Mini VOT ?

[freddi]

how about a 0.7 scale VOT (other than 2 cubic foot rear chamber with a 12 pe32 ? sim - -no drawing

https://i.imgur.com/bLaEJoV.jpg

 

[freddi]

scaled 0.7 and excess reflex volume removed, the cabinet would look more like a cute, ~20.75 wide, ~16.75" deep and maybe around 20-20" tall

total bulk around 4.3 cubic feet - a couple of these topped with a good horn plus
a tapped pipe sub might make a fun little system

power handling with a Kappa12a is only around 35w at 76Hz with the rather large
2 cubic foot reflex chamber

 

[Pano]

I used to have one made by University Sound scaled to use a 12 inch driver. It was OK, but nothing special like the big one.

 

[freddi]

maybe its just one of those things which has to reach a certain size to really work well - can you remember what 12" it ran ?

fwiw, here's a sim of full size A7/515 vs 0.7 scale front horn, 2CF reflex chamber and Kappa12a - 12pe32 might be a bit louder in the lower mids, weaker on the low end (overdamped)



https://i.imgur.com/1Ugzohk.png

 

[GM]

Hmm, you should be comparing the mini to an 816, which has a much different response than the 825/828 cab [top two plots]: http://www.lansingheritage.org/images/altec/specs/components/515g/page3.jpg

The big problem when scaling the 825/828 is finding a driver with the right specs and from dim memory one has to drop down to quarter scale to do it with typical 'off the shelf' drivers.

GM

 

[freddi]

look at Burwell and Sons ICON and its prototypes - I've never heard of that company

ICON is stated as 22"x22"x28" in size - - deeper than 0.7X

12pe32 might be ok - - maybe too lean - its ok in a K12 -never have tried it in my RCA-Fan midbass horn.

would the 816 scale better to a 12? - I'm curious is such a thing is workable

Burwell & Sons ICON
Burwell and Sons Loudspeakers


Proto types - look at #14
Burwell and Sons Loudspeakers

 

[GM]

Dunno, the problem is that the 825/828 rear chamber/vent acts as a crude two chamber [ML] BLH whereas your mini is more like a [ML]TQWT, ditto Burwell's.

GM

 

[freddi]

wonder how that might throw the prediction off? - could it have a nasty hole in the response? I remember some cabine in Speaker Builder magazine having some real problems

 

[GM]

Note that the 825/828 has a 'fuller' horn low end Vs the 816's sloped roll off.

GM

 

[freddi]

maybe that is a better choice - wonder if there's already a hornresp model for 825/828? Burwell and Sons apparently use vintage Altec 15 in their little 22" wide horn.

my builder finally had time to buff the finish on a 0.83X Belle - don't know how it will do on the top end but sure is shiny

https://i.imgur.com/HNS8hHt.jpg

 

[lhorn]

There is a small cabinet for the Pioneer PE-101A which looks quite like a mini VOT. Plans were provided by Pioneer as a cabinet sugestion for this driver.

Unfortunately, the site with the plans is not available any more. The place where I discovered the plans was a Japanese website: ?????????????????????????????.

 

[GM]

Scroll down: Pioneer PE-101

GM

 

[GM]

wonder if there's already a hornresp model for 825/828?

my builder finally had time to buff the finish on a 0.83X Belle [/url]

Not that I'm aware of; I keep planning to do it to teach myself how to use HR's compound horn, but..........

Cute!

Attached stock size vent 825/828 if just a reflex. Note how high tuned, 'peaky' when not BH loaded, even such a crude one compared to the earlier posted response:

GM

 

[freddi]

Thanks GM - there may be some subjective quality in the old Altec cone drivers lacking from a lot of today's pro speakers.

 

[GM]

You're welcome! Depends, are there any with the really high Vas the pioneers used?

GM

 

[freddi]

that little thing is ridiculously cute ! are there any cheap/cheerful FR ith fs ~80, qts ~0.5 for it?

https://i.imgur.com/nI88C1S.jpg

I think that Youtube FE206 mini might almost work

YouTube

 

[GM]

Not that I'm aware of. Maybe better to use a small wide range woofer and perch a little horn on top.

GM

 

[freddi]

yeah - a horn on top would look more "proper" - I've never heard an A7 other than one in a local hi-fi shop around 1970 driven by solid state - might have had a symbiotic diaphragm CD as there were no high F's compared to other speakers. (AMT were popular then - that shop sold B&O, JBL, Advent and Design Acoustics speakers)

 

[GM]

1970 was the Symbiotic's intro, so if a new A7, then it probably had them, though if SS driven with no CD horn EQ all the Altec 1" compression drivers at the time would roll off ~ 6 dB above ~ 1 kHz and drop like a stone above ~ 10 kHz. In either case the Symbiotic will sound much 'sharper' similar to a Ti diaphragm, so not really HIFI compared to the much 'smoother' alum. and later Pascalites.

GM