Fostex FF85wk and Mark Audio Alpair 6p tested against each other

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I received a pair of Fostex FF85 to try out and test. And I had a pair of Alpair 6p which I consider a fairly direct competitor. So I whipped up a test box for the alpair and went to town.





The Fostex box is noticeably smaller. I just whipped up something sealed about 7L. I didn't try hard, so don't laugh. Only spent about an hour so forgive the ugly factor. The driver is flush though.

Ok, here's the alpair 6p on axis, 30, and 60 degrees.



You can see the baffle step region. Some break up. And a resonance around 1200hz. I haven't measured impedance yet, but I suspect there's a blip there. I've seen a similar resonance in other MA products. I suspect this will give a little bit of annoyance on certain vocals at just that right frequency. I also suspect this will sound a bit shouty.

Here's the FF85wk on axis, 30 and 60.



The baffle step isn't quite as bad. Some high up break up. Very flat, smooth response for a full ranger. The peak at 9khz is fairly mild and may actually be enjoyable to some. Any lower in frequency and I think it would be a serious issue. But way up there, it's somewhat benign.

Here's the on axis of each driver.



Red is alpair 6p and blue is fostex. Ok, the alpair is a little more efficient, but not in a good way IMO. It's also lower impedance I think? I'll confirm that later. I haven't looked at the spec sheets. But you'll notice the sensitivity is similar down below the baffle step point. Above baffle step the fostex is surprisingly inefecient. I was expecting fostex to beat MA here. To be honest, I could here they were quite inefficient while listening. My EL70s were several db higher. The alpair has a little more top end extension. They're quite similar in fact. I'm not sure which would be the better choice.

I didn't look into bass extension because I don't believe these are any good for bass. These MUST be used as a FAST or at least with subwoofer (80hz) support, IMO. Without, these just won't do hifi sound IMO. PLEASE NOTE THE IMO stands for IN MY OPINION. IF YOU DISAGREE, FINE.

Microphone was a UMIK-1 calibrated by Cross Spectrum Labs to 25khz. Software was HolmImpulse on a windows XP. Minimum reflection distance was about 6ft. Mic distance was 65cm. I can't think of any other pertinent info other than, measurements are always subject to interpretation and if you'd like help interpreting them, feel free to ask. Use at your own risk.
 
I had a similar experience with those drivers, myself, in bass reflex enclosures.

They both had a slightly rising response, and had noticable resonances above 8k which bothered my ears (but I tend to be pretty sensitive to any undue sizzle).

However, FWIW, I was able to get a really darned decent 60hz out of the MA Alpair 6P, (which was nice, but still didn't quite balance out the quality of the highs for me)

On another note, I maybe was able to get ~90hz out of the Fostex FF85WK, but it wasn't all that enjoyable either, again, because of the rising response.

The FE83En on the other hand, which I didn't see evaluated in your study, however, has been able to confidently fill in the lower end to ~85-90hz or so room dependant in a well built BR, and it did not have the annoying rising response of either of these other drivers. Of course, these are not high volumes I'm talking about getting out of any of them tuned in a BR.

Our ideas of "HiFi" clearly differ which is totally OK. But on another note, in my general practice the overall "real world power handling" is almost identical between all these three drivers once you factor in the tuning frequency of a BR.

One thing I should mention is that (my feelings) are that the random baffle you chose for the MA Alpair 6P was not a fair comparison to the bevelled, rounded over enclosure you chose for the FF85WK. Clearly its a commercial enclosure of the onken type from Planet 10.

Did you try to model the anticipated response for the MA Alpair 6P via the Edge program or anything? It looks like you just stuck the driver in the middle of a baffle that is clearly a bit wide for the driver considering what it'd be put in in normal home use. This is bound to cause problems in the response so its hard to take the data for that driver entirely seriously.

In general, I greatly prefer "natural" solutions to baffle step - driver placement is a big factor, addressing frame resonances next, and a few other detailed considerations. Could you try swapping the drivers between the various enclosures you made?

In my own RnD work, that's kept mostly internal to my company, I find myself trying to narrow things down to just a few variables, keeping the controls well placed, and staying humble that the problem might be my experiment AND my enclosure (which is often the case!) Overall, I just make sure to try things out in many different ways. Its so tough to produce good data in acoustics.

Well, in either case, it was a fun study to read and thanks for the info!

Best,

Clark
 
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I've been living with A6pEn's in mMarKen boxes for a couple of years now on my desktop. I've also had the FF85WKEn's in the same uFonken-T box (different wood) for an extended listen. For me, the 6pEn is superior for this application, more mid-bass and top end extension. The FF85's sound a little "dark" up top, almost like the old EL70's. They do have a lovely natural tone, which some listeners may prefer over the 6p's. It really boils down to personal preference.

jeff
 
I've been living with A6pEn's in mMarKen boxes for a couple of years now on my desktop. I've also had the FF85WKEn's in the same uFonken-T box (different wood) for an extended listen. For me, the 6pEn is superior for this application, more mid-bass and top end extension. The FF85's sound a little "dark" up top, almost like the old EL70's. They do have a lovely natural tone, which some listeners may prefer over the 6p's. It really boils down to personal preference.

jeff

Wow, sounds like some really killer desktop setups you've had. I too agree, all these 3" drivers are stellar performers. So much sound from such a small package. I tend to prefer a more smooth and sultry sound myself with natural scale and the sensation of big dynamics so midbass is really, really important and I guess overall everything is very important to me. I was a music major in college, did alot of ear training and even a little bit of early keyboard instrument building so I'm usually trying to get a very smooth and non fatiguing sound coming from a vast variety of musical choices, (everything, really), but especially and including acoustic instruments and the human voice.

Cheers!

-Clark
 
Hey blumenco.

I've measured the FE83 as well and it has some issues. Rising response and huge resonance around 2khz. The only handy measurements of it that I have were in a completed speaker, in a different measurement setup, on a different day. The raw measurement of that driver is somewhere on my computer I'm sure, if you think it would be worth showing here.

The baffle is a valid concern. That's a big reason why I mentioned "measurements are subject to interpretation". :) The truth is that these drivers don't see much of the baffle above the baffle step point. Most full rangers don't have much problem with diffraction. But as far as baffle step is concerned the box I put the Alpair into will have a lower baffle step point. You can see from the measurements though, they're fairly similar. The baffle wasn't much bigger. They're both so small that the baffle step diffraction peak is about 1800hz or there abouts. I personally don't see there being an advantage for the Alpair. And I don't see the chamfers as much of an advantage either for the fostex.

I had a chance to look at the spec sheets. The fostex measurement has a very similar result and I'm impressed with Fostex's sheet. Very reliable IMO. And the impedance blip I was anticipating on the Alpair at 1200hz is there.

Both are nice drivers. On a desktop I think id agree with you Jeff, the Alpair will dig a little deeper. I'd still want a woofer on the floor though.

No comments on the excellent off axis performance of both these :D
 
need to do this again on an similar/infinite baffle to really pass judgement.

that fostex driver was already pretty well regarded, so this will probably help the sales.

All one needs to do is consider the baffle effects and compare to the spec sheet. Also, most of us will use these drivers in a similar sized enclosure to what I've used.

I should note, I wasn't really going for competition between these two. Maybe it came off that way. Really just comparing them, measurement wise. I had both so why not. And it helps to measure more than one driver to understand performance better. If all I did was post the measurements for one or the other, it wouldn't be as much help as it is with a comparison.

Yes, the fostex does quite well. I didn't test their dynamic range though, by upping the amp 3db at a time. It's a lot of work so I didn't bother. I have to wonder how the fostex would do because it would really help establish where it starts to choke and where a FAST XO should be set. A box sim can off a lot of help with that though.
 
Fair enough. I do see the center of the break up peak in my measurement is at 9khz where fostex shows it at 10khz. I'm totally speculating, but wonder if the treatment doesn't lower the amplitude and frequency of the breakup. More likely just a sample to sample variation thing though.
 
It looks like you just stuck the driver in the middle of a baffle that is clearly a bit wide for the driver considering what it'd be put in in normal home use. This is bound to cause problems in the response so its hard to take the data for that driver entirely seriously.

I already responded to you, but I just re-read your post and noticed this. Are you kidding? It's 7" wide... The driver is not centered vertically, on purpose, but it is centered horizontally, on purpose. It's a crappy phone picture of a crappy test box.

Cause WHAT problems? It's hard to take you seriously. Please clarify what problems this would cause.
 
Note that not only does the test enclosure for A6P have a much larger baffle overall than the Fostex enclosure, but it appear to be almost square, indeed the box looks to be close to a cube. On the other hand, the baffle dimensions and shape of the FonkenSET enclosure is rather carefully calculated to mitigate diffraction effects.

Could that have some impact on measurements, particularly depending on mike distance, which I don't think was indicated?

A more valid direct comparison of the drivers would be in boxes as close to identical baffle dimensions as the Alpair's frames would allow, or on an IEC open baffle.

FWIW, I've heard both drivers in stock and modified form (the Fostex extensively), and would certainly not ascribe shouty-ness to the Alpair. If anything the Fostex might be considered a bit bright and forward - as seen as the approx 6-8(?) dB difference in the 8-9K region where enclosure would have less effect I think.

As for the sonic effects of the cone treatment, without devolving into the same old polemics, let's just say that we're as eager as anyone to see a simple and easily repeatable measurement technique that can pinpoint how/why it changes what we hear "deep in the mix" . The absence of proof isn't proof of absence.
 
Ok, I see the baffle is really causing some concern. Here's the modelled diffraction character of the alpair in the enclosure I built. The enclosure was thought out to achieve golden ratio characteristics, even the depth. The only thing I didn't shoot for golden ratio was the horizontal placement, cause nobody does that.

Here it is.



See, no diffraction except the diffraction hump from baffle step. The fostex will have the exact same shape except a little higher up (maybe 1800hz or so). Diffraction is a much smaller problem than people think. Most of the testing people point to is with dome tweeters which diffract off baffle edges like crazy. This isn't that.
 
Ryan - if you look closely at Dave's GR Fonken / Marken drawings as far back as 2007, you'll see that achieving close to GR in all three dimensions was considered in the design.

modelling is one thing, but such a strongly voiced conviction should probably be verified by testing under identical conditions - such as mentioned in my earlier post
 
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Chris, I suppose what's being misunderstood is that I'm just showing two measurements. The alpair 6p in my 7x11" box. And the FF85wk in the P10 box (not sure what it's called). I think it's perfectly ok to make a comparison between the two. I think I made the thread title to strong of wording. I wasn't looking to pick a winner or something. Just show the measurements against each other for reference. Without a reference they're less useful.

My strong conviction does come with verified testing... I've tested all kinds of box sizes and shapes with various types of drivers. The model is only posted to show how minor it really is and because blumenco suggested it. For the hundreds of models posted in the FR forum and the scant few actual measurements made, I'm puzzled by the criticism. All you have to do is look at the measurements I posted and the Fostex spec sheet, and you can easily see there's hardly any box influence other than a baffle step tail below 1khz.

I'm very comfortable with criticism and welcome it. I'm just a bit baffled by this one. I expected questions like, how did you deal with reflections? How did you check the off axis angles? Why doesn't it match the MA spec sheet? Etc.
 
Sorry if I sound wound up. I am a little bit. Comments like

this

its hard to take the data for that driver entirely seriously.

and this

need to do this again

aren't appreciated. If people think the data is useless, I welcome their measurement data, which tends to not exist on this forum. I don't claim to be some expert, or suggest that a frequency response plot will tell someone if they like the driver. But if the critics wanna be critics without basis, I welcome them to put their words into actions.

And that's definitely not directed at you Chris, as it was you that suggested I nab this pair to test. So I appreciate you seeking the data. Your ears obviously already confirmed the FF85wk sounds great. This only backs up your claim. And it sounds like you like the alpair 6p as well. So this backs that up also.
 
oh, we're all entitled to get exercised when misconstrued, intentionally or otherwise.

Not to belabor the point, when I said earlier "nearly as identical" baffle dimensions as possible, that's exactly what I meant - in other words your measures so far, as rigorous as they might be, do not represent identical operating environment for the drivers under test. Data is seldom useless, but not always meaningful for direct comparisons - I think you have at least 3 variables at play here.

- drivers
- baffle dimensions
- enclosure volumes
- venting vs sealed(?)


It could be an entirely separate discussion as to whether / how much the cone treatment might affect the specific measurements shown here.

and yes, I quite like both drivers, but if pressed to make a choice between the two, it'd probably be the Fostex in this case

BTW, the oak enclosures of Dave's design are uFonkenSET - I'm not sure if drawings have been released for public consumption, but I'm sure it's much smaller cubic volume than your quick test boxes for the Alpairs - which I rather suspect would contribute somewhat to perceived and measured differences. The only way to prove that of course would be to cut another baffle for the FF85WKs on your test boxes- 95mm hole saw, IIRC, and which could take less time than the next few posts in this thread .;)
 
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