The Fairchild Ghost subwoofer project

AlienALX

Well-known member
Afternoon all. Do note, this is not a PC build. It is a build though. I built myself a cinema sub a few years ago and documented it on here, but it is time to change it. TL;DR it is a 15" tuned to 30hz. For that reason it is too much. Besides, the woofer in it is one of those dumb modern stupid high excursion woofers and they are not exactly sonically accurate. IE, they do one thing well but it's not sound quality. Besides, I also underestimated how much trouble it could get me in and it indeed did. The thing is, by the time I tune it down it's barely even there. Any more than that gets people whining. So I want something smaller, more accurate and "faster". IE, higher tuned with far more accuracy.

Sadly the woofer I want no longer exists. So this is where it goes into story time.

Many years ago when I was a young man (1990, I was 16) my friend's dad brought home his friend's car. It was full of audio gear. Like, for the time, insane. Four 18s. The guy was selling the car it was all in (Granada estate with a Chevy V8 in it) and wanted all the audio gear removed. In hindsight when I think about it I think he was basically doing an insurance job on it.

So yeah, I became a bass head overnight. Obviously a 16 year old me would love the sub I have now, but 52 year old me not so much. Any way, I fell in love with Cerwin Vega and over the years became very close friends with the owner of it and all of the staff out in Cali. I used to call in every couple of months and talk to one of the engineers who basically thought I was hilarious and thus used to send me stuff to make lots of noise with lol. He found it even funnier when the council turned up at my house and threatened to confiscate all my gear. I then grew up a lot, and ended up with one of these. Note just one, in 18".

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It looks kind of strange. Basically in the 70s Cerwin Vega did a lot of research for their Sensurround systems. For the movie Earthquake they set one up in a cinema in Cali. The woofer is very strange in that it uses two spiders. These days lots of woofers have two (the yellow suspension thing) but not in a sandwich. They have them under the woofer. For the time it was revolutionary because it allowed the woofer to remain much more controlled and more linear (and move farther without distortion) and thus it made the woofer capable of taking much more power. Other woofers would literally tear themselves apart. As you can see it achieves this with a metal pole that comes up from the pole piece inside the magnet, and that allows you to clamp on the top spider. It also allows you to tune the woofer by moving it up and down on axis.

There was only one problem. In 1992 this woofer cost £1799 plus VAT, shipping and import duties. A lot. I mean gawd, think about how much that is in today's money. As such it became my dream to own one, and own one I did. That was where I met John Fairchild. The guy that used to encourage me to get into trouble lmao. He told me a model of woofer that was in essence the same only 8 ohms, and then he sent me the parts and cone in order to make it. IE the pole, the clamp, the top spider and cone kit. I had that thing until I moved to the USA in 2001. Obviously taking it over with me would have cost more than it was worth. I figured once I got out there I would hook up with John and get another one sorted. Sadly around that time the owner of the company, Gene Czerwinski, retired and sold the company to Stanton Group. Who just so happened to be an unfriendly bunch of swear words I can't say here. They also fired John Fairchild, so I never spoke to him again /sad face.

A few years ago a friend of a friend of his told me he had passed away. He did live to be a ripe old age but yeah, for me it was very sad. I still hear his raspy American voice calling me a crazy bar steward.

So all that said I remembered one thing John said to me. A very, very, closely kept company secret. The Stroker, whilst made in the USA, was not entirely American. In fact, the actual cone of the speaker was made by a company called Fane, who just so happen to be British. And thus I found out that a few years ago Fane had released a 50th anniversary woofer.

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Which brought me back to something I did in the mid 90s. I converted a Fane woofer into a Stroker using parts my friend machined for me. The only thing I could not get easy access to was the top spider. See, a usual spider looks like this and is glued onto the voice coil.

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Which sadly is useless. However, after many hours of searching I found exactly what I needed.

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The only sod was they do not ship to the UK so I had it shipped to an old friend out there who has shipped it onto me via UPS. It wasn't cheap (£40 all in !) but the woofer was only £160. If you compare that to what Cerwin Vega (Stanton) are asking for the modern version....

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It's actually stupid cheap. Even with the metal materials needed for my friend to make me the parts to make it work I will be in less than £250. However, and most notably, they do not make the 12" one any more. So I would be screwed even if I were rich !

The way it will work is I will need to make an aluminium plug. If you look here at the back of what I bought you can see a hole with mesh in it.

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You just very carefully punch out the mesh leaving it hollow. You then remove the dust cap from the woofer and ETC. I can not design that just yet, as the woofer is not here yet. There is no point designing it without any measurements...

So yes. Welcome to the nut house. Apologies for the long post, but there is a lot of history there. In part 2 we will be talking about box design, 15mm thick cast clear acrylic, carbon, and all of the things I need to make this thing work. As per the title I have called it the Fairchild Ghost. I do not like what Cerwin Vega became, and this is much more of a tribute to John.
 
Stage two - designing the box.

The FS of the speaker is 42hz. This is much more in line with what I want.

As such I designed this. When built it will be upright. IE, the sides will be the top and bottom.

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The port will be at the bottom. So like this.

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I also had to design it so that the top panel (the sides in the pic) was surrounded. IE, not a protruding edge. So the panel you see exploded on the left.

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Now the reason I wanted that is so that I can put this in there instead of a wooden top panel.

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Yup. That is one serious lump of acrylic :D 15mm thick, which I know from past experience is more than thick enough to handle it in a ported box. This also means I need to paint the entire inside of the cabinet to finish quality. A lot of work. However, that work will be reduced by my choice of outer finish. Given the woofer will be on full display through the top panel I got these.

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Which may seem somewhat tacky. However, it will allow a good view of the woofer and will be lit in yellow/orange. So more of a warm glow than a unicorn blow off. This also means I need that top acrylic panel to be removable. So it will need a frame made from MDF, and then loaded with lots of these. Thanks to Cenedd for showing me this when I built my last sub. We used big beefy ones to put the sub feet in.

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They are M4 threadserts. I also will need to use a full gasket, so I bought some silicon sheeting.

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This time around I am not going to fit an amp into the sub. Lessons learned again from last time. I may want to change the amp, or, get a high quality monoblock at some point. As such regular binding posts are needed.

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I then bought a meter of very expensive wire.

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Again this will be fully visible. So I didn't want it to look bad. I remembered that on the very expensive wire kit I got for my main speakers they had these silicon end splitter things. Took me about an hour to find out what they were, but find out I did.

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So that should give you an idea of the sort of detail I am going into here. For the finish? I want it to closely match my white JBL studio speakers. As such I got enough of this to do the sides and bottom.

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Having learned from last time where I used all real veneer (it was hard lmao). Not quite decided what I want to use on the front and rear of the speaker yet, but it will be either 3M vinyl (very expensive) or Avery Dennison (again, very expensive).


OK let's briefly cover the amp.

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I had an 8" sub I started with. Didn't use it for long. I decided it was better to strip it than the current 15" sub. That way I can switch back to it if I want to. I doubt I would, but it cost far more than the Earthquake. 150w should be more than enough really, but as I said I am not opposed to buying a audiophile grade monoblock at some point. Problem then though is I would need an active crossover too. Now like I mentioned I am not cutting it into the box. And you can not run it like that as all of the electronics are hanging out of the bottom. So I got this for 20 quid.

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And will just cut it into the top.

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I just received noti that the sub is coming tomorrow via DPD and the spider from the USA on weds. I also forgot I drew this a few days ago when trying to explain it to my engineer friend what I wanted making.

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OK so after a lot of mulling and many hours of looking I settled on this for the front and back of the cabinet. It was hella expensive, but even with the white grain wrap it was less than the cost last time. It worked out around the same as the veneer last time, but obviously that needed contact adhesive and a lot of it (about £60 worth fgs) as well as sanding and laquer etc.

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I am also going to make my own badge and terminal plate. I will use this.

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Which was also quite expensive. I wondered if prices had all gone up, but whilst looking at the product code I found this which explained it.

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It's literally licensed.


I also have some forged carbon, which will be used.

The woofer hath arriveth. And I think unit sums it up well lol.

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The funny thing is the basket is almost identical to the original 12" Stroker too.

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And the magnet. A whole lot arrived today. Mostly small bits I won't need until the cabinet is built. I have also ordered some surgical scalpels so I can remove the dust cap without making any mess.

Spider

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OK so more ordered.

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One spider clamp sent over to the engineer. Do note I have not included the sizes because the Stroker has a patent.

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lol this is crazy !

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OK so this was terrifying. One slip and it is game over. Also, one crumb down that coil gap and it is also game over. I cut out the dust cap with a scalpel and put a blu tak sausage around the coil gap to stop anything falling in.

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And then used a plastic tyre lever with some gentle taps from a plastic hammer.

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I have now designed the clamp in piece that will hold the centre pole.

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The last thing I need to do is measure up the stainless rod part, then draw it.


OK so one thing I don't have and don't really want is the brass plate with the CV logo on.

So I designed my own and am machining it now.

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This is one of three pieces I am going to machine. The other two double in machining time each time. So the next one? two hours. The last one? four hours lol.
 
Modding a subwoofer. Now I've seen it all ;)

Thanks for the detail in this, not something I'd even thought of as something that can be done, but so interesting.
 
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