Help with ideas for Altec mid-bass front horn using 416's

I'm developing a two-way horn system, using 416 for bass and 902 for horn...probably 511 or 811 style.

I've looked at the large Onken bass cabinet...but I want to build a horn for the mid-bass that provides decent slam and attack to match the top horn.

I already have the GPA 416's, so I'm keen to try a horn for these drivers.

Opinions and help greatly apprecoated on what's available...and I'll be building the horns myself.

Some restrictions -

Cabinet size not to exceed 700mm deep...width OK...height OK.

I have small tapped horns to cater for the 30-80Hz range...so 70/80Hz target is sought...perhaps 90Hz at a pinch.

Upper cross-over around 800.

I've looked at a tractrix horn, with slotted (onken style) ports to aid bass depth. Cabinet size is quite good. On the b-d Design show room page, there's an example here. Another here.

Volvotreter has a very good small bass horn as well, see here.

I'm wondering how these style horns would compare with, say, the Altec 816? Should I consider the larger dual driver 817? (Cabinet depth 67cm, good.)

Are there any other designs worth looking at? For example, a modified 816 with dual ports for slightly lower bass extension (that is, same shape as 817, but with one driver?

Sorry for so many questions...but I'm really keen to get the right bass sound for my listening style.

Kind regards.

Andrew

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Originally Posted by atilsley

I'm developing a two-way horn system, using 416 for bass and 902 for horn...probably 511 or 811 style.

I've looked at the large Onken bass cabinet...but I want to build a horn for the mid-bass that provides decent slam and attack to match the top horn.

I already have the GPA 416's, so I'm keen to try a horn for these drivers.

Opinions and help greatly apprecoated on what's available...and I'll be building the horns myself.

Some restrictions -

Cabinet size not to exceed 700mm deep...width OK...height OK.

I have small tapped horns to cater for the 30-80Hz range...so 70/80Hz target is sought...perhaps 90Hz at a pinch.

Upper cross-over around 800.

I've looked at a tractrix horn, with slotted (onken style) ports to aid bass depth. Cabinet size is quite good. On the b-d Design show room page, there's an example here. Another here.

Volvotreter has a very good small bass horn as well, see here.

I'm wondering how these style horns would compare with, say, the Altec 816? Should I consider the larger dual driver 817? (Cabinet depth 67cm, good.)

Are there any other designs worth looking at? For example, a modified 816 with dual ports for slightly lower bass extension (that is, same shape as 817, but with one driver?

Sorry for so many questions...but I'm really keen to get the right bass sound for my listening style.

Kind regards.

Andrew

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Pick your poison ;

http://www.hostboard.com/forums/hbmc...2013/01/18.jpghttp://www.hostboard.com/forums/hbmc...2013/01/19.jpg

:)

Quote:

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Originally Posted by atilsley

Sorry for so many questions...but I'm really keen to get the right bass sound for my listening style.

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How your room is set up, the location of your speakers and the acoustic treatments you employ in the space will affect the bass response far more than small differences in enclosure configuration.

As Earl's references imply, 700 mm is too short, so must be folded, making a high SQ 800 Hz XO very 'iffy' with a 416 or any other mid-bass horn driver.

GM

Hoffman's Iron Law is visited once again. :D

Thanks guys

How about this from David Haigner?

Mouth is 840 x 650mm.

My drawings is the CAD 3D image....

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Originally Posted by bowtie427ss

Hoffman's Iron Law is visited once again. :D

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My education continues. I never heard of Hoffmam's Iron Law before:

Sensitivity and Hoffman?s Iron Law, or ?why you can?t have your cake and eat it too?

Given my current commitment to OTL amps, I am relegated to relatively low power. So I need high sensitivity and a sizable cabinet. Hoffmans Iron Law does not address the usual deterrent to this...the girlfriend/spouse. Get rid of her and the problem resolves itself.

Quote:

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Originally Posted by atilsley

Thanks guys

How about this from David Haigner?

Mouth is 840 x 650mm.

My drawings is the CAD 3D image....

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You're welcome, but no clue without design details, but again, your 70 cm depth precludes a 70-90 Hz XO point at any HF horn matching efficiency/transient response unless you increase the number of low Qt mid-bass horn drivers to further truncate it.

GM

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Originally Posted by GM

You're welcome, but no clue without design details, but again, your 70 cm depth precludes a 70-90 Hz XO point at any HF horn matching efficiency/transient response unless you increase the number of low Qt mid-bass horn drivers to further truncate it.

GM

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Thanks GM

Yes, I realise now the xover will be closer to 100Hz, not 70. I'm OK with that, as the objective for this assignment is bass attack, without a massive cabinet. If that means 100Hz xover, so be it. I can't imagine Haigner promoting an expensive product in Europe if the bass wasn't fairly good. Remember, I still have dual tapped horns running nicely up to 100Hz. These are punchy and fast.

Last night I started on a to-scale mock up.

You're welcome!

Even if Haigner's has rear vents I can't imagine it having what I consider proper bass response for good bass attack. Vents tuned high enough will have an 'impossible' phase response through the XO BW and tuned low enough will lean out the mid-bass too much for the TH's to fill. Like bowtie noted, the physics of the situation is against it.

Then again, the pair of DSL DTS20s I auditioned in Gainesville, Ga. didn't strike me as either punchy or fast, just 'accurate', like a good TL or very low tuned EBS, so have to wonder if we're having a failure to communicate. The Synergy horns OTOH had plenty of punch, speed, but then look at how deep they are, then you would have to add the depth of the compression chamber.

GM

Always a journey getting this tight.

Do you have a personal choice on the bass, given what we've discussed?

I could always build an A5/7 and shorten the height to make more room friendly, but I don't really want to bastardise that or any other design.

Kind regards

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Originally Posted by GM

You're welcome!

Even if Haigner's has rear vents I can't imagine it having what I consider proper bass response for good bass attack. Vents tuned high enough will have an 'impossible' phase response through the XO BW and tuned low enough will lean out the mid-bass too much for the TH's to fill. Like bowtie noted, the physics of the situation is against it.

Then again, the pair of DSL DTS20s I auditioned in Gainesville, Ga. didn't strike me as either punchy or fast, just 'accurate', like a good TL or very low tuned EBS, so have to wonder if we're having a failure to communicate. The Synergy horns OTOH had plenty of punch, speed, but then look at how deep they are, then you would have to add the depth of the compression chamber.

GM

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Given the depth limitation, don't have one for a single driver unless the XO is higher.

Earlier, I fiddled with Bruce Edgar's old short 80 Hz horn, but at least with the 416 it didn't look doable. For an 800 Hz XO, the early 825 cab's horn is the shortest one to have, but as shown earlier, it needs a ~150 Hz XO.

Adding 3.56" to it to get to 70 cm will only lower it down to around 136 Hz if a bigger mouth is acceptable, though if GPA says the rear cover can be right up next to the motor, then the path-length can be a bit lower assuming an even larger mouth. Both would still be the original's ~112 Hz flare frequency, so that's the limit.

I did some ages ago that performed well down to 80 Hz, but it was close to 4 ft deep since it had the same path-length as the 210/211.

GM

I am wondering, since we are talking about strick depth limitations, are these speakers going against a wall and we just don't want them sticking out too much? 'Cause if so, the bass response is going to be limited anyway.

Loudspeakers need to be away from the wall, out into the room a bit an allowed to "breathe" for the fullest sound. Unless they are specifically designed as a wall or corner speaker, but that's not we're discussing here.

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Originally Posted by alancohen

I am wondering, since we are talking about strick depth limitations, are these speakers going against a wall and we just don't want them sticking out too much? 'Cause if so, the bass response is going to be limited anyway.

Loudspeakers need to be away from the wall, out into the room a bit an allowed to "breathe" for the fullest sound. Unless they are specifically designed as a wall or corner speaker, but that's not we're discussing here.

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Alan, unfortunately, that's also a limitation.

See attached pics of my room...you see it's part of the main house...so a trade-off for me as I don't want to be tucked away in a man cave.

So - back to the challenge, GM, what if my target xover point was increased again to 150? Would this notion of a 'simple' front-loaded mid bass be a suitable speaker for my home listening? I'd then need to reconfigure the subs, as they get a bit rattled around 100Hz.

Oh, also, last night I removed the legs of the current Altec bass cabinets, and reduced the slot by 1/3...bass improved significantly.

On the weekend, I'll test MiniDSP for the bass...adding some EQ and playing with xover points.

All this stuffing around is hardly encouraging...I might just end up keeping the current boxes, aka, Model 19 style.

Quote:

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Originally Posted by alancohen

Loudspeakers need to be away from the wall, out into the room a bit an allowed to "breathe" for the fullest sound.

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Horns project, so only need long rooms to 'breathe' and near/at a boundary only applies to the BW below its cut off, which benefits by being inside a 1/4 WL away from a wall, corner, floor or all of the above; you just need to account for it in the rear chamber tuning.

GM

So, GM, a different approach at questions -

If you were in my situation, given constraints discussed, what would you choose?

Kind regards.

Andrew

I can't really honestly answer since I haven't/wouldn't put myself in your situation. It's a lovely room, but so ill suited for what I consider 'critical' listening that right off the 'top of my head' I got nothing.

Really, a large mono system in a d?cor complementary furniture cab, or better yet for horn loaded, an early console stereo such as JBL's Paragon seems the best compromise, especially considering your woodworking skills, but adapting it to Altec components would take way more time/effort than I have to devote to it.

GM

Quote:

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Originally Posted by GM

I can't really honestly answer since I haven't/wouldn't put myself in your situation. It's a lovely room, but so ill suited for what I consider 'critical' listening that right off the 'top of my head' I got nothing.

Really, a large mono system in a d?cor complementary furniture cab, or better yet for horn loaded, an early console stereo such as JBL's Paragon seems the best compromise, especially considering your woodworking skills, but adapting it to Altec components would take way more time/effort than I have to devote to it.

GM

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Thanks. I guess one person's critical listening requirements is another's general music listening enjoyment in a normal house. I understand the difference..but I'm still trying to build a great system....but perhaps it won't be up to the laboratory/studio 99.99% standard. Hence me looking at Model 19 and similar designs. Thanks for your insights. Kind regards.

Understood, but unfortunately, a great system is only as good as the room it's in and where in the room it, and the listener, is located. You can overcome much of it with large horns that control directivity down to ~300-500 Hz, but the trade-off is a large mouth with either a lot of depth or multiple drivers to truncate it.

GM

Thanks...btw, what's your main speaker system? Amps? Thanks