over and under dual 414's cabinet help

[lokie]

I'm more of a sawdust guy than a computer model and math guy, so, please indulge my request for assistance in the designing of a cabinet for dual 414's.

What would be the optimum front baffle dimensions for two 414's on top of each other for home use hi fi? And what would be optimum cabinet volume?

I have subs, so the bottom end extension is not critical... say below 60/80hz.

For the top end, I have several horns and drivers I will experiment with but am leaning towards an Altec 32B Horn/800 variant combination.

Thanks in advance for any help.

[jocelys1]

The Altec Malibu (843a) might fit what you're looking for (vertically placed 414s)

The Altec Carmel or 9844 are options, but they don't meet your vertical requirement. Both these are horizontally placed drivers.

[mah]

Plan;

http://www.lansingheritage.org/image...ure/page11.jpg

[GM]

What would be the optimum front baffle dimensions for two 414's on top of each other for home use hi fi? And what would be optimum cabinet volume?

I have subs, so the bottom end extension is not critical... say below 60/80hz.

For the top end, I have several horns and drivers I will experiment with but am leaning towards an Altec 32B Horn/800 variant combination.

'Optimum' depends on room location, acoustics, but if the baffle's at least 30" wide, then generally no efficiency robbing baffle step compensation [BSC, up to 6 dB lost] is required.

FWIW, the 32B is too small to blend all that well to vertically oriented dual 12" in a HIFI app [acoustic center is between the two], so normally recommend rolling off the lower one for BSC, but since you only need 60-80 Hz, recommend horizontally opposed on 30" baffle.

Cab volume [Vb], dims depends on several things for best overall performance, so what's the system output impedance, sub system XO point/slope, average seated ear height?

GM

[lokie]

Fellas- Thanks for the 843A heads up.

"Optimum' depends on room location, acoustics"

I will be glad to post a schematic of my room. I sit 15' away from the speakers. behind the speakers are half walls, so kind of like corners but open between the speakers. See pictures. The grates in the floor are Infinite Baffle subs w 2-15" woofers per side.

"but if the baffle's at least 30" wide, then generally no efficiency robbing baffle step compensation [BSC, up to 6 dB lost] is required."

Not sure what this means except that as long as the baffle is 30" wide I'll be in good fine??

"FWIW, the 32B is too small to blend all that well to vertically oriented dual 12" in a HIFI app [acoustic center is between the two]"

OK. But I just love this horn as it integrates seamlessly with my 15" woofers i have now. I'm not a fan of 511 and 811's. And I only have 1" CD's (802B's).

Working on acquiring another 291B but as of right now, I only have one. (anybody??). Then i can experiment w larger horns.

" normally recommend rolling off the lower one for BSC, but since you only need 60-80 Hz, recommend horizontally opposed on 30" baffle."

What's BSC? Are you saying side by side is better?

"Cab volume [Vb], dims depends on several things for best overall performance, so what's the system output impedance, sub system XO point/slope, average seated ear height?"

My amp (Eico HF-60's) are set up for 16ohm drivers. Is that what you are asking?

My ears at my sitting position is 38" off the ground.

IB Subs.jpg

[lokie]

'Optimum' depends on room location, acoustics, but if the baffle's at least 30" wide, then generally no efficiency robbing baffle step compensation [BSC, up to 6 dB lost] is required.

FWIW, the 32B is too small to blend all that well to vertically oriented dual 12" in a HIFI app [acoustic center is between the two], so normally recommend rolling off the lower one for BSC, but since you only need 60-80 Hz, recommend horizontally opposed on 30" baffle.

Cab volume [Vb], dims depends on several things for best overall performance, so what's the system output impedance, sub system XO point/slope, average seated ear height?

GM

Fellas- Thanks for the 843A heads up.

"Optimum' depends on room location, acoustics"

I will be glad to post a schematic of my room. i sit 15' away from the speakers. behind the speakers are half walls, so kind of like cornmers but open betwean the speakers.

"but if the baffle's at least 30" wide, then generally no efficiency robbing baffle step compensation [BSC, up to 6 dB lost] is required."

Not sure what this means except that as long as the baffle is 30" wide I'll be in good fine??

"FWIW, the 32B is too small to blend all that well to vertically oriented dual 12" in a HIFI app [acoustic center is between the two]"

OK. But I just love this horn as it integrates seamlessly with my 15" woofers i have now. I'm not a fan of 511 and 811's. And I only have 1" CD's (802B's).

Working on acquiring another 291B but as of right now, I only have one. (anybody??). Then i can experiment w larger horns.

" normally recommend rolling off the lower one for BSC, but since you only need 60-80 Hz, recommend horizontally opposed on 30" baffle."

I don't know what BSC is. Are you saying side by side is better?

"Cab volume [Vb], dims depends on several things for best overall performance, so what's the system output impedance, sub system XO point/slope, average seated ear height?"

My amp (Eico HF-60's) are set up for 16ohm drivers. Is that what you are asking?

My ears at my sitting position is 38" off the ground.

[lokie]

"Optimum' depends on room location, acoustics"

Pictures are worth a thousands words as they say.

First picture is a view from behind the listening chair (old speakers).

middle image is a layout of the room. Notice the halfwalls behind the listening chair as well as just behind the speakers.

Third picture is current speakers. Notice the grates in the floor which are infinite baffle subs with 2-15" woofers per side.


DSC_0002.jpgimg016.jpg

[GM]

"but if the baffle's at least 30" wide, then generally no efficiency robbing baffle step compensation [BSC, up to 6 dB lost] is required."

Not sure what this means except that as long as the baffle is 30" wide I'll be in good fine??

"FWIW, the 32B is too small to blend all that well to vertically oriented dual 12" in a HIFI app [acoustic center is between the two]"

What's BSC? Are you saying side by side is better?

My amp (Eico HF-60's) are set up for 16ohm drivers. Is that what you are asking?

You're welcome!

Build a narrow speaker that sims flat and when put in a room well away from walls the sound will begin rolling off at whatever the baffle's lower corner frequency is because the frequency sound 'bubble' gets too large to 'set' on the baffle [half /2 pi space], so begins folding over the baffle with decreasing frequency into full [pi] space and bye-bye [mid] bass.

BSC rolls off/'shelves' the bandwidth [BW] above this corner frequency to keep it tonally balanced like the sim predicted. Make the baffle wide enough and don't move it too far from the back wall and no obviously audible BS loss occurs. I haven't needed BSC and apparently all the folks who have built my 30" wide cab designs haven't either AFAIK. Some have even claimed there was too much [mid]bass for their app, either adding more damping and/or tuning them lower, another indication that a 30" baffle's wide enough.

Assuming you're going to XO the 32B with a 9844's XO or similar, then its horizontally mounted drivers seems a better choice overall as it will allow using Altec's c-t-c spacing: http://www.lansingheritage.org/image...closures20.jpg

Well, I was asking for the amp's series resistance/damping factor [DF], but found it's 12, so with 16 ohm drivers it's 12/16 = 0.75 ohms, not a significant enough amount to affect a fairly large cab alignment.

GM

- - - Updated - - -

This room looks familiar; have we discussed this room previously, maybe on another forum?

Anyway, it's a series of high tuned cavities, each one acting mostly as a lossy room, so are these going to replace the A8s?

GM

[Elitopus1]

Well, I was asking for the amp's series resistance/damping factor [DF], but found it's 12, so with 16 ohm drivers it's 12/16 = 0.75 ohms, not a significant enough amount to affect a fairly large cab alignment

Slightly OT, and not trying to threadjack, but what if the OP had an amp with a higher damping factor? Lets say it is 250 @ 8 ohms. How would that affect the speakers? Just trying to get my head around how the damping factor works.

I have heard different things about what the damping factor does to a speaker. But with everything else the same, how does this change things? And if we said his speakers were 8 ohm, and you did the equation 250/8=31.25, what does this change versus the small number you got from 12/16=.75?