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Footers under LaScala / FH1 bass horns


Rolox
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It's not the first time I'm trying this, but every time I'm gobsmacked by the difference (both good and bad) it makes to the sound.

I own home-made speakers that are very similar to Lascala on steroids: peavey FH1 bass horns with Kappa 15C woofers, A55G midranges on SM120 horn lenses, Beyma CP25 tweeters.

The "top bins" are separated from the bass bin by 9 hockey pucks (3x3) stacked. That raises the mids and highs at ear level.

Well, if I take 3 hockey pucks from each side and put them UNDER each bass horn (thus keeping mids and treble at the exact same position in space), raising the bass horns 1inch (hockey puck height, more less) off the floor, the sound takes on a COMPLETELY different flavor: the lower mids / upper bass suddenly BLOOM and fill the room in a very different manner; on some tracks it's very nice, and some other it's quite overpowering.

I'm trying to explain such a variation...

1) bass horn "decoupled" from the floor has a very different output due to the specificities of bass horn loading?

2) bass horn enclosure resonates differently when suspended on 3 footers rather than directly on the floor?

3) phase relationship between midrange and bass is now changed - due to the (tiny) difference in path length between both 

 

I'm not sure yet if I will keep the bass horns off the floor but it sure sounds interesting. 

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My guess is that since the change is in the lower mids and upper bass, that it has to do with a change in the distance between the bins.  You are altering the comb filtering that results from the interaction between the two.  I think that if it were a matter of changing the bass response of your FH1s, you'd hear it in the lower bass instead.  Without measurements, of course, a guess is all anyone can offer.

 

 

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An observable effect from spacing the mid and high frequency section away from the bass bin is lobing of the polar response. This reduces energy from the dominant lobe and puts the energy into the side lobes. The side lobes then hit the walls of the room the speakers are in, causing early reflections which "smear" the sound due to different arrival times (comb filtering).

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On 6/18/2020 at 3:12 AM, Rolox said:

3) phase relationship between midrange and bass is now changed - due to the (tiny) difference in path length between both 

 

You haven't changed the path LENGTH, but spacing apart will change the interaction and lobing (already pointed out). Path length differences would be the length of the bass horn compared to the mid horn length (and tweeter). The bas horn is longer than the mid horn, and if a straight horn, would be substantially longer than your mid horn.

 

Having the cabinets closer to the floor should help the bass. If you want to raise them up, they should have a solid perimeter base, as on the Forte and Chorus series. You could use 2x4 of 2x6 on edge to make a base, although 3/4 inch material would work, but you would would have to make long cuts.

 

I like the FH1 cabinets, though.

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8 minutes ago, Marvel said:

 

 

 

 

Having the cabinets closer to the floor should help the bass. If you want to raise them up, they should have a solid perimeter base, as on the Forte and Chorus series. You could use 2x4 of 2x6 on edge to make a base, although 3/4 inch material would work, but you would would have to make long cuts.

 

I like the FH1 cabinets, though.

 

or - I raised the hatch on these with 10 inch sides installed a pair of 4 inch ports. pretty much DJK's mod

 

Gary

 

Dsc00328.jpg

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20 hours ago, Marvel said:

Nice looking, Gary. So you have the FH1s upside down? I would put the ported boxes on the bottom so the FH1 and top horn are closer together, They should should better that way.

The FH-1 bass cabs are in the back of the garage and not meant for critical listening. I had a pair of Cornwalls for support and they were replaced by a pair of Klipsch KP201.  I used a single Khorn top for the upper frequencies on top of the FH-1's. Mostly, I am outside doing something and the system is running in mono as I just want some outside music.

 

ported Fh-1 with Klipschorn top.JPG

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