Alpair 7.3 Bookshelf Bass Reflex?

[StevenZ]

Hey guy,

So I've been playing with my Alpair 7.3's lately and have put them in a small 7l sealed enclosure for office duties. They're lacking a bit of bass and I was wondering if anyone out there had any cabinet plans for a 7.3 bookshelf made out of 18mm material. Any help is appreciated!

Thanks,
Steven

 

[planet10]

Hi Steven,

To get any bass out of A7.3 you really need a box with a hole in it, and if it is a bookshelf then it is likely a reflex enclosure (althou, the folded halfTower ML-TL should do reasonably well with the A7,3)

dave

 

[tuxedocivic]

Hey,

I use the EL70 in a 7L sealed box on my desk and it's pretty bass shy. I knew it would be. So I add bass boost. Tons of it. Works like a charm. I also correct for baffle step with the same program. I've just been using Realtek in windows.

You can see what I did here

I may upgrade these to the alp 7 one day.

 

[StevenZ]

Hi Steven,

To get any bass out of A7.3 you really need a box with a hole in it, and if it is a bookshelf then it is likely a reflex enclosure (althou, the folded halfTower ML-TL should do reasonably well with the A7,3)

dave

Thanks Dave. Any chance you could whip up a quick bass reflex bookshelf for the A7.3 using 18mm material? I doubt I'm the only guy here that could use an enclosure like this. Also, any idea where I can get the detachable outter mounting rings? I seem to have misplaced the 2 that came with mine.

Thanks,
Steven

 

[markaudio]

Hi Steven,
For various plans, take a look at:
p10 hifi | Box Library / Mark Audio
Plans | Markaudio

You'll find some BR plans in the Alpair 7 plans section on the Markaudio site

Thanks
Mark.

 

[StevenZ]

Thanks Mark!

 

[chrisb]

Hey,

I use the EL70 in a 7L sealed box on my desk and it's pretty bass shy. I knew it would be. So I add bass boost. Tons of it. Works like a charm. I also correct for baffle step with the same program. I've just been using Realtek in windows.

You can see what I did here

I may upgrade these to the alp 7 one day.

I think that's definitely something not to try with any of the Alpairs - the really does like a vented or MLTL - I have several examples of them, and for a non-floorstander, the resistively ported 'Kens are very nice.

 

[vinylkid58]

the resistively ported 'Kens are very nice.

Yes they are.

jeff

 

[planet10]

Thanks Dave. Any chance you could whip up a quick bass reflex bookshelf for the A7.3 using 18mm material? I doubt I'm the only guy here that could use an enclosure like this. Also, any idea where I can get the detachable outter mounting rings? I seem to have misplaced the 2 that came with mine.

A7.3 Planset is littered with them :^)

Including the CGR Mar-Ken7.3. Or you could adapt the free 15mm plans.

I could suggest a vent for your current boxes (but i am currently away from my software), but with the caveat that i feel a regular tubular port has some downsides i don't like.

dave

 

[StevenZ]

Interesting. I've run a couple sims using WinISD and have found a .5ft box tuned to 50hz to be just about perfect. Flat all the way to 50hz. This is using a 2" port with a 5.18" length. Would this enclosure size and porting offer any advantages or dissadvantages over the MarkAudio supplied plans spec'ing 8l boxes tuned to 58hz? Perhaps lower power handling, etc.? Also, what's the going rate for a planset?

Thanks,
Steven

 

[tuxedocivic]

I think that's definitely something not to try with any of the Alpairs

Why not?

I wouldn't do that in my living room, but nearfield the EL70 barely exceeds 1mm of travel.

 

[planet10]

When i was simming these my 1st derivative rule was broken for any box over about 9 litre (1.2 ft^3 ~ 14 litre)

dave

 

[StevenZ]

And what is your 1st derivative rule? I'm not sure I follow where you were going with that statement. Are you confirming that the .5ft@50hz box sim would work, or would not work?

-Steven

 

[planet10]

The 1st derivative of the FR curve does not cross 0 more than once.

Sticking to this rule has allowed us to keep tight tuneful bass response.

dave

 

[StevenZ]

Oh, I see. Thanks for the clarification. Using the box porting and size I posted earlier it doesn't cross more than once, though it comes close. It's lowest point is a 0.52db drop at 70hz and finishes off with a 0.3db drop at 50hz.

 

[planet10]

It's lowest point is a 0.52db drop at 70hz and finishes off with a 0.3db drop at 50hz.

For that to be true the 1st derivative has to cross zero at least 2x

dave

 

[StevenZ]

I'll take your word for it as you obviously have a vast knowledge of box designing and I'm sure a more accurate way of measuring frequency response of enclosures. From what I'm seeing in WinISD is that it never crosses 0 even with those two figures I gave you. What could be the difference of results between what I'm modeling and what you're modeling? Is WinISD inadequate for designing enclosures using FR drivers?

-Steven

 

[StevenZ]

I've attached a couple photos for you to take a look at. Let me know if you see any discrepancies in the parameters that I'm not seeing that may be causing it to not show the frequency response rising above zero.

Thanks,
Steven

 

[tuxedocivic]

Does winisd allow for modelling of stuff in a vented box? I know unibox does and I find (in the model and audibly) that adding stuffing to a response like you have there can mellow out the tuning peak.

 

[chrisb]

Why not?

I wouldn't do that in my living room, but nearfield the EL70 barely exceeds 1mm of travel.

I'd be concerned about over stressing the much more delicate metal cone of the Alpair, but we could always ask Mark about that.