MoFi Electronics SourcePoint 10 loudspeaker

"A 10" two-way?!?!" I couldn't help gasping in surprise when I unboxed the MoFi Electronics SourcePoint 10 standmounted loudspeakers, which cost $3699/pair.

Some background is in order. Using a large-diameter woofer endows a conventional two-way speaker with potentially high sensitivity and extended low frequencies. However, the large woofer's radiation pattern narrows at the top of its passband, whereas that of a tweeter mounted on a flat baffle is at its widest at the bottom of its passband. Even if the drive units' outputs are well-matched in the speaker's on-axis response, this discontinuity in the speaker's off-axis behavior results in an in-room balance that will sound bright. This is why favorably reviewed two-way designs tend to use a woofer with a 6.5" or even smaller diameter.

But ...

The SourcePoint 10 was designed by Andrew Jones, a well-respected veteran loudspeaker engineer with highly regarded models from KEF, Infinity, Pioneer, TAD, and ELAC in his resumé (footnote 1). Andrew, who is now celebrating two years with MoFi, has indeed done something different with his first design for the company.

The SourcePoint 10
The first thing you notice about this speaker is that the sculpted, 2"-thick front baffle has a single, centrally placed drive unit with a 1.25" soft-dome tweeter mounted concentrically at the center of the 10" woofer's paper-pulp cone. The second thing you notice is that instead of a conventional half-roll rubber surround for the cone, the woofer, which is reflex loaded with twin ports on the rear panel, uses an old-fashioned corrugated surround. The third thing you notice is that this is a large, heavy design for a standmount; it measures 22.5" × 14.5" × 16" with an internal volume of 50l—that's 13.2 gallons—and weighs just over 46lb.

Andrew Jones and MoFi's Jon Derda visited the day after I unboxed the SourcePoint 10s. As they prepared to set up the speakers in my room, I asked Andrew why he had settled on a two-way concentric design rather than a three-way and why, considering that, he had decided to use such a large woofer (footnote 2).

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"Pretty much 100% of the designs I've done with concentric drivers have been three-way. And that's because with a concentric driver, you don't want the cone moving too far. The more movement you allow it to have, the more compromises you're getting, because you get amplitude modulation. ... You also need a bigger surround, [which] disrupts the wavefront from the tweeter, [and the] delayed reflection off the cone causes differences in the frequency response.

"The problem [with a three-way] is the complication, the extra cost, ... and trying to pick the frequency where you should cross over" from the woofer to the midrange. "Should it be as low as 80Hz? That would be very, very costly to do in terms of parts costs for a passive crossover. And how far down do I want to take that midrange, especially given its size and everything I need to do to control how well it works as a waveguide for the tweeter? So, could I do a two-way concentric? Because if I'm concerned about minimizing movement of the cone in a concentric, there's only two ways to do it. One is to restrict the frequency ranges, which is what you do when you turn it into a three-way. Or you make the woofer so big that most of the time it doesn't have to move hardly at all. Going from a typical 4.5" or 5" driver to a 10", I've got nearly four times the area and a quarter of the movement, which is significant.

"Because one of the briefs from MoFi was to have good, impactful, and extended bass. As well, as it's getting back into fashion to have big woofers, it would be fun to work with a big woofer. That could be cool, but I'd never done one before."

I asked how, in a two-way design with a 10" lower-frequency driver, which will start beaming at a relatively low frequency, does he match it to the wider dispersion of a tweeter?

"When you put the tweeter in a waveguide, it's not that it's narrowing the directivity everywhere. It's narrowing it at the lower frequencies, which is where you have the problem in matching the directivity to the woofer. So now you're going to narrow it progressively as you go down in frequency, correlating with how much sensitivity you gain due to the waveguide loading at the lower frequencies. With a good waveguide, you can reach about +10dB of on-axis output compared to no waveguide. And that's a huge advantage for working the tweeter because 10dB is a 10th of the power input you need in a critical range where there's still a lot of energy in the music. The waveguide ... reduces the energy input, the thermal compression, and the excursion requirement [of the tweeter].

"So if you can engineer a low resonant–frequency tweeter, you can run it down to a lower frequency"—it's 1.6kHz in the SourcePoint 10—"because it's running at a lower excursion compared to not having a waveguide, which more than makes up for the extra extension that you need to cross over the tweeter lower. And with a 10" waveguide, the improvement in efficiency or sensitivity and the reduction in excursion more than make up for the fact that you're crossing over at 1.6k. It enables you to get a very good, progressive, consistent off-axis performance.

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"When the waveguide also needs to be a woofer or midrange cone, you've got to decide what is the best shape for it to act as a waveguide and what is the best shape for it to act as a cone, with controlled cone resonances. You hope that it's the same shape. So there's a choice of sizes and materials and everything else to optimize both the shapes simultaneously. So I started designing waveguides and getting them 3D-printed to see, what were the directivity characteristics? I came up with a shape that seemed to work very well. So the next thing was, okay, so now I have a cone that's going to work and need a surround. I knew I couldn't have a half-roll surround because that would disrupt the [tweeter's] wavefront. So it's got to be one of these corrugated surrounds like they use on pro speakers."

I asked Andrew why he had chosen a paper cone for the woofer. Wouldn't a 10" paper cone break up at a low frequency?

"About 3kHz. It's very smooth up to that frequency if you have the right curvature and the right pulp. So I tooled up some cones, tooled up some surrounds, got a sample built, which sounds easier than it actually was. ... It took a long while before I had anything that I could start listening to."

We discussed the MoFi's soft-dome tweeter, which, as well as being larger than usual for a two-way design, has a relatively large surround. Andrew explained that the surround acts as a ring radiator, emitting sound. He said that with a conventional tweeter, the surround's output at very high frequencies may well be in the opposite polarity to that of the dome, resulting in a loss of output. "I knew I wanted a slightly larger diameter, 1.25" rather than 1", with a wide roll surround, because that gives you extra capability at the lower frequencies. Counterintuitively, if you put a wider roll surround on the tweeter, you actually improve HF response. You think it would interfere and cut off earlier, but it doesn't; it actually extends it. ... [T]he phases will be additive up to a higher frequency." Andrew said the SourcePoint 10's tweeter goes out to beyond 30kHz.


Footnote 1: See my video interview with Andrew Jones here.

Footnote 2: A white paper on the design of the SourcePoint 10 can be downloaded here.

COMPANY INFO
MoFi Electronics
713 W. Ellsworth Rd.
Ann Arbor, MI 48108-3322
(734) 369-3433
ARTICLE CONTENTS

COMMENTS
Indydan's picture

The sound quality of these speakers is nowhere near the level of hype it is receiving! Mr. Atkinson seems to like it, but it does not sound like he is doing backflips, nor that the speaker is in any way a giant killer.

Glotz's picture

If so, where is the speaker a let down, man?

Just asking for clarification of your position- "Nowhere near"...

Indydan's picture

Yes, I have heard it. The Mofi is roughly in the same ballpark price wise as my Harbeth C7es3-XD.
I would NEVER trade my Harbeths for the Mofi. Not even close.
AS another plus, my Harbeths are made in the UK, not China.

Glotz's picture

Very valid comparison. Thank you!

Indydan's picture

Regards.

Ortofan's picture

... Suntan capacitors from Hong Kong?

https://www.on-mag.fr/images/stories/2017/02/gal_harbeth_superhl5plus/6Harbeth_SuperHL5Plus.jpg

https://www.suntan.com.hk/

Indydan's picture

Yes they are.

Ortofan's picture

... imported, as well.

So, how much of the speaker's content can be imported into the UK before the finished product can no longer be considered to be "made in the UK", versus merely assembled in the UK from foreign and domestic components?

Indydan's picture

If we start looking at it like that, we could make the same argument for many, if not every product.

A lot of scotch is aged in bourbon barrels. The bourbon barrels are from the USA. I guess scotch isn't really Scottish...

remlab's picture

The measurements are WAY better than I thought they would be. Interesting that they chose the side mounted configuration for the review, because very few people, other than sound engineers, would use them that way.

DavidMA's picture

Regardless of what one thinks about the sound of these speakers, I do appreciate the extended discussion of the design decisions (and their alternatives) that went into the creation of the speakers. Usually, design decisions are glossed over for fawning praise or superficially discussed. I wish more in-depth discussion of design decisions and their alternatives would be incorporated into reviews of equipment - speakers or electronics.

Jazzlistener's picture

I was excited to read this review given this is an Andrew Jones design and an unusual one at that, but the reviewer clearly lacked any interest in reviewing this speaker. I came close to dozing off part way through it, but forced myself to read it until the end. Two thumbs down.

cognoscente's picture

As an Andrew Jones design owner myself I always read reviews of one of his designs with extra interest. Good to read that Andrew Jones stays true to his design philosophy. I myself own the Elac's Adante AS-61 which I bought at the end of the sales cycle as a demo model (I wonder why the Adante series has not been a commercial success, because of the sound or because of the looks, too big for a contemporary look, do large speakers only sell if they have a vintage retro look? After all, the Adante only received very good international reviews (BE/DE/NL/UK/USA, the ones I read). I assessed them in a direct comparison at the time with the Cabasse Murano (no radiator design) which sounded a fraction better but also cost more than double my demo model deal. The Adante replaced my older Elac speaker (which now serve in the study) with their famous jet tweeter. Fresh and tight, the Adante sounds mature in comparison, more deep bass and attack (and why the Adante is so big I guess, good deep bass requires cabinet volume). The dealer described the Adante at the time as Andrew Jones's working-class Tad. I think that not doing justice to Elac. Anyway what strikes me is that Andrew Jones often changes assignments, from Kef, Infinity, Pioneer, Tad, and Elac now to MoFi Electronics. I don't know if that speaks for him.

funambulistic's picture

I have this speaker as well and think it is fantastic. I, too, wonder why the Adante line was not a bigger hit, but don't mind too much as it is like I uncovered a rare gem. I am sure it was due to a number of reasons, most likely that it did not fit the "affordable" marketing optics that Elac was pushing with Jones' less expensive designs, including the previous Pioneer offerings (I am sure most folks purchasing at the Debut or UniFi level have never heard of TAD). Of course, it could have been because of Guttenberg's not so glowing CNET review or the silly one over at ASR... Anyway, I would love to demo the Sourcepoint to hear what AJ has concocted. It would have to be very good indeed to make me consider giving up my Adantes! Unfortunately, I am sure it is.

Glotz's picture

You guys are way critical of John here... impolite and harsh.

That being said, say what you want. I enjoy freedom as well.

This product speaks to the mastery of Andrew Jones as a speaker designer, especially in light of him working for several mfgs. It's validation not condemnation.

michelesurdi's picture

tin,ten,whats that word?ah yes,tannoy.

David Harper's picture

so what is it specifically about these speakers that makes them worth almost 4K? because price determines sound quality? Looks like they're worth maybe 1K/pair.

ChrisS's picture

...build some yourself.

LukeW's picture

I would lean toward a set of the ZU AUDIO UNION 6 SUPREME Loudspeakers and save a couple of bucks in the process. I love the concept of a a large single driver speaker. One that is made in the USA is pretty amazing too.

Indydan's picture

There is already a pair for sale used on Canuck audio mart.

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