QUEST New Eclosures

[The Observatory]

QUEST New Enclosures

Hi, all you courageous folks out there!

Strange things happen all the time - I was able to purchase panels, electronics and woofer plus plans for two (almost) new Quests. We had them mounted up - they sound good! The guy had started the project of dismantling his speakers and wanted to put the ingredients into new wood enclosures because he felt the ML wood treatment was not up to snuff (his opinion). Naturally, he threw the old wood away already .

I have the original dimensions of the QUEST (not ReQuest) but was wondering if somebody has already had some experience with building a new enclosure for them. In particular, the gentleman felt, it would benefit to add more space to the woofer (and different padding) and he thought the wood box was too flimsy and not nice with the black rubber stuff. He felt, I should use some beech or similar solid wood about 1.5" thick for the bass box.

It is peculiar that the electronics is mounted right inside the bass box. I would at least isolate it from the wooden box (like in the CLS II and Sequel II) and put it into a separate metal case to shield any stray signals.

Any suggestions for tweaks while everything is open and easy? My wood man is ready to tackle the job immediately. Thought I could add more improvements while I am with just speaker, electronics and panels.

Arthur

 

[JonFo]

Sounds like an interesting project

If starting from scratch, I’d suggest thinking about a line array of mid-bass drivers instead of trying to mate the 12” driver to a box. I did that in my SL3XC center and the results are awesome (listening to Porcupine Tree – Stupid Dreams in DVD-A right now and the bass hits on the line array are amazingly clean and strong.)
Then just add a sub for the 80Hz and under frequencies so you can optimize the placement.

Also think about going full active on the crossovers, it’s easy and the results are vastly superior to passives.

Whatever you do, make sure the panels are very solidly held and mounted in such a fashion as they won’t vibrate. Panel movements, especially small ones due to not being well anchored induce distortions (time smearing) and will not let you appreciate the awesome sound of an ESL.

This should be a fun project.

 

[Brad225]

I don't know anything about the design fabrication of the Quest, but I would use MDF (Medium Density Fiberboard) for the enclosure. Many of the high end speakers sold today use this because of it's stability, density and ability to not transfer vibration as much as other materials. A minimum of 3/4" but thicker if you like. Here in the USA it is available from 3/8" up to 2" thick. You could then build much of the frame to hold the panels out of solid if you want. I would use MDF for all of the frame and cover it with paint, veneer or solid wood trim. The problem with solid wood for all parts is it will always move with the change in humidity possibly changing the panel position and not seal the bass enclosure.
I'm not sure you would have to separate the crossover from the bass box. Most MLs and other speakers are built this way.
Just make sure everything is secure and no pieces can rattle or vibrate against each other. The fabrication should not be that difficult as long as you now what they should look like when finished

 

[HsvToolFool]

He felt, I should use some beech or similar solid wood about 1.5" thick for the bass box.

I'm an avid amatuer woodworker, but I've never attempted speaker cabinets. That said...

If I were using natural materials (and I wouldn't), I'd use only the most dense, stable hardwood possible. You're trying to create the opposite of a violin's sounding board. Common North American hardwoods like rock-maple, walnut, and cherry probably aren't dense enough for a high-end speaker cabinet. I think beech is even less dense than the above species and would resonate too much.

Instead, I'd investigate more exotic tropical woods which tend to be available in thicker and wider stock. Of those commonly found in the US market, I think African Bubinga is the best choice. It is so dense and heavy to almost be considered a true "ironwood". I have some 2-inch thick boards which weigh twice the same sized walnut board. But you'll typically pay $8 per board-foot (one cubic foot) for Bubinga, perhaps more for thick and wide boards.

So for cost reasons alone, I'd use High Density Fiberboard (HDF) which is what modern speaker manufacturers use. HDF is very dense, affordable, available in the exact thicknesses you want, and you can slap on some awesome exotic veneers. Medium Density Fiberboard (MDF) is found at Home Depot, but you'll need to call local cabinet shops to order HDF for you (if it's not stocked). MDF would be useful for making a mock-up or templates.

Good luck! This is a very challenging and ambitous project. If you have a gooood friend with Quests who would pull a woofer and let you examine the cabinet, it would be a big help. Or pehaps there's a cutaway diagram somewhere on this forum.

 

[The Observatory]

QUEST New Enclosures

Thanks for the suggestions, all of you.

So, the consensus is HDF better than MDF, not solid wood but rather veneers for sides, etc. Sounds okay.

Jonathan, I have read about your SL3XC project in depth (what is there). I am a bit confused, can I get to you on this in detail in your post?
Basically, you are saying that an active crossover separated from the existing electronics (they to be modifed, of course, as indicated) with added low / mid bass speakers instead of the two woofers in the Quest now is a much better idea. Makes sense. If you are extending the frequency range of the (mid) bass to some 500 Hz, aren't you already pretty 'high up' in the audible spectrum? And would this not counteract the ESL philosophy somewhat? I guess, hearing the difference is believing.

Arthur

 

[IWalker]

The crossover point is one of personal taste, I think...at some point, the speed and coherence of having a single ESL panel is trumped (in my opinon) by the ability of midrange drivers in a closed configuration to pressurize the room. As long as a cone driver has low inductance, and the cabinet is built to resist resonance and minimize secondary reflections (the wave bounces off the back of the inside of the cabinent and is reprojected through cone, causing muddiness.... then there is no reason that a cone driver, can't "keep up" with an ESL in the lower ranges.

I made a dipolar mid-bass line array, and only tested it minimally, but found that it had a similar sonic signature to the ESL (lacking the "punch")...making me think that the main sound difference is between a pressure and velocity source (closed box vs dipolar) and I prefer, for most music, a pressure source in the midbass and lower. While directionality is improved with dipolar setup, which makes positioning easier, the sound just doesn't sound as full as I like in the midbass range. As with all of this, it's a matter of taste!

 

[Chuck Lee]

Quest enclosure

What's wrong with using sand or lead filled metal for the frame?
Anyone with basic welding skills should be able to come up with a very sturdy design eliminating all the problems of wood.CLS speakers are enhanced when they are locked into an Arcici or Sound Anchor stand.
As far as the out board up-graded crossover,I agree.
The separate sub enclosure material should also be weighted down and I would try to mate more but smaller and faster drivers with the original woofer,again using a three way crossover in this instance.
If you go active you could experiment with tri-amping your system,use tubes for the stat panels and solid state for the mid bass drivers and then ss for the sub bass driver in a three way system.
Stat panels mated to single woofers never sounded correct to my ears,you are asking that woofer to do too many things poorly and not anything correctly.
If I were to design a subwoofer it would be a bi-amp affair with separate amps and crossover points and mid and sub woofer drivers.
It would be similar to a Depth sub, except one woofer would be a 12 or 15 and it would have its own amplification and handle everything below 30 hz.

 

[IWalker]

another aspect of mating a single woofer is that it is a point source, as opposed to a line-source (even if it's essentially omni-polar at lower frequencies) so the sound level drops off at a different rate at distance than does a line array...causing the sound balance to vary by position. Using line arrays to cover more of the spectrum should make the sound more balanced. There's a misconception about driver "speed," any driver with low inductance, and a well damped cabinent (also with enough absorbtion inside) should sound "fast," in the low registers whether it's a 1" or a 15" driver. a 15" driver has to move MUCH less to create the same amount of air movement(SPL). Slow sounding drivers are generally a result of poor room interaction or poor cabinent execution (or overexertion of the driver, leading to high levels of distortion)

If you're going to go that route, why not just take the Quest's sub out of the mix? Build/buy an external sub, cross it over at the same point...you have a lot more options in terms of design and placement...so would probably sound a lot better than upgradeing the cabinent as is. Doing this, ALONG with a midbass line array would probably provide the best results (see JonFo's system...the perfect storm of IB sub, and the line array+stat panel...I'd very much like to hear his system, especially if he ever does the the same thing to his Monoliths(create a midbass line array)) though just doing the seperate sub would probably go a good portion of the way there.

my 2 more cents.

 

[IWalker]

I'm sure sand or lead filled metal would do fine...but I have the capability to easily build stuff out of MDF or HDF, as I think a lot of people might, but have no exposure to tools to build things out of metal. Building speakers out of metal would be very cool, though...and some speakers are already made that way (Krell's mondo subwoofer I believe is metal)

I think metal lends itself more to sub building than regular speaker building, because it resonates at a higher frequency at wood...so would eliminate some of those resonance issues sometimes found with building wood sub boxes...

 

[Chuck Lee]

Quest enclosure

Another material for consideration,although costly, would be corian,and could probably be a custom job not too difficult for the folks at the Home Depot.
My secret wish project is to have the wood panels of my CLS11Z replaced by custom carbon fibre ones.
These would be very nice to look at as well as having less flex than wood.

 

[Brad225]

Here is a link to a person in Michigan selling parts to make stats. There are a few pictures but I am sure you could contact him for some suggestions. The cost for parts is quite reasonable. It would be fun to build some to see how they sound.

http://www.justrealmusic.com/XPLS_Series.htm