Mass Loading A7s, VERY inexpensive, reversible, needed -

[LowOhms]

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Hello,

Even if you braced your A7 internally, they all need Mass Loading IMHO.

In December 2015, I reported liking 265 pounds over 215 pounds, from my listening tests. For the last six months, my rig has been stable with 350 to about 400 pounds on top of each 825 enclosure. Huge improvement over " no mass loading " in sonics. TRY IT !!

Lowes Hardware chain, in my area, carries a 11.7 inch " square stone". In reddish color, which I used, its ONLY $1.47 each, yet it weighs 16.5 to 17 pounds. Eighteen on each A7 cost only $31.71 plus tax per enclosure, and these are stack-able, adds over 300 pounds, which I highly recommend. The gray rectangular ones were another 40 pounds, estimated, and also - there is the weight of the audio components.

Mass loading sounds GOOD !!

Lowes REDDISH is Item # 19184, Model # 104601201

Lowes Gray square is Item # 19183, Model # 104601999


The 5 rectangular Gray units Lowes calls a " Gray Stone " and measure 7.7 by 15.5 inches, above and below my Emilar EH-500 Clone ( SHOWCO 9000 ) . WOW, only $1.05 each.

TRY it, LISTEN to it. It will put a smile on your audiophile face I 'betcha !! Post your LISTENING results up here so others will learn from your A-B ing!!

Jef Medwin, Low Ohms

[bowtie427ss]

I would opine that A7's are probably not the only speaker systems that can benefit from mass loading.

With particular thanks to GM's input long ago i have come to appreciate the beneficial gains in some speaker systems from mass loading the woofer itself by the use of bracing to rigidly couple the woofer's frame and motor to the entire mass of the cabinet structure. With some Altecs that have woofers mounted to the rear of the baffle this can be as simple as running a brace from side to side such that the woofer can be "clamped" between said brace and the front baffle.

Over the years gleaning bits and pieces from various sources i have come to understand the important relationship between the linear acceleration forces of the moving assembly of the motor, and the sheer mass of the driving motor structure. From subwoofers to supertweeters, more mass in the stationary structure directly translates to lower distortion.

Great stuff Jeff! While it splits hairs that will be beyond the interest of many, please keep it coming.

[LowOhms]

I would opine that A7's are probably not the only speaker systems that can benefit from mass loading.

With particular thanks to GM's input long ago i have come to appreciate the beneficial gains in some speaker systems from mass loading the woofer itself by the use of bracing to rigidly couple the woofer's frame and motor to the entire mass of the cabinet structure. With some Altecs that have woofers mounted to the rear of the baffle this can be as simple as running a brace from side to side such that the woofer can be "clamped" between said brace and the front baffle.

Over the years gleaning bits and pieces from various sources i have come to understand the important relationship between the linear acceleration forces of the moving assembly of the motor, and the sheer mass of the driving motor structure. From subwoofers to supertweeters, more mass in the stationary structure directly translates to lower distortion.

Great stuff Jeff! While it splits hairs that will be beyond the interest of many, please keep it coming.

Hi Bow Tie,

You wrote this :

"I would opine that A7's are probably not the only speaker systems that can benefit from mass loading."

You are so correct. I have been DIY building a new Type 45 SET for my A7, April 2016 through September. Thought it was about done, three days ago. Am going to bring it over to a friend's A2 system in Kansas City, but checked it out three days ago, so I don't get "egg on my face", on my Fulton FMI 80 bookshelf speakers, a trusted speaker of mine since 1978.

OMG, the amp sounded terrible on the FMI 80s. No definition, no resolution. My heart sunk, as it flew on the A7s. Then I looked across the room, at my A7s, with close to 400 pounds mass on each 825.

I said to myself, " Maybe my trusted FMI 80 is lying to me, about the amp", maybe IT needs mass loading. "

SO, I added three $1.47 concrete squares ( about 51 pounds ) to each FMI 80 enclosure's top, and it was MUCH better. Listened for awhile, and added two more to each top, a total of 81 pounds. I stopped there. It was a really NEAT improvement, all sorts of music fine detail ( that this all-out Type 45 amp was designed for - and CAN reproduce on ALTECS ) , was starting to be heard on the FMI 80s, whereas without 81 pounds, and an hour earlier, this was MIA.

Lesson learned.

It was also pretty EXCITING to me to hear the FMI 80s at a new level of mass-loaded performance, realizing that Mr. Fulton, nor I, nor anyone else, likely had never HEARD before. ' Had em 38 years now !! Because of a variety of reasons, I'll stay with ALTEC, but it was illuminating to first hear 51 and then later 81 pounds added to each box, with a good amp and source ( Pioneer Elite Blu Ray player, BPD-09FD ) .

Yes, you are correct IMHO Bow Tie, Mass - Loading is helpful for likely ALL speakers. I would highly encourage people who have " braced" A7 enclosures " and THINK they have it covered " : to simply, cheaply 'TRY OUT " adding mass, as I described, and LISTEN to the result....report back here please. !

Please let me know, you " braced A7 owners ", WHAT you hear, needs to be, just guessing, about 15 or more 11.7 by 11.7 inch squares, on each A7 top. I am pretty sure, people with good set ups, will never go back to the stock mass. But I could be wrong !! Sometimes am. :-)

Jeff Medwin Low Ohms


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[VolvoHeretic]

Or, screw some eye hooks into the floor joists/trusses and cinch the speakers down using ratcheting straps? I guess that my idea of building spherical concrete subs is right on? Should weigh around 300 lbs each and be easy to roll around.

[LowOhms]

Or, screw some eye hooks into the floor joists/trusses and cinch the speakers down using ratcheting straps? I guess that my idea of building spherical concrete subs is right on? Should weigh around 300 lbs each and be easy to roll around.

Ratcheting straps is a form of a brace. It will not do as well as a mass load, distributed all over the top of an A7 box. The straps will set up " nodes " where they touch the box, which is undesirable.

The point of my post is three - fold :

(a) Mass loading is HIGHLY beneficial on almost any A7 ..... and conventional speakers also

( With these Lowes $1.47 17 pound concrete blocks, its cheap, non destructive, and totally reversible )

(b) Just because you have braced your A7 box, there is likely MORE to be had, you need to still TRY Mass Loading.

( I THINK it will bring something positive to the music's presentation, that you can NOT get ANY other way, not by bracing alone. )

(c) TRY it out, its reversible, and report back what your LISTENING experience is, with 200 to 300 pounds on one box versus stock, or both boxes so treated.

I bet you all a cup of coffee, it will put a SMILE on your face when you hear it !!

Get off 'yer butt today and DO something !! ................. :-)

BTW, Volvo Guy, the concrete sub woofer me thinks will be very good, give it a rip, but only "after" you lay $1.47 blocks on yer A7 and HEAR that !! There is more music content in the mids and highs to enjoy than below 40 HZ.

Have FUN and please let us all know what you hear.

Jeff Medwin Low Ohms

[Elitopus1]

Jeff
I understand that mass loading can be and probably is beneficial to A7's. My question is why are you so against extra bracing? I as well as most other A7 owners on the forum who have done any work to their A7's have added extra bracing. I just accept it as a standard practice when building or improving speakers.

This is the first time I have heard of using pavers for loading but I have heard of using bags of concrete. I have also heard of filling the flare area with sand. That adds a bunch of weight also but is inside the speaker

[LowOhms]

Jeff
I understand that mass loading can be and probably is beneficial to A7's. My question is why are you so against extra bracing? I as well as most other A7 owners on the forum who have done any work to their A7's have added extra bracing. I just accept it as a standard practice when building or improving speakers.

This is the first time I have heard of using pavers for loading but I have heard of using bags of concrete. I have also heard of filling the flare area with sand. That adds a bunch of weight also but is inside the speaker

Hi Don !!

So if you " understand ", why don't you go out THIS WEEK, and TRY IT on one or both enclosures Don ????

When you add braces internally, you are upsetting the air flow in the enclosure, which I do not want to do. WE don't usually brace musical instruments, is one example I think of. I think it would be fine to add braces externally, but then " looks" such as they are with an A7, suffer.

Also, you can not glue 3/8ths of Baltic Birch to all the outside surfaces, because there WILL be voids, which will sound poor.

Internally in an A7, I would like to put a fillet, in all 90 degree corners, to avoid that sharp transistion. I have 1 inch Baltic Birch, and I may have someone build a better A7 box for me in future years, with fillets at all 90 degree internal-box junctions, and maybe NOT a square, rectangular, or round port in the front, but rather, an OVAL-shaped port. Wanna get the STOCK box going and set up to a reference - quality sound level. Its been TOUGH and lotsa work. But its coming along.

I do not care much what " all the people " on this Forum do as far as bracing internally. I will LISTEN and make up my own mind, not just read and trust others. I usually consider the "crowd" to be wrong. ( I am 100% "short " or " have sold short " the stock market presently, like Billionaire Carl Ichan has ). I'm no billionaire for sure . :-) I have my own sensibilities, developed over my life, and I simply follow them.

Been listening to ALTEC since 1952, 604Bs, as a child. If I did what " all the people " did here, I 'd be doing things I detest, like bi-amping, un-necessary digital signal manipulation, etc, etc etc. I prefer a real SIMPLE high-quality system !! KISS rules, the more you mess with the signal, the LESS you obtain, is my mantra.

Everyone has to do .....whats best for them !!

Have FUN, I am !!

Jeff Medwin Low Ohms

[Elitopus1]

The guy I bought my 828 cabs from has his A7's mass loaded. He had 300+ lbs slabs of granite cut for the top of each one.
If I go and buy a bunch of patio pavers my wife would kill me if I put them on my speakers instead of around the back porch like I promised her I would do a few years ago

[mah]

Taking mass-loading further:Patent US8695753 - Mass loading for piston loudspeakers - Google Patents


If a couple of milli-ohms of wire has a big effect, imagine the potential of this idea.

[LowOhms]

The guy I bought my 828 cabs from has his A7's mass loaded. He had 300+ lbs slabs of granite cut for the top of each one.
If I go and buy a bunch of patio pavers my wife would kill me if I put them on my speakers instead of around the back porch like I promised her I would do a few years ago

Don,

That is VERY reassuring to me, that the experienced ALTEC A7 owner who was selling things to you, a novice, spent the money to have, not 100, or 200, but 300 pounds of Granite on the top of his A7. That is just about what I did, by ear, earlier this year. ( 215, 265, and then 350 + pounds ) .

Have you EVER thought that this guy did that for a GOOD reason, and MAYBE YOU should imitate it and LISTEN to what that does.?????

WHY would he spend the time and money, on custom cut granite. ??

Eighteen of these Lowes concrete 11.7 inch squares will GET you the 300 pounds he and I both like. It is only a cost of $1.47 times 18 or $26.46 to hear it, per enclosure.

Don't give me this lame "wife" baloney.

IF she loves you enough to put two or four of those huge and ugly ALTEC theatre gray boxes in the room, she will be OK with the red colored stones, if not on a permanent basis, at least on a temporary one.

IF you, and she, does NOT like what it does sonically, then you CAN use it out back !!

When you HEAR this on your A7, there is absolutely NO going back. I PROMISE you Don !!

Ask the guy who sold you the enclosures. Take my word on it, and for under 30 or 60 dollars, LISTEN to it !!! Do so, THIS WEEKEND . Report back to us all, not for my edification, but so as to encourage and help others !!

Have FUN, ...,...I sure am!!

Jeff