probably won't impress.
Copa1934
My ears are bleeding
Wow, the contributions here have been crazy cool. I have another set I'm playing with. Sadly they have blown VC's in the tweeters. However, I'm now looking into replacement VC's, which I found on ebay. Woofers have new surrounds, and mids next. Unfortunately after my divorce MANY things were lost in audio equipment. Some stuff is still in storage, but I'm hoping to pull out and begin audio tinkering again. It's been a slow go for me. Divorce really can take a lot out of you, so audio will be part of my therapy. Glad y'all have hung in there and made more contributions.
DonQuixote99
just give me some truth
Hi Copa, glad to see you around.
SHK
New Member
Hi Copa, and welcome back to the topic. That is very cool. 
About 1 year ago when i got the opportunity to buy mine i'm was searching the net to find some information in regard to the appreciation these Two's are getting... And when i saw the enthusiastic discussions between you, RickeyM and Evo4jon this is when i got motivated and made the move.
I saw an ad locally for a pair of MachTwo tweeters, well those are the equivalent Realistic 40-1377, for really cheap. He is asking $20 CAD (that's about $15 USD). Might get them for even lower. They are not in cosmetically top shape condition. One of them appear to have a cracked corner where they bolt-on. At that price i think i will grab them just in case. For parts. And in the worst case where you are'nt able to restore yours and can't find an economical solution to your problem, i could offer you some help, who knows...
Anyway, best of luck with your upcoming projects man !
About 1 year ago when i got the opportunity to buy mine i'm was searching the net to find some information in regard to the appreciation these Two's are getting... And when i saw the enthusiastic discussions between you, RickeyM and Evo4jon this is when i got motivated and made the move.
I saw an ad locally for a pair of MachTwo tweeters, well those are the equivalent Realistic 40-1377, for really cheap. He is asking $20 CAD (that's about $15 USD). Might get them for even lower. They are not in cosmetically top shape condition. One of them appear to have a cracked corner where they bolt-on. At that price i think i will grab them just in case. For parts. And in the worst case where you are'nt able to restore yours and can't find an economical solution to your problem, i could offer you some help, who knows...
Anyway, best of luck with your upcoming projects man !
Copa1934
My ears are bleeding
Let me know about the tweeters. The donor idea didn't pan out. Physical differences made them proposition too complicated. What ever solution I ultimately come up with I want for others to be able to do with the least amount of complications. I'll be ordering replacement VC's shortly. Only issue is they are 4-ohm, so crossover mods will be in order. Stay tuned.