HF 811b sectoral horn mounted in large A210 mid-bass horn mouth?

[Bigun]

Was looking at all the interest in A7 VOTT and saw some work on ‘split‘ 210 cabs. I think the taller vertical horn (split 210) might be more home-friendly as well as having a lower cutt-off. But it pushes the hf horn far away from the mid-bass driver which must be bad for anything other than a huge room in terms of integrating the sounds at the listening position. So why not embed the hf horn into the curved wall of the mid bass to narrow the gap?

 

[GM]

Yes, a good option if centered in front of the woofer (rear of CD can be quite close to 'taste' to act as a crude phase plug) and rotated vertically to match polar responses (wide horizontal/narrow vertical) now that DSP can time/phase align them and experiment with XO point from 800 - 1600 Hz and of course 'stick a sock' over the CD to quell reflections back to the woofer and at least a damping strip on one parallel side opposite the woofer (personally covered all of one side with my dual driver ones) .

If wanting to vent the woofer, then vertical slit vents down each side in the bottom flare ala' Synergy concept if small, otherwise horizontally across the bottom front or both ends as these folks do.

 

[Bigun]

I'm not sure about a phase plug, when I read about these things they are very carefully designed for h.f. extension and have to be a particular shape etc.

I thought maybe better to search and read up a bit more on nested horns. However, what I got was not what I expected...

 

[Bigun]

I had better luck searching for Coaxial horns.

 

[GM]

The horn acts as a crude plase plug, so need to damp the CD to quell any reflections back to the woofer, but otherwise the XO is going to be well below this BW, so moot WRT altering it's upper mids response.

 

[AllenB]

in terms of integrating

It depends. However, at this stage there's little rhyme or reason to your horn choices and knowing what you find most important about horns would help you make those choices. It takes time, and compromises need to be identified and balanced. For example just one of those compromises that springs to mind is you're talking about getting them close, where the sectoral horn has a short vertical dimension and this raises the crossover frequency and shortens wavelengths.

 

[GM]

Yeah, as I previously noted, the 811 needs to be vertical to ~ polar match them, i.e. narrow vertically, wide horizontally.

 

[Bigun]

‘rhyme or reason’…. I have a pair of Altec 1202’s bought off a local chap, an impulse buy after reading about Altec speakers one day. This partly because I have a pair of DIY Khorns in my basement that use 511B with 808-8A’s which sound really nice but are more or less dedicated for movies. So I have these 1202A ‘disco’ speakers that are sitting in my garage and I’m looking at them wondering what to do with them. My gf says they’re ugly and I read that they aren’t the best speakers Altec ever made so can I put some lipstick on these pigs and use them for garden bbq’s or do I need to tear them down and make something better, something hi-fi’ish out of them for music listening. I was thinking of making a new pair of cabs and putting the woofers in a mid-bass horn where distortion is lower due to less cone motion. I wondered whether I could make something proven, famous, of Altec lore, despite not having holy grail woofers to work with. Not worth going overboard then, something reasonably easy for me to build or I'd be better to walk away and start over with some new Great Plains woofers, a larger budget worthy of all the time and effort. So, keeping it simple - where is the fame and glory with Altec at? The A7 gets lots of thumbs up and there are plenty of photos of them looking nicely made out of stained wood with a reasonable build effort and cost.. I thought OK, A7, but then I started to look more closely and of course then the limitations become more visible. I should’ve just started sawing wood. But no, I start noticing that the A7 is a wide box and so will be harder to place in a home setting and after all that it doesn’t do much bass from what I gather. Could add a sub but that’s more drivers/$ and more boxes and now the whole thing is just getting out of hand. Maybe the A7 can be pushed to go lower so I read on and I see plenty of accounts on the web of folk trying to do just that but these attempts give me the feeling of it being more of wishful thinking than producing actual bass. So I thought, how about turn the A7 mid-bass horn through 90 degrees to make it a narrower box, fixes that limitation, and increase the mouth size vertically, making it a longer horn, hopefully to lower the cut off some. And would I know it, but such a thing already exists in the form of the split A210. Amazing how the internet leads you on a journey like this. So I thought perhaps the split A210, it’s still an Altec of lore and fame even if not The A7, it could be a relatively easy to build, be elegant looking and give some home listening hi-fi experience as it reputedly goes deeper than the A7. I saw a few examples of people with split A210’s with sectorial or multicell h.f. horns perched up on the tops. That puts the two horns quite far apart whereas I noticed the A7 cleverly keeps the two horns close together so I concluded maybe this is something I gotta give due consideration. So I got thinking about being cleverer than all those Altec designers and moving the mid-woof and tweeter closer together. This means making something unproven, risky even, and I just wanted a simple project to justify my impulse purchase of a pair of 1202’s. Hope that clears up the reasoning so far ?

 

[Bigun]

’what you find most important about horns’… unstrained, unconstrained, clean sound, even with modestly powered amplifiers. This is what I find most important about horns.

 

[AllenB]

Using these as learning tools should put you ahead of the curve, so it's good you've decided to entertain them for a while.

The things mentioned about shapes don't have to be that bad. Room treatments can substitute if you understand the limitations. Maybe a nice ceiling cloud.

I wouldn't push the driver spacing issue without understanding the tradeoffs and solutions and if I did, I'd first look at proper adjustment of the crossover with everything else as is.

It's going to be beneficial to have access to EQ, and at some stage a multi-sub arrangement can help your room, regardless of which speakers are in it.

 

[Bigun]

It's an old question, but any thoughts on the pros/cons for putting my altec woofers into an A7/A210 FLH vs putting them into a BLH (aka scoop) ?

The thought popped up after noticing this: https://josephcrowe.com/blogs/news/15-back-loaded-horn-no-2095

 

[GM]

BLH loads (a lot if using the low Fs woofers) lower and over a wider BW, so your call.......