Newbie Jack 10 build(s) in south east London

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tallevan
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Newbie Jack 10 build(s) in south east London

#1 Post by tallevan »

Hi all,

Excited to be here. After lurking for a month, I am embarking on a build of at least one, perhaps three Jack (10, 12?) cabinets for electric bass, upright bass and drum use.

This is my brief:

Loud: My bass rig has served me well for various electric and upright bass gigs over the last 20 years, but is no longer able to cope with my band's ever-increasing volume.

Tone: I've never liked the "smiley" EQ curve on bass, though every bit of bass gear from the Fender tone stack to modern "enhance" controls seems to promote it. I’m fussy about my tone, and like all my gear to sound great with controls set flat, then make small adjustments from there.

Weight: I’m a big guy, but the massive set ups and tear downs are starting to grind my corn, so light and small is good.

Flexibility: Most of my playing these days is a four-string electric bass strung with flats. But I also play round wounds on a fretless, five-string and amplified acoustic upright. My wife plays drums, including the electronic ones. (no, we don’t play together. Weird..) Some of my gigs are big, some small. So, having a couple small cabs is better than one monolith.

Cost: Most modern cabs are cheap, especially second hand. The reason is, they are mostly nasty. I don’t mind spending a bit of coin, if it meets my brief.

Waste: On the other hand, I hate waste. This might be controversial, but I’ll be trailing a few 10-inch drivers and other materials that I have on hand. Might not work, but a nice disaster is more instructive than a flawless success, eh?

I would very much like to continue using my very beautiful sounding but modestly-powered bass heads, rather than shell out for some weird massive expensive Chinese-made monster amp.

I’m a cautious man. After researching and auditioning new cabs (Barefaced, fEARful, Epifani Tour 3x10, Markbass Ninja) I purchased Bill’s plans for the Jack 10, Jack 10 Lite and Simplexx 10 and pored over them.

I’ll leave the Simplexx for now. Great design, but the Jacks look like a better fit with my brief, particularly the leap in efficiency.

I have 2/3 of a sheet of 18mm pine floor decking left over from a shower repair. My first plan is to make a Jack 10 Airhead, and see how it sounds.
If it works out, I’ll put my old SWR Studio 220 head in it and give it to my wife to use for her drums.
Then I’ll decide how to proceed for my rig. Jack 10 Lite? Jack 12 with new drivers? Jack 10 made from Italian Poplar?

All comments and advice welcome.

tallevan
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Re: Newbie Jack 10 build(s) in south east London

#2 Post by tallevan »

This is my build so far. I've actually mostly completed the Airhead Jack 10, and am trialing drivers.
Bill's plans are great. The writing is a model of economy. Everything important, nothing superfluous.

Airhead_Braces
Airhead_Braces
Note to self: clean up your shed.

Airhead_Squeezeout
Airhead_Squeezeout
My first time using expanding polyurethane adhesive, haven't quite got it down. Check the squeezeout!

Airhead_Glue_Damage
Airhead_Glue_Damage
This is what happens when you don't remove the jig quickly enough.

Airhead_Plywood_Void
Airhead_Plywood_Void
For this build, I used some cheap pine decking ply from a DIY shed I had lying about. Yes, I read and understood Bill's comments on plywood.
The quality is shocking, as you can see. Some of the voids go the entire length of the sheet. Some big knots, but they seem tightly filled with some plastic filler that will not finish well.
I avoided the worst of it, and filled the voids (at least the exposed edges) with auto body filler. We'll see if it rattles or refuses to hold screws.
In spite of that, it went together quite well and feels unbelievably stiff.
My subsequent builds will use higher quality Baltic birch or Italian poplar, probably.

Airhead_In_Situ_1
Airhead_In_Situ_1
Sealed up now, I'm trialling drivers. No tweeters yet, I'm seeing how it sounds without first.


Very exciting. First impressions:
- Very loud, very efficient.
- Bill's advice on the effect of wall and floor on bass response is spot on. The difference between mid-room on a chair and on the floor near a wall is astonishing.


More later. Comments and advice are most welcome.

tallevan
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Location: London, England

Re: Newbie Jack 10 build(s) in south east London

#3 Post by tallevan »

I've finished my first Jack 10 Airhead.

I've not yet leak tested, nor checked the HF driver polarity. Just put it in the corner of my lounge and whacked my bass through it.

I started this as a trial using up some nasty 12mm decking ply and an old 10 inch driver that I had knocking about.
This is not a recommended approach, Bill's specified drivers and materials are there for good reasons.
Nonetheless, it turned out remarkably well. So loud!

IMG_20191115_144641648.jpg

The cabinet was made exactly to plan, with a few small alterations:

- I went ahead and blindly used Bill's measurements for the 2u space above the speaker without measuring my amp first.
My amp has feet, and requires a little passive cooling space above it. So I made the top oversized and put it on top of the sides rather than between the sides as the plan dictates. This gained me the required 1/2 inch extra.

- I don't know what I'm doing, but the substantial weight of the HF driver on the back of the shop-made horn makes me a little nervous. I've had roadies sheer the magnets off the back of woofers by dropping cabinets off the back of a truck. So I made these little cleats to nail and glue behind the horn ends. I then bolted the horn into the cabinet with tee nuts.
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IMG_20191108_102141653.jpg

tallevan
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Re: Newbie Jack 10 build(s) in south east London

#4 Post by tallevan »

I won't comment extensively on the voicing just yet, except to say it sounds good and is incredibly loud.

One reason I can't comment seriously is because the woofer I'm currently using doesn't match a single parameter that Bill specifies in his plans. Not even one.
It's the discontinued Eminence Gamma 10A.
I bought this many years ago thinking it would make a good substitute in one of my bass cabinets. It's cheap, has an Xmax of 1.6mm and sounded terrible in everything.

But it sounds remarkably good in this Jack. Could use a little more bottom, but with my ancient SWR Studio 220 amp head it has acceptable bottom and fine mids and highs. It gets loud enough to hurt.

I'll consider a Deltalite II, but for a small gigging bass amp doubling as an electronic drum monitor it's already better than the backline I am supplied normally.

Compared to my early trial as woofer-only with no crossover, the bass sensitivity sounds much better to me with the tweeter and filters.

I'll take a better picture later. The flash reflections don't do it justice.

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Bill Fitzmaurice
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Re: Newbie Jack 10 build(s) in south east London

#5 Post by Bill Fitzmaurice »

The Gamma 10 specs aren't bad, except for xmax. It would take two of them to equal the maximum output of a Beta 10, three to equal a 2510.

tallevan
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Re: Newbie Jack 10 build(s) in south east London

#6 Post by tallevan »

Yes, I can hear that the ASD1001 in your horn could certainly keep up with a lot more woofer xmax than I'm making available at the moment.
Frankly, I'm just happy to make such good use of a driver I had written off as useless.

I chose the ASD1001 option for no better reason than the usual predjudice many bass players have against piezo tweeters.
I'm beginning to realise I just don't like cheap piezo tweeters.

For bass, would a four-piezo array be a better for a lower-spec woofer?

I have to say, the ASD1001 sounds really good..

pahaeno
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Re: Newbie Jack 10 build(s) in south east London

#7 Post by pahaeno »

Bill Fitzmaurice wrote: Fri Nov 15, 2019 11:41 am The Gamma 10 specs aren't bad, except for xmax. It would take two of them to equal the maximum output of a Beta 10, three to equal a 2510.
Eminence Gamma 10A has not been measured with Klippel. Xmax value could be more like 3,5-4 mm if measured.

The Xmax value on the Gamma 10A data sheet is the conservative value or voice coil overhang.

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Seth
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Re: Newbie Jack 10 build(s) in south east London

#8 Post by Seth »

pahaeno wrote: Tue Nov 19, 2019 3:11 pm The Xmax value on the Gamma 10A data sheet is the conservative value or voice coil overhang.
Is that not the case with other Eminence drivers too?
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

Grant Bunter
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Re: Newbie Jack 10 build(s) in south east London

#9 Post by Grant Bunter »

pahaeno wrote: Tue Nov 19, 2019 3:11 pm
Bill Fitzmaurice wrote: Fri Nov 15, 2019 11:41 am The Gamma 10 specs aren't bad, except for xmax. It would take two of them to equal the maximum output of a Beta 10, three to equal a 2510.
Eminence Gamma 10A has not been measured with Klippel. Xmax value could be more like 3,5-4 mm if measured.

The Xmax value on the Gamma 10A data sheet is the conservative value or voice coil overhang.
No Eminence driver is measured with Klippel AFAIK.
From the eminence site:
Xmax/Xlim
... Eminence has historically been very conservative with this measurement and indicated only the voice coil overhang (Xmax: Voice coil height minus top plate thickness, divided by 2). The Xmax figures on this website are expressed as the greater of the result of the formula above or the excursion point of the woofer where THD reahes 10%...
The way I see it, the comparison to the other Eminence drivers stands..
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Bill Fitzmaurice
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Re: Newbie Jack 10 build(s) in south east London

#10 Post by Bill Fitzmaurice »

pahaeno wrote: Tue Nov 19, 2019 3:11 pm Eminence Gamma 10A has not been measured with Klippel. Xmax value could be more like 3,5-4 mm if measured.
Going by the results with Eminence drivers that have been measured with Kippel and comparing that to the coil depth minus plate thickness/2 method the Gamma 10 might have 2mm xmax at 10% THD.
No Eminence driver is measured with Klippel
The Xmax figures on this website are expressed as the greater of the result of the formula above or the excursion point of the woofer where THD reahes 10%...
!0% THD is the Klippel standard. Eminence was one of the first to use it, going back to around 2004.

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Re: Newbie Jack 10 build(s) in south east London

#11 Post by pahaeno »

SethRocksYou wrote: Tue Nov 19, 2019 3:52 pm
pahaeno wrote: Tue Nov 19, 2019 3:11 pm The Xmax value on the Gamma 10A data sheet is the conservative value or voice coil overhang.
Is that not the case with other Eminence drivers too?
Other not Klippel measured that I know is Beta 12B, Gamma 10A and Beta 12B are speakers that I have used in bass cabs and if I remember right, they both have 1,6 xmax on data sheet.

My earlier reply was more or less word by word the answer that I got from Eminence.

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Bill Fitzmaurice
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Re: Newbie Jack 10 build(s) in south east London

#12 Post by Bill Fitzmaurice »

There is no Beta 12B, it was discontinued years ago. The voice coil overhang of the 12B was 0.8mm.
There was a more or less complete redesign of the entire Eminence line in the early 2000s, when DuPont stopped supplying Kapton to the industry for voice coil formers. Most of their existing products got new voice coils, which required re-measuring the specs. This coincided with their purchase of a Klippel analyzer, so the data sheets with the new voice coils were done via Klippel. Drivers that continued to use old stock voice coils, like the Gamma 10 and Beta 12B, weren't re-measured. When the existing stock of parts was exhausted those drivers were discontinued.

The difference between voice coil overhang and Klippel measured xmax runs around 25%. It does not even remotely approach 100%. You can't see this on Eminence data sheets, because they only show one or the other, not both. You'd need to see the engineering sheets that show the voice coil length. Those documents aren't accessible by the general public.

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Re: Newbie Jack 10 build(s) in south east London

#13 Post by pahaeno »

Bill Fitzmaurice wrote: Wed Nov 20, 2019 8:31 am There is no Beta 12B, it was discontinued years ago. The voice coil overhang of the 12B was 0.8mm.
There was a more or less complete redesign of the entire Eminence line in the early 2000s, when DuPont stopped supplying Kapton to the industry for voice coil formers. Most of their existing products got new voice coils, which required re-measuring the specs. This coincided with their purchase of a Klippel analyzer, so the data sheets with the new voice coils were done via Klippel. Drivers that continued to use old stock voice coils, like the Gamma 10 and Beta 12B, weren't re-measured. When the existing stock of parts was exhausted those drivers were discontinued.

The difference between voice coil overhang and Klippel measured xmax runs around 25%. It does not even remotely approach 100%. You can't see this on Eminence data sheets, because they only show one or the other, not both. You'd need to see the engineering sheets that show the voice coil length. Those documents aren't accessible by the general public.
Beta 12B discontinued years ago, ok. I bought mine in 2015 and it was available in many stores back then in Europe.

Info that I got from Eminence was like: "We do not stock the Beta-12B here in the states, so it has not been tested as extensively as the Beta-12A-2."

and

"You could use the cabinet plans for the Beta-12A-2. They are the same design except for the DC resistance and voice coil wire size."

I received that info at the same year before I bought them, 2015. Used those drivers in reflex and sealed cab and still have them somewhere. You can still find Beta 12B here and there in Europe. Same goes with Gamma 10A. Hard to find, yes, but not impossible.

I can't remember when I bought the Gamma 10A, maybe 2015 or 2016. I think I first build the 212 and later the vertical 410 what I never finished.

Hmmm.... I slipping OT now. Sorry.

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Re: Newbie Jack 10 build(s) in south east London

#14 Post by Bill Fitzmaurice »

pahaeno wrote: Wed Nov 20, 2019 9:07 am Info that I got from Eminence was like: "We do not stock the Beta-12B here in the states, so it has not been tested as extensively as the Beta-12A-2."
Whoever gave you that bit of nonsense did not work in the engineering department. Completely thorough testing is done with every driver they make before they enter production. I get pre-production data sheets on new drivers sometimes as much as a year before they hit the shelves.

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Re: Newbie Jack 10 build(s) in south east London

#15 Post by pahaeno »

Bill Fitzmaurice wrote: Wed Nov 20, 2019 11:15 am
pahaeno wrote: Wed Nov 20, 2019 9:07 am Info that I got from Eminence was like: "We do not stock the Beta-12B here in the states, so it has not been tested as extensively as the Beta-12A-2."
Whoever gave you that bit of nonsense did not work in the engineering department. Completely thorough testing is done with every driver they make before they enter production. I get pre-production data sheets on new drivers sometimes as much as a year before they hit the shelves.
Eminence Design Engineer/Technical Support gave me that bit of nonsense. Interesting and confusing.

Well actually not very interesting but confusing. Anyway thanks for the info Bill, eventough this info reached me too late, I mean, I bought those Eminences, build cabs and was happy with 'em!

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