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On 3/22/2020 at 8:36 AM, Marvel said:

 I thought (maybe Jim Hunter would know, or even Andy) what the Klipsch pro stuff was made with early on was a marine grade plywood. It would have had better glues and fewer/no voids.

I left Klipsch in October of 1983.  Our professional stuff was called our "Industrial line"..."PRO" came along years after I left.  The Industrial models were all built outta the same Georgia-Pacific "void-free" birch plywood we used for the decoratotrs and later the birch raw units while3 I worked there from 76-83.  Of course this also applies to all of the industrial line while I was there, INCLUDING the MCM 1900 system components:  MTM, MSM, MSSM, and MWM.  We used quite a bit of approximately 1/2" thick baltic birch on the K-horn bass bin construction, though...with the  finely-veneered panels for the K-horn being poplar-lumber-core plywood.  I can only speak about what was used while I was there.  We had lots of the approximately 3/4" Baltic birch, and constantly tried to find uses for it in cabinets, but it seems that nothing we came up with while I was there was conducive to use in regular construction, mostly due to the types of construction fasteners we used: finish nails and staples would either fold or not drive up completely so those ideas got scrapped !  That's what happens when you buy a huge amount of something like Baltic birch, in various thicknesses and sheet sizes because you are "getting a great deal" on it, but nobody can figure out how to utilize the thick sheets of it while using the standard product-construction methods at the time!.  It is what it was!  Klipsch tende3d to be at odds with Georgia-Pacific due to the constant price-raising of their void-free plywoods we used, and the problems the seemed to be having with quality control during those years.  They were looking for something else so that they didn't have to constantly haggle with GP over quality control and rising costs!

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On 3/21/2020 at 11:38 AM, moray james said:

 Both mdf and ply can perform well if used properly, the application and cost will be the concern. Built in pro cabinets could be made of mdf but touring cabinets would never be made from mdf due to the huge weight disadvantage as well as has been rightly suggested the diminished physical strength of mdf when presented with stressors such as impact.

 

This has been my take on the subject. I have had and still have some 20-30+ year old MDF Klipsch speakers that are like new and sound great, I also have a newer set of Klipsch pro speakers made out of some sort of plywood and they sound fantastic as well. 

 

 

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Plywood for sure is far more sturdy than MDF for mobile use, bumps and scratches and the occational rain shower. For a stationary indoor loudspeaker however, it appears that bracing and damping/lamination to be more important. There are differences but they are not that huge. Here is a test conducted by the German magazine Hobby & HiFi.

The setup is a dual chamber box with a driver in bisecting wall.

HH-Testsetup1.png

A board to be tested was  placed in front of the driver and both soundpressure in front of the box (compared to no board) as well vibrations of the board was measured

HH-Test-Setup2.png

Vibrations to the left and reduction in sound level to the right. The referense was the 19 mm MDF at the bottom. That result is inserted in the other graphs for comparison.

HH-Test-Boards1.png

Not much difference between 16 mm MDF, 19 MDF and 18mm Plywood.  Fire retarding concrete chipboard 20mm is better but hard to come by.

HH-Test-Boards1.png

28 mm MDF is better but not by that much, 20mm stone is way better, 19mm chipboard is slightly worse than MDF and 19mm blockwood a bit worse than chipboard.

 

These measurements were made in the frequency -amplitude domain, I have seen measurement in the time domain and they show most effect of bracing and lamination more than the instrinsic qualities of the board.

 

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On 3/16/2020 at 5:27 PM, Dave A said:

Here is a picture of real BB. All the plys are the same thickness. If the lumber yard told you they were selling you BB they misrepresented their product.

 

 

 

 

wdw_48_bbbb_18_1_577a95da2e11b_1000.jpg

 

We always use this kind of Baltic Birch Plywood the premium quality. Iran is close to Russia and we have access to this material made by Sveza much cheaper than in the US. there is also Wisa of Finland which is more expensive than Sveza and have that little bit of extra quality.

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On 3/23/2020 at 2:52 PM, HDBRbuilder said:

They were looking for something else so that they didn't have to constantly haggle with GP over quality control and rising costs!

When Woody Jackson gave me a plant tour in August of 1985, he pointed to a big stack of routed KG4 front panels full of voids. He said they were going back, but I'm not sure if they were Georgia Pacific or not.

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10 hours ago, Randyh said:

Dave , tell me how you do that ------ I guess you''re  speaking of LSI  bass bins , not   the original 1 piece LS ---

Easy. You get a big rubber mallet and start whacking on the bottom front edge and work your way up. A wide pry bar is useful to pull the piece being removed from parts you want to preserve after you open up a small gap to prevent splintering of edges you want to keep.The only piece that may get damaged is the very top which you have to replace anyway since the 25 MM Baltic will leave a ledge there if you don't. Those old glue joints break out pretty easy and I have done maybe four of these now with no issues.

  I have one I am going to do this to in the shop right now. Maybe I will do a thread on this with pictures. I have also contemplated a rebuild so the top section would have enough space to let me use an LMAHL rather than an SMAHL. Then again I just might make it a two piece if I go that far. Decisions decisions.

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On 3/21/2020 at 12:47 PM, jjptkd said:

I know a guy who set up very large pro gear venues and he tells me pro gear is mostly "raw" as everything is EQ'd heavily after it is installed which is why a lot of pro gear does not sound good in the home without some electronic "help" if you will, not plug and play like home systems.

 

It's nice that he gives you his opinion and shares his knowledge.

 

I know a guy (acquaintence actually, as the first time we met he flipped me the bird) However, he knew PWK, worked for the company and is the official historian....   Mr. Jim Hunter.  He said that when they design their speakers, be they residential OR commercial, they work to put high fidelity into any/all of their designs.

 

Certainly a chance that another company might be more cavalier about that goal.

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52 minutes ago, Coytee said:

  He said that when they design their speakers, be they residential OR commercial, they work to put high fidelity into any/all of their designs.

 

Certainly a chance that another company might be more cavalier about that goal.

So all Klipsch Pro gear present and past need no EQ-ing because they're designed with Hi-Fi in mind? Plug n play huh? Nice! Good to know thanks.

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Hello,

Has anybody done an A/B sonic comparison between a MDF enclosures and a BB enclosures? All this talk about durability is great but bottom line is sound quality.It would be interesting if DIZ can comment on the before and after sound differences with his Heresy. I have a set of Forte ll and thinking of redoing the enclosures out of BB but only if it improves SQ.

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29 minutes ago, andym said:

Hello,

Has anybody done an A/B sonic comparison between a MDF enclosures and a BB enclosures? All this talk about durability is great but bottom line is sound quality.It would be interesting if DIZ can comment on the before and after sound differences with his Heresy. I have a set of Forte ll and thinking of redoing the enclosures out of BB but only if it improves SQ.

 

Too many variables for me to make a valid qualitative comparison of sound quality.  The only MDF Klipsch I’ve auditioned in my home are H2s.   That said, my favorite speakers in my system are plywood HIPs that have DE-120 tweeters and a “Super Heresy” network with Crites 3636 autotransformers.  I (and my wife) prefer them slightly to my DIY Baltic birch Supers.  

 

I add egg crate foam to the interiors of all my plywood enclosures.  I can not imagine that taking all the components from a plywood enclosure and installing them in an MDF enclosure would result in an observable difference in sound quality.

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if you were to take any two identical cabinet designs one in MDF the other in Baltic Birch and give them the knuckle wrap test and you or anyone standing within ear shot can hear the difference between the two materials. For that matter wrap in a scrap piece of each material you will hear the same difference. Yet people wonder if they will sound different. If you don't want to believe your ears then you won't hear a difference I guess or you will convince yourself that it does not exist. Only you can determine if you prefer one to the other or what the differences are to you. These materials are physically different and if you want similar performance then you will need to build accordingly at which point differences will me minimized. Your ear will always be the judge. However if you cannot tell the difference then that just makes life easier for you.

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FWIW the specifications for BBC LS3/5a monitors require birch plywood, beech battens, and bituminized felt; not a speck of MDF.  The BBC. Could have spec’d MDF if they thought it provided sonic superiority.

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2 minutes ago, DizRotus said:

FWIW the specifications for BBC LS3/5a monitors require birch plywood, beech battens, and bituminized felt; not a speck of MDF.  The BBC. Could have spec’d MDF if they thought it provided sonic superiority.

LS35A has to have live panels to help with bass response mdf panels would be far less active. The materials are just different both can be used to good effect if used properly that said sometimes you need what you need to get the job done it is not difficult.

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I would not describe a LS3/5a enclosure as live.  Claude @ClaudeJ1 would you describe those enclosures as “live.”

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I believe the English describe the BBC replica cabinets and many Harbeth models as “loosey”  -

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