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In the ongoing audio improvement project, I am looking to upgrade a pair of 828 Altec cabinets. My initial plan is to add interior 2X4 braces to the sides, and add another layer of 3/4 MDF to the sides and top. But before I do something that would be difficult to reverse, I thought I would ask for opinions on cabinet improvment and if I should use plywood VS MDF and other ideas.Currently, all I have done is put some corner spikes on the base and put a 50# bag of sand in each cabinet.
Follow Ups:
I added about 2" of concrete behind the flares of my 825s.Before add ing the concrete,screw in a bunch of 1 5/8" drywall screws(being careful that they don't go thru the front)so the concrete has something to grip onto.I also added extra bracing to the rest of the cabinet,The more the better,but you will probably have to change the port size to keep the same tuning.
A alternative if you are going to use a sub(LABhorns work well) you can cut the cabinet in half,using just the front horn.A back chamber of about 1 cu ft works well with a 416-8a,although open backed sounds good too...
I recently tried a pair of JBL 2205as in them,sounds better than the Altecs...Sounds better than my round horns,too,even though they are the same flare as the Altec cabinet.:-(
Greets!In which? Better how?
TIA,
Hi!The JBL 2205a sounds better than the Altec 416-8a in either the cut down Altec 825 or my round horns.Maybe I need to send the Altecs to GPA for refurbishing? Altecs sound muddy...
The Altec horn sounds better than my round horn...:-(
I don't want to hijack this thread,and I need to do some measuring before we discuss this further,so I will start a new thread in a day or two...
Greets!Please do, you have me curious. For sure a 416 shouldn't sound the least bit 'muddy'.
I am not familiar with the Altec cabinet, but if you are going to add an addition layer of mdf I would strongly suggest you put a constrained layer between it and the original cabinet. Additionly I have found that an interior layer of Sonic Barrier available from Parts Express did wonders for taming cabinet resonance and absorbing some of the back wave from a 15" woofer resulting in a clearer, less congested midrange.
Hi Larry,I have been thinking of a layer of interior treatment and the Sonic barrier may be a good place to start. And Parts Express is pretty dependable on their goods.
When you say a "constrained" layer between the MDF and the orginal cabinet? I am visualizing a layer of roofing felt or similar, but not sure what you have in mind.
Ron,
Yes, that is the type of material I was referring to. Additionally, Northcreek used to sell a softglue that was designed for this purpose. I am not sure if this is still available to public.
Larry
Greets!FWIW non-hardening flooring construction adhesive has worked well for me in constrained layer apps and available at any decently stocked building supply, hardware, etc., store. Note that I've only found it in caulk type cartridges.
Try Issue #6 of the Ultra Fi Times, found at www.ultrafitimes.com for our article on our experiences with and on improving the A7.
The rest of us are free with our information around here. If you want to be our pal just tell us what you know.
OK then, you asked for it.You're completely and totally wrong with respect to the A7 v. the Model 19. Further, the Model 19 crossover is completely and totally awful. One of the worst sounding ones Altec ever made from this vintage.
And, I don't think anyone here, or elsewhere for that matter, should trust or be guided by your views/opinions on sonics.
I guess you get what you pay for...
Here's a small taste:
Reduce the port area as directed and make the baffle below the bass horn one piece.
"You're completely and totally wrong with respect to the A7 v. the Model 19."How is my opinion wrong? Is there a right opinion?
"Further, the Model 19 crossover is completely and totally awful. One of the worst sounding ones Altec ever made from this vintage."
How is my opinion wrong? In any event on this and other forums where people exchange information without profit motive many hold the Nineteen in high regard. Not that their opinions or mine are any more valid than yours.
"And, I don't think anyone here, or elsewhere for that matter, should trust or be guided by your views/opinions on sonics."
A typical reaction of one whose rice-bowl had just been pissed in. And one needn't pay first to decide whether I'm full of shit or not, nope, it won't cost 'em a dime.
"I guess you get what you pay for..."
I bought Issue #6 of the Ultra Fi Times on Larry's advice and feel it was not worth the money.
The wayback machine is way cool.
Just choose which date you wish to go back to.Regards Philip
I've got to bookmark the wayback, right after I copy most of the PDF archives from the Soundpractices.Thanks for the link.
Perhaps someone here like Freddy has a copy of the Jim Dickinson articles on tweaking Altec VOTT cabinets.You might also try the Great Plains Forum and/or the unofficial Altec page to find the Dickinson articles. His mods take those cabinets to the point of diminishing returns without wasting time on deadends.
eso
altough not altec person - got both pdf - smallVot ~729kb - can emial to someone
Hi Freddy, Can you please email to me also. I have a pair of Flamencos, and am interested in possibly building new cabs for them. I would like to see the suggested improvements.
Hey Freddy, if you could email those to me it would save me from going down those dead ends.
Many folks add extra stiffening behind the wooden horn flares. You can add wood braces or fill the cavities with that insulating foam from a aerosol can, both methods work well IME.
I used the foam in a can to fill the void behind the horn flare. My advice is that you apply it in several "coats". Too much can cause the flare to separate from the front of the enclosure from the pressure. Otherwise it works fine.
as you detune the cubic volume of the load of the woofer ...
Greets!Which one can argue is way too much for optimum tuning with all but the original 803 driver and the high output impedance amp used to drive it.
Image above 4pi space.Hi GM
If you were to build a 2way Altec VOT inspired loudspeaker,with ~150hz front horn,would you use one with very low Qts,and a rising response FR on the 15"?-Looking for that 'Ben Hur cinema impact' some talk of here.
My guesstimation is that the horn will fill in the 150hz-800hz area.Not sure how the final response will be flattish though!
Mike.e
There are three constants in life: death, taxes, and the inevitability of a (speaker)wire thread being closed -SY
Greets!Well, typically the large Altec dual 515 80 Hz horns were used with the appropriate multi-cells XO'd at 500 Hz, so I guess my question is just how 'real' can your budget/floor space afford? Really, most folks are satisfied with M19 style speakers or at most, A7s, though some step up to A5s and a very few some variation of the original systems like I had once upon a time. Nowadays I find the dual 515Bs in large corner loaded EBS MLTL cabs with 511s on top suffice since I no longer sit far enough away to justify the large horns/separate LF system. Regardless, in each case a very low Fs, Qts wide BW 15" was used, so yes, this is what I recommend. FWIW mine measure ~20 Hz/0.2 Qts.
WRT getting a flat response, the objective is to design the horn so that it rolls off up high at a rate to ~blend with the driver's rising response/break-up peaking and why the Altec horns have such large throats/short pathlengths.
Hi GMOn second thoughts,the M19 looks gargantuan compared to modern 2" ipod speakers,it will do I think!
The 18sound drivers look good anyway,a few nice Qt 0.2 driver with flux shorting rings and decent FR.
Now,trying to see how much 90 x 50 PT waveguides are ,after reading audioheritage quick and dirty 4430s! EV HR9040s or other horns id like to get just arent available new.
Mike.e
There are three constants in life: death, taxes, and the inevitability of a (speaker)wire thread being closed -SY
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