Need advise re cabinet redesign for 846A Valencia drivers.

[theophile]

I have lurked on this site for over 2 years.
Thanks to the comments from members I've already DIY activated My 846A Valencias.
I read the thread posted by member "adhoc" concerning a cabinet for his 416Bs.Does the information in in that thread apply to the 416z also?
If not does anyone have any suggestions?
Thanks in advance.
P.S. Hello Mike Gibson!

[Mike Gibson]

"G'Day" to you also When I read most of the information posts here It's like I walked into a physics class instead of the bonehead math class I needed I keep hoping osmmosis will carry the day and I'll awake some morning and understand what all the terms mean and how to apply them

[martyh45]

The Z version of the 416 is essentially an A version with no magnet cover. If you have the 8-ohm ?Z? it is the same as a 416-8A, which is not the same as a 416-8B so the cabinets discussed in the earlier thread will not work as well. The cabinet of choice for the 416-8A is a 360L ?Onken?. Detailed plans are available on the internet. The Onken has been built and measured by some of the best minds in the business so plenty of performance data and subjective impressions are available also.
Have fun,
Marty

[theophile]

I should have said my woofers are 416-16z,16ohm.
I printed out the "adhoc" thread referred to in my original post.Upon reading it thoroughly,I can see that the information there does not apply to me.
I use my Valencias in "DIY activated" mode,bypassing the passive crossover,utilising an active crossover.
With that more detailed info,could anyone provide a clue as to a suitable cabinet volume/portdimensions?

[theophile]

GM,
Thanks,In my room,Brick veneer,slab floor,cathedral ceiling,(approx.25ftW x 35ftL x 12ft-8ft slopeH),I use my Valencias well away from walls (>4ft).I'm not ultra obsessive about exact placement,I just put them where they sound good,and this is a room which doesn't give big problems with sound quality.Sounds pretty good actually.
I'll keep your suggestions because they point me in just the direction I want to go.I appreciate your help in this regard.
Steve.

[GM]

Greets!
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>The Z version of the 416 is essentially an A version with no magnet cover. If you have the 8-ohm ?Z? it is the same as a 416-8A........
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From a performance POV, in my experience this isn't the case. The 'Z' series appeared to be optimized for Valencia size cabs in that they typically had a much lower Vas than their prosound versions, so for a given -8A cab alignment, some efficiency must be traded away to 'fill' the larger than optimum cab, though it should be tuned lower to flatten it out. For HI-FI apps that don't use a sub, then this makes the 'Z' series the preferred choice.

Unfortunately, unless the drivers are still OEM, there's no telling what it was reconed with so measurements are a 'must do' IMO. That, or accept a large cab/lower efficiency and dial in as much series resistance as required to 'fill' the cab, then optimize it's tuning (Fb) to suit.
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>.........which is not the same as a 416-8B so the cabinets discussed in the earlier thread will not work as well.
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Correct, for a given alignment, the -8B requires a much larger cab due to its much higher Vas.
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>The cabinet of choice for the 416-8A is a 360L ?Onken?. Detailed plans are available on the internet.
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Hmm, I thought it was for the -8B. Regardless, it's large enough to be used with any 803/416/515 series, adjusting the alignment with some form of EQ. That said, the large/long vent's harmonics cause considerable comb filtering with the driver's output, and worse, with the mid's output.

Not too shabby a design for pre-T/S, but we now know that a much simpler construction single or dual vent of somewhat less cross sectional area will work just as well without so much out of band 'hash' and the DIYer can optimize the alignment if measured specs are used. Doesn't look near as sexy as the Onken though.
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>I should have said my woofers are 416-16z,16ohm. I use my Valencias in "DIY activated" mode,bypassing the passive crossover,utilising an active crossover. With that more detailed info,could anyone provide a clue as to a suitable cabinet volume/portdimensions?
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Since you haven't given us any measured specs of your drivers or details about your performance goals, room/speaker placement, etc., I tend to recommend a cab big enough to tune to ~Fs and you can use EQ to shape the response for flattest in-room response. The trade-off is less efficiency.

All dims are inside (i.d.) and assumes 3/4" (19mm) thick material (I recommend 13 ply Baltic Birch or Appleply):

40.5"L x 329.53"^2 (I recommend 23.125"W x 14.25"D). Driver mounted at extreme top and vent = (2) 3" dia. x 5" long near/at the bottom for a ~T/S max flat alignment where Vb = Vas and Fb = Fs (based on some measured specs I have).

Due to their size they need some bracing to break them up into a number of smaller, triangular areas as well as some cross bracing to tie all six sides together so it can't 'breathe'. A cross brace to support the driver is a good idea also. Hardwood closet rod works well, doesn't affect pipe action or take up much space and is a lot easier to make than shelf braces. Lining one wall, top, and back with 1" acoustic fiberglass should be sufficient damping.

The 811 sits on top of course, either out in the open or in its own separate cab, i.e. no cutouts between the two like the M19 has.

In-room, it may sound a bit 'boomy' if there's much room gain or they are near/at a wall or a corner. If so, then damping the vents will be required to roll it off if for some reason you can't EQ it enough.

GM

[martyh45]

Hello GM,
As always, your advice regarding speaker design is far more valuable than anything I could offer. My diy experience has primarily been with amplification not speakers and my professional experience is limited to the construction of theatres and studios not electronics or transducers. Anyway?. a couple of minor points.

?From a performance POV, in my experience this isn't the case???
I?m sure you are right, I based this statement on a bit of reading and the fact that the magnet structures I have seen on z versions pulled from A-8 systems being identical to 416-A with the cover removed. At least visually, I have never measured both to compare.

?Hmm, I thought it was for the -8B.?
Me too, I have been reading about the design for a few years and finally came to the conclusion that the 8A is the original woofer for the 360L box. I have seen many references to the 8B in this cabinet but if you want to match the original ?alignment? the 8B requires much more volume. Your point about out of band hash is well taken, I assume you are referring to the mids leaking from the large vent area. I have seen a few references to the importance of the properties and location of the damping material used in this design, probably related.

Steve,
Good luck with your project, I?m sure you will get excellent results following GMs advice.