Mach One 4024, 4024A, 4029 Information and Upgrades!

I've tried a couple of different things on the passive radiators on my Polk SDA-1Bs. What I found was that whatever you use needs some mass to really dampen stamped baskets well. I wound up using something called putty tape I found at a local hardware store. It's kind of like Mortite but flat, about 3/4 wide and 1/8 thick, looks like chewing gum. It's pretty sticky, I just cut it to the lengths needed and stuck it to the baskets. I applied it to the passives a couple of months back. It really helped tighten up the bass. My only reservation is that it may dry out and fall off. I pulled one passive last weekend and it was still stuck on and hadn't seemed to dry out any. So I decided to do the mid/woofers too. I did one speaker, then did some listening in mono, the improvement in midrange detail and tonal balance was amazing. During my listening test my 10 year old daughter walked into the room. I enlisted her as an impartial test subject, after listening to both speakers three times with different music each time, I asked her if she heard any difference between the two. She pointed at the speaker I hadn't done yet and said that one sounds fuzzy.
 
I just wrapped masking tape over the back of the LPads so the vent holes were covered.

After, be sure and open those vents back up. Thermodynamics are real...:yes:

Two, when you add mass to a PR, you change the T/S params. Of course weigh the application to make R/L identical if you do this. I'd never do it for a well-designed speaker without redesigning the xovers too. Cones on Bozaks were supposed to be exactly 38 g.

I have wrapped the woofer basket parts on Amazings and tacky-ed down caps too.

I would compensate for the decreased internal volume of added bracing by externalizing the xovers... that probably is the greatest way of reducing resonance or deleterious effects on those components.

.
 
Realistic Mach 1 4024a & 4029 Test Data

Hello All, I thought I would post this information as it should answer some questions I have read here. I have been designing speakers & tube amps for 25 years as my full time job. I had a pair of these when I was 16 and was impressed with them. I have now purchased a pair of both models of the Mach 1s. After listening I have found that they do sound different. After testing both, the difference is easy to explain. It is not that the 4024a is a better speaker, but the crossover in the 4024a does a better job and produces a flatter response. I have been modeling a new crossover for the Mach 1 4029 that will put them in a league = to almost any speaker on the market. I will use all the stock drivers and cabinets, only the crossovers will change. If you look at the graphs I have included you will see that the Mach 1 crossover is not a true three-way design but a two way. The mid horn is used as a mid and tweeter. The tweeter does the same job to help try and smooth the response. The tweeter is still getting Bass energy down to 200Hz at - 35db, NOT GOOD. The mid can be cleaned up as well with another order and a bandpass filter. However, it is awesome how good they made these speakers many years ago, without the use of modeling software. Some of the speakers we manufacture today are 32,000.00 a pair. I want to see with the right crossover how close I can make the Mach 1s to our reference system. If you look at the graphs you can see the transfer function of all the drivers on both models as well as the SPL curve and impedance. The new unit is said to be 4 ohm, not so. The driver is marked 6 ohm, but in the sweeps you can see both woofers have the same low end impedance. Because of this stated impedence difference they made a different crossover for each model. But, with the right crossover in each model, one is as good as the other. Ferro-Fluid can be added to the 4024a very easy.
 

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Hello,
I understand the capacitors are grey but what is the yellow and white components? I am trying to solve a distortion issue in the mid and high horns.
Do I need to replace these additional components? The pots for both seem to function very well. Zero db seems to be the best setting for my room. They are fine at a low volume but the distort when the power is placed on them. 4024A Yellow component is a TOWA 2.2/AC.50
Thanks for any help.
DSC03952.JPG
 
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Hello,
I understand the capacitors are grey but what is the yellow and white components? I am trying to solve a distortion issue in the mid and high horns.
Do I need to replace these additional components? The pots for both seem to function very well. Zero db seems to be the best setting for my room. They are fine at a low volume but the distort when the power is placed on them. 4024A Yellow component is a TOWA 2.2/AC.50
Thanks for any help.
View attachment 209920


The yellow item is a film capacitor. No need to replace it unless you feel it is defective.

The white components are sand-cast wire-wound resistors. From what I understand they shouldn't cause noticeable distortion issues like you describe, but happy to be corrected on this!
 
Distortion Problem

The Machs have a foam gasket that holds the midrange diaphram in place. It rots like the woofer foam. If the foam has rotted the mid diaphram will jump around and produce a lot of distortion. I had to replace it on my pair to clean up the mid distortion. You can use a 1/16" to 1/8" foam tape with sticky on one side. Cut it to the same width as the mid seal that is there now. Just something to check if the caps don't fix your problem. My model is the 4029.
 
Hello All, I thought I would post this information as it should answer some questions I have read here. I have been designing speakers & tube amps for 25 years as my full time job. I had a pair of these when I was 16 and was impressed with them. I have now purchased a pair of both models of the Mach 1s. After listening I have found that they do sound different. After testing both, the difference is easy to explain. It is not that the 4024a is a better speaker, but the crossover in the 4024a does a better job and produces a flatter response. I have been modeling a new crossover for the Mach 1 4029 that will put them in a league = to almost any speaker on the market. I will use all the stock drivers and cabinets, only the crossovers will change. If you look at the graphs I have included you will see that the Mach 1 crossover is not a three design but a two way. The mid horn is used as a mid and tweeter. The tweeter does the same job to help try and smooth the response. The tweeter is still getting Bass energy down to 200Hz at - 35db, NOT GOOD. The mid can be cleaned up as well with another order on the bandpass. However, it is awesome how good they made the unit many years ago without the modeling software. Some of the speakers we manufacture today are 32,000.00 a pair. I want to see with the right crossover how close I can make the Mach 1s to our reference system. If you look at the graphs you can see the transfer function of all the drivers on both models as well as the SPL curve and impedance. The new unit is said to be 4 ohm, not so. The driver is marked 6 ohm, but in the sweeps you can see both woofers have the same low end impedance. Because of this impedance they do need a different crossover but with the right crossover in each model, one is as good as the other. Ferro-Fluid can be added to the 4024a very easy.

Superb work!!! I have owned the Mach Ones (4029) I bought with paper route money for about 30 years now. I am in the process of bringing them back to life. They are fine really just the foam has disintegrated on the woofers. Now!!!! I remember doing sine sweeps and there was a big someplace in the mid-range to woofer crossover; its very easy to forget these things.

One thing I have always known, well since tracing the crossover some 20 year ago is the woofer is a 2nd order, the mid-horn as well but it has no upper filter. The tweeter has a second order filter if I remember and with the resistors I calculated they are not much power if the user leave the level controls at 0dB or +3dB? ... I very well could be wrong. How can I get the redone cross-overs plans?

BTW reading I understand the mid-range horns such as this have a natural HF rolloff and a cross-over may now be needed. Certainly looking at the 4024 graph its very smooth for an old school 15" woofer big horn RadioShack speaker. I can't wait to finish my project and see what they would like.

Thanks for some superb long needed work.

Oh BTW the midrange horn is a solid pieces of plastic with no foam, its wound on an aluminum or plastic voice coil, is very stiff but for sure is one piece of plastic. The brown spots you see is me making a mess with the ferro-fluid in my 4029s.

MidCoilFront.jpg


MidrangeCoil.jpg


Wait... is this the gasket your referring to, and its critical. If so another great find by you. As mine have worn a bit over the years. And me taking them apart a few times has not helped.
MidrangPlate.jpg
 
Gasket on mid horn

that is it! it is the only thing that keeps the diaphram pressed to the magnet top plate. if it is rotted the diaphram can jump around and buzz like a kazoo, creating almost all distortion.
 
that is it! it is the only thing that keeps the diaphragm pressed to the magnet top plate. if it is rotted the diaphram can jump around and buzz like a kazoo, creating almost all distortion.

Thanks..

I have to ask what my be a dumb question, but because I don't have a reference to go by, would you consider mine rotted? Or is enough still there?

Also do you know what the back plastic cup and this foam piece is for and or how it works. Pic below. The obvious answer is its a second chamber to lower the mids resonance, but... I have not been sure for 30 years...:scratch2:

MidrangeWhole.jpg
 
Sorry for the poor, very poor grammar/spelling in the first post. It was late and I was staying up looking at your graphs; I was very excited. I always wanted to know!!! What I was saying is I remember doing sine wave sweeps with just a meter and watching and hearing a dip around 1kHz. Now!!! Are you sure a cap is not out of whack, and perhaps in my case as well, a common failure perhaps. Or have you replaced all the caps then measured?
 
OK I will add HQ large pics of the 4029 for refereance and make it easy for people to see whats what without taking apart thier own speakers. And add all I know about them for this post.

Also this shows the foam rot area on the midrange cover that must be looked at and fixed if need be according to user Videolady201. Again thanks to her/him for the info and graphs and let us know...

Also Videolady201 findings have collaborated with the 4029 being 6ohm driver; the 4029 is 6ohms and not 4. Videolady201 has measured the impedance difference between the 4029 and 4024; the 4029 do have a valley in the 1Khz range compared to the 4024, this is why they use different crossovers (of course :D). I think a lot of the 4029 stickers that say 6 ohms must have fallen off over the last 30 years...

My Mach One 4029 Pics external and internal, original owner of 30 years. taken just weeks ago (April 2010).

MachOneswhole.jpg


Midrange is in the top sealed off from the woofer. The woofer is in a very small cabinet! This midrange today would cost a lot. Its made up of many solid and thick plastic parts. And its just huge for a mid-range horn. More in-line with older JBLs types.

Horn.jpg

MidrangeMagnet.jpg

MidCoilFront.jpg

MidrangeCoil.jpg


Critical, according to Videolady201 the felt/foam seal here must be intact as its the only thing that presses the midrange plate down against the magnet. If its worn away distortion can/will occur. Could be why some did not like the Mach ones!!!

MidrangPlate.jpg



Large woofer and decent magnet. The vent was stuffed with fiberglass 30 years ago, by design. Well at age 16 I had better ideas I pulled off the cloth filter and removed the fiberglass so it could vent the woofer better. There is also an inner filter as well so its not exposed. I glued the outer filter back on but it most have fallen off. I won't use fiberglass when I finish restoring them but something more solid. Anyways after all these years no fiber glass has been sucked into the inner filter (that I know of). The Vc was large 2.25" or 2.5" and took some serious abuse... like pumping a few hundred watts into them of bass program material and you could smell them heating up but they did not give.:thmbsp: BTW: This trick does work, as logic would lead you to believe and as I felt with my hand the woofer ran cooler removing the fiberglass, I heard no sound difference, why they plugged it I don't know. But it made the vent useless.
Magnet.jpg


BTW. To aid in removal of the 4029 bezel around the woofer the 4024s don't have use a hair dryer and carefully heat it up and work it off. Mine had clips but was also glued?.


On to the bullet tweeter and standard but heavy duty liquid cooled 1" dome, with a decent magnet. The midrange did not have a high cut off so the horn tweeter came in with a 2nd order Xover to fill in the highs and did so nicely. It might be a horn, but it did not have that fatiguing etchy highs of some metal domes. the highs as You can see by the graphs were nicely done.

WholeMach1Tweeter.jpg


Compared to a Vifa 1" soft dome used in many, speakers.

Mach1TweetVifaTweet.jpg


And the cross-over the resistors are 1ohm and 2ohms. The lower inductor is 1.0mH, the top 2.7mH; all other values should be easy to see. The Lpads are 50 volt 8 ohm heavy duty types.

Crossover.jpg
 
not knocking the mach 1's in general : just mine in particular : and I'm looking for some help . I have the less desirable "liquid cooled" type : love the cabs and the overall looks : but for me , that's where it ends.
they sound hollow : bass is not pronounced ...very muddy ... definitely not sounding "pipe-organ -y" high end is weak : no airiness ...and the mids sound shallow.

Had them in two different rooms : one open and reflective , one smaller and pretty surface-balanced .... driven them with an sx-780 (very standard SS type sound on other speakers with it) as well as an sx 737 (very tube-y imho) ....I just can't get a sweet spot with the Mach 1's ...... they begin to get better at a ridiculously high spl ...but then definition with any speaker would begin to take a back seat to the spl at that point (imho)


question : why am I having such a mediocre experience with these fairly well-regarded speaker? some speakers need and react to a recap much more than others : Is this the problem? (although of all the mach 1 threads Ive seen recapping does not appear to be a huge, immediate, necessity)

Help : I'd really like to love these things / but they need to sound decent : right now a pair of 12" , 3-way store brand '70's cheapies (without a recap) kick their a$$ big-time....and a small pr of 8" infinities absolutely kill them

Well said, this is my experience as well. I would like to enjoy them, but to me they have the same shortcomings as you describe. I ran them with my SX-1250 too. Too bad, but still my best curb side find ever.
 
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New Test Sweeps with New Crossover

I had all the same opinions of the Mach 1 as stated here. I have been working on a new crossover design to fix these issues. The speaker is great it just needed some changes in how the voltage is delievered to the drivers. Please see the graphs attached.
 

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I have heard many times that the woofers on the 4029 are 4 ohm. Now I see the 6 ohm sticker in the picture. What's up with that? Are there some of each, or are they really all 6 ohm, and all the folks that say otherwise have been mistaken?

I'm curious because I have a pair and the previous owner tossed the woofers due to foam rot. This means I'm looking and I want to be looking for the correct woofers.
 
Woofer Impedence

They are all 8ohm 4024, 4024a and all 6ohm 4029. There were never any 4ohm bass drivers in the Mach 1s.
 
Midrange Cup

The magnet is sealed. It is not a chanber for acoustical energy. It is there to support the back of the midrange horn so it will not brake if the unit is dropped, etc. The cup screws to the cover board and the back of the horn goes in it with the foam. It is for support of the horn only. The first models had a piece of wood glued to the woofer top plate and the flange of the horn bolted to it. There was no plastic cup at all.
 
I had all the same opions of the Mach 1 as stated here. I have been working on a new crossover design to fix these issues. The speaker is great it just needed some changes in how the voltage is delievered to the drivers. Please see the graphs attached.

OH the Mach One Gods must be on my side. I have been a fan for 30 years. Kept them under wraps for the last 10 years. And now have finally decided to refurbish them (mainly re-foam them and recap them). Now you have this. A better cross-over:banana: :thmbsp: Well I will email you and see how I can get the design.
 
I'm not running a mach, but am running the speaker just under it, the Optimus 1050. I was playing around today with some vintage units and a great match is the Sony STR-6055 receiver. The smoothness is "creamy". I listen to audio via the internet and was listening to big band vocals from the 50's and 60's. You could see the smoke in the room from the cigarettes of the night club crowd as Julie london sang " My Heart belongs to Daddy" I could just close my eyes and see her in that great outfit, under the spotlight. "Waiter, pass me that martini!":music:
 
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