[quote=Altec Best;1830797]Sorry about the senior moment...meant 820cOriginally Posted by Old Guy
Well I'm working on it.I'm not going to put this amount of time and $mullah$ to go off half cockedThey are guitar speakers aren't they. I want to keep these strictly Hi-Fi with an option maybe down the road to be able to use as a Home theater.As Voices of the Theater !!
and would just have to put together a center/rear channels. But for now 2 channel Hi-Fi is what I'm looking for.
http://www.lansingheritage.org/image...ome/page08.jpg
420 is a biflex isn't it?
Your neighbors called. They like your music.
"The finest speaker available anywhere." Well I should hope so! The 820C cost $555 each in 1954. That would be equivalent to about $9000 for a pair, today.
Maybe we need to go back the days of monophonia.
Here's a nice thread on the 820. Darn, now I want one - er, two.
Altec 820A Corner horn??
You're welcome! Ah well, divided by a common language. You don't need to be at mine or anybody else's knowledge level, just when asking for help, the more info the better, especially WRT any size/budget/SAF limitations and of course ask as many Qs as you need to keep from being confused as it can save more time than not.
Speaking of 'confusion', I just noticed that I didn't complete my now defunct first draft in that I didn't finish the cab gross Vb calculation, so I was wrong, the triangular MLTLs are only ~6 ft^3 gross, so too small for a 416 to go low without significant room gain.
This begs the Q of how well is your room/house constructed? If it's anything like my old WWII G.I. tract home there's not much gain at all and actually is a bass trap below ~16 Hz.
Regardless, any shorter than a ~96" total height then means the speakers must protrude into the room even more than the theoretical 8.5" o.d. high SQ limit to get back to the ~11.5 ft^3 that's theoretically required.
At 70", the MTM is marginal since this puts the 511 centered at 35" which is a bit low for an average seated ear height, so any lower and it's not viable for best SQ unless ya'll sit really low/laid back.
Anyway, the smallest practical horn cab is 11", so with only a 29.5" o.d. woofer cab height there's not going to be hardly any extra vent acoustic damping, so of course any shorter means none for all intent and purpose.
Again, in a MTM, offsetting the woofers, horn with the ST beside the horn and outside wall seems the best compromise. Putting the tweeter between the top woofer and horn will create an oddball lobing pattern/polar response that's shifted up slightly from the horn, though I've no clue how audible it may be, but my SWAG is that over time it will rub you the wrong way on music you're familiar with.
OK, regardless of whether you use an over/under or MTM, with a 70" total height, each woofer cab has ~8.5778 ft^3 gross with including the 8.5" extension to work with, so call it ~8 ft^3 net. Using published specs and tuned to Fs, this yields a ~50 Hz F3 in half space, so in theory it would be ~42 Hz in a corner, though there's enough efficiency to digitally EQ ~flat in-room to a lower F3 if desired if you have enough clean power on tap.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
[quote=Old Guy;1830801]
Not a problemSorry about the senior moment...meant 820c
Yes it is420 is a biflex isn't it?
I actually talked to him about those speakers (Dylanl) I asked him if he wanted to sell them but he said he already sold them.:khan: That was a depressing evening.He also said that he thought they were bass shy even though they have dual 803's cabinets internal volume is too small.They are beautiful speakers.I wonder if they would work for me by enlarging the cab some Hmmm.
[quote=GM;1830812]Thank You for your understanding I appreciate that.:2thumbsup:You're welcome! Ah well, divided by a common language. You don't need to be at mine or anybody else's knowledge level, just when asking for help, the more info the better, especially WRT any size/budget/SAF limitations and of course ask as many Qs as you need to keep from being confused as it can save more time than not.
But you caught it that's all that matters.Speaking of 'confusion', I just noticed that I didn't complete my now defunct first draft in that I didn't finish the cab gross Vb calculation, so I was wrong, the triangular MLTLs are only ~6 ft^3 gross, so too small for a 416 to go low without significant room gain.
My house is an older house pre WW II I think it was built around 1928 but is built well the walls are a real thick plaster and it is like concrete with hardwood floors and some carpeting.This begs the Q of how well is your room/house constructed? If it's anything like my old WWII G.I. tract home there's not much gain at all and actually is a bass trap below ~16 Hz.
Yes I measured my listening area and in a few spots couch,chair and optimal height of horn should be 38"-42"Regardless, any shorter than a ~96" total height then means the speakers must protrude into the room even more than the theoretical 8.5" o.d. high SQ limit to get back to the ~11.5 ft^3 that's theoretically required.
At 70", the MTM is marginal since this puts the 511 centered at 35" which is a bit low for an average seated ear height, so any lower and it's not viable for best SQ unless ya'll sit really low/laid back.
8.3 ft is the same as a model 19 cabinet isn't it.That gets down to 30 Hz. What I would like to get is 30 Hz but I could live with 35 Hz I don't think I would be happy with 42 Hz as I'm kinda used to 30 Hz as I have been listening to my 19's for awhile now.What other options would I have.Power is not a problem.I have plenty of power.I hardly ever need more than 1/3 of it.Thanks GM Stay Well !!!Anyway, the smallest practical horn cab is 11", so with only a 29.5" o.d. woofer cab height there's not going to be hardly any extra vent acoustic damping, so of course any shorter means none for all intent and purpose.
Again, in a MTM, offsetting the woofers, horn with the ST beside the horn and outside wall seems the best compromise. Putting the tweeter between the top woofer and horn will create an oddball lobing pattern/polar response that's shifted up slightly from the horn, though I've no clue how audible it may be, but my SWAG is that over time it will rub you the wrong way on music you're familiar with.
OK, regardless of whether you use an over/under or MTM, with a 70" total height, each woofer cab has ~8.5778 ft^3 gross with including the 8.5" extension to work with, so call it ~8 ft^3 net. Using published specs and tuned to Fs, this yields a ~50 Hz F3 in half space, so in theory it would be ~42 Hz in a corner, though there's enough efficiency to digitally EQ ~flat in-room to a lower F3 if desired if you have enough clean power on tap.
In the times the 820 was designed for, full-range reproduction ('HIFI') was ~50-11 kHz with acceptable being only ~75-7 kHz and when driven with a period correct high output impedance it was nominally flat in-room to a half octave above/below this, so a stellar performer for its time. Today, with our ~16-20 kHz BW available on some music CDs we would need a ~11.3-28.28 kHz ~flat BW which no consumer system can come close to AFAIK, so by today's SOTA requirements it's woefully inadequate without a sub and super tweeter, but if all you do is spin vinyl and/or old tapes and/or mass market CDs, then you'll be hard pressed to want/need more BW.
Cool, back in the days when squared off trees were used for floor, ceiling joists in all but the cheapest construction and if you live above the Mason-Dixon Line it's further ~'bulletproofed' for snow/ice.
OK, that ear height is typical here in the USA, so it's your call as to which layout to use, though being use to the M19's so-so driver spacing WRT its XO point/slope that I wanted to improve on, you may find your preferred over/under layout as sounding very similar if a 500 Hz XO is used. Go with a higher XO point though and you'll need to roll off the lower woofer for best performance overall.
Martyh came up with ~9.16 ft^3 and I with ~9.43 ft^3 once I found out that the two sections were acoustically connected through a low pass filter that technically makes it a dual chambered reflex (aka DBR), but it never hurts to get another set of eyes to calculate it. So a bit shy plus the DBR adds a bit of gain down around cab tuning (Fb) which one typically doesn't want in a corner loaded app. Again though, some efficiency can be traded for a lower F3 if desired since you have plenty of power and with a Fb <30 Hz it will play at least just as low as a M19 and if there's enough room gain, at a higher efficiency.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Cool now were cookingWhatever cab you think will sound the best down to 30 hz at this point I'm not worried what the actual shape looks like because with dual 416's a 511E/288 and EV T350 it's going to look pretty darn good regardless.
[quote=GM;1830870][QUOTE]I love the 820 it is one of the coolest looking speakers Altec ever made IMO with the little 808 multicell.In the times the 820 was designed for, full-range reproduction ('HIFI') was ~50-11 kHz with acceptable being only ~75-7 kHz and when driven with a period correct high output impedance it was nominally flat in-room to a half octave above/below this, so a stellar performer for its time.
That's essentially what I use most of the time I have a lot of vinyl.I bought a lot of the Mobile Fidelity Sound Lab Master Recordings.With a nice cartridge on my turntable they sound fantastic,nothing sounds better than those analog recordings.The gold CD's come in second IMO.So if we can get the LF cabinet to sing down to 30 Hz and the super tweeters that go to 23 kHz I think they would sound quite nice.Today, with our ~16-20 kHz BW available on some music CDs we would need a ~11.3-28.28 kHz ~flat BW which no consumer system can come close to AFAIK, so by today's SOTA requirements it's woefully inadequate without a sub and super tweeter, but if all you do is spin vinyl and/or old tapes and/or mass market CDs, then you'll be hard pressed to want/need more BW.
Exactly ! The sill plates that go all the way around the top of the foundation are 6" x 8" with mortise and tenon joints that look like squared off trees.You don't see work like that anymore it is a lost art for all intensive purposes.Cool, back in the days when squared off trees were used for floor, ceiling joists in all but the cheapest construction and if you live above the Mason-Dixon Line it's further ~'bulletproofed' for snow/ice.
This is were I need your recommendation, what design should we use to get to 30 Hz while keeping it small enough to still be manageable ??OK, that ear height is typical here in the USA, so it's your call as to which layout to use, though being use to the M19's so-so driver spacing WRT its XO point/slope that I wanted to improve on, you may find your preferred over/under layout as sounding very similar if a 500 Hz XO is used. Go with a higher XO point though and you'll need to roll off the lower woofer for best performance overall.
Added: Also which design would allow for more adjustment in case I need to do some tweaking.
Again, it's your physical limits combined with its tuning that sets its usable gain BW, so in the LF BW it doesn't matter whether two separate cabs or one big one is used, i.e. either will only 'sing' down to 30 Hz if tuned at least this low and EQ is used to flatten its in-room response enough.
I don't have any experience with a MTM that puts the bottom woofer at floor level where it will have more gain than the top one plus for me personally the horn is too low for the seated ear height, so it's your call whether to use the MTM or TMM.
If I were you then, I'd cobble together two 34" W x 70" H OBs, one an MTM and the other a TMM using a 500 Hz XO and compare their basic sonic signatures to see which layout sounds the best overall.
Skip the ST since all you're interested in is comparing vertical sound-staging/imaging from ~250-2500 Hz. Ideally you would use EQ to limit them to ~this BW.
Neither. The only physical tweaking would be internal damping and vent length, so use threaded inserts to mount the driver for easy removal and make separate removable vent mounting board(s) as required. Properly phasing the horn is best done digitally. I recommend putting the XOs for all speakers in a separate box located wherever the rest of the electronics are for ease of tweaking them.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
[quote]The more I thought about it,the more I like one cabinet.With a MTM design the horn will be essentially in a fixed position (No Adjustment) with a TMM I could angle the horn down into listening position I have adjustable brackets for the sectoral horns.
Again with the MTM the horn is fixed at 35" although I just measured my 19's and the 811 is centered at 33 1/4" and they sound great.I'm leaning toward the triangular TMM just for the sole reason of being able to adjust the horn angle if the horn is up high I can point it down into the listening area.At 15' to 18' distance I'm pretty sure they will blend enough to not notice.I just wish I had the room for horizontal positioning.I don't have any experience with a MTM that puts the bottom woofer at floor level where it will have more gain than the top one plus for me personally the horn is too low for the seated ear height, so it's your call whether to use the MTM or TMM.
Sounds like a plan.I like this idea a lot.Open Baffle should be easy enough to buildIf I were you then, I'd cobble together two 34" W x 70" H OBs, one an MTM and the other a TMM using a 500 Hz XO and compare their basic sonic signatures to see which layout sounds the best overall.
OK that's easy enough then after cabinets are built all I have to do is add or subtract fiberglass insul.(damping) and (shorten/lengthen) (ports/vents) as required. Thanks Again GM for all your help.:thankU: My Regards ~ JohnNeither. The only physical tweaking would be internal damping and vent length, so use threaded inserts to mount the driver for easy removal and make separate removable vent mounting board(s) as required. Properly phasing the horn is best done digitally. I recommend putting the XOs for all speakers in a separate box located wherever the rest of the electronics are for ease of tweaking them.
GM I wanted to check one thing with you the TMM design is still triangular correct this is the best shape regardless if it is one cabinet or individual cabinets. correct ??? I'm going to do the OB mock ups like you said when I get them done I'll email you pics. :thankU: John
Posting Permissions
Bookmarks