My 19 build begins in earnest - H811b arrives....

[Coelacanth]

Hi Steve. Thanks very much for your input here.

Firstly, I found this tiny (about 5mm long) maker's mark stamped into the horn - "WD Co". This seems to attest to Altec having at least for a time, outsourced the casting work....



Re your technical observations and advice... I am not even close to having more than a very basic understanding of this stuff.. What I do have is curiosity and some skill with tools and equipment. If there is a better design, more suited to the GPA 902 driver I intend to use in this build, well, I am happy to build it. But someone would have to supply me with plans, because there is no way I could work it out myself at this point.

One of my plans however is to experiment with different horns once I have the 811 copies up and running (along with the rest of the system!), so I am happy to continue as planned with these.

I do appreciate the suggestions - and if you can point me to plans for any horn you deem more suitable, I will gladly take a hard look at them :-)

[westend9]

Check out the A300 radial horns in post #6 of this thread. There are also some comments on the 811 from Steve Schell in post #11.

I've been tossing around the idea of a wood horn for the 802 but, actually, I find very little wrong with the 811 for my listening habits. I have heard better horns that have a more dispersed presentation and a finer sound (large format drivers, to be exact) but the 802 is a damn fine driver and my 811's work all right for me. If there is a next iteration it may be a wood horn with the larger format drivers.

[Altec Best]

Hi Steve. Thanks very much for your input here.

Firstly, I found this tiny (about 5mm long) maker's mark stamped into the horn - "WD Co". This seems to attest to Altec having at least for a time, outsourced the casting work....



Re your technical observations and advice... I am not even close to having more than a very basic understanding of this stuff.. What I do have is curiosity and some skill with tools and equipment. If there is a better design, more suited to the GPA 902 driver I intend to use in this build, well, I am happy to build it. But someone would have to supply me with plans, because there is no way I could work it out myself at this point.

One of my plans however is to experiment with different horns once I have the 811 copies up and running (along with the rest of the system!), so I am happy to continue as planned with these.

I do appreciate the suggestions - and if you can point me to plans for any horn you deem more suitable, I will gladly take a hard look at them :-)

Where on the horn is this stamp ?

[Coelacanth]

I'll take a pic in an hour or so, but its on outside of the shell, towards the middle, behind where the central cabinet mounting screw hole is - it is present on both halves of the horn.

[Coelacanth]

[GM]

Hi GM, I am still open to the MLTL thing, in fact I would prefer to go that way. Just been waiting for your input.. not sure if you are getting my emails? Perhaps not. I will go the 19 duplicate route if the mltl option is beyond my ability to resolve.

Greets!

OK.......

?? I?ve only gotten one PM and I responded to it plus responded to your Qs in one of the earlier threads, so AFAIK, this one is all that?s left.

What's wrong with Westend's except done up in a stretched version of the M19?

GM

[Coelacanth]

Hi GM thanks for coming back to me. I did send an email but it must have gone astray... The stretched 19 idea is spot on what I was thinking. I need some help with the interior box dimensions for the GPA drivers however. Could you be called upon to help there? I have the TS parameters from GPA, who assure me they are pretty close.....

Thank you Sir, and feel free to tell me to bugger off if I am asking too much :-)

[GM]

Greets!

You're welcome!

Well, since you're already comfortable with the 19's width, depth, horn section, spacer/pedestal, nothing except the bass bin height changes along with the vent, bracing.

The driver will still be the same distance down from the top to preserve all of the aspects of the XO 'voicing' save one, so what?s the max height the centerline of the horn can be from the floor and roughly how high is ya?ll?s seated ear height?

GM

[Coelacanth]

Thanks GM..

Very comfortable with the dimensions of Westends mltls, which he has provided on his build page and elabourated on via pm. (Thanks L!)

Happy to proceed with similar height - I guess I really just need to know if the GPA t/s parameters dictate something different to Westend's - given that he used original Altec drivers...

I plan to make the top hat tilt adjustable - even completely removable - allowing for different room / seating positions, and also so I can experiment with different horn designs.

I could also make the bass bin tiltable... so lets set the upper limit at 2.0m tall and work backwards down to reality :-)

Thank you good Sir.

[GM]

You?re welcome!

OK, if the size of his is fine and doesn?t make the horn height too high, then just build it with the driver down 9? o.d. from the top same as the M19. Note that there will be no opening to acoustically couple the horn cab to the bass bin, so there must be some serious damping in the spacer cavity to keep it from ?drumming?, so consider filling the void with scrap knot, void, free wood, drywall or similar. This also helps to mass load the [ML]TL to the floor.

The cab is large enough to have considerable latitude spec wise and cover pretty much all the different 416 specs with enough room to spare to allow/need some form of EQ to flatten it out in room. With rare exception, all the cabs I?ve used/designed are technically too big based on T/S specs.

I currently don?t have access to the sim or my write-up, but just from what I found on his build thread you can add up to 6 ohms of series resistance before the cab starts getting acoustically small based on GPA specs, so plenty of tuning flexibility.

GM