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Old 10th April 2007, 12:42 AM   #121
49 - for the 18th time - again!
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Construction Update:

We have been having a record setting cold wave for the last 5 days now and that really slowed me down on my construction of Mamboni's Walsh 5 remakes but I did manage to get some work done over the weekend.

The 1st thing to report on is the stencil test for BudP's EnABL pattern. The test was a bust - the Polly S coating that Bud uses is simply to thin to be used with a silkscreen type stencil. We will try to thicken it up some with some acrylic thickener and see if that works next.

The 2nd thing is the construction of the Mamboni SonoTube base units and assembly went fairly well after I got over the learning curve of using my new plunge router. I purchased the Hitachi KM 12VC unit after I read some reviews on different routers and I have to say that I'm pleased with this unit. I wish it had a vacuum hose port because it sure makes a lot of dust when carving up MDF and I needed to manually vacuum stuff up between carving / cutting up pieces. I did wear a respirator, dust suit, safety goggles etc. but it took me as much time to clean up the work area as it did to do the actual work!

Once I put the base plate and center brace into the Sonotube and had everything glued up, braced, etc. I performed a knuckle test on the tube and determined that this thing really needs sound damping BAD! I'm not sure if simply filling it up half way with ACOUSTA-STUF POLYFILL is going to be enough damping because the tube resonates like a - well like a big cardboard tube! I believe that Mamboni's outter covering of carpet serves to deaden the tube quite a bit but I'm going to also apply some damping treatment to the inside of the tube in addition to the Acousta-Stuf and then adjust the stuffing to my personal taste. Hopefully I can finish this test unit tomorrow and start to break it in for a week or so.



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File Type: jpg mamboni base unit.jpg (83.7 KB, 788 views)
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Old 11th April 2007, 02:45 AM   #122
49 - for the 18th time - again!
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Construction update:

After a night of thinking about my available options as far as damping the megaphone like resonant reverberations from my SonoTube base units I decided to keep things within the boundary of DIY and select materials available to the average builder. Lead is difficult to obtain - and is fairly costly as well. I considered a dense heavy rubber matting but the material is costly and requires ordering - but there are some internet sites that offer it for around $6.00 a square ft. - ugh Heck - I can purchase some nice wood flooring for less than that! Foam rubber as used under indoor carpeting is available for a reasonable price but the materials I found were not dense enough for my taste - but I will keep them on my list for future usage. Rubberized asphalt is available at the local hardware store and might be useful - but is messy, hard to clean up, and smells very much like you have just tared your speakers and now all you need to do is find some feathers to finish the job with.

I wound up with a couple of things that looked affordable and workable. 1st was some automobile undercoating in an aerosol can. I tried a can of this material and for my uses I found it to be a waste of time and money. I was supposed to provide some degree of sound insulation but in fact provided little more than simply spraying the inside of the speakers black - plus it's messy!

I had considered gluing cut to fit wool blankets (purchased used at the local Army surplus or thrift store) or felt to the inside of the speaker - but I wanted more damping that they would provide.

In the end I stopped off at the local carpet store and purchased a 9ft. by 12 ft. carpet remnant for $65.00. That should provide enough material for my two personal speakers plus my two test speakers. At around $0.60 per sq. ft. - plus $5.00 bucks for a can of spray adhesive I'm thinking that this pretty much fits the bill without braking the bank.

I cut up a piece for the bottom of the SonoTube bass and glued it down - large improvement in reducing reverberations were noted. Still had quite a bit from the side walls - so I cut up a bit more carpet and hand fit it in for testing (no glue - yet) - great improvement and I now fell that using this oversized toilet paper roll for a speaker enclosure just might have a chance of coming out fairly decent.

I still have Acousta-Stuf to play with if more "tuning" is needed but I think the 1st speaker is about ready to fire up and get burned in.

Stay Tuned!

BTW - my little four legged supervisor is named Murphy and today is her 2nd birthday
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File Type: jpg speaker assembly 10 april 07 sd.jpg (97.6 KB, 753 views)
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Old 11th April 2007, 03:06 AM   #123
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Quote:
Originally posted by c2cthomas
Construction update:

After a night of thinking about my available options as far as damping the megaphone like resonant reverberations from my SonoTube base units I decided to keep things within the boundary of DIY and select materials available to the average builder. Lead is difficult to obtain - and is fairly costly as well. I considered a dense heavy rubber matting but the material is costly and requires ordering - but there are some internet sites that offer it for around $6.00 a square ft. - ugh Heck - I can purchase some nice wood flooring for less than that! Foam rubber as used under indoor carpeting is available for a reasonable price but the materials I found were not dense enough for my taste - but I will keep them on my list for future usage. Rubberized asphalt is available at the local hardware store and might be useful - but is messy, hard to clean up, and smells very much like you have just tared your speakers and now all you need to do is find some feathers to finish the job with.

How about trying this? Why not use concentric tubes, and fill the space in-between with sand? They don't even need to be made of the same material - you can use a plastic tube and a cardboard tube, for example.

Be sure the sand is dry - I think the dry variety is called Silver Sand. Oh yeah - once it's filled with sand it'll be VERY HEAVY, fair warning here.
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Old 11th April 2007, 04:32 AM   #124
49 - for the 18th time - again!
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Hi Lynn,

Thank you for the feedback!

I have considered double wall construction using sand, or expandable foam, or as I'm fond of kidding BudP about - pudding (no particular flavor). I acutually looked into the silicon rubber used to make those artificial soft rubber fishing lures because I think a soft but dense jelly like rubber could be of some use - needs testing of course - but discovered that it's a two part silicon made by GE and intended for injection molding and needs to be "cured" at 300 - 400f. Seeing as how the SonoTube is to large for my regular sized kitchen range and I no longer have access to an autoclave I decided to pursue that idea at a later date.

I have checked the next size of SonoTube and that is 18 inch ID and yeah - I have it on my short list.

I just use "playground" sand available at the local hardware superstore chain. I would love to get my hands on some of that very fine grain white sand you can find at places like Panama City Fla. - but I believe the local officials rather frown upon people stealing their beach front!

BTW - I'm loving your thread and thoughts on "Beyond the Ariel"

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Old 12th April 2007, 12:07 AM   #125
R. Jamm is offline R. Jamm  United States
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Hi c2cthomas,

What did you use to cut the circle with? (A circle jig or….) Also, have you tried any preliminary listening and what do you think?
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Old 12th April 2007, 06:37 AM   #126
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Hi R. Jamm,

I just finished hooking up the test unit and began it's "burn in" using the HT system to just run stuff through it for a week or so. Put on a collection of oldies that have Nat King Cole, Perry Como, Julie Andrews and a bunch of others singing classics. It is not critical listening at all - simply a break-in period. Could not help myself from doing a little bit of A - B sampling tho. I have the other ESS AMT2 that was the mate to the damaged unit being morphed into this speaker and I chose it for the mate during burn-in. I also have some Fostex 167e full rangers to compare with and they are my normal base test units - I'll fire them up for an A-B test after break these units in. Right from the get go the test speaker kicked the AMT2's butt. Much cleaner sound - much better resolution - much less coloration especially in the mid range. I haven't even had a chance to tweak 'em any (yet)

The EQ is a little off as they stand right now. The Heils are a little hot and the bass needs to come up a bit - but I'll wait a little to allow the Pioneer to break in a bit before I do anything. Most likely I'll up the resistor value going to the Heil up a peg or two and see how that works 1st. Mamboni was using a dome tweeter on his design and that most likely explains the difference in balance between the Pioneer and the tweeter. Heils are darn efficient compared to just about anything else so cutting them back a bit is the place to tweak. Heck - the Pioneer is hooked up straight to the amp - so there really isn't anything to do there except use the bass control on the amp.

I bought the wife in to give it little listen as she plays both organ and piano and she walked over the the Walsh Mamboni unit and then the ESS unit - looked up and said - "turn that one off" as she pointed to the AMT2 - "the other one is so clear that it isn't even a contest". Then she gave me a little smooch and went off to bed.

I'm attaching a photo of the test tube speaker - it's not even been positioned yet - it will sit about where it is at now but will start out at about 3 ft. from both the back and side wall to start with - and then go from there. I currently have the Heil just hanging from a support pole to play around with height adjustment before I commit to final design of the speakers I'll use day to day. The height of the tweeter in this photo is at 40 inches center.

For the real speakers I'm currently of a mind to do something like the attached photo using epoxy resin and a piano black gloss finish. But that's what I'm thinking today -

I cut the circle with a jig I purchased at the local hardware superstore. The problem there is that the fine print on the box didn't say that it would not cut circles less than 6 inches in diameter! I wound up making my own little jig out of thin plywood for the small cuts on the baffle. Guess I'll need to break down and get the Jasper jig from PE after all.

Now that the 1st unit is built I'll have some time to get back to BudP's EnABL pattern for test tube #2.

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File Type: jpg test unit 1 and concept dwg 10 apr 07.jpg (31.9 KB, 1040 views)
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Old 13th April 2007, 12:17 AM   #127
Zen Mod is offline Zen Mod  Serbia
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what a thread!

just a thought (besides my idea that I'll treat every driver from now with at least one -Mamboni or BudP treatment) :

one side of the cone treated with " usual " EnABL
other side of the cone treated with Mamboni felt way,but formed in sort of augmented EnABL pattern?
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Old 13th April 2007, 01:10 AM   #128
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by BudP
Zen Mod

Most cone speakers will benefit from the Mamboni on the backside. This should take care of 70 to 80% of the problems emited from the front side. C2C's comments seem to back this up. The EnABL process is supposed to control only the refracted energy from surface terminations, like the edge of a cone or the glue pad of a surround. This should be the remaining 20 to 30% of what needs to be cleaned up on the front.

Treating only the back with the EnABL process will provide the same results. I am not certain that they are exactly identical but certainly everything Mamboni and C2C speak of is very familiar to me from just applying the EnABL treatment. Treating only the front side with EnABL blocks also provides only 70 to 80% of all you get when both sides are treated

The two processes are going to interact and we do not yet know how. It is good that C2C is a few thousand miles from either of us, so he cannot get his hands on our necks in case things go awry.....

Seriously, I expect the two processes to be throughly compatible and highly complementary. I will use them together on a test driver myself, but only after C2C has had his fun first.

I do not think I would deviate much from Mamboni's plan, though I would explore Lynn 's notion of variable geometry sets of sizes just to see if that adds an audible benefit. I don't think I would try to duplicate the EnABL pattern with that many small Mamboni triangles but I have no experience at all, so try it, who knows what you will discover.

Bud
tnx for reply

I must say that you boyz pretty good succeeded in basic explanation how Mamboni and EnABL thingies (hehe) works; I'm more than enough educated in elementary physics to understand this (even if I can hardly wait to see (if ever) can I understand your findings in OPT area ) , but more important thing is that these two techniques (two sides of one coin etc . ) aren't in any way and in any moment in same league as many Fi-FI tricks .........

anyway- what I meant with this little idea is :
one side of cone treated with "classic" EnABL (two circles of many little rectangles of paint )
other side of cone - two circles of relatively bigger (EnABL like) felt rectangles .....

I don't know when I'll have time to try difference between already established Mamboni-EnABL treatment and this small idea of me .......
too many everyday things to do,and just 24 hours in day......

anyway- in nearest future I have obligation to decide what to do with probably no less than 3 pairs of Sonido FR 8" ,so my time will be limited even more .......

but- I'm sure that at least my pair will be enabled with at least EnABL ,if not Mamboni too........


ps
I have pair of olde Philips 12".......perfect for this game
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Old 13th April 2007, 03:09 AM   #129
49 - for the 18th time - again!
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burn-in testing - day 2:

Well I have the Mamboni Walsh5/Pioneer/Heil Version 1 Mod Zero alpha version test mule (say that three times fast!) placed into the 1st listening slot. It is 2 ft. (61 cm) from the rear wall - 3ft (91 cm) from the side wall and separated from the AMT2 reference speaker by 9 ft. (274 cm) - my listening position #1 is 12 ft (3.6 m) away and centered between the two speakers and position # 2 is 10 ft. (3 m) distance and to the left of center by 3 ft. (1 m).

Today I let temptation get the better of me and did some fooling around with things - even though the Pioneer 10 inch is only about 3 hours old - couldn't help myslef!

The Mamboni unit is really kicking the AMT2's butt all over the place in terms of just about anything! But - yeah there are some but's - as always - there are some things that need a bit of tweaking - as always! Bass response is "clean" and free of any signs of muddiness and seems quick enough to keep up with the Heil tweeter well into lower mid-range. The lower base response is tight but could use a bit more punch and I believe that to be my fault by using carpet in the inside of the Sonotube to damp the cardboard echo it had. On the next unit I will stuff with Acousta-Stuf to 1/2 full per Dr. Mamboni's original design - and damp the SonoTube wall on the outside with carpet. This very well could be key into fabricating a unit with a bit more kick in the lower base. My good friend BudP has also made some suggestions concerning mid frequency response that I will incorporate into the 2nd unit and report about.

It should be understood by all that this design does provide a responsive and clean bass but it does not provide sub-woofer performance - and it never will because it is not intended for that use. Those (like me) that want the lower octaves will need to use a proper (and quick) sub-woofer.

The mid-frequencies are rather good - even with a 3 hour old unit that most likely needs another good 80 to 100 hours to season. Not only is this (the 10 inch Pioneer) a brand new unit - it has the Mamboni triangles freshly applied and I suspect that between all of the speaker dope and felt that things will only get better with a bit of "stretching" from being worked in (or worked over ).

I am wondering about the placement height of the Pioneer because I notice that I get about a 3db (guessing by use of calibrated ear) of gain when I stand up (I'm 6 ft. tall) as to when I'm sitting. The mids sound fuller and richer as well. I know that mids are fuller by placing my ear near the speaker (about 1 ft. away) and then doing some deep knee bends to get myself below the speaker baffle which is horizontal in this case. When I slowly rise to a full standing position I can listen to Pioneer improve in fullness - and it starts getting "sweet" when I'm about 1 ft. above it (while still 1 ft. away). I'm thinking that on the 2nd test unit of chopping off about 6 inches in height of the SonoTube and playing with the rather wide baffle I used in this 1st test unit. I'm thinking that for the speaker baffle I will consider a stepped baffle that would resemble the stepped pyramids used by the Inca's and Mayan's - but it would only have two or three "steps" - I know I will use BudP's EnABL pattern around the edge of the baffle - but I'll do that after the 1st test is finished.

I have my Heil unit suspended above the rear port of the Pioneer speaker - The Pioneer is one of those that have a hole in the middle of the rear of the speaker for venting - and it's reflecting off of the bottom of the Heil tweeter. Mamboni's original design used a metal bracket to mount his tweeter with and that bracket helped to block the vent noise being radiated from the front of the speaker and this is worth some consideration. In the attached photo you can see where I have placed a damp sponge in front of the vent hole for testing purposes and it does help prevent the speaker vent from adding a bit of "clutter" to things.

The Heil units are "shinny" or "bright" with that added "sss" sound often presented by the whizzer cone on my Fostex 167's (or any untreated whizzer cone for that matter). If I reduce the treble by using the tone control on the amp the "sss" goes away - but then so do a lot of other things - and the high end starts sounding rather dead and uninvolved. Seeing as how I can't whip on one of Dave's (Planet10) phase plugs on the Heils I believe that a BudP EnABL pattern placed just next to the diaphragm inner and outer edges of the magnet flange will be worth a try. Yeah I know that the flange next to the diaphragm dose not flex like a speaker cone - but BudP's pattern will also work on fixed surfaces like speaker baffles - so I'm sure that it will provide some benefits here. I'll just need to make it a bit 3 dimensional by using a thick paint - say about 3-5 mills worth.

Well - That was a bit of a long post - especially for just a bit of fooling around today - not even really testing yet - but I thought I would share what I've learned to date for those of you that are looking at building a set of these speakers.

Are they good?

When I came in from running errands this morning my wife was playing "ABBA" and dancing with her dachshund and having a blast!

It would not be polite (or wise ) to reveal my wife's age. I will tell you that she is a Grandmother and has a 35 year old son.

I will give her a new American Indian name - and I am part (small part) American Indian - I will now call her "Dances with Dachshunds".

There are not a whole lot of speakers in the world that are musical enough to get a Grand Mama up and dancing with her dog. That vision alone is worth the price of admission!
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File Type: jpg walsh5 - pioneer with heil 2nd test april 12 2007.jpg (37.3 KB, 664 views)
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Old 13th April 2007, 04:08 AM   #130
GregOH1 is offline GregOH1  United States
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[QUOTE]Originally posted by mamboni
[B]Hello Bud:

You're EnABL approach

I believe the fibers are acting as a huge surface and providing for a much more efficient coupling of vibrating cone surface with air. tiny hairs

Micro fibers ?


http://ohioline.osu.edu/hyg-fact/5000/5546.html
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